Home

Keithley 617 - University of Virginia Demonstrations

1. Resistor 40 20 1 1 8W Composition R 88 40 2 Resistor 7150 1 1 8W Composition R 88 715 Resistor 2430 1 1 8W Composition R 88 243 Resistor 2700 5 1 4W Composition R 76 270 Resistor 5600 5 4W Composition R 76 560 Potentiometer 10kQ RP 104 10k Resistor 5 6kQ 596 Composition R 76 5 6k Resistor 150kQ 5 W Composition Resistor 16 5kQ 196 1 8W Composition Resistor 24 9 1 1 8W Composition Resistor 100kQ 5 4W Composition Resistor 5 4 W Composition Transformer Power IC 8 Stage Shift Register MC14094BCP IC Hex Inverter 74HC04 IC Hex Inverter 74HCO4 IC Operational Amplifier 741 Not Used IC Regulator 5V 7805 IC Adjustable Regulator LM337L IC Voltage Regulator 5V 78L05A IC Low Noise Op Amp R 76 150k R 76 100k R 76 5 1k TR 203 IC 251 354 354 42 93 345 223 394 Regulator selected with R213 Regulator Zener Diode 9 1V 1W 1N4739A Regulator Zener Diode 9 1V 1W 1N4730A Regulator Zener Diode 33V 1W 1N4752A 617 601 07 56 07 56 02 68 CS 476 T301 and T101 are supplied as a matched set Order TR239 for 105 125 210 250V operation TR240 for 90 110V 180 220V operation 8 9 Table 8 4 Mechanical Parts Keithley Quantity Description Part No
2. 1 Bottom Cover 30541 4 Foot FE 14 1 Shield Bottom Cover 617 305 1 Top Cover 30540 1 Front Panel 617 301 1 Front Panel Overlay 617 303 2 Black Binding Post J1003 J1007 BP 11 0 3 Red Binding Post J1002 41004 J1006 11 2 1 Binding Post 21005 BP 15 2 BNC Connector J1008 J1009 CS 249 1 Triax Connector J1001 CS 181 1 Protective 18 1 Ground Clip 617 319 1 Line Cord CO 9 1 Pushbutton Power 29465 3 1 Pushbutton Shift 228 317 4 11 Pushbutton Electrometer 228 317 5 4 Pushbutton V Source 228 317 6 3 Pushbutton Data Store Program 228 317 7 1 Fuse Holder for F102 27 8 10 o bRUHING 44 31 60697 MECA CINES fer pe Dee 22152 PA 2 2 8 22 01 A gt E gt 7 s Aka a 095220 LZ 1387 Elo QUA re FIG DE Re RAT 222 680 m Ea 12 228 cT LZT 02257 BI Caprio se A T Laeesiss c PAGE 2 ECT Rev 45 pc Annone Ao famas cA O CRIO 2 ait 3 una uns 41016 4 RUT 9 lt D Ran 0101002 j ui ut pes E g 0999 LE S 2 Ui44 E 24 EBD 9 09 lt SE D RISA 310178 QII2 CRIIS QUE an Cue IN 639 36 ES TA A 6 AL LKWA MUST BE POSITIONED A
3. 6 Aejdsig 9 8 4 in gi ZV EE I I Ed 3 3 El 3 t ZL 8 LL S 091 119 buimeig u0132907 1ueuoduio p1eog 1939410139913 71 8 aunbiy H 3 gt ARE 01587 O9 LI L aet S i zs SSS SG saa CHa de gt 390 A9 qa RS 35358va330 ee TERT BESS u313WN08123 75 AMOAVT ANINICMOSD su CMA TIO 37725 LON OU Laler osa 06 20 9 22 10007677 gs 9 f 22 2979 95 74 56 i CEPT 62 ZEN Wes 5e bc g yOZE y L ZZ 2750 a 2271 72 OY z SO 6Z 2Z CM 22 221 2 Pf j t 27 1 e ZEN EET 70 2822 46 LACS 57721 Te 241 2087 SAF RTT OE 77 291 67227 168 gt 228 88 i i 27 1661 7 2 2 22 fit 221 Breer Lw OPE 5027 7 Wry gg ZISA CHEWY GE i i 4 2027 2SS 2Z 607 26 22 47 SE 2 HEY TIEA 5552 SUO 55115 LA 221 0 7 i 15221
4. gt anche ar 3 11 Device Dependent Command Summary RR RE RARO RASA REF uA 3 12 Range Command Summary deid Ti esee SE DIRE AE 3 13 SRO M Command Parameters hor A x REP Eu Pp asd pan e ed 3 14 A sus uns uad 3 15 Typical Bus Times For Various Functions and Trigger Modes 4 1 Diode Currents and Voltages 4 7 5 1 Recommended Test Equipment for Performance Verification 5 2 Limits for Amps Verification ot 5 3 Limits for Volts Verification 24 22 24 dod dea ead 5 4 Limits for Ohms Verification 2k0 Z0MQ Ranges 6 6042 ce e bese VERE AY 5 5 Limits for Ohms Verification 200MQ 2GQ and 200GQ 5 6 Voltage Source Verification Limits os RR Meee dad 6 1 Memory e ________ 6 11 ix i 7 2 7 3 7 4 7 5 7 6 77 7 8 7 9 7 10 7 11 712 7 13 7 14 7 15 7 16 7 17 7 18 7 19 8 1 8 2 8 3 8 4 Line Voltage Selection Line Fuse Selection coser uei s Rm 2 n n q p s e lt b s e t q q s s n 4 04 2 n o9 s s q lt a q s
5. a da 6 3 Electrometer Preamplifier Configuration 6 4 Simplified Schematic of Input Stage EET 6 5 Gain Stages uri ck T e 6 6 Output Stage Configuration Volts and 6 7 Output Stage Configuration Amps and 6 8 Ohms Voltage Source Simplified Schematic 6 9 Zero Check Configuration Volts and Ohms 6 10 Zero Check Configuration Amps and 6 2 2 2 22 2 2 6 11 Simplified Schematic of Ranging Amplifier 6 12 Multiplexer and Buffer 6 13 Maltiblex er Phases cues yc pata chs coated bes deed i Ed qct 6 14 2V Reference si dc oo Saws dea es acr abb e me A ON EA p PERE ee pel UR TEAR ERS 6 15 A D Converter nse boone Ed qi dee oad ee Cees hee nea eee Vua 6 16 Simplified Schematic of Voltage Source Output Stage 7 1 Test Fixture Construction II donde Qul dd ordre ces 7 2 Calibration Jumper 7 3 Input Offset Adjustment LOCations 7 4
6. h Sh 70 ee E 500 ou ATH aE TED SS 2471 00071 21115 706 20617 506 0195 A OZ 950 2219 E E 2 62 E LES 51224 17 50 7 UN Ig 1592 5C E 97 IC i 80256 1 En TIA 700 A s 7 292821 807 271 b 17 19250 Y A AAA G7 De 927 21 611 121 S 777 179 1 id 9530 ays W383S 2554 Abr 02 8 61 8 991 719 1939u101329 3 8 a H a 611582 wx0i 991 219 YA A meno zoem 10M GIO _ ea See Xxx cw aman 1 Ga 2335 SiO 81014 9101 SlOld ____ 02010 02014 PRA PRO nu 806921018 10014 22682 1061 2129 AOIZ m 21632 Soen MED 1 60 N 5564 226245 ASSO _ C 9350 LON assn 9 SNOILVNOIS3Q DILVWAHSS 2I19W3HB2S LS3HOIH u S vv 94 901 419 SUSY HSH LOW 30 930 HLM S
7. 8573 Programming Example Place the unit in the amps function and cancel autorange with the front panel controls Now enter the following statement into the IBM computer 0 CHR H14 CALL IBCMD BRDO CMDS return When the return key 15 pressed the instrument returns to the default conditions listed in Table 3 10 3 9 6 SDC Selective Device Clear The SDC command is an addressed command that performs essentially the same function as the DCL command However since each device must be individually addressed the SDC command provides a method to clear only a single selected instrument instead of clearing all instruments simultanecusly as is the case with DCL When the Model 617 receives the SDC command it will return to the power up default conditions listed in Table 3 10 Table 3 10 Default Conditions moe E LC Value i Volts Autorange Enabled Disabled Disabled Continuous External Output off Electrometer Prefix no suffix Electrometer Disabled Disabled Both Enabied Y CR LF CR LF Suppression Trigger Voltage Source Operate Read Mode Data Format Display Data Store SRQ Mode EO and Bus Hold off Terminator Status Upon Power Up or After DCL or SDC Obtained with UO command To transmit the SDC command the controller must perform the following steps 1 Set ATN true 2 Address the Model 617 to listen 3 Place the SDC command on the data bus HP 85 Prog
8. THE 5127 AND GROUND COF as IEEE ERR rr COMPONENT LAYOUT Dxeien VA Ea MOTHER BOARD NEBST ALS iex 1ee u F vo xm AS H FORM 23510 REV D B D DE F S Figure 8 2 Mother Board Component Location Drawing Dwg No 617 100 Sheet 1 of 2 8 13 8 14 BRUHIRO 44 131 6013 A A FORM 285710 dese ZOME PART SEROL zone STAKI 5 UEN I 10 4 0047 158 FA 42 eaa 22 p re i 5 7 287 og 102 451 ROR 2 A 10001 Ai LA panto 32 2 ice D F2 El 3 179 10 DOl 44 if Rapa LET LIQ f 4 72 51 ESL A Al ii 10 509480 610 amp 2 211 2 OTK Ea n TOROS LE 64 22 54 __ 2 6109 22 12_ 25 RF k do C 227 1 CHA RE 28 77 e 8 47 RUZ Fe 152 on __ 2 3 1 2537 2 6114 20 FH LO CRNS LFS 21 11 LL 22 IES 22 2 305 1 1009 Tos 21 2510 22 03 D4 CU 64 Ga 11 22 1580 pl A WD es 2b C 237 1 G2 BN MEL 157 CREWE 2 REDD Ge 25 2857 1 125 184 ICS 288 4 2al o 2104 ARE n 7108 70 105 329 3 J DIS 5 105
9. ea bs 3 2 IEEE Handshake 2 22 2 2 3 3 Commands Groups 3 4 System Types In A 3 5 3 6 IEEEFE 488 Connections 3 7 617 Rear Panel IEEE 3 8 Contact 362 525 sanane ee ees 3 9 General Data Format 1 2 ed bs 3 10 SRO Mask and Status Byte Format 3 11 Status Word and Default 3 12 Ui Status Error Condition Format 3 13 U2 States Data Condition Format sure ies Pease ER Y YEA xp Fey ru x vi 4 1 Insulation Resistance Measurement Ungaurded a SS W O9 s 4 2442 4 2 Insulation Resistance Measurement Guarded 4 3 Insulation Resistance Measurement Using V I Ohms 4 4 Measuring High Impedance Gate Source
10. COEFFICIENT 18 28 0 18 amp 28 50 RANGE RESOLUTION rdg counts rdg counts 2 100 1 6 56 0 15 8 20 pA 1fA 16 7 0 15 1 200 pA 10 fA 1 6 1 0 15 0 1 2nA 100 fA 0 25 5 0 015 3 20 nA 1 0 25 1 0 015 0 3 200 nA 10 0 25 1 0 015 0 1 2 pA 100pA 0 15 4 0 005 3 20 inA 0 15 1 0 005 0 3 200 pA 10nA 0 154 1 0 006 F 0 1 2mA 100nA 0 15 4 0 005 3 20mA 0 15 1 0 005 0 3 When properly zeroed INPUT BIAS CURRENT Less than 5fA 5X 10 at 23 INPUT VOLTAGE BURDEN Less than 1mV except 3mV 20mA range PREAMP SETTLING TIME to 1 of final value 2 55 on pA 15715 on nA Sms on and mA ranges NMRR Greater than 95dB on pA 60dB on nA pA and mA ranges at 5082 60Hz 0 1 COULOMBS TEMPERATURE ACCURACY 1 Yr COEFFICIENT 18 28 C 0 18 amp 28 50 RANGE RESOLUTION Ao rdg counts rdg counts 200pC 0 4 4 0 02 3 2nC 100 fC 0 441 0 02 0 3 20nC 0 441 0 02 0 1 When properly zeroed INPUT BIAS CURRENT Less than S A 5 107A at 23 C OHMS TEMPERATURE ACCURACY 1 COEFFICIENT TEST 18 28 0 18 amp 28 50 C CURRENT RANGE RESOLUTION rdg counts rdg counts C 1 5 2 kR 100 m2 0 20 4 0 01 3 100 20 19 015 1 0 01 0 3 100 200 10 0 0 25 1 0 01 0 3 204A 2M2 100 Q 0 25 1 0 02 0 3 1 20M9 1 0 25 1 0 02 0 3 100nA 200M2 10 0 30 1 0 02 0 3 10nA 2
11. M Vout VIN VR 10V 1V or 0 1V VOUT VOUT i VIN de VOUT ew A VOLTS B OHMS 1000pF Qin VoUT QIN VOUT VOUT D COULOMBS Figure 6 3 Electrometer Preamplifier Configuration 6 4 0 4 BOOTSTRAPPED BOOTSTRAPPED R352 INPUT R334 R333 R351 DT o W303 No 8342 5V z E BOOTSTRAPPED BOOTSTRAPPED LO GROUND TO GAIN STAGE R335 5V BOOTSTRAPPED Figure 6 4 Simplified Schematic of Input Stage C319 TO OUTPUT STAGE Figure 6 5 Gain Stage A simplified diagram of the output stage in the volts and ohms modes is shown in Figure 6 6 Four transistors Q301 2303 0304 and Q305 are used in this configuration Each transistor pair is used for one half the output voltage swing Q301 and Q304 are used for the positive half while Q303 and 2305 are used for the negative half Because of the 210V voltage swing requirement 210V supplies are used Each transistor pair is operated in series to provide the necessary device breakdown voltage and power rating INPUT FROM GAIN STAGE OUTPUT GAIN STAGE OUTPUT GAIN STAGE COMMON Figure 6 6 Output Stage Configuration Volts and Ohms Circuit biasing components include R301 R302 R320 R321 R325 CR315 and CR316 Meanwhile CR318 and CR314 provide protection for
12. 2 4 Ohms Function Current Output Values nanana ap rl 2 5 Typical 2V Analog Output 2 6 Full Range PREAMP OUT Values 2 7 Data Store Reading Rates 2 8 Voltage and Percent Error For Various Time Constants 2 9 Minimum Recommended Source Resistance Values in 2 10 Engineering Units Conversion uaas esed fens ERE RR RR beaded as 2 11 Equivalent Voltage Sensitivity of 617 Amps Ranges 3 1 IEEE 488 Bus Command Summary X Ya e x xr 3 2 Hexadecimal and Decimal Command Codes 3 3 Typical Addressed Command Sequence 3 4 Typical Device Dependent Command Sequence o 3 5 IEEE Contact Designations 3 6 BASIC Statements Necessary to Send Bus Commands 3 7 Model 617 Interface Function 3 8 TEBE Command Groups S co uas ed 3 9 General Bus Commands and Associated BASIC Statements eT eee 3 10 Default Conditioner uu o ur
13. 40 04040400404 4044 o3 3 0000 a a 42440244406 5 3 9 W 5 8 mom mom m om mom om 404 44040404 3 9 9 o9 3 oc 9 4 4 o 4 s OR O3 P ovo o G3 4 9o Q 4 l m e W s n 8 O3 9 o9 c c9 Y 4 Y 4d 9 o Od c o9 oc v Bo toe tom tos 4 4440 406 3 9 Nos o 8 II 444444 a a v9 P 3 4 4 4 a poa 9 0 4 n a q o9 9 q q q h q s s s 2 s s v s s s 4 4 9 4 s lt o q q s 9o wq nr n n ep n 242 4 q 4404 t vov q a n n q n e E o o sot or 4 2 xa q q q op d o q q q q s 9 r q gt q q 4024 q q ot n r q q v s s 3 4 q q n q Y 3 vos 9 o on on 470404040404 v v 2 x q 24240404 v v lt 9 q q q s q s q s o 4 4 4 4 4 2240 04 Ron v 4 4 4 4 Y 4 o9 on ov oa vov n wo c 4 Q V amp 4 c P a
14. 100 1 5 1 0 04 0 3 1 20 IMQ 15 1 0 04 0 1 200 G2 15 1 0 04 0 1 1nA When properly zeroed MAXIMUM OPEN CIRCUIT VOLTAGE 300V dc PREAMP SETTLING TIME To 0 1 of final value unguarded with less than 100pF input capacitance 20 through 20Mf1 15ms 200M9 150ms 1 of final value with Input Guard and less than 1pF of unguarded input capacitance 200 10ms 20GQ 100ms 20069 15 V I MODE Used with V source displays resistance 5X 10 to 10190 calculated from measured current Ohms accuracy equal to accuracy of V Source plus accuracy of selected Amps range VOLTAGE SOURCE OUTPUT 102V to 102V in 50mV steps ACCURACY 1 Yr 18 28 C 0 2 50mV TEMPERATURE COEFFICIENT 0 005 1mV C Specifications subject to change without notice MAXIMUM OUTPUT CURRENT 20 active current limit at less than 4mA with annunciation SETTLING TIME Less than 3ms to rated accuracy NOISE lt 1 of output voltage 2004V from 0 1Hz to 10Hz IEEE BUS IMPLEMENTATION MULTILINE COMMANDS DCL LLO SOC GET GIL UNT UNL SPE SPD UNILINE COMMANDS IFC REN SRQ INTERFACE FUNCTIONS 5 1 AH1 T5 TEO L4 LEO 582 RLO PPO DC1 DT1 Co 1 PROGRAMMABLE PARAMETERS Function Range Zero Check Zero Correct Zero Suppress EOL Trigger Terminator 100 rdg Store and Retrieval Calibration V Source Output Display Format SRQ Status
15. 4 5 Leakage Current Measurement dra dde 9 P 4 6 Diode Characteiza e 4 7 EA E A 4 8 Capacitor 6 4 9 Capacitor 4 10 Configuration for Voltage Coefficient Studies s s Ds 4 11 Farady Cup Construction yay cys EO edo bs 4 12 Using the Mode 617 with an External High Voltage Source 5 1 Test Fixture Construction 5 2 Connections for Amps Verification 200nA 2mA 5 3 Connections for Amps Verification 2pA 20nA Ranges 5 4 Connections for Coulombs 5 5 Connections for Volts Verification sisas risas Fran a e AR 5 6 Connections for Ohms Verification 2 0 2 5 7 Connections for Ohms Verification 200 2GQ and 20GQ Ranges 5 8 Input Impedance Verification ise os bc 5 9 Connections for Voltage Source 6 1 Overall Block Diagram ros de 6 2 Basic Configuration Electrometer Preamplifier
16. Function Range Gain _ Volts X1 External Feedback 7 7 8 Input and Ranging Amplifiers The input and ranging amplifiers condition the input signal transforming it into a 0 2V DC voltage that is usable by the A D converter The exact conditioning process will depend on the selected range and function With the voltage ranges for example the signal is merely attenuated 20V and 200V ranges or amplified 200mV range and inverted For the amps function the input signal must undergo current voltage conversion The procedures outline in Tables 7 14 and 7 15 may be used as an aid in troubleshooting the input amplifier and ranging circuits Note that the procedure in Table 7 15 assumes that the input amplifier is operating properly WARNING Up to 300V may be present between PREAMP OUT and COM 7 7 9 Digital Circuitry Problems with the digital circuitry could cause erratic opera tion Check the various components associated with the digital circuity including the IEEE 488 interface using the procedure given in Table 7 16 7 7 10 Display Board Check out the display board by using the procedure in Table 7 17 7 7 11 Voltage Source Check out the operation of the voltage source by using the procedure in Table 7 18 Note that the power supply voltage should be checked first to ensure proper operation of the voltage source 7 8 INPUT STAGE BALANCING PROCEDURE If the input FET Q308 or associated bia
17. o4 s 0 4 4 24040 q q q 3 n a s s e a t h P q lt w st n v t q q Pos RO ON s 4 v vw v c q 3 st 3 4 s q t 9 9 s s s s s q q q q b s q o q q e n 9 b n 9 quo qa e e q 9 Shielded Fixture Construction External Feedback Procedure O Non Standard Coulombs Ranges Logarithmic Currents Non Decade Current Gains ass 444444040404 404040404044 444 9o v 040404040 4 4 9 4 4 4 o3 c 4 o o OON oa ss os d O3 Q w on E 4 9 OP dos os os lt os om on 44 444 4424 4 2444 q n q v q v s 0404 v t v v k s ot Using Zero Correct and Baseline Suppression Zero Correct and Zero Check Using A ii renee b a External Triggering 1 ce usa pep ENERO S nbi bed ve PATERE i n Ku oif External Trigger Lo coo qasay ___ Sd uM ES OPE o as Complete ua ae ctr
18. 2 The input impedance in the external feedback mode is given by the relationship Zin where is the impedance of the external feedback network and A y is the open loop gain of the electrometer typically greater than 106 Note that the input impedance is ZiN 10 Zrg when zero check is enabled 3 The voltage at the PREAMP OUT terminal is given by the formula V IRpg where is the value of the feedback resistance 4 Any feedback elements should be housed in a suitable shielded enclosure Insulators connected to Input HI should be made of Teflon or other high quality insulating material and should be thoroughly cleaned to maintain the high input impedance and low input current of the Model 617 If these insulators become contaminated they can be scrubbed with methanol and then dried with clean pressurized air 2 10 2 Shielded Fixture Construction Since shielding is so critical for proper operation of external feedback it is recommended that the shielded fixture shown 2 22 e ZERO CHECK OP AMP TO RANGING AMPLIFIER HIGH INPUT LOW COM PREAMP OUT CHASSIS Figure 2 17 Electrometer Input Circuitry Amps Mode in Figure 2 18 be used to house the feedback element The fix ture is constructed of a Pomona 2390 shielded fixture modified with the standard BNC connectors replaced with triaxial female connectors For convenience a banana jack can be mounted on the
19. Model 7024 10 Triaxial Cable 10 ft Model 8573 IEEE 488 Interface to IBM TABLE OF CONTENTS SECTION 1 GENERAL INFORMATION Introduction Features Warranty Information Manual Addenda Safety Symbols and Terms Specifications Using this Instruction Manual Unpacking and Inspection Getting Started Preparation for Use Repacking for Shipment Accessories SECTION 2 OPERATION Introduction Power Up Procedure Power Up Self Test and Display Messages Front Panel Familiarization Controls Display and Indicators TiltBail Front Panel Programs IEEE 488 Address Exponent Mode Alpha or Numeric Calibration Rear Panel Familiarization Connectors and Terminals V QGUARD Switch Line Fuse Basic Measurement Techniques Warm Up Period Input Connections Making Voltage Measurements Guarded Operation o9 Sr n 702040404 404 a 3 0 O 4 2 04 4466 0 4444444 4 44 4 46 4 24 2 4 40 440 44 44 4404 4 40 4 3 46404040404 4 9o NON SF 4 3 3 4404044 0 4 0
20. a aE Zero Additional Signal Conditioning o gt Multiplexer and Buffer Amplifier ice seres Hee ewe de 2V Reference SOUNCE 3 eed HE VO seen AD uy Digital Circuitry 1 1 y PROS PE de Mts pudeat qud adea Memory Elements Device A Input Output Circuitry __ _ DEI LE V LEWIS i NR Voltage Source T PTI Power Supplies yu pU SECTION 7 MAINTENANCE as oe ciation S Line Voltage Selection ao ore Ve AA Fuse cetero ORT nc Lie TTC COM Fuse lI db eres oleis RTT TITO E CT ET TET a U Recommended Calibration Equipment Environmental _________ __ Warm Dp Period ees tunes aus beeen ______ Calibration Jumpers z uu uy EE EE Front Panel 188 Bus Callbration dd E WM E
21. 200k2 20nC 20 08 READING DONE 200 2nA 2 200 20 16 READY 200 20nA 20MQ 20nC 20 32 ERROR 200 200 nA 200MQ 20nC 20 200 2 pA 260 20nC 20 200 20 pA 2069 20nC 200 200 20060 20nC 200 20060 20nC 200 20mA 20060 20nC Auto off for ali functions DATA STORE 0 CONVERSION RATE 121 RDG SEC 2 1 RDG 10 SEC 7 RDG MIN 1 RDG 10 MIN z 1 RDG HR 6 TRIG BUTTON 7 DISABLED 1 ON DISPLAY ZERO CORRECT 0 ELECTROMETER Q OFF 1 VOLTAGE SOURCE 1 0 lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt ZERO CHECK 0 DATA PREFIX 3 32 SUPPRESS 0 PREFIX NO SUFFIX 0 0FF 1 TRIGGER 0 CONTINUOUS TALK 1 ONE SHOT TALK 2 CONTINUOUS GET 5 GET 4 CONTINUOUS EXTERNAL 5 ONE SHOT X 6 CONTINUOUS EXTERNAL 7 ONE SHOT EXTERNAL 12 PREFIX OR SUFFIX 2 PREFIX AND SUFFIX IF B1 READ MODE 0 ELECTROMETER 1 STORE 2 3 MINIMUM 4 VOLTAGE SOURCE VOLTAGE SOURCE OPERATE 0 OFF 1 Figure 3 11 00 Status Word and Default Values The 01 command allows access to Model 617 error condi tions in a similar manner Once the sequence U1X is sent the instrument will transmit the error conditions with the format shown in Figure 3 12 the next time it is addressed to talk in the normal manner The error condition word will be sent only once each time the U1 command is transmitted
22. 39 92 9C 19 92 19 92 19 92 1 92 1 2 3998 Ar NOWWO2 SOTWNY S310N3Q A 2v 3N02 901 219 RY 8 702H Re SAVUVIODIA 44 Q33H VIA ISIMHIHLO 55371 JO LON Eon IXEN san N SGVEYIONDIN YOLIDVAVI 11 H11M 519 IE 1 5 s e 1 SWHOS3W W SWHO3TIPI N G3387W ISIMYIHLO SSIINN SWHO Ni 38Y SINIVA HOLSISSY TIV Ez p Ot ETA id MOS L L 5 volg s npa 2 68 gt el en s i Turon uix pr asl teen a 0517 166 H a 3 G d 44131 40137 dO 3 POWER SUPPLY FORM 2558 REV D 8156 ni M AD7541 BIT l MSB BITS BITIO 2 158 Rus 5 1K ae 2 1 MATES WITH PIOtS AC OF ELECTOMETER BD 617 166 ZONE 65 3 5 NOTES 1 2 3 ALL RESISTOR VALUES ARE IN OHMS UNLESS OTHERWISE MARKED K KILOHMS M MEGOHMS ALL CAPACITOR VALUES ARE IN MICROFARADS UNLESS OTHERWISE MARKED pF PICOFARADS ALL PUSHBUTTON SWITCHES ARE SHOWN IN THE PUSHBUTTON OUT POSITION k w DENOTES ANALOG Y DENOTES DIGITAL COMMON Y DENOTES SIGNAL COMMON Y DENOTES VOLTAGE SOURCE COMMON 77 DENOTES CHASSIS CONNECTION E DENOTES MAINFRAME GROUND SCREW 76 15 9 ep TO
23. 131 52 68 58 52 Giles 172 G 232 1 7 305 130105 75 25 554 3 77018 4 22 1012 TES q lt 3512 257 47 1152 TES 9261 gt 04 55 185 5 05 472 iQ 2u 10 C134 75 O aN CARIOR ER 98 2 21 1 Ylo i BE MES 20 CNA 211 TES REV D ITEM SCREM ZK 11 Vioz D 6 H zone jure jeco L CA IB haz s Ea 4 0482 e Lose wes 2 269 15941 28 ES y pra mia ES 29 520 TO 52 275 AE lzb2zee a 7 7 2 SEREM zone mew zoye eae deste ZONE E UZI R 7G 1K 14 2 er ES 1 41 412 E ELEK KHS TEM DE S 6S 202 124 1EZ HE O 320 44 05 22 A AS Kise ES x Sy KH 158 AN The ot 85 Ki 90 i G4 ook RNG TES 11126124 KBB LES 407 8127 64 124 TER ZC 22 1426 64 71 FH 2 iG3 AoT SEI lt FH 25 5 RIO te OK 228 1180 7 327 1 ICI 137 AN 20 20 16 UN MO 2 812 o Si 210 110 3284 11152 Lat 199 297 52 182 Zu
24. LOCAL 727 END LINE When the END LINE key is pressed the front panel REMOTE indicator goes off and the instrument goes into the local mode To cancel LLO send the following LOCAL 7 END LINE Model 8573 Programming Example Place the instru ment in the remote mode with the following statements 1 CALL IBSRE BRDO V return CMD X CALL IBWRT M617 CMDS return Now send GTL with the following statement CALL IBLOC M617 return After return is pressed the REMOTE indicator turns off and the instrument goes into the local mode To cancel LLO send the following V 96 20 CALL IBSRE M617 return 3 9 5 DCL Device Clear The DCL command may be used to clear the Model 617 and return it to its power up default conditions Note that the DCL command is not an addressed command so all in struments equipped to implement DCL wil do so simultaneously When the Model 617 receives a DCL com mand it will return to the default conditions listed in Table 3 10 To send the DCL command the controller must perform the following steps 1 Set ATN true 2 Place the DCL command byte on the data bus HP 85 Programming Example Place the instrument in the amps mode and cancel autorange with the front panel controls Now enter the following statement into the HP 85 keyboard CLEAR 7 END LINE When the END LINE key is pressed the instrument returns to the default conditions listed in Table 3 10
25. Limit 1 275 0 001 GQ 263 Reading Limit 11 001 ______ 263 Reading Limit x x x x x x x x Includes Model 263 error Voltage Source Verification Use the following procedure to verify that the Model 617 voltage source is within tolerance WARNING Dangerous voltage may be present on the voitage source output terminals when the voltage source output is enabled Connect the DMM to the voltage source output ter minals as shown in Figure 4 Select an appropriate DCV range on the DMM Alter nately place the DMM in the autorange mode if desired Press the DISPLAY button to view the voltage source value and turn on its output by pressing the OPERATE button Using the ADJUST buttons set the voltage source out put to 00 00V Verify that the voltage source value is within the limits stated in Table 4 Repeat steps 4 and 5 above with the remaining voltages listed in the table Repeat the procedure for negative voltages of the same amplitude listed in the table Input Impedance Verification Perform this test to verify that the input impedance of the unit is greater than 200TQ 1 2 Connect the DC calibrator Model 263 and the Model 617 as shown in Figure 5 Place the Model 617 in the volts function select the 20V range and enable ZERO CHECK Verify that the display shows 0 000V 1 count If not enable ZERO CORRECT Enable
26. Step Item Component Required Condition COM fuse Remove and check for continuity Replace if open Power on 200mV DC range Zero check off Apply 190mV DC Input 190mV Measure at PREAMP OUT and COM unless otherwise noted Apply 1 9V DC Input 1 9 Apply 19V DC input 19V Apply 190V DC input 190V Remove before siecting amps Select AMPS 2 range Apply 1 9mA Input 190mV Select 20mA range Apply 19mA Input 1 9V Select 2004A range Apply 190zA Input 19V Enable zero check volts OV Zero Correct if necessary Select OHMS R304 pin 1 10V 0 1V Referenced to PREAMP OUT R304 pin 2 1V xO 01V Referenced to PREAMP OUT R304 pin 3 0 0 001V Referenced to PREAMP OUT 1 2 3 4 5 6 7 8 9 10 Tabie 7 15 Ranging Amplifier Checks Stso trem Component ____ Required Condition Power on 200V DC range Measure between 2V ZERO CHECK off ANALOG OUTPUT and COM Apply 190V DC to input 1 9V Check X0 01 Gain Select 20V DC range Apply 19V DC to input 1 9V Check X0 1 Gain Select 2V DC range Apply 1 9V DC to input 1 9V Check X1 Gain Select 200mV DC range Apply 190mV DC to input 1 9V Check X10 Gain 7 19 7 20 Table 7 16 Digital Circuitry Checks Step Item Component Required Condition Remarks 1 Power on 200VDC range Voltages referenced to digital common 2 0109 pin 40 5V 5 5V digital supply 3 0109 pin 2 500 negative pulse every 1 6msec Interrupt clock 4 U109 pin 3 Stays l
27. To see how voltage burden can upset measurement accuracy refer to Figure 2 10 A source represented by Es with an out put resistance Rs is shown connected to the input of picoammeter The voltage burden is represented by a con stant voltage source at the input as Er If EIN were zero the current as seen by the meter would simply be 6011 CABLE INPUT MODEL 617 v Q GUARD SWITCH Z GUARD 3 GND LO PREAMP OUT VS Es Rs However if has non zero value the current now becomes Es Rs Additional considerations include source resistance and capacitance as discussed in paragraph 2 14 MEASURED SAFETY SHIELD WARNING USE SAFETY SHIELD FOR SIGNALS ABOVE 30V VOLTS AND OHMS RANGING AMPLIFIER INPUT AMPLIFIER TO A D CONVERTER 2V ANALOG OUTPUT EQUIVALENT CIRCUIT VOLTS MODE SHOWN Figure 2 8 Guarded Input Connections 2 12 6011 CABLE 15 CURRENT SHIELD RECOMMENDED BELOW 14A AMPLIFIER ZF RANGING AMPLIFIER TO A D CONVERTER 2V ANALOG PREAMP OUTPUT OUT COM EQUIVALENT CIRCUIT Figure 2 9 Current Measurements 2 7 6 Making Charge Measurements SOURCE REIN ye The Model 617 is equipped with three coulombs ranges to resolve charges as low 10fC 10 14C and measure as high as 20nC 20 x 10 9 When the instrument is placed in one Es En ERU ME of
28. tors in and out of the circuit with FETs PREAMP OUTPUT Zin 10M9 Figure 6 9 Zero Check Configuration Volts and Ohms PREAMP OUTPUT Zin 10 l Z F Figure 6 10 Zero Check Configuration Amps and Coulombs 6 7 The gain of the ranging amplifier is determined by the follow ing formula R128 Note that Re R142 in parallel with R143 R145 or R146 depending on which is selected For example for X10 gain the selected feedback resistor if 142 yielding a gain of 2MQ 10 Ay 200k2 TO FET CONTROLS SIGNAL INPUT FROM PREAMP SIGNAL OUTPUT TO MULTIPLEXER A X10 X1 X0 1 OR X0 01 Figure 6 11 Simplified Schematic of Ranging Amplifier 6 4 2 Multiplexer and Buffer Amplifier The multiplexer selects among the three signals that are part of the Model 617 measurement cycle During the common phase the multiplexer selects signal common During the reference phase the 2V reference voltage is selected while the signal from the ranging amplifier is selected during the signal phase Figure 6 12 shows a simplified schematic of the multiplexer and buffer amplifier U145 is the multiplexer IC which con tains CMOS devices that act as analog switches to select among the three input signals The multiplexer IC is con trolled by digital signals that are generated by the microprocessor Figure 6 13 shows the general signal switching phases for the three signals
29. 20pF 100V 4 8 VOLTAGE COEFFICIENTS OF HIGH MEGOHM RESISTORS High megohm resistors above 1090 often exhibit a change in resistance with applied voltage This resistance change is characterized as the voltage coefficient The Model 617 is an 4 10 ideal instrument to obtain data to determine the voltage co efficient because of its built in variable voltage source and its highly sensitive picoammeter section The basic configuration for making voltage coefficient measurements is shown in Figure 4 10 The voltage Vs is ap plied to the resistor under test by the voltage source of the in strument The current is measured by the electrometer input of the instrument The resulting current can then be used to calculate the resistance If the instrument is in the ohms mode the resistance will be calculated automatically Two resistance readings at two different voltage values will be required to calculate the voltage coefficient The voltage coefficient in V can then be calculated as follows 100 R Rj Voltage Coefficient where is the resistance with the first applied voltage R is the resistance with the second applied voltage AV is the difference between the two applied voltages As an example assume that the following values are ob tained 1 01 x 10100 R 1 X 10100 AV sV The resulting voltage coefficient is 1000 X 108 Voltage coefficie
30. 4 Amps calibration 5 Coulombs calibration 6 Volts calibration 7 Ohms calibration The voltage source is calibrated third since this is a manual adjustment This allows the digital calibration procedures to be grouped together In addition to the above sequence the ranges for each function must be calibrated in the order given Note that you should never calibrate a range using a suppress or a zero correct value taken on a different range Manual Calibration Adjustments After performing the following manual calibration ad justments proceed to either front panel digital calibration or IEEE 488 Bus Digital Calibration A Input Offset Adjustment Perform the following steps to null out any small offset in the input amplifier 1 Disconnect all input signals from the Model 617 2 Remove the two screws securing the top cover and remove the cover from the instrument 3 Select the amps function and place the instrument on the 2pA range 4 Enable zero check but leave zero correct disabled 5 Locate the offset adjustment pot R314 on the elec trometer board see Figure 7 The pot is accessible through a small hole in the shield closest to the rear of the instrument 6 Adjust R314 for a reading of 0 0000 1 count on the display 7 Replace the top cover unless the following input cur rent adjustment is to be performed REAR PANEL INPUT OFFSET ADJUSTMENT R314 INPUT CURRENT ADJUSTMENT R348 ELECTR
31. As shown in Figure 2 3 the center terminal is high the inner ring or shield is low and the outer shield is connected to instru ment chassis ground In the guarded mode the inner shield is driven at guard potential while the outer shield is chassis ground NOTE The input connector must be kept clean to main tain high input impedance The supplied Model 6011 input cable is designed to mate with the input connector The other end of the Model 6011 is ter minated with three alligator clips Input high is color coded in red input low is colored black and chassis ground is color coded in green Keep in mind that these connections are for the unguarded mode In the guarded mode red is high black is guard and green is chassis ground The COM binding post provides a connection to input low through 1000 for use in the guarded mode p INPUT HIGH Ke INPUT LOW O INPUT HIGH IN if e GUARD CHASSIS 71 GROUND COM INPUT LOW B GUARDED V 0 GUARD ON r IN CHASSIS AI TZ _ SROUND A UNGUARDED V 0 GUARD OFF Figure 2 3 Input Connector Configuration NOTE It is recommended that zero check be enabled when connecting or disconnecting input signals WARNING The maximum common mode input voltage the voltage between input low and chassis ground is 500V peak Exceeding this value may create a shock hazard CAUTION Connecting PREAMP O
32. Capcitor 104F 25V Aluminum Electrolytic 1 Cb C2 C 314 10 Capacitor 1uF 50V Ceramic Film 2 C2 F2 C 237 1 Capacitor 104F 20V Tantalum 2 B1 F2 179 10 Capacitor 22pF 1000 Ceramic Disc 2 03 F2 C 64 22p Capacitor 6204F 35V Electrolytic 1 85 B2 C 309 620 Capacitor 47zF 1 84 354 47 Capacitor 47zF 1 84 C 354 47 Capacitor 22pF 1000V Ceramic Disc 2 04 C 64 22p Capacitor 0 1uF 50V Ceramic Film 2 63 C 237 1 Capacitor 1uF 50V Ceramic Film 2 01 C 237 1 Capacitor 1uF 50V Ceramic Film 1 237 1 Capacitor 1uF 50V Ceramic Film 1 5 237 1 Capacitor 0 1uF 50V Ceramic Film 2 A4 D4 C 237 1 Capacitor 0 14 50V Ceramic Film 2 H3 F4 C 237 1 Capacitor O 1uF 50V Ceramic Film 2 H1 F4 C 237 1 Capacitor 0 14F 100V Metallized Polyester 3 B3 D4 C 305 1 Capacitor 0 014F 500V Ceramic Disc 3 G1 D4 C 22 01 Capacitor 33pF 500V Ceramic Disc 3 G3 C4 C 22 33p Capacitor 150pF 500V Ceramic Disc 3 G3 C4 C 22 150p Capacitor 0 14F 50V Ceramic Film 3 F1 4 C 237 1 Capacitor 0 1u4F 100V Metallized Polyester 3 B3 C4 C 305 1 Capacitor 0 14F 50V Ceramic Film B4 C 237 1 Capacitor 0 1nF 50V Ceramic Film 3 F4 C4 237 1 Capacitor 0 1nF 50V Ceramic Film 3 B3 04 237 1 Capacitor 0 014F 100V Metalized Polypropyiene 3 D4 Cb C 306 01 Capacitor 104F 25V Aluminum Electrolytic 1 02 C 314 10 Capacitor
33. Keep in mind that some controllers rely on EOI to terminate their input sequences In this case suppressing EO with the K command may cause the controller input sequence to hang unless other terminator sequences are used The bus hold off mode allows the instrument to temporarily hold up bus operation when it receives the X character until it processes all commands sent in the command string The pur pose of the hold off is to ensure that the front end FETs and relays are properly configured before taking a reading Keep in mind that all bus operation will cease not just activity associated with the Model 617 The advantage of this mode is that no bus commands will be missed while the instrument is processing commands previously received The hold off period depends on the commands being process ed Table 3 14 lists hold off times for a number of different commands Since a NRFD hold off is employed the hand shake sequence for the X character is completed HP 85 Programming Example To program the instru ment for the K2 mode enter the following statements into the 85 REMOTE 727 END LINE OUTPUT 727 K2X END LINE When the second statement is executed the instrument will be placed in the K2 mode In this mode EOI will still be transmitted at the end of the data string but the bus hold off mode will be disabled Model 8573 Programming Example To place the instru ment in the K2 mode enter the following statemen
34. Note that the OPERATE LED will flash when the 2mA current limit is exceeded DATA STORE The two DATA STORE buttons control the internal 100 reading data store mode of the instrument Through these two buttons data storage may be enabled or disabled the storage rate may be selected and readings may be recalled to the front panel display Paragraph 2 12 con tains a complete description of data store operation 2 3 ON OFF This control enables or disables data store opera tion In addition reading rates can be selected by holding the button in when first enabling data store When data store is enabled the indicator light next to the ON OFF button will be on Minimum and maximum values are stored and up dated as long as the ON OFF LED is on RECALL EXIT This single button serves to recall readings previously stored by data store Pressing and holding this button causes the instrument to scroll through the pointer ad dresses as indicated on the display Once the desired reading number is displayed releasing the button causes the actual reading to be displayed To exit the recall mode press SHIFT EXIT PROGRAM A single PROGRAM button controls such modes as IEEE address alpha or numeric display exponent and digital calibration Paragraph 2 5 further describes front panel programming SELECT EXIT This button enters the program mode to allow access to parameters described above Pressing SELECT repeatedly causes the inst
35. Note that the decimal points in the exponent digits indicate that the instrument is in the calibration mode 9 Use the voltage source arrow buttons to set the calibration value as seen on the display to agree with the actual calibration signal For example with a 1 9V calibration point the display should be adjusted for a reading of 1 9000V Select the next range and function to be calibrated and repeat step 9 For maximum accuracy the instrument must be zero corrected for each range and function 11 Once all points have been calibrated press PROGRAM SELECT to exit the calibration program Assuming that the calibration jumper is in place paragraph 7 4 4 calibration constants will be stored in NVRAM and the following message will be displayed 1 e Stor Also constants for uncalibrated ranges are derived at this point 12 1f the calibration jumper is in the disabled position NVRAM storage will not take place and the following message will be displayed Out Only changed constants are affected under these condi tions Note however that the new calibration values will be used by the instrument until the power is turned off even if NVRAM storage does not take place 7 4 7 4 6 IEEE 488 Bus Calibration IEEE 488 bus calibration is performed in a manner similar to front panel calibration except that calibration constants are transmitted over the bus instead of being entered from the front panel Also a s
36. Uniline Commands Sent by setting the corresponding bus line true Multiline Commands General bus commands which are sent over the data lines with ATN true low Device dependent Commands Special commands whose meanings depend on device configuration sent over the data lines with ATN high false These bus commands and their general purposes are sum marized in Table 3 1 3 4 1 Uniline Commands ATN IFC and REN are asserted only by the controller SRQ is asserted by an external device EOI may be asserted either by the controller or other devices depending on the direction of data transfer The following is a description of each com mand Each command is sent by setting the corresponding bus line true REN Remote Enable REN is sent to set up instruments on the bus for remote operation Generally REN should be sent before attempting to program instruments over the bus EOI End or Identify EOI is used to positively identify the last byte in a multi byte transfer sequence thus allowing data words of various lengths to be transmitted easily 3 3 IFC Interface Clear IFC is used to clear the interface and return all devices to the talker and listener idle states Attention The controller sends while transmit ting addresses or multiline commands SRQ Service Request SRQ is asserted by a device when it requires service from a controller 3 4 2 Universal Commands Universal co
37. approximately OV will be seen with the relay de energized off except K302 and K303 which are energized when driven with OV and de energized when driven to 5V 7 7 6 Ranging Amplifier Gain Configuration The ranging amplifier can have one of four gain values X10 X1 and X0 01 The actual value will depend on the selected range and function as summarized in Table 7 12 This information can be used to determine if the ranging amplifier is working properly To do so select the desired range and function and apply an appropriate signal to the in put of the electrometer Measure the signal at the PREAMP and 2V ANALOG OUTPUT terminals and see if the correct scaling factor is applied For example with the instrument on the 20V range an input signal of 19V could be applied Assuming the input amplifier is operating properly the voltage seen at the PREAMP OUT should also be 19 The ranging amplifier should apply gain of in this case so the voltage seen at the 2V ANALOG OUTPUT should be 1 9V If the PREAMP OUT signal is correct but the 2V ANALOG OUTPUT is not the Table 7 10 Power Supply Checks 102 Line Switch F101 Line Fuse Line Power 110V supplies 15V V Source Supplies 5V Digital Supply 210 Supplies 5V Analog Supply 9 1V Supply 5V Bootstrap Supplies 24V Supplies 5V 5 5V 5 9 1V 5 5V 5V 5 OO On DOA DWH SStep Ite
38. contamination which could give erroneous results Calculate the actual calibrator voltage by multiplying the measured resistor value by the calibration current for that range For example if the actual resistance is 99 0 the required calibrator voltage is V 99 x 106 19 x 10 9 1 881V Write the calculated value in Table 5 2 Set the calibrator voltage to the exact value obtained in step 10 Place the instrument on the 20nA range and enable zero check Verify that the display shows 0 000 1 count not enable zero correct Mount the 100 resistor in the shielded fixture con struction is covered in Figure 5 1 and connect the fixture to the instrument as shown in Figure 5 3 NOTE Disconnect floating sources when using this con figuration 14 Disable zero check and verify that the reading is within the limits given in Table 5 2 Enable zero check 15 Repeat steps 9 through 14 for the 2nA 2pA ranges For each range measure the actual resistor value and calculate the calibration voltage using that value along with the required calibration current 5 5 3 Coulombs Verification To confirm coulombs operation proceed as follows 1 2 Enable zero check and set the DC calibrator output to 00 000 Connect the 1000pF capacitor the calibrator and the Model 617 together as shown in Figure 5 4 NOTE Disconnect floating sources when using this con figuration Place the instrument in the coulombs
39. digit DMM Terohmmeter 160 0 07 100MQ 1 160 2 100GQ 2 Resistor Resistor Resistor Decade Resistor Standard Capacitor Shielded Test Fixture Figure 7 1 BNC Female Female Adapter BNC Cable BNC Cable Triax BNC Adapter 7 4 3 Warm Up Period Turn on the instrument power and allow it to warm up for at least two hours before beginning the calibration procedure If the instrument has been subjected to extremes of temperature or humidity allow at least one additional hour for the instru ment to stabilize before beginning the calibration procedure NOTE While rated accuracy is achieved after the two hour warm up period input bias current may require ad ditional time to come to its optimum level Allow two hours for input bias current to settle to less than 10fA and eight hours to less than 5fA It is preferable in sensitive applications to leave the unit on continuously 7 4 4 Calibration Jumper A jumper located on the mother board allows the disabling or enabling of front panel and 488 bus calibration When the jumper is in the disabling position permanent NVRAM storage of calibration constants will not take place However temporary calibration values may be entered and used even if NVRAM calibration storage is disabled Note however that any calibration parameters will be lost once the power is turned off unless they are stored in NVRAM The calibration jumpe
40. in Figure 7 10 MODEL 197 2 Either from the front panel or ove the IEEE 488 bus pro gram the voltage source to 0 00V The correct bus com mand is VOX 3 Turn on the voltage source output by pressing the OPERATE button 4 Place the DMM on the lowest DC voltage range possible without overranging the instrument and note the offset voltage value including sign 50mV or less should be seen 5 Set the DMM to the 200V or similar range and program the voltage source output to 100 00V The bus command to use is 100 6 Adjust the voltage source gain adjustment see Figure 7 9 so that the DMM reads a voltage of 100V offset 10mV using the offset value obtained in step 4 7 Turn off the voltage source output 1 disconnect the DMM 7 4 16 Additional Calibration Points The electrometer calibration points discussed in the preceding paragraphs were chosen to optimize instrument accuracy without making the calibration procedure overly tedious and time consuming As noted earlier these calibration points are permanently stored in NVRAM when the correct storage se quence is performed Although this calibration method is more than adequate to allow the instrument to meet or exceed specifications it should be pointed out that it is possible to temporarily calibrate those ranges not directly calibrated as part of the calibration procedure With the calibration jumper in the disabled position place the instrument in t
41. including V Source I Limit Out put Format ADDRESS MODES TALK ONLY and ADDRESSABLE TRIGGER TO READING DONE 350ms typical GENERAL DISPLAY 4V digit numeric LEDs with appropriate decimal point and polarity indica tion signed two digit alphanumeric exponent OVERRANGE INDICATION Display reads OL CONVERSION TIME 330ms RANGING Automatic or manual DATA STORE and MIN MAX 100 reading store capacity records data at one of six selectable rates from every reading to 1 reading hour or by manual triggering Also detects and stores maximum and minimum readings continuously while in the Data Store mode PROGRAMS Provide front panel access to IEEE address choice of engineering units or scientific notation and digital calibration MAXIMUM INPUT 250V peak de to 60Hz sine wave 10s per minute max on mA ranges MAXIMUM COMMON MODE VOLTAGE dc to 60Hz sine wave Electrometer 500V peak V Source 100V peak INPUT CONNECTOR Two lug triaxial on rear panel OUTPUT CONNECTORS 5 way binding posts on rear panel for V source preamp and analog outputs Rear panel BNC for External Trigger and Meter Complete 2V ANALOG OUTPUT 2V for full range input Inverting in Volts and Ohms modes Output impedance 10 0 PREAMP OUTPUT Provides a guard output for Volts and Ohms measurements Can be used as an inverting output or with externa feedback in Amps and Coulombs modes Output Impedance 1000 EXTERNAL TRIGGER TTL compatible Exte
42. may be observed when zero check is disabled If desired enable suppress to null out any zero check hop which typically will be in the 10 25 count range Connect the Model 6011 cable to the INPUT jack Connect the other end of the cable to the circuit being measured as shown in Figure 2 11 For low level measurements shielding may be required Note Do not connect the cir cuit to the instrument with zero check enabled Read the charge value from the display The exponent may be placed either in the alpha or numeric modes as described in paragraph 2 5 NOTE LEAVE Qs DISCONNECTED UNTIL ZERO CHECK DISABLED ED CHARGE SHIELD OPTIONAL TO A D CONVERTER 2V ANALOG OUTPUT EQUIVALENT CIRCUIT Figure 2 11 Coulombs Connections 2 14 Note that the coulombs function can also be used to measure current The advantage of doing so is that noise in the measurement is substantially reduced because of the in tegrating process To measure current using the coulombs function proceed as follows 1 Place the instrument in the coulombs function and select the desired range or use autoranging if desired 2 Enable zero check and connect the current to be measured to the INPUT jack see Figure 2 9 3 Disable zero check and note the charge measurement at the end of a specific interval of time for example 10 seconds 4 To determine the current simply divide the measured charge by the time in seconds For exa
43. measurements is shown in Figure 4 1 In this case the con stant current method is used Using this method insulation resistances up to 200GQ can be measured As the term im plies the test current through the unknown resistance 15 kept constant The voltage developed across the test resistance will of course depend on the value of the insulation resis tance The Model 617 measures the generated voltage and calculates the resistance value accordingly The low com pliance voltage of the Model 617 lt 2V on 2 range and lower except 300V during overload keeps error due to voltage coefficient small For resistance measurements above 1080 or for cables longer than three feet guarded measurements are recommended as shown in Figure 4 2 In this case the rear panel V Q GUARD switch is used to internally apply a guard signal to the inner shield on the connecting cable The guard is carried through to the inner shield of the test fixture The inner shield must be insulated from the outer shield which is a safety shield In cidentally a shielded fixture is recommended for both unguarded and guarded configurations for measurements above 1070 if stable readings are to be expected in the unguarded mode the shield should be connected to input low With the constant current method just discussed the Model 617 can make measurements as high as 200 However the insulation resistance of such materials as polyethylene may lie
44. results in voltage drops that can affect the measurement Even if the ground loop currents are small magnetic flux cutting across the large loops formed by the ground leads can induce sufficient voltages to disturb sensitive measurements READY C o L MODEL 705 EXTERNAL COMPLETE TRIGGER OUTPUT INPUT 7 o Li MODEL 617 Figure 2 24 External Triggering Example SIGNAL LEADS INSTRUMENT FrvPICAL GROUND LOOP y CAUSES CURRENT FLOW IN A SIGNAL LEAD POWER LINE GROUND Figure 2 25 Multiple Ground Points Create a Ground Loop INSTRUMENT INSTRUMENT INSTRUMENT Figure 2 26 Eliminating Ground Loop To prevent ground loops instruments should be connected to ground at only a single point as shown in Figure 2 26 Note that only a single instrument is connected directly to power line ground Experimentation is the best way to determine an acceptable arrangement For this purpose measuring instru ments should be placed on their lowest ranges The configura tion that results in the lowest noise signal is the one that should be used 2 14 2 Electrostatic Interference Electrostatic interference occurs when an electrically charged object is brought near an uncharged object thus inducing a charge on the previously uncharged object Usually effects of such electrostatic action are not noticable because low im pedance levels allow the induced charge to dissipate quickly However the
45. 1807 27 2Z z2 125 SS 2 EDF zi Ee 22 25 I YOU v 297 91 7 A j We 9 Mive 727 1 74 25 i toj LUZ 29 9 1707 Bt 2522 USA TA 29 28 2 22 Ah ti dBA Z 771 xwrz ew 52 207 92 207 027 Ses 10 201 Pb A 2G e ky 95 Bal Lose 2 CF OU A i f Faj RZ 07 17 105 ZZ FAHEY 9 eL SPAY COLA Y 1 1 i 1 l ON laya was moz gains ow Lave ned oen ae aues ON daya m wr u 4 2 s 95 D d 5310 335 mm LEE 3672 DLLO DoD CUSC rnMe Ge DE gen QL 1FED 2414 2007 Avery 46 WV SLP NOD 5 DIPLO BO VEVOS RY MAU VO CIA VOIM S L VIR 79 VIVA MOHAUM APIO MOL pina TITO S Iza JAIM Xx BANISH POIR gt 004 Y DELI NI MOT YD WISP PAUSOA DIAZ Ofte Mars DMAIL MEL AT Set 777772 PURAS 71 OP TAN 7 992 EH 429 arcy 2050 zog 2241250 k POSO asad COL
46. 2 pA 269 20nC 20 200M2 200 V 20 A 2069 20nC 20 20M9 200 V 200 nA 20009 20nC 20 2MQ 200 V 2 20069 20nC 20 200 kQ 200 20 20060 20nC 20 200 kQ Cancel autoranging for all functions C1 Zero Check On 21 Zero Correct Enabled Baseline Suppression Suppression Disabled 3 10 5 Suppression Enabled Function Volts 3 10 2 Fi Amps Ohms Coulombs External Feedback Ohms Display Mode Electrometer 3 10 6 Voltage Source Reading Mode Electrometer 3 10 7 B1 Buffer Reading B2 Maximum Reading B3 Minimum Reading B4 Voltage Source Data Store Conversion rate One Reading Per Second One Reading Every 10 Seconds One Reading Per Minute One Reading Every 10 Minutes One Reading Per Hour Q6 Trigger Mode Q Disabled 1 7 Voltage Source Value 102 35V to 102 4V 50mV mE increments Value V n nnnnE n Voltage Source O0 Source Output Off 0V Eom An nnnE n 1 Store Calibration Constants in NVRAM 3 10 12 3 19 Store Calibration Table 3 11 Device Dependent Command Summary Cont Command Data Format GO G1 G2 Trigger Mode EO and Off Status Word T3 T4 T5 1 M2 8 1 Y LF CR Y CR LF 5 UO U1 3 10 3 Range R Paragraph 3 10 13 Description Reading with Prefix NDCV 1 23456E 00 Reading without Prefix 1 23456 00 Reading with Prefix and Buffer Suffix if in B1
47. 20V range and enable zero check Verify the display shows 0 000 1 count If not enable zero correct Place the V 0 GUARD switch in the ON position 3 6147 ADAPTER WARNING UP TO 300V ON SHIELD Connect the DC calibrator to the 617 use the con figuration in Figure 5 8 but with a short in place of the resistor Set the calibrator output to 19 000V Disable zero check and note the reading Enable zero check and place the 10060 resistor in the shielded test fixture as shown in Figure 5 8 WARNING Up to 300V may be present on the shielded fixture in the guarded mode Disable zero check Wait a few seconds before noting the reading to allow the reading to settle Compare the reading obtained in step 5 with that noted in step 3 The two readings should be within 10 counts 10mV of one another 100 0 200 0 RANGE 160 260 4801 CABLE 1060 2060 RANGE MODEL 617 v 2 GUARD SHIELDED FIXTURE SEE FIGURE 5 1 IN GUARDED MODE SHORTING LINK IN PLACE Figure 5 7 Connections for Ohms Verification 200M9 260 and 2060 Ranges Table 5 5 Limits for Ohms Verification 200MQ 260 and 2060 Ranges Nominal Range Resistance 200M9 200 2060 From Table 5 2 Allowable Reading Ry x 100 Measured Resistance Percent Tolerance 18 28 C 0 305 1 505 1 50596 Allowable Reading 5 7 5 5 7 Voltage
48. 263 2 78k Resistor 5 025k2 0 1 1 10W Metal Film C3 F2 R 263 5 025k Resistor 5 1 596 W Composition C4 C2 R 76 5 1k Resistor 2 2kQ 5 4 W Composition C4 C2 R 76 2 2k Resistor 330k2 1096 W Composition C6 03 R 1 330k Resistor 330kQ 10 Composition C5 R 1 330k Resistor 100kQ 0 1 W Metal Film B3 D3 R 169 100k Resistor 1009 5 W Composition D5 D3 76 100 Resistor 5600 10 W Composition 05 D3 R 1 560 Resistor 1000 5 W Composition C4 D2 76 100 Resistor 470 5 YW Composition 04 03 76 47 Resistor 5600 10 Y W Composition D4 02 1 560 Resistor 5 1kQ W Composition C6 R 76 5 1k Resistor 2 2kQ 5 4 W Composition R 76 2 2k Resistor 100GQ 296 1 5W 289 1000 Resistor 100 1 1 5W B3 D3 R 269 100M Resistor 250GQ 5 1 5W Ab F2 R 319 250G Resistor 100kQ 5 W Composition A4 F2 R 76 100k Resistor 10 W Composition Ab R 76 10M Resistor Set 220k includes R336 85 R 322 Resistor Set 220k includes R335 B5 R 322 Resistor 2 2 0 5 Composition G2 R 76 2 2k Thermistor B5 F2 12 Thermistor B5 F2 12 Resistor 4 87kQ 1 1 8W Composition B4 88 4 87 Table 8 3 Electrometer Board Parts List Cont Circuit Location Keithley Desig Description Soh Part No R341 Resistor 4020 1 1 8W Composition R 88 402
49. 4 2 insulation Resistance Measurement Guarded 4 3 MODEL 6147 TRIAX MODEL 4801 CABLE TO BNC ADAPTER 6104 TEST FIXTURE 4801 CABLE HI LO Rx L UNKNOWN RESISTANCE MODEL 6104 SHIELDED TEST FIXTURE 617 SET OHMS POMONA MODEL 4585 PATCH CORDS 617 PREAMP 6147 ADAPTER A D CONVERTER I V SOURCE 1 EQUIVALENT CIRCUIT Figure 4 3 insulation Resistance Measurement Using V I Ohms Mode For example assume that the applied voltage is 100V and the measured current is 1pA The resistance is calculated as follows Since the user has fine control over the internal voltage source 102 35 to 102 4V in 50mV steps the resistance at a given applied voltage can be easily determined Such control can give rise to voltage coefficient studies as described later in this section In addition to the measurement of insulation resistances this basic method can be used to measure unwanted leakage resis tances For example leakage resistance between PC board traces and connectors can be made with either of the two methods above depending on the resistance values involved 4 3 HIGH IMPEDANCE VOLTMETER The input resistance of the Model 617 in the volts mode is greater than 20070 Because of this high value the Model 617 can be used to make voltage measurements in high impedance circuits with a minimum of loading effects on the circuit Consider the situati
50. 5 5 4 Volts Verification NOTE Current and charge verification must be per formed before volts verification Verify the volts function as follows 1 2 Enable zero check and select the volts functions with the associated front panel buttons Select the 200mV range and enable zero correct Check to see that the display shows 000 00 1 count not enable zero correct Connect the signal source to the instrument as shown in Figure 5 5 Set the calibrator output to 190mV as mdicated in Table 5 3 Disable zero check and verify that the reading is within the limits listed in Table 5 3 Table 5 3 Limits for Volts Verification Applied Allowable Reading Range Calibrator Input 18 28 C 190 000mV 189 87 to 190 13mV 1 90000 V 1 8990 to 1 9010 19 0000 V 18 990 to 19 010 V 190 000 V 189 86 to 190 14 V 5 Repeat the procedure for the 2V 20V and 200V ranges by applying the respective inputs listed in Table 5 3 Check to see that the reading for each range is within the limits listed in the table Repeat the procedure for each of the ranges with negative voltages NOTE LEAVE GREEN DISCONNECTED BLACK 6011 CABLE aL RED 0000000 54 D MAR 0 Q CHASSIS MODEL 617 v J SHORTING LINK REMOVED Figure 5 5 Connections for Volts Verification 5 5 5 5 5 Ohms Verification 2 0 20 Ranges Perform ohms verification for the 2kQ 20MQ range
51. 5 ES CHS 6 7 8 TN UI2O MATES WITH MATES WITH OF 5 2 OF DISPLAY 80 UT AY BD Men 0104 IO 617 116 ZONE AD lo DIO DS DIO 2 DIO 3 DIO 4 2 DIO 5 DIOS COMPLETE I METER DIO J P1O55 Ser IEEE d So CONNECTOR lt 1 DY 9 REN lt NRFD 8 Mic S HO NFD Siren ov S 59 Dv EXTERNAL SS FOI 3 TRIGGER m sra ATN cor sra sea b 5 GND O PAGE 3 ROSE 75161 ZONE 3 RIOS gt 12 SHIELD ZONE Hi quioza 18 430 iS 21 COMMON 4 lt D TM 2 Oi O PAGE RIOSA ZONE H3 48 ro pace wey 2 voutis 22 ZONE 2601 V SOURCE wa OPTOS 10 5 maU RIOSB O PAGE RIOS ONE 2 550 PAGE ONE H2 u25 7 RIOSF 1 5 ro PAGE FCD82O 9 OTOES ZONI ua G A 10K cou 1 2 ZONE B 4 QRIB KOK PAGE 1 ZONE y F ON mms 9 6 1 RIO5D 5 A ZONE NEXT t 5 _____ ___ pare sca 2 SCHEMATIC aires tom ara MOTHER BOARD 5 s P n ES 617 106 A FORM 285110 REV 2 B 2 6 H Figure 8 5 Mother Board Sche
52. 9 Calibrate all the elec trometer ranges listed in the table Table 5 Model 617 Amps Calibration 263 Output 617 Range 263 Range Current 617 Reading 190000 pA 19000 pA 19 0000nA 19000 19 0000 pA 19 000 pA 19 0000mA 19 000mA Coulombs Calibration Use the following procedure to calibrate the 20nC range Once this range is calibrated the two remaining ranges are automatically calibrated 1 Connect the Model 263 Calibrator Source to the Model 617 as shown in Figure 9 2 Place the Model 61 in the coulombs function and select the 20nC range 3 While in standby program the Model 263 to source 19 0000 4 On the Model 617 enable zero check and then zero rect Disable zero check and enable suppress to null the effects of zero check hop 5 Press the OPERATE button on the Model 263 The calibrator will source for one second 6 Adjust the display of the Model 617 for a reading of 19 000nC using the ADJUST buttons of the Model 617 7 Repeat steps 4 through 6 until the reading on the Model 617 reads 19 000nC after OPERATE is pressed on the calibrator 8 Place the Model 617 in zero check Volts Calibration Calibration of the volts function should be performed in the following order 200mV 2V 20 and 200V ranges The 200V range will require that an external 190V source be ap plied to the Model 263 Proceed as follows 1 Connect the Model 263 to the Model 617 as shown in F
53. 9 for the 20kQ range For the remaining Model 617 ranges repeat steps 6 through 9 by sourcing the appropriate resistances to the electrometer Note that guard must be enabled on both the Models 617 and 263 when verifying the GQ ranges Also note that COM of the Model 617 must be connected to COMMON of the Model 263 see Figure 3 Table 2 Limits for Volts Verification 617 263 Allowable Reading Range Output 18 C to 28 C 190 000 mV 1 90000 V 19 0000 190 000 to 190 09 to 1 9007 to 19 007 to 190 14 200 2V and 20V ranges allowable readings include Model 263 error The 200V range reading is based solely on Model 617 error DUAL BANANA CABLE EXT MODEL 617 pc CALIBRA TOF As 46 19900000 Ponsa MOON IIOP OO ES Externa Calibration Source MODEL 263 Figure 2 Volts Verification Setup MODEL 263 MODEL 617 BANANA CABLE Figure 3 Ohms Verification Setup Table 3 Limits for Ohms Verification 263 a Calculated Limit Range Nominal Reading Equipment Error Limit 18 to 28 C 0 0004 263 Reading Limit 013 0 001 kQ 263 Reading Limit 0 23 001 263 Reading Limit 0 225 0 0001 263 Reading Limit 0 2125 0 001 _____ 263 Reading Limit 023 0 01 MQ 263 Reading Limit 14 0 000169 Al 263 Reading
54. Composition Resistor 4300 5 4 W Composition Resistor 10 W Composition Resistor Thick Film Resistor 5600 5 W Composition Resistor 5 W Composition Resistor Thick Film Resistor Thick Fiim Resistor 10 W Composition Resistor 200kQ 5 W Composition Resistor 200kQ 5 1 4W Composition Resistor 100kQ 5 W Composition Resistor 1kQ 5 Composition Resistor 5 1kQ 5 4 W Composition Resistor 5 1kQ 5 Composition Resistor 1000 5 W Composition R 76 100 R 76 100 R 76 430 R 76 10M TF 183 1 R 76 560 R 76 30k TF 179 1 179 1 R 76 10M R 76 200k R 76 200k R 76 100k R 76 1k R 76 5 1k 76 5 1 R 76 100 Table 8 1 Mother Board Parts List Cont Circuit Location Keithley Desig Description Sch Part No 8 4 Resistor 100kQ 5 4 W Composition R 76 100k Resistor 10kQ 5 14 W Composition R 76 10k Resistor 5 49kQ 196 1 8W Composition R 88 5 49k Resistor 9 76kQ 196 1 8W Composition R 88 9 76k Resistor 6 8kQ W Composition R 76 6 8k Resistor 4700 W Composition R 76 470 Resistor 1800 5 W Composition 1 03 4 76 180 Resistor 1000 5 W Composition 1 F3 F4 76 100 Resistor 1802 5 W Composition 1 63 F4 R 76 180 Resistor 4700 5 W Compo
55. During each phase an integration is performed by the A D converter and the resulting data is then used by the microprocessor to calculate the final reading CONTROL MULTIPLEXER BUFFER TO A D CONVERTER Figure 6 12 Multiplexer and Buffer REFERENCE PHASE SIGNAL PHASE CALCULATE A READING COMMON PHASE SIGNAL PHASE CALCULATE A READING Figure 6 13 Multiplexer Phases 6 4 3 2V Reference Source Model 617 measurements are based on comparing the unknown signal with an internal 2V reference voltage source During each measurement cycle the unknown signal is sampled and then compared with signal common and the 2V reference values Figure 6 14 shows a simplified diagram of the 2V reference source VR102 provides a highly stable 6 3V reference while 0139 and elements of R153 provide a constant current to minimize zener voltage variations R146A and R146B divide down the 6 3V value to the final 2V reference voltage The output of U139 7V is used as bias for the A D converter and as a negative supply for various other components 2V REFERENCE 7V TO A D R153A x CONVERTER i R153B Figure 6 14 2V Reference Source 6 5 A D CONVERTER The Model 617 uses an A D converter that utilizes both constant frequency charge balance and single slope techni ques This combination gives the instrument both high ac curacy and relatively fast conversion times A simplified s
56. Front Panel Messages Number Error Trigger Overrun Error Bus Data Transmission Times 8o a s s t tok r s s s 77 7 7 l7 404040404404 e q e a lt s s s s b s bk s t h h 204040404 q b q s s lt q q q lt SECTION 4 APPLICATIONS Jntroduction 2 lt om w t lt s s s s t 40404040404 4 s v 8o 4 4 9 9 oS t o ON Insulation Resistance 2 2 2 2 22222 222 2 2 High Impedance Voltmeter Low Level Leakage Current Measurements Diode Characterization 4o q q t n 24 v v v q q q 2 4240 0 4 4 9 9 s V om s q q 4 Capacitor Leakage Measurements Capacitance Measurement d 9 o9 o 98 08 8 9 8 9 9 4 4 39 4 5 V v v 9 ow 9 Vo 4 3 Voltage Coefficients of High Megohm Resistors Static Charge Detection Using the Model 617 with Externa
57. GUARD on both the Models 617 and 263 On the Model 263 select the 200 range and press ZERO to source zero ohms Make sure the Model 263 is in OPERATE Set the DC calibrator to output 19 000V On the Model 617 disable ZERO CHECK and note the reading Enable ZERO CHECK on the Model 617 and press ZERO on the Model 263 to select the 100GQ resistor Disable ZERO CHECK on the Model 617 After waiting a few seconds for settling note reading on the Model 263 Compare the reading obtained in step 8 with that noted in step 6 The two readings should be within 10 counts 10mV of one another Table 4 Voltage Source Verification Limits Programmed Allowable DMM Reading Voltage 18 28 C DUAL BANANA CABLE VOLTS OHMS MODEL CA 18 1 MODEL 196 MODEL 617 VOLTAGE SOURCE GAIN ADJUSTMENT Figure 4 Voltage Source Verification Setup SHORTING UNK DISCONNECTED MODEL 617 MODEL 263 GUARD ON GUARD ON BANANA CABLE BANANA CABLE CALIBRATOR ER SEAN CSO ANS OR ORIN To 2000000 6 ES CTRL EELS EI 55555 CHASSIS Figure 5 Input Impedance Verification Setup CALIBRATION USING MODEL 263 CALIBRATOR SOURCE INTRODUCTION The following paragraphs provide detailed procedures to calibrate the Model 617 using the Model 263 Calibrator Source Most of the calibration procedures are digital in nature and can be done from the fr
58. J Obvious problem on power up 1 Batteries and fuses are OK 1 Front panel operational All ranges or functions are bad Checked all cables Display or output check one Drifts J Unable to zero Unstable B Will not read applied input LY Overload 1 Calibration only 1 Certificate of calibration required 1 Data required attach any additional sheets as necessary Show a block diagram of your measurement system including all instruments connected whether power is turned on or not Also describe signal source Where is the measurement being performed factory controlled laboratory out of doors etc AAA AAA A A A a _ C A aaa What power line voltage is used Ambient temperature Relative humidity Other Any additional information If special modifications have been made by the user please describe a eS A F n U Be sure to include your name and phone number on this service form APPENDIX This appendix contains complete procedures for calibrating the Model 617 using the Keithley Model 263 Calibrator Source Complete separate procedures are provided for performing digital calibration from either the front panel or over the IEEE 488 bus Digital calibration over the bus is automated using a BASIC program run by the HP 85 computer Using the Model 263 to verify and calibrate the Model 617 simplifies the procedure and elimina
59. Logarithmic Currents The use of a diode junction in the external feedback path per mits a logarithmic current to voltage conversion This relationship for a junction diode is given by the equation mkT q In 1 1 IRg where q unit charge 1 6022 10 19 Boltzmann s constant 1 3806 X 10 23 and T temperature K The limitations in this equation center on the factors Ij m and Rg I is the extrapolated current for An empirical proportional constant m accounts for the different character current conduction recombination and diffusion mechanisms within the junction typically varying be tween 1 and 2 Finally constitutes the ohmic bulk resis tance of the diode junction material I and limit the usefulness of the junction diode at low and high currents respectively The factor m introduces non linearities be tween those two extremes Because of these limitations most diodes have a limited range of logarithmic behavior 2 24 A solution to these constraints is to use a transistor con figured as transdiode in the feedback path as shown in Figure 2 19 Analyzing the transistor in this configuration leads to the relationship kT g lni 1 In hgg 1 hpp where is the current gain of the transistor From this equation proper selection of Q4 would require a device with high current gain hpg which is maintained over a wide range of emitter currents Suita
60. Model 196 DMM to the voltage source out put as shown in Figure 8 2 From the front panel program the voltage source of the Model 617 to 0 009 3 Turn on the voltage source output by pressing the OPERATE button 4 Place the Model 196 in autorange and note the offset voltage value A reading of 50mV or less should be displayed 5 Press ZERO on the Model 196 to cancel the offset 6 Program the Model 617 to output 100 00V 7 Adjust the voltage source gain adjustment see Figure 8 so that the DMM reads a voltage of 100V 10mV 8 Turn off the voltage source output and disconnect the DMM Front Pane Digital Calibration Perform the following procedures to digitally calibrate the Model 617 from the front panel DUAL BANANA CABLE MODEL CA 18 1 MODEL 617 VOLTAGE SOURCE GAIN ADJUSTMENT Figure 8 Connections for Model 617 Voltage Source Calibration A 10 Calibration Program The Model 617 must be placed in the calibration program in order to perform the front panel digital calibration pro cedures Select the calibration program as follows 1 Turn off the instrument for at least three seconds if it is presently turned on 2 Press and hold the PROGRAM SELECT button and then turn on the power 3 The instrument powers up as normal but the CAL pro gram is accessible in the program menu 4 Select the calibration program by pressing PROGRAM SELECT repeatedly until the following message is displayed briefl
61. Note that the error condition word is actually a string of ASCII characters representing binary bit positions An error condition is also flagged in the status serial poll byte and the instrument can be programmed to generate an SRQ when an error condition occurs See paragraph 3 10 15 Note that all bits in the error condition word and the status byte error bit will be cleared when the word is read In addition SRQ operation will be restored after an error condition by reading U1 0 1 0 1 0 1 0 1 0 1 1 IDDC 1 IDDCO 1 NO REMOTE 000 CRLF ALWAYS ZEROES TERMINATOR DEFAULT SHOWN 12 TRIGGER OVERRUN 12 NUMBER ERROR Figure 3 12 U1 Status Error Condition Format The various bits in the error condition word are described as follows IDDC Set when an illegal device dependent command such as H1X is received is illegal IDDCO Set when an illegal device dependent command op tion IDDCO such as T9X is received 9 is illegal No Remote Set when a programming command is received when REN is false NOTE The complete command string will be ignored if an IDDC IDDCO or no remote error occurs Trigger Overrun Set when a trigger is received when the in strument is still processing a reading from a previous trigger Number Error Set when an out of range calibration or vol tage source value is received In a similar manner the U2X sequence allows access to instru m
62. PAGE 2 ZONE A6 2136 6 8K Q KIO Q6 10 cw DENOTES CLOCKWISE ROTATION DENOTES REAR PANEL ADJUSTMENT 12 DENOTES FRONT PANEL CONTROL 13 DENOTES REAR PANEL MOUNTING 14 DENOTES INTERNAL ADJUSTMENT TITO H zore nevi ee L L Je LA pos 22 2 ISDLOERE Ho 160 501 Co P TAE IRA OT A MAZA A 22285 TO PAGE 2 ZONE E TO PAGE 2 ZONE 5 F TO PAGE 2 ZONE 5 TO PAGE 2 ZONE A5 LO SOURCE OUTPUT 1006 H 2 ZONE 5 HIGHEST SCHEMATIC DESIGNATIONS USED Cia 2 RISI crite 5108 Pots Fio2 TiO2 SCHEMATIC DESIGNATIONS NOT USED 121002 THRU SCHEMATIC MOTHER BOARD EEEE Tr RATA 5 mmi 617 106 F G H Yh 18 12777 Figure 8 5 Mother Board Schematic Diagram Dwg No 617 106 Sheet 1 of 3 8 21 8 22 JO 2 39vd E D E F G H 2582 sex ______ are 90 2190 VREA Tis mice e Z 1 jeep eee up a 2 12 oux 58 3 ee IEEE 8 1 4
63. Plug the other end of the line cord into an propriate power source See Section 2 for more complete information 3 Connect the supplied triaxial cable to the rear panel input jack Make sure the rear panel V 9 GUARD switch is in the off position 4 Press in the front panel POWER switch to apply power to the instrument The instrument will power up the the autorange volts mode with zero check enabled Thus you could simply connect the red and black input leads to a voltage source and take a voltage reading at this point by disabling zero check Remember that the Model 617 measures DC voltages up to 200V 5 change to a different measuring function simply press the desired function button For example to measure resistance simply press the OHMS button 6 Complete detailed operation concerning Model 617 front panel operation may be found in Section 2 If you wish to control these functions over the 488 bus consult Section 3 1 10 PREPARATION FOR USE Once the instrument is unpacked it must be connected to an appropriate power source as described below Line Power The Model 617 is designed to operate from 105 125V 210 250V power sources A special power trans former may be installed for 90 110V and 195 235V ranges The factory set range is marked on the rear panel of the in strument Note that the line plug is designed to mate with the supplied 3 wire power cord CAUTION Do not attempt to operate th
64. Red LED Red Cable Ribbon Resistor Thick Film Resistor Thick Film Switch Pushbutton Switch Pushbutton Switch PUshbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton IC UDN2585A IC UDN2585A IC 3 to 8 Line Decoder 74HCT138 IC UDN2595A IC UDN2595A IC Analog Multiplexer 4051 B2 C2 D2 E2 F2 G2 H1 H1 H2 H2 H2 H2 H2 H2 H3 H3 H3 H4 H4 5 HS H5 A1 B1 B2 D4 D4 04 D4 D4 D4 D4 D4 D4 DS DS D5 D5 D5 D5 05 05 05 05 Al A2 B3 D3 E4 1 C1 C1 C1 C1 Ci D2 D1 D1 D2 D2 D2 D2 D3 C2 C2 C2 C2 C2 C2 D1 D2 D2 D2 179 10 617 603 617 604 617 604 617 604 617 604 00 39 PL 71 PL 71 PL 71 PL 71 PL 71 PL 71 PL 71 PL 72 PL 71 PL 71 PL 71 PL 71 PL 71 PL 72 PL 71 PL 71 PL 71 PL 71 CA 30 1 TF 141 141 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 SW 435 1 405 1C 405 1C 398 IC 406 406 277 Table 8 3 Electrometer Board Parts List Circuit Location Keithley Desig Description Part No C301 Capacitor 4 7uF 350V Alumin
65. SINGLE SLOPE COMPARATOR U137A CHARGE BALANCE COMPARATOR Figure 6 15 A D Converter 6 10 6 6 DIGITAL CIRCUITRY Model 617 operation is controlled by the internal microcom puter and associated software The following paragraphs briefly describe the various aspects of the digital circuitry Descriptions are keyed to the digital circuitry schematic drawing number 617 106 page 2 located at the end of Sec tion 8 6 6 1 Microcomputer Microcomputer operation centers around the 8 bit 146805 CMOS microprocessor U109 This device utilizes an 8 bit data bus and incorporates a multiplexed data address bus for the lower eight bits of the 12 bit address bus The 146805 has 112 bytes of on chip memory two 8 bit I O ports and is cap able of directly addressing 8K bytes of memory The MPU has direct control over the display front panel switches analog to digital converter the voltage source the IEEE 488 bus as well as the Meter Complete output and the External Trigger Input Microprocessor timing is performed by Y101 a 3 2768MHz crystal The signal is internally divided by five to obtain a bus operating frequency of 655 36kHz This signal is present at the AS terminal of the processor and is used as a control signal to strobe the lower ordered eight bits of the address in to the address latch 108 A 655 36kHz signal is also present at the DS terminal to act as a system clock 6 6 2 Memory Elements Soft
66. Source Verification Use the following procedure to verify that the Model 617 voltage source is within tolerance WARNING Dangerous voltage may be present on the voltage source output terminals when the voltage source output is enabled 1 Connect the DMM see Table 5 1 to the voltage source output terminals as shown in Figure 5 9 2 Select an appropriate range on the DMM Alternate ly place the DMM in the autorange mode if desired 3 Press the DISPLAY button to view the voltage source value and turn on its output by pressing the OPERATE button 4 Using the ADJUST buttons set the voltage source output to 00 00V Table 5 6 Voitage Source Verification Limits Programmed Allowable DMM Reading Voltage 18 28 00 00V 0 050 to 0 050V 01 00V 0 948 to 1 052V 10 00V 9 93 to 10 07V 25 00V 24 90 to 25 10V 50 00V 49 85 to 50 15V 100 00V 99 75 to 100 25V SHIELDED FIXTURE 7 Verify that the voltage source value is within the limits stated in Table 5 6 Repeat steps 4 and 5 above with the remaining voltages listed in the table Repeat the procedure for negative voltages of the same amplitude listed in the table WARNING UP TO 300V MAY BE PRESENT ON SHIELD NO CONNECTIONS SEE FIGURE 5 1 4801 CABLE 6147 ADAPTER Figure 5 8 Input Impedance Verification V SOURCE OUTPUT MODEL 197 MODEL 617 Figure 5 9 Conn
67. Switch The Model 617 has provisions for connecting a guard to the inner shield of the input cable Guarding is useful in the volts and ohms modes to speed up response time and minimize the effects of leakage resistance Note that guarded operation is not recommended in amps or coulombs The V 9 GUARD switch allows easy selection of the guarded mode of opera tion See paragraph 2 7 4 for more information on guarded operation 2 6 3 Line Fuse The LINE FUSE which is accessible on the rear panel pro vides protection for the AC power line output For informa tion on replacing this fuse refer to Section 7 2 7 BASIC MEASUREMENT TECHNIQUES The paragraphs below describe the basic procedures for using the Model 617 to make voltage resistance charge and cur rent measurements 2 7 1 Warm Up Period The Model 617 is useable immediately when it is first turned on However the instrument must be allowed to warm up for at least two hours to achieve rated accuracy NOTE While rated accuracy is achieved after the two hour warm up period input bias current may require ad ditional time to come to its optimum level Allow two hours for input bias current to settle to less than 10fA and eight hours to less than 5fA It is preferable in sensitive applications to leave the unit on continuously 2 7 2 Input Connections The rear panel liNPUT connector is Teflon insulated recep tacle intended for all input signals to the Model 617
68. West Germany Great Britain France the Netherlands Switzerland and Austria Information concern ing the operation application or service of your instrument may be obtained from the applications engineer at any of these locations 1 4 MANUAL ADDENDA Information concerning improvements or changes to the in strument which occur after the printing of this manual will be found on an addendum sheet included with this manual Please be sure that you read this information before attempt ing to operate or service your instrument 1 5 SAFETY SYMBOLS AND TERMS The following safety symbols and terms are used in this manual and found on the instrument The A symbol on the instrument indicates that the user should refer to the operating instructions in this manual for further details The WARNING heading as used in this manual explains dangers that might result in personal injury or death Always read the associated information very carefully before per forming the indicated procedure The CAUTION heading used in this manual explains hazards that could damage the instrument Such damage may in validate the warranty 1 1 1 6 SPECIFICATIONS Detailed Model 617 specifications may be found immedi ately preceding the table of contents of the manual Note that accuracy specifications assume that the instrument has been properly zero corrected as discussed in Section 2 1 7 USING THIS INSTRUCTION MANUAL This manual contains all
69. adequate for this situation because the error due to meter loading is substantially better than the required 1 value stated earlier In addition the 4 digit resolution of the instrument allows the designer sufficient precision to make use of the high input impedance 4 4 LOW LEVEL LEAKAGE CURRENT MEASUREMENTS Many devices exhibit low level leakage currents that may re quire measurement Typically such leakage currents might lie in the nA 10 9 pA 10 2 or even the 10 5 range The Model 617 is an ideal instrument for such current measurements because it can detect currents as low as 0 1fA An example of a situation requiring low current measurement is shown in Figure 4 5 In this example the gate leakage cur rent of a JFET is to be measured Although the device manu 4 5 facturer may specify the current value it is often desirable to verify the specification for a particular sample of the device Then too the specified leakage current might be at a higher voltage than required For example the specified leakage cur rent might be 1nA with an applied voltage of 25V while that figure might be much less at an operating value of 10V An added bonus of using the Model 617 in this situation is that the instrument has a built in voltage source Thus the voltage source could be programmed to the desired value or values and the leakage current could be measured for each voltage In this manner leakage current charac
70. an inversion in amps and coulombs while in volts and ohms it does not 6 3 4 Ohms Voltage Source In the constant current ohms mode a bootstrapped voltage source is connected in series with a range resistor to force a constant current through the resistance being measured A simplified schematic diagram of this source is shown in Figure 6 8 The source itself is made up of U304 and associated com ponents VR301 provides the voltage reference while VR304 is a clamping diode to protect the circuit in case of line over voltage R347 limits power dissipation in Q302 The current through the reference is produced by the 10V output through R315 R316 R313 and R317 divide the output to provide feedback for U304 R313 and VR301 are selected at the factory to provide an accurate 10V output The actual R347 Figure 6 8 Ohms Voltage Source Simplified Schematic 6 6 souce output is 10V but this value is divided to 1V and 0 1V by a voltage divider made up of elements of R304 Q302 buffers the output of U304 since R304 will draw 10mA Only a single voltage source value is used for a given range with the value being selected by the appropriate relay con tacts For the 2MQ range however all relay contacts are open and 1 current is sourced through the precision 900kQ resistor R303 and feedback element R322 6 3 5 Zero Check The zero check mode provides a means for determining and cancelling offsets internal to the instrument The
71. analog outputs are discussed the the following paragraphs WARNING When floating Input Low above 30V from earth ground hazardous voltage will be present at the analog outputs Hazardous voltage may also be present when measur ing in ohms or when the input voltage ex ceeds 30V in the volts mode CAUTION Connecting PREAMP OUT COM or 2V ANALOG OUTPUT to earth while floating input may damage the instrument 2 9 1 2V Analog Output The 2V ANALOG OUTPUT provides a scaled 0 2V output that is inverting in the volts and ohms modes Connections for using this output are shown in Figure 2 15 For a full range input the output will be 2V typical examples are listed in Table 2 5 The 2V ANALOG OUTPUT is not corrected dur ing calibration Gain errors of up to 3 may appear at this output depending on function and range selection Note that the output impedance is 10kQ to minimize the ef fects of loading the input impedance of the device connected to the 2V ANALOG OUTPUT should be as high as possible For example with a device with an input impedance of 10 0 the error due to loading will be approximately 0 1 2 9 2 Preamp Out The PREAMP OUT of the Model 617 follows the signal amplitude applied to the INPUT terminal Some possible uses for the preamp output include buffering of the input signal as 2 19 well as for guarding in the volts and ohms modes Connec tions and equivalent circuits for the preamp output are shown in
72. and Bus Hold off K and Terminator Y Thus to force a particular command sequence you would follow each command with the execute character as in the example str ing C1XZ1XCOX which can be used to zero correct the in strument These programming aspects are covered at the end of this paragraph Device dependent commands can be sent either one at a time or in groups of several commands within a single string Some examples of valid command strings include FOX Single command string FOK1DOROX Multiple command string 6 X Spaces are ignored Typical invalid command strings include H1X Invalid command as is not one of the instrument commands F9X Invalid command option because 9 is not an option of the F command If an illegal command IDDC illegal command option IDD CO is sent or if a command string is sent with REN false the string will be ignored Device dependent commands that control the Model 617 are listed in Table 3 11 These commands are covered in detail in the following paragraphs The associated programming ex amples show how to send the commands with both the HP 85 and the IBM PC 8573 NOTE Programming examples assume that the Model 617 is at its factory default value of 27 In order to send a device dependent command the controller must perform the following steps 1 Set ATN true 2 Address the Model 617 to listen 3 Set ATN false 4 Send the command string over the bus one b
73. and ELEC TROMETER COMPLETE connections Also do not attempt to force a 3 lug triaxial connector onto the INPUT Connec tor The Models 6171 and 6172 adapters are available to make the necessary conversion 2V ANALOG OUTPUT The 2V ANALOG OUTPUT pro vides a scaled 0 2V output from the electrometer 2V output for full range input The output uses a standard 5 way bind ing post and is inverting in the volts and ohms modes PREAMP OUT The PREAMP OUT provides a guard out put for voltage and resistance measurements This output can also be used as an inverting output or with external feedback when measuring current or charge The PREAMP OUT has maximum output value of 300V and uses a standard 5 way binding post WARNING Hazardous voltage may be present at the PREAMP OUT depending on the input signal 2 6 Picoamperes Nanocoulombs Microamperes Millivolts Kilohms Megohms Gigohms Teraohms Petaohms COM Terminal The COM terminal is a 5 way binding post that provides a low connection for both the 2V ANALOG OUTPUT and the PREAMP OUT This terminal is also used for input low connection when in guarded mode COM is internally connected to input low through a 1000 resistor Do not connect PREAMP OUT COM or 2V ANALOG OUTPUT to earth when floating input V SOURCE OUTPUT The HI and LO outputs are the con nections for the internal voltage source This source can be used as a stand alone source or in conju
74. are D0 Electrometer 01 Voltage source Upon power up or after receiving a DCL or SDC command the instrument will be in the DO electrometer mode NOTE When in the D1 mode sending an electrometer command F R C Z N or T will cause the instrument to revert to the DO electrometer mode To program the desired display mode over the bus you need only send the appropriate command string For example D1X would be transmitted to view the voltage source value on the display HP 85 Programming Exampie Using the front panel DISPLAY button place the display in the electrometer mode Now type in the following lines REMOTE 727 END LINE OUTPUT 727 D1X END LINE When the END LINE key is pressed the second time the display shows the voltage source value 8573 Programming Example Momentarily power down the instrument and then enter the following lines into the IBM computer 1 CALL IBSRE BRDO V return CMD D1X CALL IBWRT M617 CMD return Note that the instrument changes from the electrometer display mode to the voltage source display mode when the return key is pressed the second time 3 10 7 Reading Mode B The reading mode command parameters allow the selection of the source of data that is transmitted over the IEEE 488 bus Through this command you have a choice of data from the electrometer voltage source data store reading or minimum and maximum values Note that the
75. are affected with uncalibrated ranges unaffected The new calibration constants will be used by the instrument until power is turned off Tem porary calibration is denoted by the flashing exponent decimal points MODEL 617 BANANA CABLE Figure 9 Connections for Model 617 Calibration DUAL BANANA CABLE MODEL CA 18 1 DC EXT INPUT MODEL 263 Figure 10 Connections for External Voltage Source A 13 IEEE 488 Bus Digital Calibration After completing the manual calibration adjustments per form the following procedure to digitally calibrate the Model 263 over the IEEE 488 bus 1 2 Connect the Models 263 and 617 to the GPIB interface of the HP 85 computer Set the IEEE 488 address of the Model 263 to 8 and set the address of the Model 617 to 27 Enter the calibration program into the HP 85 computer To calibrate the instrument simply press the RUN key on the computer and follow the instructions on the CRT display CLEAR 727 708 CLEAR BEEP 5 After all functions are calibrated the program will prompt for permanent storage of calibration constants in NVRAM line 880 This provides the user the op portunity to stop at this point in order to avoid perma nent calibration The calibration constants will be lost when the instrument is turned off Storage of calibration constants into NVRAM is per formed by line 940 of the program and is indicated by the Stor me
76. as the low current card In this manner a single Model 617 could monitor up to 20 measurement points By connecting the triggering inputs of the two instruments together a complete automatic measurement sequence could be performed Data obtained from each measurement point could be stored by the data store mode of the 617 Alternatively the Model 617 could be connected through the IEEE 488 bus to a printer which would print out the data for each point as it is measured Once the Model 705 is programmed for its scan sequence the measurement procedure is set to begin When the Model 705 closes the selected channel it triggers the Model 617 to take a 2 30 reading When the Model 617 finishes the reading it triggers the Model 705 to scan to the next channel The process repeats until all channels have been scanned To use the Model 617 with the Model 705 proceed as follows 1 Connect the Model 617 to the Model 705 as shown in Figure 2 21 Use shielded cables with BNC connectors The Model 617 METER COMPLETE OUTPUT jack should be connected to the Model 705 EXTERNAL TRIGGER INPUT jack The Mode 617 EXTERNAL TRIGGER IN PUT should be connected to the Model 705 CHANNEL READY OUTPUT Additional connections which are not shown on the diagram will also be necessary to apply signal inputs to the scanner cards as well as for the signal lines between the scanner and the Model 617 2 Place the Model 617 in the one shot tri
77. front panel calibration program as described in paragraph 7 4 4 The instrument will then display a reading that reflects its present calibra tion point for the selected range The exact point can be set by using the voltage source adjust buttons to set the dis played value to exactly 1 9000mA 5 After all points have been calibrated exit the program by pressing SHIFT then SELECT 6 If bus calibration is desired instead send the calibration signal over the bus In this case the command would be 1 9 3 7 Any non standard calibration points will be only tem porary as stated earlier 7 5 SPECIAL HANDLING OF STATIC SENSITIVE DEVICES CMOS devices operate at very high impedance levels for low power consumption As a result any static charge that builds up on your person or clothing may be sufficient to destroy these devices if they are not handled properly Table 7 7 lists static sensitive devices used in the Model 617 When handling these devices use the precautions below to avoid damaging them 1 The ICs listed in the table should be transported and hand led only in containers specially designed to prevent static build up Typically these parts will be received in anti static containers of plastic or foam Keep these devices in their original containers until ready for installation 2 Remove the devices from their protective containers only at a properly grounded work station Also ground yourself with a suitable
78. goes high while the U136C output is high a pulse is fed to the microprocessor The MPU then counts the total number of pulses that occur during the charge balance phase BUFFER INTEGRATOR LEVEL SHIFT CURRENT R149A INTEGRATOR OUTPUT WAVEFORM DELAY DELAY INPUT ENABLE DISABLE 1 2288MHz CLOCK CHARGE BALANCE PHASE SINGLE SLOPE PHASE NEXT MEASUREMENT CLOCK GENERATOR CHARGE BALANCE CURRENT The charge balance phase lasts for 100msec At the end of this period the output of the integrator is resting at some positive voltage Since the integrator output is connected to the non inverting input of the single slope comparator U137A the single slope comparator output remains high until the in tegrator output ramps in the negative direction During the single slope phase Q108 is turned off to discon nect the input and charge balance currents from the integrator input In place of these two currents the single slope current Iss is injected into the integrator input This current is developed by connecting one end of R149H to 5V through U136B As long as the integrator output remains positive the Q2 pulses from 0127 are transmitted to the microprocessor where they are counted to be used in the final reading Once the single slope comparator output goes low the Q2 pulses are turned off by U135C SINGLE SLOPE ENABLE DISABLE
79. high for several minutes following measurement of high volts or ohms Place the V 0 GUARD switch in the OFF position unless otherwise noted Input Current Verification Perform input current verification as follows NOTE The following procedure must be performed at an ambient temperature of 23 1 1 Disconnect all cables from the Model 617 input 2 Place the input cap supplied with the instrument on the INPUT connector 3 Select the amps function 2pA range enable zero check and then enable zero correct 4 Connect a jumper between the rear panel COM and chassis ground terminals 5 Disable zero check and allow one minute for the reading to stabilize 6 Verify that the reading is 50 counts less Enable zero check 7 Remove the jumper connected between the COM and chassis ground connectors Amps Verification Connect the Model 617 to the Model 263 as shown in Figure 1 and perform amps verification as follows 1 On the Model 617 enable zero check and select the 20mA range Do not use autorange 2 Check that the display reads 0 000 1 count If not enable zero correct 3 Using the AMPS active current source program the Model 263 to output 19 0000mA to the Model 617 4 Disable zero check and verify that the reading on the Model 617 is within the limits in the table 5 Using Table 1 as a guide repeat steps 1 through 4 for the 2mA through 2nA current ranges 6 Using the AMPS V R passiv
80. high impedance levels of many Model 617 Elec trometer measurements do not allow these charges to decay rapidly and erroneous or unstable readings may result These erroneous or unstable readings may be caused in the follow ing ways 1 DC electrostatic field can cause undetected errors or noise in the reading 2 AC electrostatic fields can cause errors by driving the amplifier into saturation or through rectification that pro duces DC errors Electrostatic interference is first recognizable when hand or body movements near the experiment cause fluctuations in 2 31 the reading Pick up from AC fields can also be detected by observing the electrometer output on an oscilloscope Line frequency signals on the output are an indication that elec trostatic interference is present Means of minimizing electrostatic interference include 1 Shielding Possibilities include a shielded room a shielded booth shielding the sensitive circuit and using shielded cable The shield should always be connected to a solid connector that is connected to signal low If circuit low is floated above ground observe safety precautions when touching the shield Meshed screen or loosely braided cable could be inadequate for high impedances or in strong fields The Keithley Model 6104 Test Shield can provide shielding under many circumstances Note how ever that shielding can increase capacitance in the measur ing circuit possibly slowing down re
81. in the one shot on talk mode with the following statements REMOTE 727 END LINE OUTPUT 727 T1X END LINE One reading can now be triggered and the resulting data ob tained with the following statements ENTER 727 A END LINE DISP A END LINE In this example the ENTER statement addresses the Model 617 to talk at which point a single reading is triggered When the reading has been processed 360msec later it is sent out over to the bus to the computer which then displays the result Model 8573 Programming Exampie Place the instru ment in the T1 mode with the following statements V 1 CALL IBSRE BRDO V return CMD T1X CALL IBWRT M617 CMDS return The instrument can now be addressed to talk to trigger a con version and the resulting data displayed with the following statements RD SPACES 20 CALL IBRD M617 RD return PRINT return Each time the IBRD function is called the instrument is ad dressed to talk at which time it is triggered When the con version is complete 360msec later the reading is sent out over the bus to the computer which then displays the result ing data 3 10 15 SRQ Mask M and Status Byte Format The SRQ command controls which of a number of conditions within the Model 617 will cause the instrument to request ser vice from the controller by asserting SRQ Once an SRQ is generated the status byte can be checked to determine if the Model 617 was t
82. instru ment and experiment as far away from the RFI source as possible Shielding the instrument experiment and test leads will often reduce RFI to an acceptable level In extreme cases a specially constructed screen room may be necessary to suffi ciently attenuate the troublesome signal If all else fails external filtering of the input signal path may be required In some cdses a simple one pole filter may be sufficient In more difficult situations multiple pole notch or band stop filters tuned to the offending frequency range may be required Keep in mind however that such filtering may have other detrimental effects such as increased response time on the measurement 2 14 5 Leakage Resistance Effects At normal resistance levels the effects of leakage resistance are seldom seen because any leakage resistance present is generally much higher than the resistance levels encountered in the circuit under test At the high resistance levels of many Model 617 measurements however leakage resistance can have a detrimental effect on the measurement Such leakage resistance can occur in the circuit under test on PC boards for example in the connecting cable or even at the elec trometer input itelf especially if the input connector is not kept clean To see how leakage resistance can affect measurement ac curacy let us review the equivalent circuit in Figure 2 27 Es and Rs are the source voltage and source resistance resp
83. instrument in the G1 mode and obtain a reading enter the following statements into the HP 85 keyboard REMOTE 727 END LINE OUTPUT 727 BOXG1X END LINE ENTER 727 A END LINE DISP A END LINE When the second statement is executed the instrument will change to the G1 mode The last two statements acquire data from the instrument and display the reading string on the CRT Note that no prefix appears on the data string The above procedure can be repeated with the CO command to re turn to the normal prefix mode Model 8573 Programming Example in the follow ing statements to place the instrument in the G1 mode V 1 CALL IBSRE BRDO 96 V return CMD BOXG1X CALL IBWRT M617 CMD return RD SPACES 20 CALL IBRD M617 CMD return PRINT RD return When the second statement is executed the instrument will be placed in the G1 mode The last two lines obtain the data string from the instrument and display it on the CRT Note that the prefix is absent from the data string The instrument may be returned to the prefix mode by repeating the above procedure with the GO command 3 10 14 Trigger Mode T Triggering provides a stimulus to begin a reading conversion within the instrument Triggering may be done in two basic ways in a continuous trigger mode a single trigger stimulus is used to re start a continuous series of readings In a one shot mode a single reading will be processed each time
84. low frequency noise and drift Cs and can momentarily be ignored 2 34 TO RANGING AMPLIFIER Figure 2 29 Simplified Model for Source Resistance and Source Capacitance Effects Table 2 9 Minimum Recommended Source Resis tance Values in Amps Minimum Source Range Resistance Input amplifier noise and drift appearing at the output can be calculated as follows Equation 1 F Output Input Envise X 1 Tx S Thus it is clear that as long as gt Output in put Enoise When Rs output Enoise 2 X Input Enoise The same applies for Eos The Model 617 will typically show insignificant degradation in displayed performance with the noise gain of 2 resulting from allowing Rs Rpp Typical amplifier input Ejoise is about 94V in a bandwidth of 0 1 10Hz Amplifier can be nulled by using suppress The temperature coefficient of Eos lt 304V C These numbers can be used with Equation 1 to determine ex pected displayed noise drift given any source resistance Note also that the values given in Table 2 9 for minimum source resistance also represent the value of on that range 2 14 8 Source Capacitance In amps the Model 617 is designed to accommodate up to 10 000pF input capacitance Cs This limit will preclude problems in most test setups and allow extremely long input cable lengths without inducing instability or oscillations Increasing capac
85. occurred the instrument was trig gered while processing a reading from a previous trigger 4 A number error has occurred calibration or voltage source values were out of limits Keep in mind that you can program the instrument to assert SRQ under any of these conditions simply by setting bit 5 in the SRQ mask M32X Paragraph 3 10 18 describes how to use the U1 command to obtain information on the type of error from the instrument The 1 command is used to clear the error bit and restore operation of SRQ on error after the error byte is read The bits in the status serial poll byte have the following meanings Reading Overflow Bit 0 Set when overrange input is applied to the instrument except when a current overload oc curs in V I ohms Cleared when a non overflowed reading is available Data Store Full Bit 1 Set when all 100 readings in data store have been taken Cleared by reading a stored reading over the bus B1X Reading Done Bit 3 Set when the Model 617 has com pleted the present reading conversion Cleared by re questing a reading over the bus Ready Bit4 Set when the instrument has processed all previously received commands and is ready to accept addi tional commands over the bus Error Bit 5 Set when an error condition occurs as describ ed above Cleared by reading the error word with the U1 command ROS Bit 6 Set if the Model 617 has asserted SRO Bits 2 and 7 are no
86. on its display is test lead resistance and zero offset 14 Enable suppress on the Model 617 to zero the display 15 Press ZERO on the Model 263 to source 10kQ to the Model 263 The actual value of that resistor will be displayed by the Model 263 16 Adjust the displayed reading on the Model 617 to cor respond to the reading on the Model 263 Table 7 Model 617 Ohms Calibration 617 263 Calibration 617 Guard 263 Resistance 617 Range Switch Guard Nominal Reading ON Enabled OFF Disabled OFF Disabled OFF OFF Disabled Disabled Actual calibration resistance value is displayed on the Mode 263 Permanent Storage of Calibration Constants The procedures given in the preceding paragraphs will temporarily store calibration constants in internal RAM memory and will be lost when the instrument is turned off For calibration to be permanent you must perform NVRAM storage Once all points have been calibrated press PROGRAM SELECT to exit the calibration program Assuming that the calibration jumper is in the enable posi tion calibration constants will be stored in NVRAM and the following message will be displayed briefly Stor MODEL 263 Also constants for uncalibrated ranges are derived at this point If the calibration jumper is in the disable position NVRAM storage will not take place and the following message will be displayed briefly Out Only changed constants
87. pointer Scrolling becomes more rapid if the RECALL button is held in Release the button when the desired data point is displayed 8 The recall mode can be cancelled simply by pressing SHIFT RECALL The instrument will then return to the normal display mode As long as data store is not disabled and then re enabled readings are retained within memory You can return to the recall mode at any time to review data 9 To cancel data store operation press the ON OFF but ton The ON OFF LED will turn off indicating that data store is disabled Data is retained until data store is en abled once again Thus you can still recall data even after data store is turned off Data Store Operating Notes 1 Data logging continues at the selected rate during the recall until all 100 locations have been filled Logging stops when all 100 locations are full as indicated by the flashing DATA indicator 2 The data store trigger mode should not be confused with the front panel trigger mode The data store trigger mode is enabled by entering the special trigger parameter r 6 at the beginning of the data storage process while the front panel trigger mode is entered by pressing SHIFT TRIG 3 If the instrument is placed in the front panel one shot trig ger mode display readings will be triggered at the data store rate interval except when 0 For example if the in strument is set up for 10 minute intervals one reading will be triggered an
88. re moved earlier 7 4 CALIBRATION An advanced feature of the Model 617 is its digital calibration capabilities Instead of the more conventional time consuming method of adjusting numerous calibration poten tiometers the technician need only apply an appropriate calibration signal and digitally calibrate the instrument either from the front panel or over the IEEE 488 bus Some of the calibration procedures will require a shielded test fixture Construction of this fixture is detailed in Figure 7 1 The fixture should be used wherever a shielded enclosure is called for at various places in the procedure Calibration should be performed every 12 months or if the performance verification procedures in Section 5 show that the instrument is out of specification If any of the calibration procedures cannot be performed properly refer to the troubleshooting information in this section NOTE Place the V 9 GUARD switch in the OFF posi tion unless otherwise noted 7 4 1 Recommended Calibration Equipment Table 7 3 lists recommended calibration equipment Alter nate equipment may be used as long as equipment accuracy is at least as good as the specifications listed in the table 7 4 2 Environmental Conditions Calibration should be performed under laboratory conditions having an ambient temperature of 23 C 1 C and a relative humidity of less than 70 Table 7 3 Recommended Calibration Equipment DC Voltage Calibrator 5
89. s s m s ga t t n Recommended Calibration Equipment reiecit E Amps Calibration Volts Calibration Ohms Calibration 02020 404 4 44 6 02 202404244 te ccc sx Static Sensitive Devices 2 2 2 22 22 222 2 Recommended Troubleshooting Equipment Diagnostic Program Phase asa Power Supply Checks Relay Configuration E mS OS OS Oo o tomos o9 o9 o9 omo oo O3 OO os osos SO 40402040402 04 oS t t t on a Q a Ranging Amplifier Gams u s A7D Converter Checks O a ig Preamplifier Checks Ranging Amplifier Checks ovis cedex cosa se ees eee et o a a epi dB Display Board Checks 8o Boa 9 mom om on hos oa 04040040404 090 20420204042 Voltage Source Check o rus ore m eue ode dr pactio ird gt Input Stage Balancing Mother Board Parts List boven __ _ am e CU QUIM prater atta Display Parts AA asas una Electrometer Board Parts 1451 cc ee ae ae Mechanical Parts List O3 dos 3 3o s o t t sg n9 SAFETY PRECAUTIONS The following safety precautions should be obser
90. see Figure 2 23 will appear at the METER COMPLETE OUT PUT jack each time the instrument completes a reading To use the meter complete output proceed as follows 1 Connect the Model 617 to the instrument to be triggered with a suitable shielded cable Use a standard BNC connec tor to make the connection to the Model 617 2 29 CAUTION Do not exceed 30V between the METER COMPLETE common outer ring and chassis ground or instrument damage may occur 2 Select the desired function range trigger mode and other operating parameters as desired 3 In a continuous trigger mode the instrument will output pulses at the conversion rate each pulse will occur after the Model 617 has completed a conversion 4 In a one shot trigger mode the Model 617 will output a pulse once each time it is triggered after it completes the reading conversion READING DONE BEGIN NEXT CONVERSION y Y LS TTL HIGH 3 4V TYPICAL LS TTL LOW 0 25V TYPICAL 1055 MINIMUM Figure 2 23 Meter Complete Pulse Specifications 2 13 3 Triggering Example an example of using both the external trigger input and the meter complete output assume that the Model 617 1 to be used in conjunction with a Keithley Model 705 Scanner to allow the Model 617 to measure a number of different signals which are to be switched by the scanner The Model 705 can switch up to 20 2 pole channels 20 single pole channels with special cards such
91. stops for any reason Once all NDAC and NRFD are properly set the source sets DAV low indicating to accepting devices that the byte on the data lines is now valid NRFD will then go low and NDAC will go high once all devices have accepted the data Each device will release NDAC at its own rate but NDAC will not be released to go high until all devices have accepted the data byte DATA SOURCE DAV SOURCE ACCEPTOR TRANSFER BEGINS DATA TRANSFER ENDS Figure 3 2 IEEE Handshake Sequence Once NDAC goes high the source then sets DAV high to in dicate that the data byte is no longer valid NDAC is returned to its low state and NRFD is released by each device at its own rate until NRFD goes high when the slowest device is ready and the bus is set to repeat the preocess with the next data byte The sequence just described is used to transfer data talk and listen addresses as well as multiline commands The state of the ATN line determines whether the data bus contains data addresses or commands as described in the following paragraph 3 4 BUS COMMANDS While hardware aspects of the bus are essential the interface would have minimal capabilities without appropriate com mands to control communications among the various devices on the bus This paragraph briefly describes the purposes of the various device commands which are grouped into the following three general categories
92. the 210V supplies in case a high exter nal voltage is applied to the PREAMP OUT terminal Output voltage V from the gain stage causes a current to flow through the emitter resistor which is approximately equal to Vin Rg This same current flows through the load resistor which produces a buffered output voltage of Viy and is non inverting 6 5 INPUT FROM GAIN STAGE R309 2 STAGE COMMON OUTPUT R324 do UNE Figure 6 7 Output Stage Configuration Amps and Coulombs 91V AN R304C R317 oV OUTPUT Output stage configuration for the amps and coulombs func tions is shown in Figure 6 7 Q306 and Q307 are the active devices for this configuration Since the power supply voltages are much lower 24V only a single pair of tran sistors is required As with the high voltage configuration signal input is applied through the two diodes to the bases of the transistors This input causes a current V Rg to flow through R309 and R323 This current develops an output voltage V Rj Rg R327 and R324 limit power dissipation at high current outputs for Q306 and Q307 respectively CR306 and CR307 provide protection for the 24V supplies in case a high external voltage is applied to the PREAMP OUT terminal R305 and R308 provide protection for the output stage in this same situation Note that the output stage pro vides
93. the information necessary for you to operate and service your Model 617 Programmable Elec trometer The manual is divided into the following sections Section 1 contains general information about your instru ment including that necessary to unpack the instrument and get it operating as quickly as possible Section 2 contains detailed operating information on how to use the front panel controls and programs make connec tions and basic measuring techniques for each of the available measuring functions Information necessary to connect the Model 617 to the IEEE 488 bus and program operating modes and functions from a controller is contained in Section 3 Typical applications for the Model 617 are included in Sec tion 4 At least one application for each of the measuring functions is included in this section Performance verification procedures for the instrument may be found in Section 5 This information will be helpful if you wish to verify that the instrument is operating in compliance with its stated specifications Section 6 contains a complete description of operating theory for the Model 617 Analog digital power supply and IEEE 488 interface operation is included Should your instrument ever require servicing refer to the information located in Section 7 This section contains in formation on fuse replacement line voltage selection calibration and troubleshooting Replacement parts may be o
94. the instrument s maximum allowable input as defined in the specifications and operation section Safe operation and good measurement practice dictates use of an external resistor when necessary to limit input currents to less than 30mA 1 GENERAL INFORMATION 1 1 INTRODUCTION The Keithley Model 617 Programmable Electrometer is a highly sensitive instrument designed to measure voltage cur rent charge and resistance Two forms of resistance measurements are included in the standard configuration a constant current method and a constant voltage method that uses a built in voltage source for greater sensitivity The measuring range of the Model 617 is between 104V and 200V for voltage measurements O IfA and 20mA in the current mode 0 10 and 200GQ up to 10160 using the built in voltage source and 10fC and 20nC in the coulombs mode The very high input impedance and extremely low input offset current allow accurate measurement in situations where many other instruments would have detrimental effects on the circuit be ing measured A 4 digit display and standard IEEE 488 in terface give the user easy access to instrument data 1 2 FEATURES Some important Model 617 features include 414 Digit Display An easy to read front panel LED display includes a 4 digit mantissa plus a two digit alpha or numeric exponent Autoranging Included for all functions and ranges Digital Calibration The instrument may b
95. the unit must receive a talk command before it will transmit its data The a Date Model 617 is shipped from the factory with a programmed 2 DIO2 Data primary address of 27 Until you become more familiar with 3 DIO3 Data your instrument it is recommended that you leave the ad I 4 DIO4 Data dress at this value because the programming examples includ 5 24 Management ed in this manual assume that address 6 DAV Handshake 380 Handshake The primary address may be set to any value between 0 and 8 NDAC Handshake 30 as long as address conflicts with other instruments are 9 IFC Management avoided Note that controllers are also given a primary ad 10 SRQ Management dress so you must be careful not to use that address either 11 Management Most frequently controller addresses are set to 0 or 21 but 12 SHIELD Gre nd you should consult the controller s instruction manual for details Whatever primary address you choose you must 13 DIOS Data make certain that it corresponds with the value specified as 14 0106 Data part of the controller s programming language 15 0107 Data 16 DIO8 Data 17 REN 24 Management To check the present primary address or to change to a new 18 6 Ground one use the following sequence 19 Gnd 7 Ground 1 Press the PROGRAM SELECT button repeatedly until the 20 Gnd 8 Ground following message is displayed 21 Gnd 9 Ground 22 Gnd 10 Ground IEEE 27 2 d er C 22 2 Thi
96. then transmitted line 90 and the error condition word is then obtained and displayed lines 100 and 110 Line 120 then sends the U2 command and the data condition word is obtained and displayed in lines 130 and 140 To show that status is transmitted only once a normal reading is then re quested and displayed lines 150 and 160 3 11 Front Panel Messages The Model 617 has a number of front panel messages associated with IEEE 488 programming These messages are intended to inform you of certain conditions that occur when sending device dependent commands to the instrument The following paragraphs describe the front panel error messages associated with IEEE 488 programming 3 11 1 Bus Error A bus error will occur if the instrument receives a device dependent command when it is not in remote or if an illegal device dependent command IDDC or illegal device depen dent command option IDDCO is sent to the instrument Under these conditions the complete command string will be rejected and the following message will be displayed b Err In addition the error bit and pertinent bits in the U1 word will be set paragraph 3 10 15 and 3 10 18 and the instru ment can be programmed to generate an SRQ under these conditions paragraph 3 10 15 A no remote error can occur when a command is sent to the instrument when the REN line is false Note that the state of REN is only tested when the X character is received An IDDC error ca
97. to the IEEE 488 bus in general is located in paragraphs 3 2 through 3 6 2 Information necessary to connect the Model 617 to the IEEE 488 bus is contained in paragraphs 3 7 and 3 8 3 General bus command programming is covered in para graph 3 9 4 Device dependent command programming is described in paragraph 3 10 These are the most important commands associated with the Model 617 as they control most of the instrument functions 5 Additional information necessary to use the Model 617 over the IEEE 488 bus is located in the remaining para graphs 3 2 BUS DESCRIPTION The IEEE 488 bus which is also frequently referred to as the GPIB General Purpose Interface Bus was designed as a parallel transfer medium to optimize data transfer without us ing an excessive number of bus lines In keeping with this goal the bus has only eight data lines that are used for both data and with most commands Five bus management lines and three handshake lines round out the complement of bus signal lines typical configuration for controlled operation is shown in Figure 3 1 The typical system will have at least one controller and one or more devices to which commands are given and in most cases from which data is received Generally there are three categories that describe device operation controller talker and listener TO OTHER DEVICES DEVICE 1 ABLE TO TALK LISTEN AND COMPUTER S DATA BUS DEV
98. 0 474F 100V Metalized Polyester 3 B3 05 C 305 047 Capacitor 22pF 1000V Ceramic Disc 1 1 E5 C 64 22p Capacitor 0 472 50V Ceramic Film 1 4 E5 237 47 Capacitor 33pF 1000V Ceramic Disc 3 F3 F5 C 64 33p Capacitor 104F 25V Aluminum Electrolytic 3 C4 C5 C 314 10 Capacitor 0 1nF 16V Ceramic Disc 1 54 F5 C 22 02 Capacitor 390pF 500V Polystyrene 1 F3 F5 C 138 390p Capacitor 47gF 25V Aluminum Electrolytic 1 5 F5 C 314 4 7p Capacitor 100V 00474F Ceramic Disc C 64 0047 Capacitor 33uF Polyester C 344 33 Capacitor 0154F 500V Ceramic Disc C 22 015 Capacitor 0 1 500V Ceramic Disc 22 01 Diode Silicon 1N4006 1 B5 B1 RF 38 Diode Silicon 1N4148 2 A3 01 RF 28 Diode Silicon 1N4148 2 A3 El RF 28 Diode Silicon 1N4148 2 B2 El RF 28 Diode Silicon 1N4148 2 B3 El RF 28 Diode Silicon 1N4148 2 81 F1 RF 28 Diode Silicon 1N4006 1 85 82 RF 38 Diode Silicon 1N4006 1 84 B2 RF 38 Diode Silicon 1N4006 1 85 B2 RF 38 Bridge Silicon 1A 100PIV 1 B5 C2 RF 52 Diode Silicon 1N4148 1 F3 F4 RF 28 Diode Silicon 1N4148 RF 28 Diode Silicon 1N4148 RF 28 Table 8 1 Mother Board Parts List Cont Circuit Location Keithley Desig Description Sch Part No CR114 115 CR116 F101 F101 F102 41010 101
99. 1 1012 1013 4014 1015 J1016 J1017 J1018 J1019 K101 Q101 0102 0103 0104 0105 0106 0107 0108 0109 0110 0111 0112 0113 R101 R102 R103 R104 R105 R106 R107 R108 R109 R110 R111 R112 R113 R114 R115 R116 R117 Diode Silicon 1N4148 Diode Silicon 1N4148 Diode Silicon 1N4006 RF 28 RF 28 RF 38 Line Fuse A 250V 3AG SLO BLO 105 125V operation Line Fuse 1 8 250V 3AG SLO BLO 210 250V operation Fuse 1 16A 250V AGC 1 16 Connector IEEE Connector Not Used Connector Connector 14 pin Connector Connector Pin Contact Connector Connector 17 20 FU 86 1 CS 377 CS 388 5 288 3 CS 389 5 CS 339 3 50 68 24249A CS 339 3 F4 CS 339 3 Relay RL 90 Transistor Silicon NPN 2N3904 Transistor Silicon PNP 2N3906 Transistor N Channel JFET Transistor P Channel JFET Transistor N Channel JFET Transistor Selected Transistor N CHannel JFET Transistor N Channel JFET Transistor Silicon PNP 2N3906 Transistor P Channel JFET Transistor NPN Silicon Annular Transistor PNP Silicon Annular Transistor N Channel Enhancement Mode MOSFET TG 47 TG 84 TG 139 TG 166 TG 128 617 600 TG 139 TG 128 TG 84 TG 166 TG 146 TG 147 TG 177 Resistor 1000 5 W Composition Resistor 1000 5 W
100. 1 23456E 00 012 Continuous Trigger by Talk One Shot Trigger by Continuous Trigger by GET One Shot Trigger by GET Continuous Trigger by X One Shot Trigger by X Continuous Trigger by External Trigger One Shot Trigger by External Trigger Disable SRO Reading Overflow Buffer Full Reading Done Ready Error Enable EO and Bus Hold off On X Disable EOI Enable Bus Hold off On X Enable EO Disable Bus Hold off On X Disable both EOI and Bus Hold off On X Terminator LF CR Terminator CR LF Terminator ASCII Character No Terminator Send Status Format 617 FRRCZNTOBGDOMMKYY Error Conditions Data Conditions 3 10 14 3 10 17 HP 85 Programming Example Make sure the instrument is in the autorange mode and then enter the following statements into the HP 85 The range command gives the user control over the sensitivi ty of the instrument This command and its options perform essentially the same functions as the front panel AUTO and up and down range buttons Range command parameters and the respective ranges for each measuring function are sum marized in Table 3 12 The instrument will be ready to take a reading after the range is set up when responding to a range command Upon power up or after receiving a DCL or SDC command the instrument will be in the RO autorange mode 3 20 REMOTE 727 END LINE OUTPUT 727 R3X END LINE When t
101. 101 and associated resistors The purpose of these components is to make sure that erroneous and possible dangerous voltages do not appear at the voltage source output during power up For example if the Model 617 power is briefy turned off and then back on the voltage source output might otherwise be at some undetermined value because of random data appearing on the DAC inputs The protection circuit eliminates this potential problem by briefly opening up the contacts of K101 under these circumstances 6 8 POWER SUPPLIES The Model 617 has numerous power supplies which are used to power the analog digital and voltage source circuits Diagrams of these supplies may be found on drawing numbers 617 106 page 1 and 617 166 The power supplies are essentially divided into two groups one group powers the digital and voltage source circuits while a second group of supplies is used to power the input circuits Each group of supplies has its own power supply transformer This configuration is used to maintain proper isolation between the voltage source and digital circuits and sensitive analog circuitry AC power is applied to J1011 which is the power connector located on the rear panel of the instrument 5101 is the POWER switch located on the front panel while S102 is the line voltage selection switch When S102 is in the 115V posi tion the primary windings are connected in parallel when S102 15 in the 230V position the T101 windings
102. 11 and 6011 10 Triaxial Cables The Model 6011 is made up of 3 feet of triaxial cable that is terminated with a triax plug on one end and 3 alligator clips on the other end The Mode 6011 10 is a similar cable 10 feet in length Note that the Model 6011 is supplied with the Model 617 Model 6012 Triax to UHF Adapter The Model 6012 allows the Model 617 to be used with accessories having UHF type connectors Model 6101A Shielded Test Lead The Model 6101A is a straight through probe and shielded lead equipped with 0 8m 307 of shielded low noise cable terminated by a Teflon insulated UHF connector The Model 6012 must be used to adapt the Model 6101A to the Model 617 triaxial input Model 6103C Voltage Divider Probe The Model 6103C ex tends Model 617 voltage measurement range to 30kV The Model 6103C has a division ratio of 1000 1 with a nominal accuracy of 5 The probe has an input resistance of 4 5 X 1010 and is equipped with a UHF male plug The Model 6012 adapter must be used to connect the Model 6103C to the Model 617 Model 6104 Test Shield The Model 6104 facilitates resistance voltage or current measurements with either 2 or 3 terminal guarded connections at voltages up to 1200V The Model 6104 provides excellent electrostatic shielding and high isolation resistance Clips plug into banana jacks allowing custom connections The Model 6104 has a BNC connector on one side and binding posts on the other The Model 6147 ada
103. 12 Non Volatile Memory Storage L The Model 617 uses non volatile NV RAM to store calibra tion parameters Once the instrument has been calibrated as described in the last paragraph the NVRAM storage com mand should be sent to permanently store these parameters This procedure is performed by sending the following se quence 1 NVRAM storage will take place when the in strument receives this command over the bus Note that storage may be disabled by changing the position of a Calibration jumper as described in Section 7 If the jumper is in the enabled position all calibration must be properly done or calibration of all functions and ranges will be af fected NOTE Do not perform the following programming ex amples unless actual NVRAM storage is desired Unless proper calibrating parameters have been previously programmed inadvertent use of this command could affect instrument accuracy HP 85 Programming Example Use statements to perform NVRAM storage the following REMOTE 727 END LINE OUTPUT 727 L1X END LINE NVRAM storage will be performed when the second state ment is executed Model 8573 Programming Example Perform storage with the following Model 8573 statements V 1 CALL IBSRE BRDO CMD return CMD 11X CALL IBWRT M617 return NVRAM storage is performed when the second statement is executed 3 10 13 Data Format G Through the use of the G comman
104. 206 the LED annunciators DS207 DS224 the segment drivers U201 and U202 and the digit select circuitry U204 0201 and U203 DS202 DS205 are standard 7 segment units while DS206 is a dual 14 segment display The display is updated at 1 56msec intervals Timing for this process is performed by a 640Hz clock which controls the seg ment latches U110 and U116 located on the mother board Each time an interrupt is generated the MPU writes segment data for two digits to the segment latches The two latches outputs are then enabled in sequence by the 640Hz clock When a latch output is enabled segments in the selected digit are turned on Digit selection is performed by data from the PA3 PA4 and PAS outputs of the MPU to control U203 A single U203 out put corresponding to the selected digit will go low when the correct data appears on its inputs For example if 010 ap pears on the inputs of U203 DS201 will be turned on Selection of the display annunciators is performed in a similar manner The data stored in the corresponding segment lat ches will then turn on the appropriate annunciator LEDs Front panel switches are read in a somewhat similar manner by using a row column matrix along with U206 To select a particular row data is transmitted out the MPU PA3 PA4 and PAS lines to U206 This action selects one of the rows by placing the corresponding output of U206 high Matrix col umns are then read by reading data in
105. 3 Electrometer Board Parts List Cont Circuit Location Keithley Desig Description Sen re Part No DIP Cable CA 27 2 Transistor NPN Silicon Annular MPS U10 C4 D2 TG 146 Transistor N Channel J FET 2 TG 128 Transistor PNP Silicon Annular MPS U60 D3 TG 147 Transistor NPN Silicon Annular MPS U10 C3 D2 TG 146 Transistor PNP Silicon Annular MPS U60 C6 D3 TG 147 Transistor NPN Silicon Annular MPS U10 04 D2 TG 146 Transistor PNP Silicon Annular MPS U60 DS D3 TG 147 Transistor Selected Dual JFET B4 617 606 Transistor NPN Silicon Annular MPS U60 64 TG 145 Transistor PNP Silicon Annular MPS U60 E2 E2 TG 177 Resistor 330kQ 1096 W Composition C3 D2 R 1 330k Resistor 330kQ 10 Composition C4 C2 R 1 330k Resistor 900kQ 0 1 1 10W Metal Film B3 F2 R 283 900k Resistor Thick Film B3 F2 191 Resistor 10kQ 596 5 D4 D2 R 329 10k Resistor 7680 1 1 8W Composition C4 02 R 88 768 Resistor 7680 1 1 8W Composition C5 D3 R 88 768 Resistor 10kQ 5 W D5 D3 R 329 10k Resistor 1000 5 W Composition D4 02 R 76 100 Not Used Resistor 1800 5 Composition G4 R 76 180 Resistor 1002 0 1 W Metal Film B4 2 R 169 100 Resistor Selected B3 F2 617 601 Potentiometer 10kQ 2 RP 89 10k Resistor 1 87kQ 1 1 8W Composition C3 F2 R 88 1 87k Resistor 2 78kQ 0 196 1 10W Metal Film C3 F2 R
106. 4 Zero correct the instrument by enabling zero check and then zero correct in that order 5 Disable zero check and allow sufficient time for the reading to settle Set the Model 617 calibration value to the exact resistance obtained for the 1 resistor in step 1 Either use the front panel calibration program or send the calibration value over the bus For example if the resistor measured 1 012GQ the following command would be sent A1 012E9X 6 Enable zero check and disconnect the 100 resistor from the instrument Substitute the 100MQ resistor in its place The shielded enclosure should be retained 7 Set the instrument to the 200 range and disable zero check 160 100MQ 10 000MQ 1 900 0 190 000 19 617 Displayed IEEE 488 Value Bus Command 8 After allowing sufficient settling time set the Model 617 calibration parameter to the exact resistance value obtain ed for the 100MQ resistor in step 1 Again use either the calibration program or send the value over the bus 9 Enable zero check and place the GUARD switch in the OFF position Disconnect the 100 0 resistor and shielded enclosure from the instrument Substitute the decade resistance box in its place as shown in Figure 7 9 10 Select the 20M range and set the decade box to the value listed in the table 11 Zero correct the instrument With zero check disabled set the Model 617 calibration parameter to the requ
107. 65 program for 19nC 350 OUTPUT 727 CQX 617 disable zero check 350 WAIT 2000 570 OUTPUT 727 NiX 617 enable suppress 580 OUTPUT 708 01 283 output 20 to 617 390 WAIT 2500 400 2 200 8 OUTPUT 727 ALSE SX 617 send cal value 410 WAIT 2000 420 PRINT RANGES CALIBRATED 430 PRINT 2 nC 8 PRINT 440 OUTPUT 708 F2RIUISQOE 3X 263 program for 180mU 450 DATA 19 1 9 19 46 FOR 1 1 TO 3 470 OUTPUT 727 C1ZO0NOFOR I X 617 select volts range 480 OUTPUT 708 R I Z101X 265 select range output 490 OUTPUT 727 ZiXCOX 617 enable z cor and disable z chk 500 OUTPUT 727 NIX 617 enable suppress 510 OUTPUT 708 ZOX 263 output programmed voltage 520 READ U 530 WAIT 2000 CLEAR 540 2 200 8 OUTPUT 727 A U X 617 send cal value 550 WAIT 2000 550 NEXT 1 570 OUTPUT 727 Z NORAX 617 select 200 range 580 OUTPUT 708 F501X 253 source ext V to 617 590 WAIT 2000 600 2 200 8 OUTPUT 727 190 617 send cal value 510 WAIT 2000 620 OUTPUT 727 C1F2R8X 617 select 20 range 630 PRINT VOLTS RANGES CALIBRATED 64 PRINT All 6 PRINT 650 OUTPUT 708 FORSUIX 283 select range guard on 660 8 DISP SET GUARD SWITCH TO POSITION 670 DISP 8 DISP PRESS CONT TO CONTINUE 680 PAUSE 530 FOR 1 8 TO 2 ST
108. 8 0117 Quad 2 input NOR Gate 74 2 Sev D3 IC 412 U118 IC Triple 3 Input NAND Gate 74 10 Sev IC 341 0119 Octal GPIB Transceiver 75161A 2 H3 iC 299 0120 Octal GPIB Transceiver 75160A 2 H2 IC 298 0121 Opto Coupler HCPL 2601 2 A4 D4 1C 239 0122 IC Opto Coupler HCPL 2601 3 G1 04 239 0123 Opto Coupler HCPL 2200 1 ET E4 IC 411 U124 IC Opto Coupler HCPL 2200 1 2 E4 1C 411 0125 Opto Isolator FCD 820 2 5 F4 82 0126 Dual D Flip Flop 74HC74 3 F3 B4 337 0127 74HC4040 B4 407 0128 Quad 2 NOR Gate 74 2 Sev C4 412 0129 CMOS Static Shift Register CD4015AE 3 F2 4 IC 136 0130 IC Operational Amplifier ICL7650 3 B3 D4 IC 316 U131 1 8 Stage Shift Store Register MC14094 1 B3 E4 IC 251 U132 4520 1 B2 E4 IC 324 U133 8 Stage Shift Store Register MC14094 3 C2 C4 IC 251 0134 Operational Amplifier 741 1 81 E5 IC 42 0135 IC Triple 3 Input Gate 74HC10 Sev C5 341 136 Triple 2 Channel Multiplexer CD4053BC Sev B5 283 0137 Dual Voltage Comparator LM393 4 B5 1C 343 0138 Operational Amplifier TLC272C 3 04 C5 1C 408 0139 IIC Programmable Operational Amplifier TLC271 3 B4 C5 1C 347 U140 1 8 Stage Shift Store Register MC14094 1 83 E5 IC 251 U141 12 Bit DAC AD7541JN 1 C3 E5 iC 247 0142 Operational Amplif
109. 85 Programming Example This sequence 15 automatically performed by the HP 85 when the following is typed into the keyboard REMOTE 727 END LINE After the END LINE key is pressed the Model 617 will be in the remote mode as indicated by the REMOTE light If not check to see that the instrument is set to the proper primary address 27 and check to see that the bus connections are properly made Model 8573 Programming Example To place the Model 617 into the remote mode type the following lines into the computer V 1 CALL IBSRE BRDO return CMD X CALL IBWRT M617 return Table 3 9 General Bus Commands and Associated BASIC Statements HP 85 Model 8573 Statement Affect On Model 617 V 1 CALL IBSRE BRD0 V Goes into remote when next addressed CALL IBSIC BRD0 Goes into talker and listener idle states LOCAL LOCKOUT 7 CMD CHR amp H11 CALL IBCMD Front panel controls locked out M61796 CMD CALL IBLOC M61796 Cancel remote CMDS CHRS amp H14 CALL IBCMD Returns to default conditions 617 CMD CALL IBCLR M617 Returns to default conditions CALL IBTRG M61796 Triggers reading in T2 and T3 modes V 0 CALL IBSRE BRDO V96 Cancel LLO LOCAL 727 CLEAR 7 CLEAR 727 3 13 The instrument will go into the remote mode when the return key is pressed the second time 3 9 2 IFC interface Clear The IFC command is sent by the controller to place the
110. A 11 Ee 151 KISA DS A Tes 25150 28 3 H3 716 2000 WNIS amp K 76 4 34 i6 148 7 7 235 2220 4824 179 2 124 7 IC 6152 FS AA 2zG 2 42 52 Y 3 1201 7155 F4 Ubolle IMi 215105 1760 1122 CA MCN Al 5 meum qm pol ______ assem y Conor scare sona Ounces 5 2 COMPONENT LAYOUT ojo VA ate tr MOTHER BOARD KEITHLE FRAC NO mum mee 617100 D E G H Figure 8 2 Mother Board Component Location Drawing Dwg No 617 100 Sheet 2 of 2 8 15 8 16 8L 8 L 8 0LL ZL9 Bulmeig pieog ejdsig 2 8 3 Y 07 1177 O 24 5g 9 7 sas 9 LA SEE ALA r UREA ESA PL L FT WES Cem E2277 56 N TEE 22 22 Y 72 C Oy V EAr PROL Sy OZE 5m E i ON 1474 123735 NOLLNSHSAd EE Sere TELAS PS 26 Ru EZ 7721572 OI SD sprees 57 tea Fave A at 2 3 27 Ste 1725 M eG WZS u 05 bf ZQ j mM i Sm lt 125
111. BACK ELEMENTS SWITCHES OUTPUT RANGING STAGE AMPLIFIER V SOURCE VOLTAGE CONTROL SOURCE LO CURRENT LIMIT PANEL BUTTONS POWER SUPPLY Figure 6 1 Overall Block Diagram ANALOG DIGITAL A D CONVERTER DISPLAY IEEE 488 INTERFACE FEEDBACK AND SWITCHING GAIN STAGE 0309 INPUT STAGE 0308 OUTPUT STAGE 0301 0302 0307 OUTPUT TO RANGING AMPLIFIER SIGNAL INPUT Figure 6 2 Basic Configuration of Electrometer Preamplifier The exact configuration of the input preamplifier will depend on the measuring function Figure 6 3 shows circuit con figuration for the four measuring functions In the volts func tion the circuit is set up as a high input impedance 2 X 10140 unity gain non inverting buffer amplifier In the ohms function a bootstrapped reference 15 placed in series with a range resistor drives a constant current through the measured resistance Ry The reference has a value of 10V 1V or 0 1V depending on the selected range The voltage developed across the unknown resistance is propor tional to its value In the amps and coulombs modes the circuit is configured as a feedback type current to voltage converter In the amps mode the feedback element is a resistor with the value dependent on the selected range In the coulombs mode the feedback element is a capacitor 6 3 1 Input Stage A simplified schematic of the input stage is shown in Figure 6 4 The
112. Connections for Amps Calibration 20pA 7 5 Connections for Amps Calibration 20nA 204A and 20mA Ranges 7 6 Connections for Coulombs 2222222222222 222 2 2 22 aa 7 7 Connections for Volts Calibration pk TERE Oe ODORS Sede Os 7 8 Connections for Ohms Calibration 20GQ and 200 9 7 9 Connections for Ohms Calibration 20 0 20 0 7 10 Connections for Voltage Source Calibration vies da nhieu gas 7 11 Model 617 Exploded View CS vii 8 1 Electrometer Board Component Location Drawing 8 2 Mother Board Component Location Drawing 8 3 Display Board Component Location 22222 222 8 4 Electrometer Board Schematic Diagram 8 5 Mother Board Schematic Diagram 8 6 Display Board Schematic Diagram vili LIST OF TABLES 2 1 Display Error Messages 2 2 Front Panel Program Messages 2 3 Typical Display Exponent Values
113. Current Gains 2 11 USING ZERO CORRECT AND BASELINE SUPPRESSION The Model 617 has zero correction and baseline suppression modes that allow the cancellation of any internal offsets or the storage of a baseline value that can be subtracted from subsequent readings 2 11 1 Zero Correct and Zero Check The ZERO CORRECT and ZERO CHECK buttons work together to cancel any internal offsets that might upset ac curacy Note that the specifications listed for the instrument at the front of this manual assume that the instrument has been zeroed Use the following procedure to zero the instru ment Note that the zero should be corrected on the range to be used or on the lowest range of the function being used 1 With the zero correct mode off press the ZERO CHECK button Be sure ZERO CHECK light is on In this mode the input signal is disconnected from the input amplifier and the input circuit is configured as shown in Figure 2 21 The internal preamplifier is configured to measure its own offset when zero check is enabled 2 Press the ZERO CORRECT button to zero the instrument Note that if zero check is not enabled the zeroing process will not take place The previously stored zero parameter will be used instead 2 26 3 To take readings press ZERO CHECK to disable the zero check mode 4 Readings can now be taken in the normal manner Note that the instrument will remain zeroed even if the instru ment is upranged 5 For maxim
114. DATA STORE ON OFF RECALL EXIT PROGRAM SELECT EXIT O OPERATE ESO 2mA Figure 2 1 617 Front 2 4 FRONT PANEL FAMILIARIZATION The front panel layout of the Model 617 is shown in Figure 2 1 The front panel may be divided into two sections con trols and display indicators The following paragraphs describe each of these items in detail 2 4 1 Controls All front panel controls except POWER are momentary con tact switches Many control buttons include an annunciator light to indicate the selected mode Some buttons have a secondary function that is entered by pressing the SHIFT but ton before pressing the desired button All such buttons ex cept ADJUST are marked in yellow The controls are color coded into functional groups for ease of operation POWER The POWER switch controls AC power to the in strument Depressing and releasing the switch once turns the power on Depressing and releasing the switch a second time turns the power off The correct positions for on or off are marked on the front panel immediately above the POWER switch 2 2 SHIFT The SHIFT button adds a secondary function to some of the other front panel controls including VOLTS TRIG OHMS RECALL and PROGRAM SELECT Note that the shift function is entered by pressing SHIFT before the second button rather than pressing the two simultaneously ELECTROMETER The ELECTROMETER buttons control the
115. Duc e EN Calibration Sequence o AATPERS x EARS bod Xx apasha hunta Sa Input Offset Adjustment A Input Current d bsp s Permanent Storage of Calibration Amps Calibration u dec us cn _ _ _ _ BUR Rea M EE Coulombs Calibration ea ei Volts Calibration Shims E Voltage Source Additional Calibration Points dee ce Special Handling of Static Sensitive Devices Disassembly a Troubleshooting ses ore nook Recommended Test Equipment lle he Power Up PM E Self Diagnostic Program Power Supply Checks coches nie Relay Configuration ones irritan da RR Heese EC RSS REPE Red EE WE Ranging Amplifier Gain Configuration 7 7 7 A D Converter and Display i5 ia gu RARA b e an bee Paco de ed 7 7 8 Input and Ranging Amplifiers r edid 7 7 9 Digital Circuitry daha o sa sa 7 7 10 Display Board O OCT LT UTD AS 7 7 11 Vol
116. EP 1 700 IF 1 8 THEN 770 710 I 7 THEN 770 720 CLEAR 730 0 DISP SET 617 GUARD SWITCH TO OFF POSITION 740 DISP DISP PRESS CONT CONTINUE 750 PAUSE 760 CLEAR 8 OUTPUT 708 WOX 263 disable guard 770 OUTPUT 708 R I XZ101X 263 output ohms to 617 780 OUTPUT 727 Ci1Z0NOR I X 617 select range 790 OUTPUT 727 ZiXCOXNI1X 617 zero display OUTPUT 708 Z X 1 263 source programmed resistance 617 CALIBRATION PROGRAM Cont A 15 16 WAIT 7000 ENTER 708 263 send resistance reading 2 200 OUTPUT 727 B17 send cal value WAIT 3000 NEXT 1 PRINT OHMS RANGES CALIBRATED PRINT 208ohm 26ohm 200Mohm 20Mohm 2Mohm 200kohm 20kohm 8 DISP B DISP DO YOU WISH TO PERMANENTLY STORECAL CONSTANTS Y NO INPUT B CLEAR IF B Y THEN 940 DISP CAL CONSTANTS NOT STORED 6 DISP DISP ALTERED RANGES TEMPORARILY CAL IBRATED 5070 970 OUTPUT 727 L1X 617 store cal constants DISP IF JUMPER IN ENABLE POSITION 015 8 DISP ALL FUNCTIONS RANGES PERMANENTLYCALIBRATED END 617 CALIBRATION PROGRAM Cont KEITHLEY Service Form Model No Serial No Date Name and Telephone No Company List all control settings describe problem and check boxes that apply to problem 1 Intermittent 1 Analog output follows display J Particular range or function bad specify J IEEE failure
117. Figure 2 16 Full range outputs for various functions and ranges are listed in Table 2 6 The PREAMP OUTPUT is not corrected during calibration Gain errors of up to 3 may appear at this output depending on function and range selec tion For all volts ranges PREAMP OUTPUT accuracy is typically 5ppm Table 2 5 Typical 2V Analog Output Values Applied 2V Analog Range Signal Output Value Rs 10 0 2V ANALOG OUTPUT MODEL 617 Rp 2 0 X10 200kQ X1 20 0 X0 1 2kQ X0 01 INPUT FROM PREAMP Table 2 6 Full Range PREAMP OUT Values Full Range Range Value 20GQ Coulombs 200pC 2nC WARNING Open circuit voltage of 300V present at PREAMP OUT in Ohms 2 2nA 24A 2mA 20pA 20nA 204A 20mA 200pA 200nA 200 2kQ 20k0 2GQ MODEL 1683 TEST LEAD KIT MEASURING DEVICE EXAMPLE CHART RECORDER 617 2V ANALOG OUTPUT INPUT RESISTANCE OF MEASURING DEVICE EQUIVALENT CIRCUIT Figure 2 15 Typical 2V Analog Output Connections 2 20 WARNING Note that the output resistance is 1000 The output resistance High voltage may be present between the appears between Input Low and Analog Output Low to keep PREAMP OUT and COM terminals depend the resistor out of the loop when using external feedback ing on the input signal see Table 2 6 elements To keep loading errors under 0 1 the device con nected to the PREAMP OUT should have a minimum input CA
118. For example to enable SRQ under reading overflow and buffer full conditions send M3X To disable SRQ send MOX This command will clear all bits in the SRO mask Table 3 13 580 M Command Parameters Generate SRQ Disabied Reading Overfiow Data Store Full Reading Done Ready Error M1 Status Byte Format The status byte contains information relating to data and error conditions within the instrument The general format of the status byte which is obtained by using the serial polling sequence as described in paragraph 3 9 is shown in Figure 3 9 Note that the various bits corres pond to the bits in the SRQ mask as described above sosmon 57 se ss sa sz o uo vo vo ve o e wo occa Pete pelo WEIGHTING 12 READING OVERFLOW 12 DATA STORE 1 READING DONE 1 ROS BY STATUS BYTE ONLY 1 ERROR 1 READY Figure 3 10 Mask and Status Byte Format Bit 6 provides a means for you to determine if SRQ was asserted by the Model 617 If this bit is set service was re quested by the instrument Bit 5 flags a Model 617 error con dition which can be further checked with the Ul com mand If this bit is set one of the following errors has occurred 1 An illegal device dependent command IDDC or illegal device dependent command option IDDCO was trans mitted 2 The instrument was programmed when not in remote 3 trigger overrun has
119. GINEERING UNITS CONVERSION The Model 617 is a highly sensitive instrument with wide ranging measurement capabilities In the amps mode for ex ample the unit can detect currents as low as 10 16A At the other extreme resistances in the 10160 range can be measured The instrument can display its reading either in engineering units such a or in scientific nota tion such as 10 3A Table 2 10 lists engineering units and their equivalent scientific notation values Tabie 2 10 Engineering Units Conversion f p n k M G T Table 2 11 Equivalent Voltage Sensitivity of 617 Amps Ranges Equivalent Voltage Sensitivity V count Range 2pA 2nA 2uA 2mA 20pA 20nA 204A 20mA 1004V 200pA 200nA 200 1mV te M M M e e 2 35 2 36 SECTION 3 488 PROGRAMMING 3 1 INTRODUCTION The IEEE 488 bus is an instrumentation data bus with hard ware and programming standards originally adopted by the IEEE institute of Electrical and Electronic Engineers in 1975 and given the IEEE 488 designation In 1978 standards were upgraded into the IEEE 488 1978 standards The Model 617 conforms to these IEEE 488 1978 standards This section contains general bus information as well as the necessary programming information and is divided into the following sections 1 Introductory information pertaining
120. ICE 2 ABLE TO TALK AND LISTEN 617 DATA BYTE TRANSFER CONTROL DEVICE 3 ONLY ABLE TO LISTEN PRINTER GENERAL INTERFACE MANAGEMENT DEVICE 4 ONLY ABLE TO TALK DMM 0101 8 DATA 8 LINES DAV NRFD SRQ 7 BUS MANAGEMENT REN EOI Figure 3 1 IEEE Bus Configuration The controller does what its name implies it controls other devices on the bus A talker sends data usually to the con troller while a listener receives data Depending on the in strument a particular device may be a talker only a listener only or both a talker and a listener There two categories of controllers system controller and basic controller Both are able to control other in struments but only the system controller has the absolute authority in the system In a system with more that one con troller only one controller may be active at any given time Certain protocol is used to pass control from one controller to another The IEEE 488 bus is limited to 15 devices including the con troller Thus any number of talkers and listeners up to that limit may be present on the bus at one time Although several devices may be commanded to listen simultaneously the bus can have only one active talker or communications would be scrambled A device is placed in the talk or listen state by sending an ap propriate talk or listen command These talk and listen c
121. LrC 2 11482 126 32 22 A OS 2 ZAR TCA 125 3 sr z 154 2 eL 1214 2 725 Ea 1215 70 393 1157 KS 2 gt Iio E B ISIE R ANVIL Ne Ben DAR 471211100 04 an RISE 24 EA Le as beta eee UII e E C VNS ETA 1 VEN 1001 05294 F5 en oe 180 22 18 Oe El see ES 101 10 225 95 224117 205 11143 jes Te ito 1421 7 8 0 TA 7 147 RISE 1104 2 11 O2 E W 10O KIS 1125 aa T T A E ZL 22K 2 795 52 52 11101 102 ANC Se tros MI 021 702 _______ amp i5 200K 52 5 S Z C 538 DDA 1872425 25 2 4 4011 L1 RT a 0108 Ee _ 52 38 124 1051 R 7 i00 Di 4 FS OS vela 21 521 2 142 DS 2272381 TO 02 54 118115125 TE 1501071427200 1900 14 EZ KANP 20 L 1 07 004 122 1 ie K 203 ZoKR OS 7 J 52 49 221 YA ES 157 K 252 2x DS 192 70 253 10104 14853 23211 o 28 Yo ___ 15211 152 05 T AEREAS ANA if A AUA O T1 43 255 103 EL pd Flo A ae 72 5116 42 nap D StSC 55 ZA SSO GOM He w RIOT iFZ Bil 172 RIMA DNS 1235 1 4 VETA e EIA SEC
122. Model 617 in the local talker and listener idle states The unit will respond to the IFC command by cancelling front panel TALK or LISTEN lights if the instrument was previously placed in one of those modes To send the IFC command the controller need only set the IFC line true for a minimum of 100ysec HP 85 Programming Example Before demonstrating the IFC command turn on the TALK indicator with the follow ing statements REMOTE 727 END LINE ENTER 727 END LINE At this point the REMOTE and TALK lights should be on The IFC command can be sent by typing in the following statement into the HP 85 ABORTIO 7 END LINE After the END LINE key is pressed the REMOTE and TALK lights will turn off indicating that the instrument has gone in to the talker idle state Model 8573 Programming Example Place the instru ment in the remote and talker active states with the following statements V 1 CALL IBSRE BRDO V return CMD CHR amp H5B CALL IBCMD BRDO CMD return After the return key is pressed the second time the instrument should be in the remote and talker active states as indicated by the respective indicators To send IFC enter the following statement into the IBM PC CALL IBSIC BRDO return 3 14 After the return key is pressed the instrument will return to the local and talker idle states 3 9 3 LLO Local Lockout The LLO command is used to remove the instrument from the
123. Model 617 exhibits low input voltage burden and extremely low input offset current The low voltage burden is achieved because the Model 617 measures current as a feedback type picoammeter rather than the shunt method used by many DMMs NOTE After measuring high voltage in volts or follow ing an overload condition in ohms it may take a number of minutes for input current to drop to within specified limits Input current can be verified by placing the protection cap on the IN PUT jack and then connecting a jumper between the COM and chassis ground terminals With the instrument on the 2pA range and zero check disabled allow the reading to settle until the in strument is within specifications NOTE Safe operation and good measurement practice dictates the use of an external resistor when necessary to limit currents to less than 30mA To measure current with the Model 617 use the following procedure 1 Turn on the power and allow the instrument to warm up for at least two hours to obtain rated accuracy 2 Select the current mode by pressing the AMPS button on the front panel Set V 0 GUARD to OFF 3 To achieve rated accuracy select the 2pA range zero the instrument by enabling zero check and then pressing the ZERO CORRECT button Select the desired range or use autoranging if desired 4 Connect the Mode 6011 or other similar cable to the rear panel INPUT jack Connect the other end of the circuit to be measured as
124. O iem 16 e Seo 2195 3 We L 279 ES ZAR Ei 7241 Ot d 222728 21 5 gt 2777 yt 617 60 ______ E ES 41109 Sinh PERFORMANCE VERIFICATION USING MODEL 263 CALIBRATOR SOURCE INTRODUCTION Performance verification may be performed when the in strument is first received to ensure that no damage or misadjustment has occurred during shipment Verification may also be performed whenever there is a question of instrument accuracy or following calibration if desired NOTE If the instrument is still under warranty less than 1 year from the date of shipment and its perfor mance falls outside the specified range contact your Keithley representative or the factory to deter mine the correct course of action ENVIRONMENTAL CONDITIONS All measurements should be made at 18 28 C 65 82 F and at less than 70 relative humidity unless otherwise noted INITIAL CONDITIONS The Models 617 and 263 must be turned on and allowed to warm up for at least one hour before beginning the verification procedures If the instruments have been sub ject to extremes of temperature additional time should be allowed for internal temperatures to reach normal operating temperature Typically it takes one additional hour to stabilize a unit that is 10 C 18 F outside the specified temperature range TEST EQUIPMENT Along with the Model 263 Cali
125. OLTS buttons inthat order The 5 external feedback mode may be cancelled by pressing AMPS and VOLTS indicators will illuminate simul one of the four functions keys VOLTS OHMS COUL or taneously in the external feedback mode AMPS or by pressing SHIFT OHMS to enter V I OHMS 2 23 2 10 4 Non standard Coulombs Ranges In its standard form the Model 617 has three coulombs ranges allowing it to measure charge between 10fC and 20nC Different charge measurement ranges can be used by placing an external feedback capacitor between the PREAMP OUT and Input HI and then placing the instrument in the external feedback mode Charge is related to capacitance and voltage by the formula Q CV where Q is the charge C is the capacitance and V is the voltage The Model 617 display will read charge directly in units determined by the value of C For example a 1 capacitor will result in a displayed reading of 14C V In practice the feedback capacitor should be greater than 100pF for feedback stability and of suitable dielectric material to ensure low leakage and low dielectric absorption Polystyrene polypropylene and Teflon dielectric capacitors are examples of capacitor types with these desirable characteristics The capacitor should be mounted in a shield ed fixture like the one in Figure 2 18 To discharge the external feedback capacitor enable zero check The discharge time constant will be given by 7 10MQ Cpp 2 10 5
126. OMETER BOARD FRONT PANEL Figure 7 input Offset Adjustment Locations Model 617 Input Current Adjustment Use the following procedure to null out any input current in the input stage 1 Disconnect all input signals from the Model 617 Place the protection cap CAP 18 on the INPUT connector 2 Remove the two screws securing the top cover and remove it from the instrument 3 Place the Model 617 in the amps function and the 2pA range 4 Enable zero check and zero correct in that order 5 Disconnect floating sources and connect a ground link between the COM and chassis ground binding posts Disable zero check but leave zero correct enabled 6 Wait several minutes until the reading on the display settles down about 15 counts 1 5 of noise is normal 7 Locate the input current pot R348 on the electrometer board It is accessible through a small hole in the shield see Figure 7 8 Carefully adjust R348 for a reading of 0 0000 15 counts on the display Iterative adjustment may be necessary 9 Replace the top cover and secure it with the two screws removed earlier C Voltage Source Calibration Use the following procedure to calibrate the voltage VOLTS OHMS MODEL 196 source Since the voltage source is independent from the electrometer section voltage source calibration can be per formed at any time WARNING Hazardous voltage will be used in some of the following steps 1 Connect the
127. OUT COM Table 2 4 Ohms Function Current Output Values Output Current Ranges 41 5 2kQ 20kQ 200 kQ 2MQ 20MQ 200M9 260 2060 20060 Rx MEASURED RESISTANCE SHIELD RECOMMENDED ABOVE 100 0 RANGING AMPLIFIER CONVERTER 2V ANALOG OUTPUT EQUIVALENT CIRCUIT Figure 2 12 Resistance Measurement Connections 2 16 2 8 USING THE VOLTAGE SOURCE The Model 617 has a built in voltage source that can be used to make V I resistance measurements The voltage source can be adjusted between 102 35V and 102 4V in 50mV in crements and has a maximum output current of 2mA The following paragraphs describe the basic procedure for using the voltage source as well as the method for making V I resistance measurements 2 8 1 Basic Operating Procedure Use the following procedure for connecting the voltage source and adjusting its output value 1 Connect the circuit under test to the V SOURCE OUTPUT HI and LO binding posts as shown in Figure 2 13 Rr represents the resistive load of the circuit under test Note that RI has a minimum value of 50 at an output voltage of 100V This value is based on the 2mA current limit of the voltage source WARNING The maximum common mode voltage voltage between SOURCE LO and chassis ground is 100V Exceeding this value may create a shock hazard 2 Press the DISPLAY button to observe the voltage source value 3 Press either of the V SOURCE ADJUST button
128. RODUCTION This section contains information necessary to maintain calibrate and troubleshoot the Model 617 Fuse replacement and line voltage selection procedures are also included WARNING The procedures included in this section are for use only by qualified service personnel Do not perform these procedures unless qualified to do so Many of the steps in this section may expose you to potentially lethal voltages that could result in personal injury or death if normal safety precautions are not observed 7 2 LINE VOLTAGE SELECTION The Model 617 may be operated from either 105 125V or 210 250V 50 or 60Hz power sources A special transformer may be installed for 90 110V and 195 235V ranges The in strument was shipped from the factory set for an operating voltage marked on the rear panel To change the line voltage proceed as follows WARNING Disconnect the Model 617 from the power line and all other sources before removing the top cover 1 Remove the screws securing the top cover to the rear panel and carefully lift the cover away from the instrument 2 Locate the line voltage switch adjacent to the POWER switch on the mother board Place the switch in the correct position as outlined in Table 7 1 3 Install a fuse consistent with the operating voltage as described in paragraph 7 3 CAUTION The correct fuse type must be used to main tain proper instrument protection 4 Mark the selected line voltage on the rear p
129. Range R q wq x s q n n s n b s n q q s amp s aq s q s s b s lt s s s s s s Zero Correct and Zero Check Zand Baseline Suppression N Display Mode Reading Mode Data Store Mode Voltage Source Value V Voltage Source Operate O Calibration Value A 04 00 404 04004040404 40404 6 442 4 eq o t s s s pP wt t t w p 2 t s on 404 417404040404 s t s s 6 t s s h q kt s amp s s s s os s s s sen s s s s t os s s s x sea t h h v p s s 4 n 4 4 s n s s s s s e 0 s 04 0 n 222 4 424404 q q s s s s s Non Volatile Memory Storage L Data Format G Trigger Mode T 0 4 4 40 40 OOO O 9 9 o9 4 4 amp 93 9 9 9 k s s s d h s s s s s s s SRQ Mode M and Status ByteFormat es EOI and Bus Hold Off 0 Terminator Y Status ID
130. Resistor 5 4W Composition 1 81 E5 R 76 10k Resistor Set 10k includes R158 332 Resistor Set 10k includes R157 R 332 Resistor 200k 0 1 W Metal Film R 264 200k Resistor 2M 0 1 Metal Film R 321 2M Resistor 10k 5 Composition R 76 10k Switch Line SW 466 Switch Line Voltage Selection SW 397 Switch SPDT Slide SW 318 Transformer Power 90 110V 180 220V TR 240 Transformer Power U S and Europe version TR 239 Toroid TR 214 IC Voltage Regulator 5V 7805 32469 2 IC Quad 2 Input Gate 74 500 IC 163 IC HC4040 407 Matched set with T301 Table 8 1 Mother Board Parts List Cont Circuit Location Keithley Desig Description Sch Part No U104 1 16 x 16 Bit Serial NVRAM X2443D 2 B2 1 353 0105 CMOS Dual D Flip Flop 4013 2 B3 IC 103 0106 FIC PROM 27128 2 F5 02 617 800 0107 2k x 8 Static CMOS RAM 6116 2 F5 D2 LSI 58 0108 Octal Tri State Latch 74HC373 2 03 E2 IC 338 U109 8 Bit CMOS Microprocessor 146805E2 2 C1 E2 LSI 60 U110 Tri State Octal Latch 74HC373 2 F2 D3 IC 338 U111 Quad 2 Input Gate 74 2 05 D3 1C 351 U112 Triple 3 Input OR Gate 4075 Sev 10 143 0113 1 GPIB Adapter 9914A 2 62 LSI 49 0114 15V Voltage Regulator 1 32017 15 1 85 253 1115 Regulator 78115 1 C5 IC 170 0116 Tri State Octal Latch 74HC373 2 F3 D3 1C 33
131. SIVA 2019 2999 Sec 82 3NOZ 901 219 AS 3808 30 096 SLV AZZ LOYO vetu e SN AGT amp ool COLOR word 2 lt Buy L rus CEST pee 594 0 ee 1 iO 815 9052 m 27 2 692 2 ese E sg 9x IAS WO 9Ocu2 253 a 20 5 2 Mom dal AE eed case EN po 1222 1 N 5 NO ol 205 7 104100 0 z al i soco ED z IE i Met Md azos 1 5 909 3 cu Muir eur ul xit x bo Cn lt 9 Qe 01 1 2052 COCO Nac vor nots 29 3 idi 41560 P OL 03123NN02 ZICH 2023 30 SOTZIHS zi 1065 780111506 NMOHS SAVTSU TIY u i IN3W1S nrdv 1vNH31Ni SILONIA 0 i ONILNOOW S310N30 5 1 83123135 AHOI2V3 SILONIC NOLLVLOY 3814432012 SILONIG 2 Z NOLLSANNOD 5165 2 S310N3G Y 9 NOWWO2 2151008 N 905 goer POLA 2122 90 OIEX 60 NOWWOD N
132. TO LO OF 617 AND CHASSIS Table 7 5 Volts Calibration 190 000mV 190 00mV A0 190X CABLE BNC CABLE SHIELD POMONA 4530 C 1 90000 V 1 9000 V 1 9 10000600 9 e po D cnassis O 19 0000 V 19 000 V A19X 190 000 V 190 00 V A190X 4801 CABLE 6147 ADAPTER NOTE LEAVE GREEN DISCONNECTED MODEL 617 1000pF STANDARD GROUND LINK AIR CAPACITOR IN PLACE Figure 7 6 Connections for Coulombs Verification 7 4 13 Volts Calibration 6011 CABLE Calibration of the volts function should be performed in the following order 200mV 2V 20V and 200V ranges Proceed as follows HORTING LINK REMOVED 1 Select the volts function and place the instrument on the 200mV range 2 Set the DC calibrator to OV and connect it to the instru MODEL 617 ment as shown in Figure 7 7 Figure 7 7 Connections for Volts Calibration 7 8 7 4 14 Ohms Calibration 1 Using the teraohmmeter measure the actual resistance values of the 1GQ and 100 resistors Record these values in Table 7 6 NOTE Do not touch the body of these resistors to avoid contamination that could give erroneous results 2 Connect the 1GQ resistor to the Model 617 as shown in Figure 7 8 Use the shielded fixture in Figure 7 1 Enable zero check and place the V Q GUARD switch ON WARNING Up to 300V may be present on the shielded fixture in the guarded mode 3 Select the ohms function and place the instrument on the 260 range
133. UT COM or 2V ANALOG OUTPUT to earth while floating input may damage the instrument 2 8 CAUTION The maximum voltage between input hiqh and input is 250V rms DC to 60Hz sine wave 10 seconds maximum in ranges Exceeding this value may cause damaqe to the instrument 2 7 3 Making Voltage Measurements The Model 617 can be used to measure voltages in the range of 10nV to 200V In principle the instrument operates much like an ordinary DMM but its special characteristics allow it to make measurements in cases where an ordinary DMM would be unable to perform well In particular the very high input resistance of 200 2 X 10140 allows it to accurately measure voltage sources with high internal resistances In contrast an ordinary DMM may have an in put resistance of only 10MQ resulting in inaccurate measurements because of instrument loading Use the procedure below to make voltage measurements 1 Turn on instrument power and allow it to warm up for two hours to reach rated accuracy 2 Check to see that the voltage function is selected by press ing the VOLTS button Use the autorange mode or select the desired range with the ranging pushbuttons 3 To achieve specified accuracy especially on the lower ranges it is recommended that you zero the instrument To do so first enable zero check and then press the ZERO CORRECT button Correcting zero in the lowest range of any function will correct all ranges bec
134. UTION impedance of 100kQ Connecting PREAMP OUT COM or 2V ANALOG OUTPUT to earth while floating input may damage the instrument e PREAMP OUT LO MODEL 1683 TEST LEAD KIT MEASURING DEVICE MODEL 617 HF VOUT VIN VouT iNRE lin VIN PREAMP OUT RL LO COM COM el 5 1000 1000 GND GND 5 5 VOLTS AMPS PREAMP OUT COM COULOMBS EQUIVALENT CIRCUITS Figure 2 16 Typical Preamp Out Connections 2 21 2 10 USING EXTERNAL FEEDBACK External feedback provides a means to extend the capabilities of the Model 617 Electrometer to such uses as logarithmic cur rents non decade current ranges as well as non standard coulombs ranges The following paragraphs discuss the basic electrometer input circuitry and methods to implement these functions 2 10 1 Electrometer Input Circuitry A simplified diagram of the electrometer input in the amps mode is shown in Figure 2 17 An input current applied to the inverting input of the op amp is nulled by a current fed back through the internal feedback network made up of and Crp Because the output of the op amp appears at the PREAMP OUT this internal network can be replaced by an external network connected between the preamp output and Input HI connections When using external feedback the following factors must be taken into account 1 The maximum current value that can be supplied by the preamp output is 20mA in amps 1mA in V Q
135. a into two 1K pages Because of the paging scheme employed several devices can occupy a given address within the microprocessor s address ing space Table 6 1 gives the general address range for each device Table 6 1 Memory Mapping RAM U107 0000 S03FF ROM U106 0800 1FFF 50412 040 0418 041F Display Control U110 Display Control 0116 IEEE 488 0113 6 6 4 IEEE 488 The Model 617 has standard IEEE 488 interface that allows the instrument to be programmed from a system controller Commands can be sent over the bus to the instrument and data can be requested from the instrument as well The IEEE 488 interface is made up of U113 U119 and 0120 U113 is a 9914 GPIA General Purpose Interface Adapter while U119 and U120 are 75160 and 75161 interface bus drivers The 9914 GPIA simplifies MPU interfacing to the IEEE 488 bus because many control sequences take place automatical ly For example when the MPU writes to the GPIA data out put register the handshake sequence is performed automati cally Without the GPIA chip complex MPU routines would otherwise be required On the MPU side of the GPIA data transmission is handled much like any other data bus transaction MPU data access is performed through the 20 07 lines while the RSO RS2 lines which are connected to the three least significant address lines serve to select among the 14 internal registers seven read seven write of
136. able 3 6 take on a somewhat different form Each of these state ments uses the IBM BASIC CALL statement with various variables passed as shown in the table The command words such as IBCLR Interface Bus Clear and IBSRE Interface Bus Send Remote Enable are in fact BASIC variables themselves which must be initialized at the start of each BASIC program In addition you must remember not to use these keywords for any other purpose in your BASIC gram Before using the Model 8573 examples throughout this sec tion you must configure the software by using the procedure below Note that the binary handler file called GPIB COM and the system configuration file called CONFIG SYS must be present on the DOS boot disk as described in the Model 8573 Instruction Manual 1 Boot up your system in the usual manner and enter BASICA 2 Place the Model 8573 software disk into the default drive and load the program called DECL BAS Modify the program by changing the XXXXX values in lines 1 and 2 to 16000 3 Add the following lines to the declaration file 7 NAS GPIBO CALL IBFIND NAS BRDO 8 NA DEVO0 CALL IBFIND NA M617 95 9 27 CALL IBPAD M617 V 4 Now save the modified declaration file for future use Remember that you must load and run this short program before using the Model 8573 programming examples throughout this section Also do not use the BASIC CLEAR or NEW commands after running this program Tabl
137. above this range By using the Model 617 to make resistance measurements in the constant voltage mode measurement range can be extended up to 1016Q Also for a given resistance range the V I mode will be faster A typical configuration for using the Model 617 in this man ner is shown in Figure 4 3 Here the built in voltage source of the instrument is used to force a current I through the unknown resistance R The insulation resistance is then autornatically calculated by the Model 617 as follows where I is the current through the resistance as measured by the instrument and V is the programmed voltage Note that COM is connected to input LO thru 1000 and ap pears in series with the resistor under test This resistance is below the resolution of the instrument on ranges above 2M2 4 1 MODEL 6147 E TRIAX TO BNC ADAPTER HIGH Ou QU M BESS KEITHLEY MODEL ail O O SHIELDED TEST F URE ge 617 SET TO OHMS 617 PREAMP _6104 SHIELD 4801 CABLE 6147 ADAPTER 2 EQUIVALENT CIRCUIT Figure 4 1 Insulation Resistance Measurement Unguarded 42 6011 CABLE INPUT UNKNOWN RESISTANCE UC MN II on A VQ GUARD SAFETY SHIELD 617 SET TO OHMS V 2 GUARD ON WARNING SAFETY SHIELO RECOMMENDED FOR GUARDED RESISTANCE MEASUREMENTS ABOVE 3069 UP TO 300V MAY BE PRESENT ON GUARD 617 PREAMP A D CONVERTER EQUIVALENT CIRCUIT Figure
138. address of 27 is being used 3 5 1926 ONVYAWOD AYVGNGDIS N 34994 sdno4t pueuiulj02 ONN WINOD AU WIUd 553 3151 g S S3800V AUVIAldd 553840 x 53494 AWVWIUd e1n814 318 3400 X Lo vota 00 310N 19 POW PS uSuuSidun you Jontio 121 pue yog repete 19inBuuo2 1108 244 1990 959 371059 GNVWW02 GNVWNW02 WSHIAINI asssayody MOY 3 6 Note that an UNL command is generally sent before the LAG SDC sequence This is usually done to remove all other listeners from the bus so that the desired device responds to the command Table 3 3 Typical Addressed Command Sequence Data Bus Stepi Command State ASCII Hex Decimal Set low 63 Stays low 3B 59 Stays low 04 4 Returns high Assumes primary address 27 3 6 2 Universal Command Sequence Universal commands are sent by setting ATN low and then placing the command byte on the data bus ATN would then remain low during the period the command is transmitted For example if the LLO command were to be sent both ATN and LLO would be asserted simultaneously 3 6 3 Device Dependent Command Sequence Device dependent commands are transmitted with ATN false Howev
139. al polling sequence gt Once instruments are in the serial poll mode steps 3 through 5 above can be repeated by sending the correct talk address for each instrument ATN must be true when the address is transmitted and false when the status byte is read HP 85 Programming Example The HP 85 SPOLL state ment automatically performs the sequence just described To demonstrate serial polling type in the following statements into the HP 85 REMOTE 727 END LINE S SPOLL 727 END LINE DISP 5 END LINE When the END LINE key is pressed the second time the com puter conducts the serial polling sequence The decimal value of the status byte is then displayed on the computer CRT when the END LINE key is pressed the third time More infor mation on the status byte may be found in paragraph 3 10 15 Model 8573 Programming Example Use the following sequence to serial poll the instrument and display the decima value of the status byte on the computer CRT V 1 CALL IBSRE BRDO 96 V return CALL IBRSP M617 SB return PRINT SB return When the return key is pressed the second time the serial polling sequence is conducted The status byte value is displayed when the return key is pressed the third time 3 10 DEVICE DEPENDENT COMMAND PROGRAMMING IEEE 488 device dependent commands are used with the Model 617 to control various operating modes such as func tion range trigger mode and data format Each command
140. alculations by maintaining a known ratio between the external value and the programmed voltage of the Model 617 For example assume that an external voltage of 200V is used If you programmed the Model 617 voltage source to 20V you could easily determine the actual resistance by noting the displayed value and moving the decimal point one place to the right The same general considerations apply to making voltage coefficient studies at voltages higher than 100V The basic configuration shown in Figure 4 12 would be used As discussed in paragraph 4 8 the resistance would be measured at two different voltages and the resulting voltage coefficient could then be calculated As long as a known ratio is main tained between the external high voltage and the programmed voltage of the Model 617 resistance calculations would be relatively simple 4 13 4 14 SECTION 5 PERFORMANCE VERIFICATION 5 1 INTRODUCTION The procedures outlined in this section may be used to verify that the instrument is operating within the limits stated in the specifications at the front of this manual Performance verifi cation may be performed when the instrument is first received to ensure that no damage or misadjustment has occurred dur ing shipment Verification may also be performed whenever there is a question of instrument accuracy or following calibration if desired NOTE If the instrument is still under warranty less than 1 year from the date of shipme
141. alues there are two primary factors that can affect measurement accuracy and speed Any leakage resis tance in the connecting cable or test fixture can decrease the actual resistance seen by the instrument Also capacitance of the cable or input circuit can slow down the response time considerably These two problems can be minimized by using guarding especially when measuring resistances above 109 Guarding is further discussed in paragraph 2 7 4 Noise pickup can also be a problem in which case the resistor must be shielded Connect the shield to input low At low resistances lead resistance can be a consideration the effects of lead resistance by shorting the input leads and enabling suppress with zero check disabled Leave suppress enabled for subsequent measurements 2 15 2 7 8 Using the Ohms Function As A Current Source The Model 617 ohms function may also be used to generate currents in decade values between 1nA and 100 To use the instrument in this manner simply connect the Model 6011 cable to the INPUT jack and connect the red and black alli gator clips to the circuit under test Select the resistance range in accordance with the desired current see Table 2 4 Note that current flows from input high through input low The test voltage is less than 2V for all ranges 200 and less except when an overload occurs in which case the compliance is 300V 6011 CABLE MODEL 617 INPUT AMPLIFIER PREAMP
142. am press the F2 function key After placing the instrument in remote line 40 the program then sets the SRQ mode line 50 An attempt is made to program an illegal command option line 60 at which point the instrument generates an SRQ and sets the error and RQS bits in its status byte Other bits may also be set depending on instru ment status Lines 70 90 display the bit positions set the mask value to the most significant bit and serial poll the in strument Since the status byte is in decimal form lines 100 130 are used to generate the binary equivalent of the status byte value 3 10 16 EO and Bus Hold off Modes K The command allows contro over whether or not the in strument sends the EOI command at the end of its data string and whether or not bus activity is held off through the NRFD line until all commands sent to the instrument are internally processed once the instrument receives the X character K command options include 3 30 KO Send EOI with last byte hold off bus until commands processed on X Do not send EOI with last byte hold off bus until com mands processed on X K2 Send EOI with last byte do not hold off bus on X K32 Send no EOI with last byte do not hold off bus on X Upon power up or after the instrument receives a DCL or SDC command the KO mode is enabled The EOI line on the IEEE 488 bus provides a method to positively identify the last byte in a multi byte transfer se quence
143. anel for future reference to avoid confusion erase the old mark 5 Replace the top cover and connect the instrument to the power line Table 7 1 Line Voltage Selection 50 60Hz Voltage Selection Line Voltage Switch Position 105 125V 210 250V 90 110V 195 235 Requires special power transformer 3 JUMPER FOR USE AS OHMS SOURCE NOTE NOT TOUCH BODY OF RESISTOR AVOID CONTAMINATION DC CALIBRATOR ie INPUT INPU Sy 4801 CABLE P aa p JUM T CON INECTIONS R 5 ov L __ FIiXTURE PARTS LIST PER RESISTOR ELEMENT 1 SHIELDED BOX POMONA P N 2906 2 BNC CONNECTOR KEITHLEY P N CS 15 3 THREE BANANA JACKS KEITHLEY P N BP 11 4 DUAL BANANA PLUG POMONA P N 4585 MODEL 4801 BNC CABLE AND 6147 TRIAX BNC ADAPTER NECESSARY TO CONNECT FIXTURE TO INSTRUMENT lt U Figure 7 1 Test Fixture Construction 7 3 FUSE REPLACEMENT 7 3 1 Line Fuse A rear panel fuse protects the power line input of the instru ment Use the following procedure to replace the line fuse WARNING Disconnect the instrument from the power line and other equipment before replacing the fuse 1 With the power off place the end of a flat blade screw driver into the slot in the rear panel LINE FUSE holder Push in gently and rotate the fuse carrier one quarter turn counterclockwise Release pressure on the holder and its internal spring will push the fuse and
144. ange by determining the percent value and adding or subtracting from the actual value 2 Place the instrument in the ohms mode and select the 200MQ range Enable zero check and verify that the display shows 00 00 1 count If not enable zero correct Place the 100 resistor in the shielded fixture and con nect the fixture to the instrument as shown in Figure 5 7 Note that the fixture is modified from the original con figuration so that one side of the resistor is connected to the rear panel COM terminal Place the 0 GUARD switch in the ON position WARNING Up to 300V may be present on the test fix ture when using guarded operation Enable zero check and disconnect the fixture from the instrument before installing or remov ing test resistors NOTE Do not touch the body of the test resistors as the resulting contamination could give erroneous results Disable zero check and verify that the resistance value is within the tolerance calculated in step 1 Repeat the above procedure for the 260 and 20 ranges using the 109 and 1060 resistors and verify that the in strument is within specified limits Enable zero check and disconnect the test fixture from the instrument 10060 standardized resistor is necessary to check the 200GQ range This test verifies that the input impedance of the unit is greater than 200 0 Proceed as follows 1 Place the instrument in the volts mode select the
145. ange is calibrated the two remaining ranges are 5 Either from the front panel or over the IEEE 488 bus set automatically calibrated the calibration value to 190 00mV see Table 7 6 From the front panel enter the calibration program paragraph 1 Set the DC calibrator output to OV and connect the 7 4 4 and use the voltage source arrow buttons to adjust calibrator and the 1000pF 0 1 standard capacitor to the the display for the correct value Over the IEEE 488 bus instrument as shown in Figure 7 6 send the following command A0 190X 2 Select the coulombs mode and select the 20nC range 6 Repeat steps 3 5 for the remaining calibration points listed 3 Zero correct the instrument by enabling zero check with in Table 7 5 Zero correct the instrument before zero correct disabled Then enable zero correct and calibrating each range To do so select the range being disable zero check Enable suppress to null the effects of calibrated and disable zero correct Enable zero check and zero check hop zero correct in that order Disable zero check to calibrate 4 Set the DC calibrator to 19 000V the range in question 5 Set the Model 617 calibration constant to 19 000nC either with the front panel calibration program or over the bus The correct bus command value would be A19E 9X 6 Set the DC calibrator output to and enable zero check 617 Calibrator 617 Display IEEE 488 Range Value Value Bus Command NOTE CONNECT SHIELD
146. ard It is accessible through a small hole in the shield See Figure 7 3 8 Carefully adjust R348 for a reading of 0 0000 15 counts on the display Iterative adjustment may be necessary 9 Replace the top cover and secure it with the two screws removed earlier REAR PANEL INPUT OFFSET ADJUSTMENT Ta R314 E L INPUT CURRENT ADJUSTMENT R348 ELECTROMETER BOARD FRONT PANEL Figure 7 3 Input Offset Adjustment Locations 7 4 10 Permanent Storage of Calibration Parameters The procedures given in the following paragraphs will tem porarily store calibration constants in internal RAM memory For calibration to be permanent you must perform NVRAM storage once all calibration procedures have been performed If you are calibrating the instrument from the front panel simply press SELECT EXIT to leave the calibration program From the JEEE 488 bus simply send the following command L1X Note that this storage procedure need be performed only once after all calibration parameters have been entered Keep in mind that the calibration jumper must be in the correct position as described in paragraph 7 4 4 7 6 7 4 11 Amps Calibration Calibration of the amps function should be performed in the following order 200 20nA 202A and 20mA ranges Once these ranges are calibrated the remaining ranges are auto matically calibrated Proceed as follows 1 Using the teraohmmeter accurately measure t
147. are placed in series T101 has three secondary windings which are used to supply the 110V 15V and 5V supplies The 110V and 15V sources supply the voltage source and the 5V sup ply is used for the digital circuitry The 110V supplies consist of half wave rectifier diodes CR108 and CR107 and filter capacitors C109 and C110 Each of the 15 supplies has a similar half wave rectifica tion scheme CR101 and C103 for the 15V supply CR109 and C108 for the 15V supply Regulation for these supplies is performed by 1114 and 0115 which are IC regulators 6 14 The third winding of T101 supplies the 5V source that is used to power the digital circuits Rectification is done by elements of CR110 while filtering is performed by C101 The supply voltage is regulated by U101 which is a standard 7805 IC regulator The same secondary of T101 that supplies the 5V digital source also supplies power to the primary of the electrometer section power transformer T301 This transformer supplies power to all the DC supplies that power the analog circuits The 210V supplies which are used to power the pre amplifier output circuit are generated by one secondary win ding of T301 and two voltage doubling circuits CR301 CR303 C301 and C304 perform the rectifier and filtering functions for the 210V supply while CR302 CR304 C302 and C303 are similar components in the 210V supply The 210V supplies are not regulated and a
148. at all commands in the previous string were valid HP 85 Programming Example Enter the following statements into the HP 85 keyboard REMOTE 727 END LINE OUTPUT 727 X END LINE When the END LINE key is pressed the second time the X character will be transmitted to the instrument No mode changes will occur with this example because no other com mands were sent Note that the instrument remains in the listener active state after the command is transmitted 3 18 Model 8573 Programming Example Enter the following statements into the IBM computer V 1 CALL IBSRE BRDO V return CMD X CALL IBWRT M617 return When the return key is pressed the second time the X character is transmitted to the instrument although no mode changes occur because no other commands are transmitted Note that the instrument remains in the listener idle state after the command is transmitted because IBWRT automatically sends UNT Untalk and UNL Unlisten at the end of the transmission sequence 3 10 2 Function F The function command allows you to select the type of measurement made by the 617 The parameter options associated with the function command set the instrument to measure voltage current resistance charge external feed back or V I ohms When the instrument responds to a func tion command it will be ready to take a reading once the front end is set up The function may be programmed by sen
149. at can be measured The basic method involves using the voltage source to apply a step voltage across the capacitor as shown in Figure 4 9 Since charge is to be measured the Model 617 should be in the coulombs function to make the measurement Just prior to turning on the voltage source zero check should be dis abled and the charge suppressed Then turn on the voltage source and note the final charge value The capacitance can then be computed as follows AQ AV where Q final charge initial charge assumed to be 0 AV V step voltage V4 initial voltage assumed to be 0 DIODE CURRENT 1 1004 A 104 A 14A 100nA 10nA Figure 4 7 Diode Curves 0 4 0 6 4 9 o 7 7777 77 771 SHIELD HI Hl 617 AAA ELECTROMETER 67 IN VOLTAGE SOURCE LO LO 4 RECOMMENDED VALUES lt 100 107 1 10nA 1uF 100kQ Figure 4 8 Capacitor Leakage Tests puce 6 C R HI HI 617 cet tee ELECTROMETER 1 IN VOLTAGE V2 om COULOMBS SOURCE STEP VOLTAGE LO RECOMMENDED R VALUES lt 100pF 10nF 1MQ 10nF 14F 100 Figure 4 9 Capacitor Measurement As an example of the above procedure assume that an unknown capacitor is to be measured If the step voltage is 100V and a AQ value of 2nC is obtained the capacitance value is 2nC C e
150. at of status is shown in Figure 3 11 Note that the letters correspond to modes programmed by the respective device dependent commands The default values in the status word upon power up or after a DCL or SDC command are also shown in Figure 3 11 Note that all returned values except for those associated with the terminator correspond to the programmed numeric values For example if the instrument is presently in the R3 range the second R byte in the status word will correspond to an 5 3 The returned terminator characters are de rived by ORing the actual terminator byte values with 30 For example a CR character has a decimal value of 13 which equals 0D in hexadecimal notation ORing this value with 30 yields 30 6110 which prints out as an ASCII equal sign This terminator conversion step is necessary to con vert the standard terminators into displayable form as they will not normally print out on a computer CRT 3 31 0 00100680000700 0 617 F RR C Z N T O B G D Q MM K YY LF MODEL NUMBER PREFIX TERMINATOR ASCII FUNCTION CR LF 0 VOLTS LF CR 1 AMPS 2 OHMS EOt BUS HOLD OFF 32 COULOMBS 0 EOI HOLD OFF 4 XFDBK 1 2 NO EOI HOLD OFF 5 V I 2 EOI HOLD OFF 3 NO EOI NO HOLD OFF RANGE Volts Amps Ohms Coulombs XFDBK SRQ Auto Auto Auto Auto Auto 00 DISABLED 200mV 2 pA 2 0 200 200mV 01 READING OVERFLOW 2 20 pA 20 2nC 2 02 DATA STORE FULL 20 V 200
151. ause of internal scal ing NOTE The input c rcuit configuration changes with zero check enabled See paragraph 2 11 1 4 Connect the Model 6011 triaxial input cable or other similar cable to the rear panel INPUT jack on the instru ment For sources with high output resistance the cable should be kept as short as possible to minimize cable capacitance 5 If response time and leakage resistance are considerations place the instrument in the guarded mode as described in the next paragraph 6 Connect the other end of the cable to the voltage to be measured as shown in Figure 2 4 Disable zero check 7 The reading may be obtained directly from the display The exponent can be placed either in the alpha or numeric mode as described in paragraph 2 5 6011 CABLE 617 INPUT INPUT AMPLIFIER PREAMP OUT COM MEASURED VOLTAGE SHIELD OPTIONAL RANGING AMPLIFIER gt TO A D CONVERTER 2V ANALOG OUTPUT EQUIVALENT CIRCUIT Figure 2 4 Connections for Voltage Measurements Voltage Measurement Considerations Two primary con siderations come to mind when making voltage measurements especially for voltage sources with high out put resistances For one thing the loading effects of the measuring instrument come into play at the high resistance levels involved Secondly the distributed capacitance of the source the input cable and the input circuit of the instrument itself come into pl
152. ay when making these measurements To see how meter loading can affect accuracy refer to Figure 2 5 In this figure there is a voltage source with a value Es and an output Rs connected to the input of the electrometer which has its input resistance represented by The percent error due to loading can be calculated as follows 100 Rs ERROR Rs RIN Thus to keep the error under 0 1 the input resistance must be about 1000 times the value of the source resistance R At very high resistance levels the very large time contants created by even a minimal amount of capacitance can slow down response time considerably For example measuring a source with an internal resistance of 100GQ would result in an RC time constant of one second when measured through a cable with a nominal capacitance of 10pF If 1 accuracy is required a single measurement would require at least five seconds Basically there are two ways to minimize this problem 1 keep the input cable as short as possible and 2 use guarding With the first method there is a limit as to how short the cable can be Using guarding can reduce these effects by up to a factor of 1000 The Model 617 has a rear panel switch to allow guarding to be easily applied to the input circuit see the next paragraph for details At low signal levels noise may affect accuracy Shielding of the unknown voltage can reduce noise effects substantially When using shieldi
153. be quite difficult Tabie 7 9 Diagnostic Program Phases Display A D Converter Phase Message input Signal Analog Common Zero Common Calibration 2V Reference Reference Output of Ranging Amplifier Signal Table 7 10 outlines the various power supply voltages that should be checked In addition to the usual voltage checks it is a good idea to check the various supplies with an oscilloscope to make sure that no noise or ringing is present WARNING The electrometer board shield is connected to analog common and can float up to 800V above chassis ground depending on the input signal 7 7 5 Relay Configuration Instrument functions are controlled by configuring the input amplifier with a number of relays These relays are themselves controlled by serial parallel converter ICs that decode control information from the microprocessor Since each relay must assume a given state for proper operation it is possible to verify input configuration switching by deter mining which relays are energized for every range and func tion Table 7 11 gives a summary of status for each of the twelve relays associated with the electrometer input section You can verify proper relay operation for a given combination by selecting the range function in question and then measur ing the control voltage at the IC driver output When a relay is energized on the voltage at the output will be high while
154. ble devices for this ap plication include Analog Devices AD812 and Precision Monolithics 01 Use the enclosure in Figure 2 18 to shield the device Frequency compensation stabilization is accomplished by ad ding a feedback capacitor The value of this capacitor depends on the particular transistor being used and the maxi mum current level expected Compensation at maximum cur rent s required because the dynamic impedance will be minimum at this point It should be noted that the response speed at lower currents will be compromised due to the in creasing dynamic impedance which is given by the following formula dV KT ql 0 026 1 25 C dI Using the above transistors a minimum RC time constant of 100 at maximum input current would be used At IN max of 100 this value would correspond to 0 4uF Note that at 100nA this value would increase the RC response time constant to 100msec A minimum capacitance of 100pF is recommended Although the input signal to this particular circuit is assumed to be a current conversion to voltage input could be per formed by placing a shunt resistor across the input However the nominal voltage burden of ImV must be considered as an error signal that must be taken into account Further processing of the current response can be achieved by using suppress For example suppress could be enabled with a reference input current applied For all subsequent curren
155. box to make the necessary PREAMP OUT connection Alternately a wire could be run through a rubber grommet mounted in a hole in the side of the box Note that input low is connected to chassis ground within the shielded box This connection can be made by using a small solder lug secured with a screw INPUT LOW INNER SHIELD SOLDER LUG INPUT HIGH CENTER CONDUCTOR 2 re i A TO 617 INPUT JACK FROM SIGNAL FEEDBACK ELEMENT TO PREAMP OUT A CONSTRUCTION FEEDBACK ELE PREAMP OUT TO RANGING AMP AND A D 617 AS 6011 CABLE 7024 CABLE 8 EQUIVALENT CIRCUIT PARTS LIST DESCRIPTION MFR PART NUMBER SHIELDED FIXTURE POMONA 2390 FEMALE TRIAXIAL KEITHLEY CS 181 BANANA JACK KEITHLEY BJ 9 2 TRIAXIAL CABLE KEITHLEY 6011 TRIAXIAL CABLE KEITHLEY 7024 Figure 2 18 Shielded Fixture Construction 2 10 3 External Feedback Procedure 3 The display will show the voltage measured at the output of the input preamplifier PREAMP OUT However the V exponent will not appear as in the valts mode For Use the following procedure to operate the Model 617 in the ample with 150mV output the display will show external feedback mode 150 00 m dback el t bet the PREAMP OUT s High ET 4 External feedback may be temporarily digitally calibrated 2 Place the instrument in the external feedback mode by 25 Outlined in paragraph 7 4 16 cessing the SHIFT then V
156. brator Source the follow ing equipment is needed to verify all functions of the Model 617 Alternate equipment may be used as long as their specifications are at least as good as the specifications in parenthesis Fluke 343A DC Calibrator 190V 0 002 Keithley 196 DMM 0 015 VERIFICATION PROCEDURES The following paragraphs contain procedures for verify ing instrument accuracy with each of the four measuring functions volts ohms amps and coulombs In addition A 2 a procedure to verify accuracy of the internal voltage source is also included These procedures are intended for use only by qualified personnel using accurate and reliable test equipment If the instrument is out of specifications refer to Section 7 for calibration procedures unless the unit is still under warranty WARNING The maximum common mode voitage voltage between input low and chassis ground is 500V Exceeding this value may cause a breakdown in insulation creating a shock hazard Some of the procedures in this section may expose you to dangerous voltage Use standard safety precautions when such dangerous voltages are encountered CAUTION The maximum voltage between the high and low input terminals is 250V 10 seconds imum on the mA ranges Instrument damage may occur if this value is exceeded NOTE Verify the electrometer section in the order listed input current amps coulombs volts and ohms Input current may remain
157. bs mode place a typical IC in the tube to be tested allow it to slide the full length of the tube and fall into the Faraday cup The amount of charge built up during the test will then be registered on the Model 617 The test can be repeated with other tubes as required In order for the test to be valid all tubes should be the same length and the same IC should be used in every case The tube that generates the smallest static charge as seen on the electrometer is the one with the best anti static characteristics The amount of charge seen during this test will depend on many factors including the type of tube material tube length the IC used as well as the relative humidity Typical values might be in the 0 5 1nC range for a good anti static tube while one without anti static protection might generate 10 times that amount 4 10 USING THE MODEL 617 WITH EXTERNAL VOLTAGE SOURCES The internal voltage source of the Model 617 should be more than adequate for most measuring situations However there may be a few applications where a voltage higher than the nominal 100V value is required For example it may be desirable to increase the measurement range of the V I ohms mode In another instance voltage coefficient studies at high voltages may required These functions can be performed with the Model 617 if an external high voltage source is used Accuracy of the ohms mode will depend largely on the relative current seen by the
158. carrier out of the holder 2 Remove the fuse and replace it with the type recommended in Table 7 2 CAUTION Do not use a fuse with a higher current rating than specified or instrument damage may occur If the instrument re peatediy blows fuses locate and correct the cause of the troubie before replacing the fuse 3 Install the new fuse and the fuse carrier into the holder by reversing the above procedure Table 7 2 Line Fuse Selection Line Keithley Voltage Fuse Type Part No 90 125 1 4A 250V 3AG Sio Blo FU 17 195 250V 1 8A 250V 3AG Slo FU 20 7 3 2 COM Fuse The COM fuse F102 which is located internally protects the instrument from damage in situations where COM is inadvertently connected to earth ground with input LO floating Use the following procedure to replace this fuse WARNING Disconnect the line cord and all test leads and cables from the instrument before removing the top cover 1 Remove the screws that secure the top cover to the in strument then remove the cover 2 Pry the COM fuse free of its holder using a screwdriver The fuse holder is mounted on the inside of the rear panel 3 Replace the fuse only with the following type 1 16A 250V BUSS AGC 1 16 Keithley Part No FU 86 1 CAUTION Replace the fuse only with the recommended type Installing a fuse with a larger rating may result in instrument damage 4 Install the top cover and secure it with the screws
159. ce value is returned in a similar manner by sending B4X Once the desired reading mode has been selected the data string can be read by addressing the instru ment to talk and reading the bytes in the string in the normal manner HP 85 Programming Example Use the following se quence to read the voltage source value and display it on the computer CRT REMOTE 727 END LINE OUTPUT 727 B4X END LINE ENTER 727 A END LINE DISP 5 END LINE The second command above changes the reading mode to ac cess the voltage source while the third and fourth statements acquire the reading and display it on the CRT Model 8573 Programming Example To display the voltage source value on the computer CRT enter the follow ing program statements into the IBM computer V 1 CALL IBSRE BRDO V return CMD B4X CALL IBWRT M617 CMD return RD SPACESQS5 CALL IBRD M617 RD return PRINT RD return The second statement above programs the reading mode to access the voltage source value The third statement addresses the instrument to talk and reads the data string from the in strument while the fourth statement prints the data string on the computer CRT 3 10 8 Data Store Mode The data store commands enter the data storage mode and allow you to store up to 100 readings with internal memory of the Model 617 By entering an appropriate parameter readings may be stored at one of six intervals between the conversion rat
160. ch 49 89 8493070 Fax 49 89 84930759 GREAT BRITAIN Keithley Instruments Ltd The Minster 58 Portman Road Reading Berkshire RG30 1 44 118 9575666 Fax 44 118 9596469 ITALY Keithley Instruments SRL Viale 8 Gimignano 38 20146 Milano 39 2 48303008 Fax 39 2 48302274 NETHERLANDS Keithley Instruments BV Avelingen West 49 4202 MS Gorinchem 31 0 183 635333 Fax 31 0 183 630821 SWITZERLAND Keithley Instruments SA Kriesbachstrasse 4 8600 Diibendorf 41 1 8219444 Fax 41 1 8203081 TAIWAN Keithley Instruments Taiwan 1FL 1 Min Yu First Street Hsinchu Taiwan R O C 886 35 778462 Fax 886 35 778455 Model 617 Programmable Electrometer Instruction Manual 1984 Keithley Instruments Inc Test Instrumentation Group All rights reserved Cleveland Ohio U S A Document Number 617 901 01 Rev G SPECIFICATIONS VOLTS TEMPERATURE ACCURACY 1 Yr COEFFICIENT 18 28 C 0 18 amp 28 50 C RANGE RESOLUTION rdg counts x e rdg counts 200mV 10 0 054 4 0 004 3 2 100 0 05 1 0 004 4 0 3 20 V imV 0 05 1 0 005 0 1 200 10mV 0 07 1 0 007 0 1 When properly zeraed NMRR Greater than 80dB on 200mV 60dB on 2V and 20V 5548 on 200V range 502 60Hz 0 1 CMRR Greater than 120dB at dc 50Hz or 60Hz INPUT IMPEDANCE Greater than 20070 in parallel with 20pF lt 2pF guarded AMPS TEMPERATURE ACCURACY 1
161. ch connector is equipped with two metric screws Model 7023 Female Triaxial Connector The Model 7023 is a chassis mount connector that mates with the Models 6011 and 7024 triaxial cables Model 7024 Triaxial Cables The Model 7024 cables are similar units with male triaxial connectors on each end The Model 7024 1 is 0 3m 1 ft in length while the Models 7024 3 and 7024 10 are 0 9 3 ft and 3 0m 10 ft long respectively These cables may be used to connect the Model 617 signal input to other equipment having similar triaxial connections Model 8573 IEEE 488 Interface for the IBM PC The Model 8573 allows the Model 617 to be connected to and controlled from the IBM PC via the IEEE 488 bus SECTION 2 OPERATION 2 1 INTRODUCTION Operation of the Model 617 may be divided into two general categories front panel operation and JEEE 488 bus operation This section contains information necessary to use the instru ment on a front panel basis Note that many of these func tions can also be programmed over the IEEE 488 bus as described in Section 3 The following paragraphs contain a complete description of Model 617 front panel operation First a complete description of each front and rear panel function is presented Next the complete procedure for each of the measuring functions is presented followed by a description of the built in voltage source Finally the analog output and guard functions are described along with a m
162. chematic of the A D converter is shown in Figure 6 15 along with an associated integrator waveform The charge balance phase begins when the input ENABLE DISABLE line is set high This action occurs at the end of a software generated delay period that allows the signal to set tle following signal selection Once the input is enabled the signal from the buffer amplifier is added to the level shift cur rent applied through R153H In this manner the 2V bipolar signal from the buffer amplifier is converted to a unipolar signal that can be integrated The integrator is made up of U138B and C128 When the in put to the integrator is applied the integrator output ramps up until its voltage is slightly higher than the voltage applied to the inverting input of the charge balance comparator 01378 When the 4 output of the clock generator 0127 goes high the output of U135B is low the Q1 output of U126A will go high This action injects the charge balance current into the integrator input Since the charge balance current is much larger than the sum of the input and level shift currents the integrator output now ramps in the negative direction The integrator output will continue to ramp in the negative direction until the output of U135A goes low Note that the 03 Q4 and Q5 outputs of U127 must all be high for the output of U135A to go low The output of U136C is gated with the Q2 output of the clock generator by Ul35C Each time Q2
163. commands associated with data store are always available however the suffix of the reading string will show 000 if data store is disabled as in NDCV 1 2345 00 000 Minimum maxi mum values returned will be the last values stored unless these parameters are requested after a DCL in which case unuseable readings will be returned Parameters associated with the reading mode include Electrometer B1 Data store reading B2 Maximum reading B3 Minimum reading B4 Voltage source value Upon power up or after receiving a DCL or SDC command the unit will be in the BO electrometer mode When in BO normal electrometer readings will be sent In a continuous trigger mode readings will be updated at the con version rate one reading every 360msec In B1 readings will be taken from consecutive data store locations beginning with the oldest reading and progressing to the newest reading until all readings currently stored have been read Once all readings have been requested the unit will cycle back and begin again These readings may be accessed even if data store is still taking place While data store is enabled the maximum most positive and minimum most negative readings may also be requested by sending the B2 or B3 commands Note that the maximum and minimum values are updated at the maximum reading rate while data store is enabled See paragraph 3 10 8 for a com plete description of data storage The voltage sour
164. complete 7 9 HANDLING AND CLEANING PRECAUTIONS When troubleshooting or otherwise working inside the instru ment care should be taken not to indiscriminately touch PC board traces and open wires to avoid contaminating them with body oils or other foreign matter In particular there are two areas within the Model 617 that have numerous high im pedance nodes where contamination could cause degraded performance These include the input amplifier area on the electrometer board and the ranging amplifier section location on the mother board The same general precautions apply when replacing parts in these areas When unsoldering and soldering parts be careful not to spread the flux around the board to adjacent areas After replacing parts or if contamination is suspected use the following procedure to clean the affected area 1 Using a squeeze bottle carefully apply clean uncon taminated methanol to the area to be cleaned Use suffi cient solution to throughly wet the circuit board 2 Using a small clean brush wipe the area thoroughly unti it is free of flux or contaminants In some cases it may be helpful to tilt the board at an angle and brush con taminants away from the affected area allowing con taminated residue and methanol to run off the board 3 Wash the area again with fresh clean methanol 4 Once the area is thoroughly cleaned is should be dryed with pressurized dry clean air or nitrogen Do not use
165. compressed air from an ordinary air compressor as oil particles in the air could contaminate the circuit board 5 After cleaning or parts replacement check to see that any components connected to the Teflon insulators are not physically touching the board or adjacent parts Table 7 13 A D Converter Checks short input U127 pin 10 U127 pin 7 U127 6 U127 pin 5 U127 pin 3 U127 pin 1 U135 pin 6 307 2kHz gated clock 153 6kHz gated clock 76 8kHz gated clock 38 4kHz gated clock 300Hz gated clock 5V to duration every 22usec Integrator ramp 1 5V DC U138 pin 7 U137 pin 6 U137 pin 7 U126 pin 6 U135 pin 8 U136 pin 10 U126 pin 9 7 18 Step Item Component Required Condition Turn on power select 2V range and All A D checks referenced to 1 2288MHz gated clock OV pulse train Variable pulse train OV to 5V Variable pulse train to 5V Variable pulse train 0 to 5V 5msec positive going pulse 100msec positive going pulse analog common A D Clock Synchronous clock for A D Synchronous clock for A D Synchronous clock for A D Synchronous clock for A D Synchronous clock for A D Charge balance synchronization signal Comparator reference Comparator output Reference current generator A D Data Output Control line for charge balance single slope Integrator control line Table 7 14 Preamplifier Checks
166. con 1A 800PIV 1N4006 1 38 CR302 Diode Silicon 800 1N4006 B1 RF 38 CR303 Diode Silicon 1A 800PIV 1N4006 G3 B1 38 CR304 Diode Silicon 1A 800PIV 1N4006 G3 81 38 CR305 Diode Silicon 800PIV 1N4006 RF 38 CR306 Diode Silicon 1A 800PIV 1N4006 D4 D2 RF 38 CR307 Diode Silicon 800PIV 1N4006 05 D3 38 CR311 Bridge Rectifier 100PIV FA RF 52 CR314 Diode Silicon 1A 800PIV 1N4006 06 C3 RF 38 CR315 Diode Silicon 800PIV 1N4006 D2 RF 28 CR316 Diode Silicon 1N4006 Cb PD2 RF 28 CR317 Diode Silicon 800PIV 1N4006 C4 C2 RF 38 CR318 Diode Silicon 134148 03 C2 RF 38 CR319 Diode Silicon 1A 1N4006 FA RF 38 CR320 Diode Silicon 1A 800PIV 194006 FA B3 RF 38 CR321 Diode Silicon 1N4148 D2 02 28 CR322 Diode Silicon 1N4006 F5 RF 38 CR323 Diode Silicon 1 800PIV 1N4006 Fb RF 38 K301 Relay Electromechanical D2 RL 86 K302 Relay Electromechanical 02 D2 RL 86 K303 Relay Reed E2 F2 RL 44 K304 Relay Reed C2 2 RL 44 K305 Relay Reed C2 22 RL 44 K306 Relay Reed 02 F2 RL 44 K307 Relay Reed D2 2 RL 70 K308 Relay Reed B2 E3 RL 70 K309 Relay Reed 2 RL 70 K310 Relay Reed A2 RL 70 K311 Relay Reed B2 RL 70 K312 Relay Reed 82 RL 70 Table 8
167. controllers available each of which has its own programming language Also different in struments have differing capabilities In this section we will discuss programming languages for two typical controllers the HP 85 and the IBM PC interfaced to the bus through a Keithley Model 8573 JEEE 488 interface In addition interface functions codes that define Model 617 capabilities will be discussed 3 8 1 Controller Handler Software Before a specific controller can be used over the JEEE 488 bus it must have IEEE 488 handler software installed With some controllers the software is located in ROM and no software initialization is required on the part of the user With other controllers software must be loaded from disk or tape and be properly initialized With the HP 85 for example an addi tional ROM that handles interface functions must be in stalled With the Keithley Model 8573 interface for the IBM PC software must be installed and configured from a diskette Other small computers that can be used as IEEE 488 con trollers may have limited capabilities With some interface programming functions may depend on the interface being used Often little software tricks are required to obtain the desired results From the preceding discussion the message is clear make sure the proper software is being used with the interface Often the user may incorrectly suspect that the hardware is causing a problem when it was the s
168. conventions are shown below Normal Scientific V25 V2 5E 1 99 1 0 99 2 V0 05 V50E 3 V 11 V 1 1E 1 Note that merely programming the source value does not ap ply the voltage to the voltage source output terminals The output must be separately programmed on or off as described in the following paragraph HP 85 Programming Example program the voltage source to a value of 10V press the front panel DISPLAY button to view the source value and enter the following state ments into the computer REMOTE 727 END LINE OUTPUT 727 D1V 10X END LINE When the second statement is executed the source value is programmed for a value of 10V Model 8573 Programming Example Momentarily power down the instrument and then select the voltage source with the front panel DISPLAY button Now enter the following statements into the IBM computer V 1 CALL IBSRE return CMD D1V 10 IBWRT 617 CMD return The voltage source will be programmed to a value of 10V when the second statement is executed 3 10 10 Voltage Source Operate O The voltage source operate command performs essentially the same operations as the front panel OPERATE button The parameters included with this command are 0 Source output off Output 0V 01 Source output on Output programmed value Upon power up or after receiving a DCL or SDC command the instrument will be in the OO Sou
169. correct disabled 5 Locate the offset adjustment potentiometer R314 on the electrometer board see Figure 7 3 The pot is accessible through a small hole in the shield closest to the rear of the instrument 6 Adjust R314 for a reading of 0 0000 1 count on the display 7 Replace the top cover unless the input current adjustment below is to be performed 7 4 9 Input Current Adjustment Use the following procedure to null out any input current pre sent in the input stage The input current will then be automatically temperature compensated to reduce the effects of high ambient temperature Low input current is particular ly important when making very low current or charge measurements or when high input impedance is critical in volts and ohms Proceed as follows 1 Disconnect all input signals from the instrument Place the protection cap CAP 18 on the INPUT connector 2 Remove the two screws securing the top cover and remove it from the instrument 3 Select the amps function and place the instrument on the 2pA range 4 Enable zero check and zero correct in that order 5 Disconnect floating sources and connect a jumper wire be tween the COM and chassis ground binding posts Disable zero check but leave zero correct enabled 6 Wait several minutes until the display on the reading settles down about 15 counts 1 564 of noise is normal 7 Locate the input current potentiometer R348 on the elec trometer bo
170. cur rent being integrated 2 7 7 Resistance Measurements The Model 617 can make resistance measurements using two different methods the constant current method and the cons tant voltage method The constant voltage method which is discussed in paragraph 2 8 uses the built in voltage source With the constant current method discussed here the instru ment can resolve resistances as low as 0 10 and measure as high as 200GQ To measure resistance with the Model 617 use the following procedure 1 Turn on the power and allow a two hour warm up period for rated accuracy 2 Press the OHMS button to place the instrument in the cor rect mode 3 For maximum accuracy place the instrument on the 2kQ range and zero the instrument by enabling zero check and then pressing the ZERO CORRECT button 4 Select the desired range or use autoranging if desired 5 Connect the Model 6011 or similar cable to the INPUT jack Keep the cable as short as possible to minimize the ef fects of cable capacitance Connect the other end of the cable to the resistance to be measured as shown in Figure 2 12 For measurements above 160 it is recommended that you use guarded connections as described in paragraph 2 7 4 6 Disable zero check 7 Take the reading from the display The exponent may be placed in either the alpha or numeric modes as described in paragraph 2 5 Resistance Measurement Considerations When measuring high resistance v
171. d the format of the data the instrument sends over the bus may be controlled as follows 0 Send reading with prefix Example NDCV 1 23456E 00 G1 Send reading without prefix Example 1 23456 00 G2 Send reading with prefix and suffix when in B1 data store mode Example 1 23456E 00 023 In this example memory Hoca tion 23 is being accessed Upon power up or after the instrument receives a DCL or SDC command the instrument will be in the GO mode Figure 3 9 further clarifies the general data format Note that the prefix defines a normal or overflow reading as well as the measuring function The mantissa is always 5 digits although the most significant digit will assume a value of 2 under overload conditions except for a current overload in V I ohms In V I ohms all zeroes will be returned when a current overload condition occurs Keep in mind that the B command affects the source of the data See paragraph 3 10 7 for complete details If the B4 voltage source mode is enabled the VSRC prefix will be sent DATA STORE MANTISSA LOCATION 5 DIGITS 81 G2 ONLY aaa NDCV 1 23456 E 02 011 CR LF N NORMAL OVERFLOW EXPONENT TERMINATOR DCV VOLTS DCC COULOMBS EXTERNAL FEEDBACK VSRC replaces NDCV when reading V Source B4 Figure 3 9 General Data Format HP 85 Programming Example To place the
172. d completely clear C To replace the top cover reverse the above procedure Be sure to instal the tabs at the front of the cover before completely installing it 2 Remove the electrometer board as follows A Remove the four screws that secure the top shield to the electrometer board Carefully lift the shield clear of the board Disconnect the input wires from the electrometer board Disconnect the power transformer wires at the mother board end Remove the three screws that secure the electrometer board to the standoffs adjacent to the power transformer F Carefully remove the electrometer board taking care not to touch the PC board surfaces or any components When the board is partially removed disconnect the ribbon cable at the mother board end 3 Remove the mother board as follows A Disconnect the display board ribbon cable near the front of the instrument B Remove the four screws securing the mother board shield and remove the shield from the board Perform this step only on Rev A boards C Remove the standoffs three spacers and the one addi tional screw that secure the mother board to the bot tom case Do not remove the three standoffs down the center of the board D Remove the two screws that secure the rear panel to the bottom case and remove the mother board and rear panel as a single unit 4 The display board can now be removed as follows A Remove the two screws securing the display boa
173. d dde Bub incedo gt Qna Qasa nio d Triggering __ _ Ground A SUR PR MAU Rad A Electrostatic Interference ssiorperrobencia Thermal EMFs over acarrea rS Gaede eee e eee Leakage Resistance Effects Fr ER aq bebe ta AR ARA Input Capacitance Source Resistance Source Capacitance nh E kits Menor sce ne SHES PEE ae bua Engineering Units Conversion E e SECTION 3 IEEE 488 PROGRAMMING la e a pa du uds ama JEEE 488 BUS LINES Stee PRES ote ke ee eae Data Lines ore twee nie ee ee ee oe eae ios aes ours Bus Management Lines ci Fac TR dC Handshake _ 4 Bus Commands Uniline COATS __ _ Universal Commands os dees de ce basher Nee Addressed Commands arid eee gt patei e RU Unaddressed Commands 62620 6564 naaa Apa UR 04 Pd be nerd Device Dependent Commands Command Codes lt lt oe os ora odes gt Command Sequences Addressed Command Sequence Universal Command Sequ
174. d displayed every 10 minutes When r 0 a single reading is stored each time an appropriate trigger is received for example GET in the T3 trigger mode as described in paragraph 3 10 14 4 The data store rate can be used to control the data output rate in the IEEE 488 talk only mode To use the Model 617 in this manner place the instrument in the talk only mode see paragraph 3 7 Now enter the data storage mode and select the desired interval as described above The instru ment will then output readings over the IEEE 488 bus at the selected rate 5 The storage rate r 0 and r 1 may be affected if the in strument is in autorange and a range change occurs Typically it takes about 350msec per range change Minimum Maximum Operation Minimum Maximum operation is essentially separate from data store except for the fact that both are enabled or disabled by the ON OFF button Thus the minimum and maximum data points are continuously updated with each triggered conversion as long as the ON OFF LED is Note that only range not function is indicated when reading maximum and minimum values Maximum and minimum values can be ob tained during the recall process as indicated in step 4 above 2 13 EXTERNAL TRIGGERING The Model 617 has two external BNC connectors on the rear panel associated with instrument triggering The EXTERNAL TRIGGER INPUT allows the instrument to be triggered by other devices while METER COMPLETE OUTPUT all
175. d test fixture will be necessary for some of the amps ohms and coulombs verification procedures Construction of Table 5 1 Recommended Test Equipment for Performance Verification DC Calibrator 5 Digit DMM Teraohmmeter 0 015 DC Accuracy 100MQ 0 035 169 0 05 1000 0 07 100GQ 0 08 100M9 1 160 2 1069 2 10060 2 Decade Resistor 109 10 0 03 Standard Capacitor 1000pF 0 1 Shielded Test Box See Figure 5 1 Manufacturer and Model 0 19 1 9V 19V 190V 0 002 Fluke 343A Keithley 197 Guildline 9520 Keithiey R 289 100M Keithley R 289 1G Keithley R 319 10G Keithley R 319 100G ESI DB 62 Hewlett Packard 16384A 5 1 this shield is noted in Figure 5 1 Note that the jumper figuration will depend on whether the amps or ohms mode is being calibrated 3 JUMPER FOR USE AS OHMS SOURCE NOTE DO NOT TOUCH BODY OF RESISTOR TO AVOID CONTAMINATION 617 INPUT 4801 CABLE uus DC CALIBRATOR INPUT _________ Fixture PARTS LIST PER RESISTOR ELEMENT 1 SHIELDED BOX POMONA P N 2906 2 BNC CONNECTOR KEITHLEY P N CS 44 3 THREE BANANA JACKS KEITHLEY P N 11 4 DUAL BANANA PLUG POMONA P N 4585 MODEL 4801 BNC CABLE AND 6147 TRIAX BNC ADAPTER NECESSARY TO CONNECT FIXTURE TO INSTRUMENT Figure 5 1 Test Fixture Construction 5 5 VERIFICATION PROCEDURES The following paragraphs contain procedures for
176. default CR LF terminator sequence type the following lines into the computer REMOTE 727 END LINE OUTPUT 727 Y CHR 10 CHR 13 X END LINE When the second statement is executed the normal ter minator sequence will be reversed the instrument will ter minate each data string or status word with a LF CR se quence Model 8573 Programming Use the following statements to reverse the default terminator sequence V 1 CALL IBSRE BRDO V 96 return CMD Y CHR 10 CHR 13 X CALL IBWRT M617 CMD return The terminator sequence will be reversed when the second statement is executed 3 10 18 Status U The status command allows access to information concerning instrument operating modes that are controlled by other device dependent commands such as F function and R range Additional parameters of the status command allow data and error conditions to be accessed Status commands include U0 Send status word U1 Send instrument error conditions U2 Send instrument data conditions When the command sequence is transmitted the instru ment will transmit the status word instead of its normal data string the next time it is addressed to talk The status word will be transmitted only once each time the UO command is given To make sure that correct status is transmitted the status word should be requested as soon as possible after the command is transmitted The form
177. ding one of the following commands F0 Volts 1 Amps F2 Ohms Coulombs 4 External Feedback F5 V I Ohms Upon power up or after the instrument receives a DCL or SDC command the FO Volts mode will be enabled HP 85 Programming Example Place the instrument in the current function with the front panel AMPS button and enter the following statements into the HP 85 keyboard REMOTE 727 END LINE OUTPUT 727 FOX END LINE When END LINE is pressed the second time the instrument changes to the volts mode as indicated by the associated LED Model 8573 Programming Example Place the instru ment into the current mode with the front panel AMPS but ton Now type the following statements into the computer keyboard V 1 IBSRE BRDO 6 V return CMD FOX CALL IBWRT M617 return When the return key is pressed the second time the instru ment changes to the volts function Table 3 11 Device Dependent Command Summary Mode Command Paragraph Execute x Execute other device dependent commands 3 10 1 FO lt lt lt lt lt lt lt lt lt lt Range External 3 10 3 Volts Amps Ohms Coulombs Feedback Ohms Auto Auto Auto Auto Auto Auto 200 2 2kQ 200pC 200mV 200TQ 2 V 20 20kQ 2 2 2070 20 V 200pA 200 20nC 20 2T2 200 2nA 2MQ 20nC 20 20009 200 20nA 20 0 20nC 20 2060 200 V 200 n 200 0 20nC 20 260 200 V
178. e but it is of no consequence since that current is supplied by the low im pedance source rather than by the signal itself EQUIVALENT CIRCUIT Figure 2 6 Unguarded Circuit 2 10 617 PREAMP Figure 2 7 Guarded Circuit Rs ES M When the rear panel V Q GUARD switch is placed in the ON position guard potential is placed on the inner shield of the triaxial cable The other shield remains at chassis ground Thus it is necessary to use the COM terminal for low signal connections as shown in Figure 2 8 For very critical meas urements a shielded guarded enclosure should be used WARNING Hazardous voltage up to 300V may be pre sent on the inner shield when V 0 GUARD is on depending on the input signal safe ty shield connected to chassis ground is recommended when making voltage measurements over 30V or guarded resistance measurements NOTE The use of guarding is not recommended in amps or coulombs The PREAMP QUT terminal may be used for guarding in the volts and ohms modes in a similar manner In this mode the preamplifier acts as a unity gain amplifier with low output impedance WARNING Hazardous voltage up to 300V may be present at the PREAMP OUT terminal depending on the input signal 2 7 5 Making Current Measurements The Model 617 can resolve currents as low as 0 1 fA 10 16A and measure as high as 20mA in 11 ranges The
179. e current source repeat steps 1 through 4 for the 200pA through 2pA ranges Coulombs Verification Connect the Model 617 to the Model 263 as shown in Figure 1 and perform coulombs verification as follows 1 Using the COUL active charge source of the Model 263 select the 2nC range 2 Place the Model 263 in the coulombs function and per form zero correction by enabling zero check and zero correct in that order 3 Release zero check on the Model 61 4 Program the Model 263 for 1 90000nC and press OPERATE to source charge to the Model 617 5 Verify that the Model 617 reads between 1 8943 and 1 9057nC Table 1 Limits for Amps Verification AMPS AMPS AMPS AMPS AMPS AMPS AMPS AMPS AMPS V R AMPS Includes Model 263 Error MODEL 263 MODEL 617 Figure 1 Amps Verification Setup Volts Verification NOTE Current and charge verification must be performed before volts verification Connect the Model 617 and 190V calibration source to the Model 263 as shown in Figure 2 and perform volts verifica tion as follows 1 2 10 the Model 617 enable zero check and select the 200mV range Check to see that the display reads 000 00 1 count If not enable zero correct Program the Model 263 to output 190 000mV Disable zero check and verify that the reading on the Model 617 is within the limits listed in Table 2 Using Table 2 as a guide repeat steps 1 through 4 for t
180. e 3 6 BASIC Statements Necessary to Send Bus Commands Transmit string to device 27 OUTPUT 727 A Obtain string from device 27 ENTER 727 Send GTL to device 27 LOCAL 727 Send SDC to device 27 CLEAR 727 Send DCL to all devices CLEAR 7 Send remote enable REMOTE 7 Cancel remote enable LOCAL 7 Serial poll device 27 SPOLL 727 Send local lockout LOCAL LOCKOUT 7 Send GET to device TRIGGER 727 Send IFC ABORTIO 7 Action ____________ 85 Statement Model 8573 Statement CALL IBWRT M617 5 CALL IBRD M617 RD CALL IBLOC M617 CALL IBCLR M617 CMD amp H14 CALL IBCMD BRDO CMD V96 1 CALL IBSRE BRD096 V V 0 CALL IBSRE BRDO V CALL IBRSP M61796 58 CMD 11 CALL IBCMD BRDO CMD CALL iBTRG M617 CALL IBSIC BRDO 3 11 3 8 3 Interface Function Codes The interface functions codes which are part of the IEEE 488 1978 standards define an instrument s ability to support various interface functions and should not be confus ed with programming commands found elsewhere in this manual The interface function codes for the Model 617 are listed in Table 3 7 These codes are also listed for convenience on the rear panel adjacent to the IEEE 488 connector The codes define Model 617 capabilities as follows SH Source Handshake Function SH1 defines the ability of the Model 617 to initiate the
181. e and one reading per hour Either during or after the storage process readings including maximum and minimum values may be recalled by using the B command as described in the last paragraph Once the unit has logged all 100 readings the instrument will stop data storage until another command is sent to enable 3 23 data store once again Note that the instrument may be grammed to generate an SRQ when memory is full as described in paragraph 3 10 15 The available storage intervals include Q0 Conversion rate one reading every 360msec Q1 One reading per second Q2 One reading every 10 seconds Q3 One reading per minute QA One reading every 10 minutes Q5 One reading per hour Q6 Trigger mode TRIG button Q7 Data store disabled In addition to the various rates data store can be used at a rate determined by the TRIG button Q6 mode When in this mode one reading will be stored in memory each time TRIG button is operated Upon power up or after a DCL or SDC command the data store will be disabled Q7 mode NOTES 1 To use data store on a one shot basis with other trigger stimuli place the instrument in the QO mode and select the desired one shot trigger mode paragraph 3 10 14 2 In Q0 and QI the storage rate may be decreased if the in strument is in autorange and a range change occurs HP 85 Programming Example Enter the program below to enable data store operation and
182. e digitally calibrated from the front panel or over the IEEE 488 bus Zero Correct A front panel zero correct control allows the user to cancel any offsets Baseline Suppression One button suppression of a baseline reading is available from the front panel or over the 488 bus One shot Triggering A front panel control for triggering one shot readings from the front panel is included Isolated 100V Voltage Source A built in 100V source is isolated from the electrometer section The voltage source is programmable in 50mV steps Selectable Guarding A selectable driven cable guard is in cluded to optimize speed Standard IEEE 488 Interface The interface allows ful bus programmable operation of the Model 617 Analog Outputs Both preamp and 2V full range analog outputs are included on the rear panel 100 Point Data Store An internal buffer that can store up to 100 readings is accessible from either the front panel or over the IEEE 488 bus Minimum and maximum data points can be stored and are accessible from the front panel or over the IEEE 488 bus 1 3 WARRANTY INFORMATION Warranty information for your Model 617 may be found in side the front cover of this manual Should you need to use the warranty contact your Keithley representative or the fac tory for information on obtaining warranty service Keithley Instruments Inc maintains service facilities in the United States
183. e instrument on a supply voltage outside the indicated range or instrument damage might occur Line Voltage Selection The operating voltage of the instru ment is internally selectable Refer to Section 7 for the pro cedure to change or verify the line voltage setting Line Frequency The Model 617 may be operated from either 50 or 60Hz power sources IEEE 488 Primary Address If the Model 617 is to be pro grammed over the 488 bus it must be set to the correct primary address The primary address is set to 27 at the fac tory but it may be programmed from the front panel as described in Section 3 1 11 REPACKING FOR SHIPMENT Before shipping the instrument should be carefully packed in its original packing material If the instrument is to be returned to Keithley Instruments for repair or calibration include the following Write ATTENTION REPAIR DEPARTMENT on the ship ping label Include the warranty status of the instrument Complete the service form at the back of this manual 1 12 ACCESSORIES The following accessories are available to enhance Model 617 capabilities Models 1019A and 1019S Rack Mounting Kits The Model 1019A is a fixed or stationary rack mounting kit with two front panels provided to enable either single or dual side by side mounting of the Model 617 or other similar Keithley in strument The Model 10195 is a similar rack mounting kit with a sliding mount configuration Model 60
184. e listed in columns 4 A through 5 B The preceding address groups are combined together to form the Primary Command Group PCG The bus also has another group of commands called the Secondary Command Group SCG These are listed in Figure 3 3 for informational purposes only the Model 617 does not have secondary ad dressing capabilities Note that these commands are normally transmitted with the 7 bit code listed in Figure 3 3 For many devices the condition of DIOS is unimportant However many devices may require that DIOS has a value of logic 0 high to properly send com mands Hexadecimal and decimal values for each of the commands or command groups are listed in Table 3 2 Each value assumes that DIO8 has a value of 0 Table 3 2 Hexadecimal and Decimal Command Codes Hex Value Decimal Value 3 6 COMMAND SEQUENCES The proper command sequence must be sent to the instru ment before it will respond as intended Universal com mands such as LLO and DCL require only that ATN be set low when sending the command Other commands require that the instrument be properly addressed to listen first This section briefy describes the bus sequence for several types of commands 3 6 1 Addressed Command Sequence Before a device will respond to one of these commands it must receive a LAG command derived from its primary ad dress Table 3 3 shows a typical sequence for the SDC com mand the example assumes that a primary
185. e range the instrument is in Pressing the up ar row button will move the instrument up one range each time it is operated while the down arrow button will move the in strument down range one increment each time it is pressed Note that pressing either of these buttons will cancel autorange if that mode was previously selected The display mantissa will remain blank until the first reading is ready to be displayed AUTO The AUTO button places the instrument in the auto range mode While in this mode the Model 617 will switch to the best range to measure the applied signal Note that the in strument will be in the autorange mode when it is first turned on Autoranging is available for all functions and ranges Autoranging may be cancelled either by pressing the AUTO button or one of the two RANGE buttons ZERO zero check mode is used in conjunction with the ZERO CORRECT control to cancel any offsets within the instrument and is also used as a standby mode Pressing ZERO CHECK once will enable this mode as shown by the associated indicator light When zero check is enabled the electrometer input circuit configuration changes see paragraph 2 11 No readings can be be taken with zero check enabled Pressing ZERO CHECK a second time will disable this mode Zero check should be enabled when making connections or when changing functions ZERO CORRECT The zero correct mode works with zero check to cancel electrometer of
186. e reading will be stored in memory each time the front panel TRIG button is pushed For rapid starts the rate can be pre selected by pressing ON OFF releasing the button when the selected rate is dis played and then turning off data store Storage will then begin at the pre selected rate the next time the ON OFF button is pressed When data store memory is full after all 100 readings have been stored the instrument will stop logging data and the DATA LED will flash to indicate that memory is full Readings can be recalled any time even if the instrument is still logging by pressing and holding the RECALL button Holding the RECALL button in causes the data pointer to be displayed Releasing the RECALL button causes the cor responding data to be displayed The first data point to be displayed will be the last reading stored For example if reading 65 was the last point the display will show n 65 The second and third points will be the high and low data points For example for the high value the display will show n HI 2 28 Similarly the display will show the following for the low data point n Lo 6 Following these three points the remaining data points will be displayed beginning with the first one stored The data pointer will increment from 1 to the maximum point stored For example the tenth reading appears as n 10 7 To continue recalling readings use the RECALL button to scroll the data
187. e within the instrument More information on the using the voltage source is located in paragraph 2 8 DISPLAY The DISPLAY button toggles the front panel display between the voltage source and the present display mode electrometer or data store Pressing DISPLAY once will switch the display from the present mode to the source mode as indicated by the LEDs adjacent to the display more information on the display is located in paragraph 2 4 2 Pressing DISPLAY again will return the display to the previous display mode ADJUST These two buttons control the voltage source out put value The up arrow button increases the voltage value in 50mV increments while the down arrow decreases the voltage source output in 50mV increments The values may be scrolled by holding the desired ADJUST arrow in The in strument will stop on the value currently displayed when the button is released The scrolling can be made more rapid by pressing the SHIFT key before pressing the desire ADJUST key Note that the ADJUST keys are also used with certain front panel programs as described in paragraph 2 5 Note that the maximum voltage values are 102 4V and 102 35V OPERATE The OPERATE button turns the actual voltage source output on or off Pressing the OPERATE button once turns on the output The LED next to the OPERATE button will be illuminated when the source is turned on Pressing the OPERATE button a second time will turn off the output 00 00V
188. ec tively The leakage resistance is represented by while the voltage as seen by the electrometer is Rs and form a voltage divider that attenuates the input signal in accordance with the formula EsRy Rs Ry Thus if has a value of 10060 and Rg is 1060 the actual voltage measured by the electrometer with a 10V source would be 10 x 100GQ VM 10GQ 100GQ VM 9 09V Thus we see that the effects of leakage resistance can be substantial resulting in an error of almost 10 in this case Certain steps can be taken to ensure that the effects of leakage resistance are mimimal The most obvious remedy to ensure that the leakage resistance itself is as high as possible Use only good quality triaxial cable for signal connections and make sure that the circuit under test and connectors are kept free of contamination Even with these steps however there is a limit as to how high the leakage resistance can be In those cases guarded input connections should be used as described in paragraph 2 7 4 Figure 2 27 Leakage Resistance Effects 2 14 6 Input Capacitance Effects Virtually any circuit has at least some small amount of distributed capacitance that can slow down the response time of high impedance measurements Even if the circuit itelf has minimal capacitance cable or instrument input capacitance effects can be noticable As an example assume that the Model 617 is being
189. ections for Voltage Source Verification 5 9 5 10 SECTION 6 THEORY OF OPERATION 6 1 INTRODUCTION This section contains an overall functional description of the Model 617 in block diagram form as well as details of the various sections of the instrument Information concerning the electrometer section mother board circuitry IEEE 488 in terface power supplies and display circuitry is included Information is arranged to provide a description of each of the functional blocks within the instrument Many of these descriptions include simplified schematics and block dia grams Detailed schematic diagrams and component layout drawings for the various circuit boards are located at the end of Section 8 6 2 OVERALL FUNCTIONAL DESCRIPTION A simplified block diagram of the Model 617 is shown in Figure 6 1 The instrument may be divided into four discrete sections analog digital voltage source and power supplies The analog digital and voltage source sections are electrical ly isolated from one another by using opto isolators for con trol and communications Separate power supplies for the various analog sections digital section and the voltage source ensure proper isolation Because of these isolation techniques the analog low connection may be floated up to 500V above chassis ground while voltage source common may be floated up to 100V ground and digital common may be floated up to 30V above ground The analog section co
190. eme MPU time necessary to read the A D converter data is minimized and the processor can concentrate on other important tasks The voltage source is controlled in a manner similar to that used to control the A D converter Control information is transmitted out the PB3 and PB4 terminals of the MPU through 102 Once again a pulse width modulation scheme is used to transmit the 12 bit data necessary to control the DAC in the voltage source section 100V isolation is af forded by opto isolator U124 located in the voltage source section Data transmission is controlled by a 81 92kHz clock This clock is generated by U103 by dividing down the 655 36kHz system clock The clock signal is transmitted through R105D through isolator 17123 which is located in the voltage source section Voltage source overload data is fed in through opto isolator U125 to the PA7 terminal of the MPU When the 2mA cur rent limit of the voltage source is exceeded PA7 goes high The necessary software routine is used to flash the OPERATE LED indicating to the operator that an overload has occur red 6 6 6 Display Circuitry Display circuitry includes those elements necessary to control the seven and 14 segment readouts the front panel annun ciator LEDs and to read the front panel switches The display circuitry schematic may be found on drawing number 617 116 located at the end of Section 8 The display circuitry consists of the LED readouts DS201 05
191. ence Device Dependent Command Sequence Hardware Typical Controlled Systems ospis csick Bits COMMECHONG os NA ta Primary Address Programming OS pr ad pes M Software Considerations te ts aa a eda Controller Handler SOFWARE 0 rr ao A Interface BASIC Programming Statements Interface Function IEEE Command GEIOUDS co ae General Bus Command REN Remote da Sed dg IFC Interface Clear Vas tcs LLO Local Lockout uuu eee asus a gt gt DECL E d d SDC Selective Device Clear rro GET Group Execute Trigger Serial Polling radio dy aa d eda dos Device Dependent Command 3 10 1 3 10 2 3 10 3 3 10 4 3 10 5 3 10 6 3 10 7 3 10 8 3 10 9 3 10 10 3 10 11 3 10 12 3 10 13 3 10 14 3 10 15 3 10 16 3 10 17 3 10 18 3 11 3 11 1 3 11 2 3 11 3 3 12 Execute X Function F
192. ended talker capabilities 3 12 LE Extended Listener Function The Model 617 does not have extended listener capabilities E Bus Driver Type The Model 617 has open collector bus drivers Table 3 7 Modei 617 Interface Function Codes Interface Function SH1 Source Handshake Capability Acceptor Handshake Capability T5 Talker Basic Talker Serial Poll Talk Only Mode Unaddressed To Talk On L4 Listener Basic Listener Unaddressed To Listen On TAG SR1 Service Request Capability jRemote Local Capability PPO No Parallel Poll Capability DC1 Device Clear Capability DT1 Device Trigger Capability CO Controller Capability E1 Open Collector Bus Drivers TEO No Extended Talker Capabilities No Extended Listener Capabilities 3 8 4 IEEE Command Groups Command groups supported by the Model 617 are listed in Table 3 8 Device dependent commands which are covered in paragraph 3 10 are not included in this list 3 9 GENERAL BUS COMMAND PROGRAMMING General bus commands are those commands such as DCL that have the same general meaning regardless of the instru ment type Commands supported by the Model 617 are listed in Table 3 9 which also lists both HP 85 and Model 8573 statements necessary to send each command Note that com mands requiring that a primary address be specified assume that the Model 617 primary address is set to 27 its default ad dress If you are usin
193. ent data conditions When this command is transmitted the instrument will transmit the data condition word shown in Figure 3 13 the next time it is addressed to talk This informa tion will be transmitted only once each time the command is received with the U1 error word the U2 word is made up of ASCII characters representing binary values Unlike the U1 error word however the U2 data condition word will not be cleared when read thus instrument status in the U2 word is always current 617 0 1 0 0 1 0 1 0 1 0 1 000 CRLF MODEL NUMBER PREFIX 1 DATA STORE FULL ALWAYS ZEROES TERMINATOR DEFAULT VALUES 2 ZERO CORRECT SHOWN O OFF 1 ON N SUPPRESS 0 OFF 1 1 TEMPORARY CALIBRATION 1 VOLTAGE SOURCE OVER I LIMIT Figure 3 13 U2 Status Data Condition Format The various bits in the data condition word include Data Store Full Set when all 100 readings have been stored in the data store memory Z and N Represents the same information as the corresponding zero correct Z and suppress N bytes in the UO status word Temporary Calibration Set when new calibration para meters not yet stored in NVRAM have been received or if power up recall of NVRAM data was in error Cleared when NVRAM storage is performed Voltage Source I limit Set when the 2mA current limit of the voltage source has been exceeded HP 85 Programming Exampie Enter the following pro gram into the computer t
194. eparate command is included to perform storage By combining appropriate IEEE 488 compatible calibration equipment with a suitable test pro gram calibration of 617 could be performed on an automated basis Use the following basic procedure when calibrating the Model 617 over the IEEE 488 bus 1 Program the desired range and function over the bus For example to select the 200V range and volts function send FOR4X 2 Zero correct the instrument by sending C1XZ1X 3 Apply the calibration signal to the input jack Disable zero check by sending 4 Send the required calibration value preceded by the A command letter For example to calibrate the 200V range at the 190V calibration point send A190X 5 Repeat steps 1 4 for the remaining ranges and functions For maximum accuracy zero correct the instrument for each range and function 6 After all points have been calibrated send LIX to store calibration constants in NVRAM NOTE NVRAM storage will not take place if the calibration jumper is in the disabled position See paragraph 7 4 4 for details HP 85 Programming Example The simple program below will allow you send the desired calibration command string to the Model 617 The program assumes that the instru ment primary address is at its default value of 27 PROGRAM COMMENTS 10 REMOTE 727 Send remote enable 20 DISP CALIBRATION Prompt for command COMMAND 30 INPUT A Input comma
195. er a device must be addressed to listen before these commands are transmitted Table 3 4 shows the byte se quence for a typical Model 617 command FOX which sets the instrument for the volts mode of operation Table 3 4 Typical Device Dependent Command Sequence State Hex Decimal Set low Stays low Set high Stays high Stays high Assumes primary address 27 3 7 HARDWARE CONSIDERATIONS Before the Model 617 can be operated over the IEEE 488 bus it must first be connected to the bus with a suitable cable Also the primary address must be programmed to the correct value as described in the following paragraphs 3 7 1 Typical Controlled Systems System configurations are many and varied and will depend on the application To obtain as much versatility as possible the IEEE 488 bus was designed so that additional instrumen tation could be easily added Because of this versatility system complexity can range from the very simple to ex tremely complex Figure 3 4 shows two possible system configurations Figure 3 4 a shows the simplest possible controlled system The controller is used to send commands to the instrument which sends data back to the controller The system in Figure 3 4 b is somewhat more complex in that additional instruments are used Depending on programm ing all data may be routed through the controller or it may be sent directly from one instrument to anothe
196. er that is entered when the storage mode is first enabled Alternatively a special one shot trigger mode can be used to control the fill rate from the front panel Once data is stored readings can be easily recalled from the front panel Minimum and maximum values can also be retained for future recall As long as data store is enabled maximum and minimum values are updated with each conversion Enter the data storage mode as follows 1 Press and hold the DATA STORE button The instrument will then scroll through the various reading rates that are listed in Table 2 7 In addition to the con tinuous rate which stores readings at the conversion rate five additional intervals from one reading per second to 2 27 one reading hour are available A special trigger mode allows you to control the interval with the TRIG button During the rate selection process the display will appear as follows r 3 In this example the rate parameter is 3 indicating a 1 rdg min interval Table 2 7 Data Store Reading Rates Conversion Rate every 360msec 1 Reading Per Second 1 Reading Every 10 Seconds 1 Reading Per Minute 1 Reading Every 10 Minutes 1 Reading Per Hour Front Panel Trigger Mode To select the desired interval simply release the ON OFF button when the desired rate appears in the display The Model 617 will then begin storing readings at the selected rate If you selected the triggered mode on
197. ethod to apply external feedback 2 2 POWER UP PROCEDURE Use the procedure below to connect the Model 617 to line power and power up the instrument 1 Connect the female end of the power cord to the AC recep tacle on the rear panel of the instrument Connect the other end of the cord to a grounded AC outlet WARNING The Model 617 is equipped with a 3 wire power cord that contains a separate ground wire and is designed to be used with grounded outlets When proper connec tions are made instrument chassis is con nected to power line ground Failure to use a grounded outlet may result in personal in jury or death because of electric shock CAUTION Be sure that the power line voltage agrees with the indicated range on the rear panel of the instrument Failure to observe this precaution may result in instrument damage necessary the line voltage may be changed as decribed in Section 7 2 Turn on the power by pressing in the front panel POWER switch The switch will be at the inner most position when the instrument is turned on 3 The instrument will power up in the volts function in the autorange mode and with zero check enabled as indicated by the associated front panel LEDs All other LEDs will be off when the instrument is first turned on 2 3 POWER UP SELF TEST AND DISPLAY MESSAGES The RAM memory is automatically tested as part of the power up procedure If a RAM memory error occurs the rr message will
198. evels Digital and analog waveform checks Note that the revision level of your instrument may be dif ferent 5 At this point the instrument will enter the diagnostic mode that switches the instrument among the zero common calibration reference and signal phases of its measure ment cycle The unit can be cycled through these phases by repeatedly pressing the TRIG button The decimal point will indicate the range During the zero common phase the display will appear as follows P 0 6 During the calibration reference phase the display will show Pec 7 Finally the display will show the following message during the signal phase 5 8 remove the instrument from the diagnostic mode turn off the power During normal operation the instrument cycles through these three phases in rapid succession This cycle action makes it difficult to troubleshoot the instrument utilizing normal signal tracing techniques However by using the diagnostic program to freeze the instrument on the appropriate phase troubleshooting is greatly simplified Table 7 9 summarizes phases display messages and signals applied to the A D con verter during each of the three phases 7 7 4 Power Supply Checks All power supply voltages should be checked first to make sure they are within the required limits If the various operating voltages are not within the required limits troubleshooting the remaining circuitry can
199. exact con figuration of the zero check circuitry will depend on the selected function A simplified schematic of the zero check circuitry for volts and ohms functions is shown in Figure 6 9 When zero check is enabled K307 is energized providing a path to signal com mon through the normally closed contacts of K301 A 10M9 resistor R334 is placed across the electrometer input when zero check is enabled while the preamp input is shorted to in put low In amps and coulombs contacts on K301 connect the invert ing input and the output of the op amp together This con figuration gives the circuit unity gain allowing any input offset voltage to appear at the output Note that when zero check is enabled the input impedance is the combined im pedance of the feedback element in parallel with R334 which has a value of 10 see Figure 6 10 6 4 ADDITIONAL SIGNAL CONDITIONING Before the signal can be applied to the A D converter for digitization it must be further scaled as described in the following paragraphs 6 4 1 Ranging Amplifier The ranging amplifier provides inverting gain values of X10 X1 1 or 01 The actual gain value will depend on the selected range and function A simplified schematic of the ranging amplifier is shown in Figure 6 11 The ranging amplifier itself is U130 while gain is set by feedback resistors R142 R143 R144 R145 and input resistor R128 The gain is modified by switching these resis
200. f Table 7 4 Disable zero check 11 Set the Model 617 calibration constant to exactly 19 000nA either with the front panel calibration pro gram or over the IEEE 488 bus 12 Repeat steps 9 through 11 for the 204 and 20mA ranges as listed in the table For maximum accuracy zero correct the instrument after each range is selected Table 7 4 Amps Calibration Calibration Resistor Calibrator 617 Display IEEE 488 Current Value Value Value Bus Command 190 00 pA i m 190 00 pA 190 12 19 00 nA 10 00MQ 0 19000V 19 000 nA A19E 9X 19 00 pA 1 000MQ 19 0000V 19 000 A A19E 6X 19 000mA 1000 0 0 19 0000V 19 000mA AT9E 3X Use 10060 resistor for 200pA range decade box for other ranges Values to be determined using procedure outlined in text NOTE LEAVE GREEN DISCONNECTED OO CHASSIS SHIELDED FIXTURE FIGURE 7 1 e DO 0 LD chassis 6 O 0 chassis O E10 00000 6011 CABLE MODEL 617 4801 CABLE 6147 ADAPTER GROUND LINK REMOVED GROUND LINK IN PLACE MODEL 617 Figure 7 5 Connections For Amps Calibration 20nA 204A and 20mA Ranges Figure 7 4 Connections For Amps Calibration 20pA 7 7 7 4 12 Coulombs Calibration 3 Zero correct the instrument by enabling zero check and then zero correct in that order 4 Disable zero check and set the calibrator output to Use the following procedure to calibrate the 20nC range 190 000mV Once this r
201. fsets If zero check is enabled pressing ZERO CORRECT will store a new value that will be used to cancel any offset If the range is changed while zero correct is enabled the stored value will be scaled accordingly Zero correct may be cancelled by pressing the ZERO COR RECT button a second time More information on using zero correct may be found in paragraph 2 11 SUPPRESS The suppress mode allows you to cancel exter nal offsets or store a baseline value to be subtracted from subsequent readings For example if you applied 10V to the instrument and enabled suppress that value would then be subtracted from subsequent readings Once suppress is en abled the value is scaled when the range is changed Suppress may be disabled by pressing the SUPRESS button a second time and is cancelled if the function is changed TRIG The TRIG button allows you to enter the one shot trigger mode and trigger single readings from the front panel To enter the one shot mode press SHIFT then TRIG The SGL indicator light will show that the instrument is in the one shot mode Each time the TRIG button is pressed a single reading will be processed and displayed The displayed reading will flash when the TRIG button is pressed The one shot trigger mode can be cancelled by pressing SHIFT then TRIG a second time Additional information on triggering may be found in paragraphs 2 13 and 3 10 14 V SOURCE These buttons control the internal 100V sourc
202. g Model 8573 programming examples remember that the modified declaration file must be loaded and run first as described in paragraph 3 8 2 Table 3 8 IEEE Command Groups HANDSHAKE COMMAND GROUP DATA ACCEPTED READY FOR DATA DAV DATA VALID UNIVERSAL COMMAND GROUP ATN ATTENTION DCL DEVICE CLEAR INTERFACE CLEAR LLO LOCAL LOCKOUT REN REMOTE ENABLE SPD SERIAL POLL DISABLE SPE SERIAL POLL ENABLE ADDRESS COMMAND GROUP LISTEN LAG LISTEN ADDRESS GROUP MLA MY LISTEN ADDRESS UNL UNLISTEN TAG TALK ADDRESS GROUP MY TALK ADDRESS UNT UNTALK OTA OTHER TALK ADDRESS ADDRESSED COMMAND GROUP ADDRESSED COMMAND GROUP GROUP EXECUTE TRIGGER GTL GO LOCAL SDC SELECTIVE DEVICE CLEAR STATUS COMMAND GROUP 5 REQUEST SERVICE SRQ SERIAL POLL REQUEST STB STATUS BYTE END 3 9 1 REN Remote Enable The remote enable command is sent to the Model 617 by the controller to set up the instrument for remote operation Generally the instrument should be placed in the remote mode before you attempt to program it over the bus Simply setting REN true will not actually place the instrument in the remote mode Instead the intrument must be addressed after setting REN true before it will go into remote To place the Model 617 in the remote mode the controller must perform the following sequence 1 Set the REN line true 2 Address the Model 617 to listen HP
203. gger mode by press ing the SHIFT and TRIG buttons in that order 3 Program the Model 705 scan parameters such as first and last channel as required Place the instrument in the single scan mode 4 Install the desired scanner cards and make the required in put and output signal connections See the Model 705 In struction Manual for details 5 If data storage is required enter the data storage mode as described in paragraph 2 12 6 Begin the measurement sequence by pressing the Model 705 START STOP button The Model 705 will close the first channel and trigger the Model 617 to take a reading When the Model 617 completes the reading it will trigger the Model 705 to go to the next channel The process repeats until all programmed channels have been scanned 2 14 MEASUREMENT CONSIDERATIONS The Model 617 is a highly sensitive instrument that can measure extremely low signal levels At these low signal levels a number of factors can affect a measurement Some considerations when making measurements with the Model 617 are discussed in the following paragraphs 2 14 1 Ground Loops Ground loops that occur in multiple instrument test set ups can create error signals that cause erratic or erroneous measurements The configuration shown in Figure 2 25 in troduces errors in two ways Large ground currents flowing in one of the wires will encounter small resistances either in the wires or at the connecting points This small resistance
204. he IEEE 488 bus 6 HP 85 Computer equipped with HP 82937 GPIB Inter face and I O ROM 7 Keithley Model 7008 IEEE cable Accuracy requirement of calibration equipment O O JUMPER MOTHER BOARD FRONT OF INSTRUMENT Figure 6 Calibration Jumper Location Model 617 Environmental Conditions Calibration should be performed under laboratory condi tions having an ambient temperature of 23 1 C and a relative humidity of less than 70 With both the Models 617 and 263 on allow them to warm up for one hour If either instrument has been subjected to extreme tempera ture or humidity allow at least one additional hour for the instrument to stabilize before beginning the calibration procedure NOTE While rated accuracy of the Model 617 is achieved after the two hour warm up period input bias cur rent may require additional time to come to its op timum level Allow two hours for input bias cur rent to settle to less than 10fA and eight hours to less than Calibration Sequence Model 617 calibration must be performed in the order given in the following paragraphs with the exception of the voltage source calibration which can be done at any time The basic sequence is Manual Adjustments 1 Input offset adjustment 2 Input current adjustment 3 Voltage source calibration adjustments Digital Calibration Front Panel or 488 Bus
205. he 2V and 20V ranges Set the Model 617 to the 200V range Set the external calibration source to output 190 000V to the Model 263 Source 190 000 to the Model 617 by pressing SHIFT VOLTS on the Model 263 Verify that the reading on the Model 617 is within the limits listed in the table Enable zero check on the Model 263 and turn off the external calibration 190V source Ohms Verification Connect the Model 617 to the Model 263 as shown in Figure 3 and perform ohms verification as follows 10 21 Charge and current verification must performed before resistance verification Set the Model 617 to the 2 range Zero correct the Model 617 by enabling zero check and zero correct in that order Set the Model 263 to the 1kQ range and while in OPERATE press ZERO to source zero ohms to the Model 617 Release zero check on the Model 617 and allow the reading to settle On the Model 617 press SUPPRESS to cancel offset and test lead resistance On the Model 263 source the 1kQ resistor to the Model 617 The actual value of the output resistance is displayed on the Model 263 Record the reading on the Model 263 in Table 3 Calculate the Model 617 reading limit using the formula in the table Verify that the reading on the Model 617 equals the Model 263 reading to calculated limit Referring to Table 3 repeat the basic procedure in steps 3 through
206. he END LINE key is pressed the second time the in strument cancels the autorange mode and enters the R3 range instead Model 8573 Programming Example Make sure the in strument is in the autorange mode Now enter the following statements into the IBM PC keyboard V 1 CALL IBSRE BRDO V return CMD R3X CALL IBWRT M617 CMDS return When the return key is pressed the second time the instru ment cancels the autorange mode and switches to the R3 range 3 10 4 Zero Correct and Zero Check Z and C The zero correct and zero check commands work together to cancel any internal offsets that might upset accuracy lf the instrument is placed in the zero correct mode with zero check enabled it will store a new offset value to be used for subse quent readings If the instrument is zero corrected with zero check disabled the previously stored zero value will be used instead Note that the specifications at the front of this manual assume that the instrument has been properly zeroed Zero correct and zero check commands include CO Zero check off C1 Zero check on 20 Zero correct off Z1 Zero correct on The instrument will be ready on reading done zero correct or when the front end 1 set up zero check Upon power up or after receiving a DCL or SDC command the unit will be in the C1 and ZO modes zero check on and zero correct off Use the following procedure to zero the instrument 1 With zero correct off p
207. he desired function and select the range to be calibrated Apply the necessary calibration signal and enter that value into the instrument s memory either with the front panel calibration program or over the 488 bus The flashing exponent decimal points 0 MODEL 617 V SOURCE OUTPUT VOLTAGE SOURCE GAIN ADJUSTMENT Figure 7 10 Connections for Voltage Source Calibration 7 10 will indicate parameters have been entered The nominal adjustment range is 6 12 in external feedback However it is important to note that such calibration will be only temporary as these parameters will be lost when the power is turned off Under these conditions the instrument will revert to calibration constants previously stored in NVRAM the next time it is turned on Note that the IEEE 488 DCL and SDC commands will also cancel temporary calibra tion constants As an example of this procedure let us assume that you wish to temporarily calibrate the 2mA range that is not part of the normal calibration sequence The following basic procedure could be used to calibrate this range 1 Select the amps mode and place the instrument on the 2mA range 2 Zero correct the instrument by enabling zero check and then zero correct in that order 3 Connect a suitable calibration signal to the instrument Typically calibration is done at 95 of full range or 1 9000mA in this case 4 Disable zero check and enter the
208. he instrument that asserted SRQ and if so what conditions caused it to do so Note that additional data and error conditions can be checked by using the U1 and U2 commands as described in paragraph 3 10 18 3 28 The Model 617 can be programmed to generate an SRQ under one or more of the following conditions 1 If an overrange condition occurs 2 When the data store memory is full 100 readings 3 If a reading is completed 4 When the instrument is ready to accept bus commands 5 If an error occurs The nature of the error can then be determined with the Ul command as described in paragraph 3 10 18 use U1 to restore SRQ after an error occurs Upon power up or after a DCL or SDC command is re ceived 5 is disabled 5 Mask The Model 617 uses an internal mask to deter mine which conditions will cause to be generated Figure 3 10 shows the general format of this mask which is made up of eight bits The SRQ has the same general format as the status byte described below except for the fact that bit 6 is not used in the SRQ mask SRQ can be programmed by sending the ASCII letter M followed by a decimal number to set the appropriate bit in the SRQ mask Decimal values for the various bits are summar ized in Table 3 13 Note that the instrument may be pro grammed for more than one set of conditions simultaneously To do so simply add up the decimal bit values for the re quired SRQ conditions
209. he instrument to the normal mode press the SUPPRESS button The SUPPRESS Light will go off and the instrument will be taken out of the suppression mode The previously stored suppressed value will be cancelled NOTES 1 Using suppress reduces the dynamic range of the measure ment For example if the suppressed value is 100mV on the 200mV range an input voltage of 100mV or more would overrange the instrument even though input vol tages up to 199 99mV are normally within the capabilities of the 200mV range If the instrument is in the autorange mode it will move up range if necessary 2 Setting the range lower than the suppressed value will overrange the display the instrument will display the OL message under these conditions 3 To store a new baseline suppress must first be disabled and the enabled once again The new value will be stored with the first triggered conversion 4 Do not move the instrument down range when using sup press 5 If the instrument is in the V I ohms when suppress is en abled the displayed resistance value will be supressed supression will be cancelled temporarily by going to amps 6 To suppress the current in V I ohms enter amps and then enable suppress Enter V I ohms in the usual manner 2 12 DATA STORAGE The Model 617 has an internal 100 point data store mode that can be used to log a series of readings The fill rate of the data store can be set to specific intervals by a paramet
210. he value of the 10060 resistor Record the value in the first line of Table 7 4 Using this value calculate the calibration vol tage as follows E 1 x where is the nominal calibra tion current 190pA and R is the measured resistance value For example if the actual resistance value is 101GQ the calibration voltage value would be 19 19V NOTE Do not touch the body of the resistor to avoid contamination that could give erroneous results 2 Connect the DC calibrator and 10000 resistor to the Model 617 as shown in Figure 7 4 Note that the resistor is to be placed in a shielded enclosure as shown on the diagram See Figure 7 1 for recommended shield 3 Place the instrument in the amps mode and select the 200pA range 4 Zero correct the instrument by enabling zero check and zero correct in that order 5 Set the calibrator voltage to the exact value obtained in step 1 Disable zero check 6 Either from the front panel or over the IEEE 488 bus set the Model 617 calibration constant to exactly 190 00pA 7 Reduce the calibrator voltage to zero and enable zero check 8 Disconnect the resistor shield fixture from the instrument and connect the decade resistance box in its place as shown in Figure 7 5 9 Select the 20nA range and zero correct the instrument by disabling zero correct With zero check enabled enable zero correct once again 10 Set the decade box and calibrator to the values listed in the second line o
211. i 42 O B NO r paj g Eb a 9 2 g o Q gres ses ibo EAS PROGRAM d 5 2524252 nie quie 2236 S 45542576 54 ation Inform ing Contains Operating and Servic gt eke WARRANTY Keithley Instruments Inc warrants this product to be free from defects in material and workmanship for a period of 1 year from date of shipment Keithley Instruments Inc warrants the following items for 90 days from the date of shipment probes cables rechargeable batteries diskettes and documentation During the warranty period we will at our option either repair or replace any product that proves to be defective To exercise this warranty write or call your local Keithley representative or contact Keithley headquarters in Cleveland Ohio You will be given prompt assistance and return instructions Send the product transportation prepaid to the indicated service facility Repairs will be made and the product returned transportation prepaid Repaired or replaced products are warranted for the balance of the origi nal warranty period or at least 90 days LIMITATION OF WARRANTY This warranty does not apply to defects resulting from product modification without Keithley s express writte
212. ibration or voltage source value out of Message Description OL Overrange input applied for negative value Trigger Overrun Error Instrument triggered while proces sing reading from previous trigger The display in the alpha mode appears as dISPm Once the desired exponent mode is selected press SHIFT then SELECT EXIT to return to normal operation or simply PRO GRAM SELECT if a change was made 2 5 3 Calibration An advanced feature of the Model 617 is its digital calibration program The instrument can be calibrated from the front panel or over the IEEE 488 bus To use the front panel calibration program refer to the calibration procedures out lined in Section 7 2 6 REAR PANEL FAMILIARIZATION The rear panel of the Model 617 is shown in Figure 2 2 2 6 1 Connectors and Terminals AC Receptacle Power is applied through the supplied power cord to the AC receptacle Note that the supply voltage is marked adjacent to the receptacle 488 Connector This connector is used to connect the instrument to the IEEE 488 bus IEEE 488 function codes are marked above the connector 2 5 Table 2 3 Typical Display Exponent Values Engineering Scientific Display Units Notation Value INPUT The INPUT connector is a 2 lug triax connector to be used for all electrometer signal inputs Note that you should not confuse a triaxial connector with the BNC type that is used for the EXTERNAL TRIGGER
213. icators apply to opera tion of the Model 617 over the IEEE 488 bus The REMOTE indicator shows when the instrument is in the IEEE 488 remote state while the TALK and LISTEN indicators show when the instrument 15 in the talk and listen states respect ively See Section 3 for more information on using the Model 617 over the IEEE 488 bus 2 4 3 Tilt Bail The tilt bail which is located on the bottom of the instru ment allows the front panel to be elevated to a convenient viewing height To extend the bail rotate it out 90 from the bottom cover and latch it into place To retract the bail pull out until it unlatches and rotate it against the bottom cover 2 5 FRONT PANEL PROGRAMS The Model 617 has three front panel programs that can be used to set the primary address set the display exponent mode alpha or numeric or calibrate the instrument from the front panel To select a program press PROGRAM SELECT button repeatedly while observing the display The instru ment will scroll through the available programs with identify ing messages as shown in Table 2 2 When in the program mode the DISPLAY and DATA STORE RECALL buttons are inoperative the data store mode may be turned off but not on The operation of the various programs is described in the following paragraphs To exit a program press SHIFT EXIT If a change was made pressing SELECT alone will exit the program 2 5 1 IEEE 488 Address Selection of the IEEE 488 addres
214. ier OP 14E 1 Es 1C 423 U143 IC Linear Amp 308A 1 F3 F5 203 U144 IC Quad Comparator LM339 Sev F5 1 219 U145 C Triple 2 Channel Muitiplexer CD4053BC 3 C3 IC 283 VR101 Regulator Zener Diode 6 35V 400mW 1 05 4 102 58 VR102 Regulator Zener Diode 6 35V 400mW 3 84 C5 02 58 VR103 Reguiator Zener Diode 5 1V 400mV IN751 3 C4 C5 02 59 W101 Jumper 2 B3 G2 5 476 Y101 Crystal 3 276800MHZ 0 25 2 D3 F2 CR 21 102 1 2288MHz 3 63 C4 19 Last two digits determined by software revision level For example if revision level is 1 order 617 800 8 6 C201 05201 05202 05203 05204 05205 05206 05207 05208 DS209 DS210 05211 05212 05213 05214 05215 05216 08217 05218 05219 05220 05221 05222 05223 05224 1016 R201 R202 201 202 203 204 205 5206 5207 5208 5209 5210 5211 5212 5213 5214 5215 5216 5217 5218 5219 9201 0202 0203 0204 U205 U206 Table 8 2 Display Board Parts List Circuit Keithley Desig Description Part No Capacitor 104F 20V Tantalum Display Digital 1 Display 7 Segment 8 Display 7 Segment 8 Display 7 Segment 8 Display 7 Segment 8 Display Dual 14 Segment LED Red LED Red LED Red LED Red LED Red LED Red LED Red LED Yellow LED Red LED Red LED Red LED Red LED Red LED Yellow LED Red LED Red LED
215. igure 7 11 Part numbers are indicated on the diagram 8 4 ORDERING INFORMATION Keithley Instruments Inc maintains a complete inventory of all normal replacement parts To place an order or to obtain information concerning replacement parts contact your Keithley representative or the factory When ordering parts include the following information 1 Instrument Model Number 2 Instrument Seria Number 3 Part Description 4 Circuit designation including schematic diagram and com ponent layout numbers if applicable 5 Keithley Part Number 8 5 FACTORY SERVICE If the instrument is to be returned to the factory for service carefully pack the unit and include the following 1 Complete the service form which follows this section and return it with the instrument 2 Advise as to the warranty status of the instrument see the inside front cover for warranty information 3 Write the following on the shipping label ATTENTION REPAIR DEPARTMENT 8 6 COMPONENT LAYOUT DRAWINGS AND SCHEMATIC DIAGRAMS Component layout drawings and schematic diagrams for the mother board electrometer board and the display board can be found immediately following the parts lists 8 1 8 2 Table 8 1 Mother Board Parts List Dena Description Sch Capacitor 47004F 16V Aluminum Electrolytic 1 85 C 313 4700 Capacitor 0 1u4F 50V Ceramic Film 2 G5 D C 237 1 Capacitor 104F 25V Electrolytic 1 85 B2 C 309 620
216. igure 9 11 2 Place the Model 617 on the volts function and 200mV range 3 Zero correct the Model 617 by enabling zero check and zero correct in that order 4 Program the Model 263 to output 00 000mV and release zero check on the Model 677 5 Zero the display of the Model 617 by pressing SUPPRESS 6 Program the Model 263 to output 190 000mV 7 Adjust the display of the Model 617 to read 190 00mV using the ADJUST buttons on the Model 677 8 Program the Model 263 to output 00 000mV by press ing ZERO 9 On the Model 617 disable zero correct and suppress 10 Using Table 6 as a guide repeat steps 3 through 9 for the 2V and 20V ranges 11 With the Model 342A set to zero volts connect it to the Model 263 as shown in Figure 10 Leave the Model 263 connected to the Model 617 as shown in Figure 9 12 Select the 200V range and zero correct the Model 617 by enabling zero check and zero correct in that order 13 Set the Model 343A to output 190 000V to the Model 263 14 Release zero check on the Model 617 and program the Model 263 to output the external voltage source by pressing SHIFT VOLTS 15 Adjust the display of the Model 617 to read 190 00V using the ADJUST buttons of the Model 617 16 Place the Model 263 and the Model 343A in standby 17 On the Model 617 disable zero correct 18 Turn off the Model 343A and disconnect it from the Model 263 Table 6 Model 617 Volts Calibration 263 External 617 Outp
217. imize accuracy In most cases it is best use the maximum voltage value possible ex cept as indicated below and set the current range according ly As with other Model 617 measurements the instrument should be placed on the most sensitive range possible without overranging the electrometer section Doing so will optimize the measurement for resolution and accuracy Autoranging can facilitate range selection At very high resistance values the corresponding current as seen by the instrument will be extremely low Thus any cur rent generated by the triaxial input cable will be reflected in the final measurement To minimize such problems use low noise graphite triaxial cable such as the Model 6011 Tie down the cable to avoid any triboelectric currents that might be generated by cabling flexing In many situations shielding of the circuit under test will also be required to minimize noise pickup Although resistance measurements are much less suscep tible to the effects of leakage resistance than resistance measurements made with the constant current method there are some cases where leakage resistance could affect resistance measurements For example test fixture leakage paths may appear in parallel with the device being measured introducing errors in the measurement As with other Model 617 high impedance measurements these errors can be minimized by using proper insulating material such as Teflon in fixture termi
218. ine is active low with approximately zero volts representing a logic 1 true The following paragraphs describe the pur pose of these lines which are shown in Figure 3 1 3 2 3 3 1 Data Lines The IEEE 488 bus uses eight data lines that allow data to be transmitted and received in a bit parallel byte serial manner These lines use the convention DIO1 DIO8 instead of the more common 00 07 DIO1 is the least significant bit while DIO8 is the most significant bit The data lines are bidirec tional with most devices and as with the remaining lines low is considered to b true 3 3 2 Bus Management Lines The five bus management lines help to ensure proper interface control and management These lines are used to send the uniline commands that are described in paragraph 3 4 1 Attention The line is one of the more impor tant management lines in that the state of this line determines how information on the data bus is to be interpreted IFC Interface Clear As the name implies the IFC line con trols clearing of instruments from the bus REN Remote Enable The REN line is used to place instru ment on the bus in the remote mode EOI End or Identify The EOI line is usually used to mark the end of a multi byte data transfer sequence SRQ Service Request This line is used by devices when they require service from the controller 3 3 3 Handshake Lines The bus uses handshake lines that o
219. instrument For best accuracy in this mode it is best to choose a range that will result in a cur rent that is equal to a large percentage of the full range value On the 200 range for example a full range resistance measurement will result in a current of 0 5pA assuming a voltage of 100V is being used For resistances above 200TQ the current seen by the instrument will be less than 0 5pA For very high resistance values above 2PQ the current will be very small indeed and accuracy will be reduced Figure 4 12 shows a test set up using the Model 617 along with an external supply to make V I resistance measure ments The basic set up is much like that used when making measurements with the Model 617 voltage source the resistance under test is connected in series with the elec trometer input lead The voltage supplied by the external sup ply forces a current which is read by the electrometer through the resistor The current and voltage values are then used to calculate the resistance The maximum voltage between input high and input low is 250V 10sec maximum mA ranges Exceeding this value may damage the instrument OUTPUT V MODEL 617 ELECTROMETER EXTERNAL SUPPLY Figure 4 12 Using the Model 617 with an External High Voltage Source Since an external voltage source is used resistance values can not be automatically calculated by the Model 617 You can however simplify these c
220. ired value 12 Repeat steps 10 and 11 with the remaining ranges listed Be sure to zero correct the instrument and set the decade box to the required value 160 260 RANGE 100 200 0 RANGE 1 CABLE SHIELDED FIXTURE SEE FIGURE 7 1 6147 480 ADAPTER MODEL 617 V Q GUARD ON WARNING UP TO 300V ON FIXTURE GROUND IN GUARDED MODE IN PLACE Figure 7 8 Connections for Ohms Calibration 2GQ 200 Ranges Table 7 6 Ohms Calibration Nominal Measured 617 Calibration Calibration Range Resistance Resistance 10 000M2 A10E6X 1 9000MQ 1 9 6 190 00 190 19 000 19 Use measured resistance values as calibration point Measurement of decade resistance values not necessary due to inherent accuracy 7 9 GROUND LINK REMOVED MODEL 617 4 V Q GUARD OFF A sas _ e Figure 7 9 Connections for Ohms Calibration 20 and 20 Ranges 7 4 15 Voltage Source Calibration Use the following procedure to calibrate the voltage source Since the voltage source is independent from the electrometer section voltage source calibration can be performed at any time separate from electrometer calibration WARNING Hazardous voltage will be used in some of the following steps 1 Connect the DMM to the voltage source output as shown
221. is made up of a single ASCII letter followed by a number representing an option of that command For example a command to control the measuring function Volts Ohms Amps Coul is programmed by sending an ASCII F follow ed by a number representing the function option The 488 bus actually treats these commands as data in that is false when the commands are transmitted A number of commands may be grouped together in one str ing A command string is usually terminated with an ASCII X character which tells the instrument to execute the com mand string Commands sent without the execute character will not be executed at that time but they will be retained within an internal command buffer for execution at the time the X character is received If any errors occur the instrument will display appropriate front panel error messages and generate SRQ if programmed to do so Commands that affect the electrometer section 2 T and A will trigger a reading when the command is ex ecuted These bus commands affect the Model 617 much like the front panel controls Note that commands are not necessarily executed in the order received instead they will be executed in the same order as they appear in the status word Function Range R Zero Check Zero Correct 2 Suppress N Trigger T Voltage Source Operate Read Mode B Display Mode D Data Storage Q SRQ Mode M EOI
222. itance beyond this level may increase noise and induce instrument instability The noise gain of the measurement circuit can be found from Equation 2 Zr Output E Input E X 1 25 where 2 NV Qr fRECr 2 1 and 25 Rs fRsCs 2 1 Clearly as f 0 equation 2 reduces to equation 1 Refer to Table 2 11 for equivalent voltage sensitivity of 617 amps ranges The frequency range of interest is 0 1 to 10Hz which is the noise bandwidth of the A D converter The value of Cz is 5pF for pA ranges 22pF for nA ranges and 1000pF for ranges In general as Cs becomes larger the noise gain becomes larger An application where Cg may be greater than 10 000pF is leakage measurement of capacitors In this case Input E must include the effects of the voltage source used to bias the capacitor any noise in the source voltage will increase the input noise When measuring leakage currents on capacitors larger than 10 000pF stability and noise performance can be maintained by adding a resistor in series with the capacitor under test The value of this resistor should be around 1 For large capacitor values gt the value of the series limiting resistor can be made lower in order to improve settling times however values below 10kQ are not generally recommended This resistor is not critical in terms of tolerance or stability Any carbon composition resistor will prove adequate 2 15 EN
223. k only mode without prefix on data string Example 1 2345E 01 To place the instrument in the talk only mode perform the following steps 1 Press the PROGRAM SELECT button so that the follow ing message is displayed IEEE 27 2 Press the up arrow V SOURCE ADJUST button repeated ly until the desired talk only parameter 40 or 41 is shown 3 To exit the program press SHIFT then SELECT EXIT The unit is now programmed for the talk only mode and it will remain programmed in this manner even if the power is turned off The data output rate in the talk only mode can be selected as follows 1 Press and hold the DATA STORE ON OFF button until the desired rate is displayed as indicated below Displayed r Value Data Output Rate Conversion Rate Every 360msec One reading per second One reading every 10 seconds One reading per minute One reading every 10 minutes One reading per hour reading each time TRIG is pressed r 0 t Tad 2 Press the PROGRAM SELECT button until the IEEE gram message is displayed and then release the button Select the desired 488 talk only parameter 40 41 using an ADJUST button 3 Press SELECT EXIT to return to normal operation The in strument will then enter the talk only mode and output readings over the JEEE 488 bus at selected intervals 3 10 3 8 SOFTWARE CONSIDERATIONS There are a number of IEEE 488
224. kers or listeners from the bus ATN is true when these commands are asserted UNL Unlisten Listeners are placed in the listener idle state by the UNL command UNT Untalk Any previously commanded talkers will be placed in the talker idle state by the UNT command 3 4 5 Device Dependent Commands The meaning of the device dependent commands will depend on the configuration of the instrument Generally these com mands are sent as one or more ASCII characters that tell the device to perform a specific function For example the com mand sequence FOX is used to place the Model 617 in the volts mode The IEEE 488 bus actually treats these commands as data in that ATN is false when the commands are transmit ted 3 5 COMMAND CODES Each multiline command is given a unique code that that is transmitted over the bus as 7 bit ASCII data This section briefly explains the code groups which are summarized in Figure 3 3 Addressed Command Group ACG Addressed commands and corresponding ASCII codes are listed in columns and O B Universal Command Group UCG Universal commands and values are listed in columns 1 A and 1 B Listen Address Group LAG Columns 2 through 3 B list codes for commands in this address group For example if the primary address of the instrument is 27 the LAG byte will be an ASCII left bracket Talk Address Group TAG TAG primary address values and corresponding ASCII characters ar
225. l 617 input 2 Place the input cap supplied with the instrument on the IN PUT connector 3 Select the amps function 2 range enable zero check and then enable zero correct 4 Connect a jumper between the rear panel COM and chassis ground terminals 5 Disable zero check and allow the reading to stabilize typically one minute 6 Verify that the reading is 66 counts or less Enable zero check 7 Remove the jumper connected between the COM and chassis ground connectors 5 5 2 Amps Verification Perform amps verification as follows 1 Enable zero check and select the amps mode 2 Select the 20mA range and make sure autorange is disabl ed 10 11 12 13 Connect the DC calibrator and decade resistance box to the instrument as shown in Figure 5 2 With zero check still enabled verify that the display reads 0 000 1 count If not enable zero correct Apply the correct input by setting the DC calibrator and decade box to the values listed in Table 5 2 Disable zero check Check to see that the reading is within the limits listed in the table Repeat the procedure for the 200nA 2mA ranges as listed in Table 5 2 Be sure to set both the decade box and DC calibrator to the values listed Using the teraohmmeter measure the actual value of the 100 2 resistor and record its value in the appropriate space in the table NOTE Do not touch the body of the resistor to avoid
226. l Voltage Sources SECTION 5 PERFORMANCE VERIFICATION Introduction Environmental Conditions Initial Conditions o 42 4 4 24 4 2 44444 4 9 4 4444 Yea 39 9 c9 00 Recommended Test Equipment RR RYE Y CERERI RU E Verification Procedure Input Current Verification Amps Verification Coulombs Verification Volts Verification Ohms Verification 4 2 424404 4 40 amp 4 3 4 424 4 BOR Q 8 94 0424 24 204044 414 4 4 4 9 9 3 9 9 9 3 9 9 Ohms Verification 200 and Ranges Voltage Source Verification 7 7 77 6 SECTION 6 OF OPERATION ___ Overall Functional Input Preamplifier _ ___ S A US SUE E eee ert METELLI TTC TRETEN IET IIT 8 e reee ea E E a a ens Ohms
227. lace the instrument in zero check by sending C1X 2 Zero correct the instrument by sending Z1X 3 Disable zero check by sending COX Readings can then be taken in the usual manner HP 85 Programming Example Enter the following lines into the HP 85 computer REMOTE 727 END LINE OUTPUT 727 C1XZ1XCOX END LINE When END LINE is pressed the second time the instrument is first placed in zero check the unit is zero corrected and the zero check mode is then disabled Model 8573 Programming Example Enter the following statements into the IBM computer V 1 CALL IBSRE BRDO V 96 return CMD C1XZ1XCOX CALL IBWRT M617 CMD return The zero check and zero correct sequence will be performed when the return key is pressed the second time Table 3 12 Range Command Summary Auto N 3 lt lt lt lt lt lt lt lt lt lt lt o 200 200 200 200 200 200 200 200 External V i com mand Voits Feedback Ohms Cancel Auto Cancel Auto Cancel Auto Cancel Auto Auto Auto 200mV 20079 2 V 20TQ 20 V 270 20 V 20060 20 2069 20 V 260 20 V 200MQ 20 V 20M9 20 V 2MQ 20 V 200 kQ 20 V 200 kQ Cancel Auto Cance Auto Full range value based on 100V 10 000 displayed counts of current 3 21 3 10 5 Baseline Suppression N The baseline suppression mode allows a stored offset value to be subtracted from subsequent readings When the su
228. local operating mode After the unit receives LLO all its front panel controls except POWER will be inoperative REN must be true for the instrument to respond to LLO REN must be set false to cancel LLO To send the LLO command the controller must perform the following steps 1 Set true 2 Place the LLO command on the data bus HP 85 Programming Example The LLO command is sent by using the following HP 85 statement REMOTE 7 END LINE LOCAL LOCKOUT 7 END LINE After the second statement is entered the instrument s front panel controls will be locked out Model 8573 Programming Example To send the LLO command from the IBM PC type in the following statement 1 CALL IBSRE BRDO RETURN CMD CHRS amp H11 CALL IBCMDS BRDO CMDS return After the return key 15 pressed Model 617 front panel con trols will be locked out 3 9 4 GTL Go To Local and Local The GTL command is used to take the instrument out of the remote mode With some instruments GTL may also cancel LLO With the Model 617 however REN must first be placed false before LLO will be cancelled To send GTL the controller must perform the following se quence 1 Set true 2 Address the Model 617 to listen 3 Place the GTL command on the bus HP 85 Programming Example Place the instrument in the remote mode with the following statement REMOTE 727 END LINE Now send GTL with the following statement
229. ly type in EXIT and press the return key at the command prompt 7 4 7 Calibration Sequence Model 617 calibration must be performed in the the order given in the following paragraphs with the exception of voltage source calibration which can be done at any time The basic sequence is Input offset adjustment paragraph 7 4 8 Input current adjustment paragraph 7 4 9 Amps calibration paragraph 7 4 11 Coulombs calibration paragraph 7 4 12 Volts calibration paragraph 7 4 13 Ohms calibration paragraph 7 4 14 a i WN F In addition to the above sequence the ranges for each func tion must be calibrated in the order given Note that you should never calibrate a range using a suppress or zero correct value taken on a different range NOTE Several minutes must be allowed for the input current to settle to within specified limits follow ing high voltage or ohms measurements 7 4 8 input Offset Adjustment Use the following procedure to null out any small offset in the input amplifier Input offset adjustment is particularly critical if input voltage burden is a consideration since any offset will increase the voltage burden as seen by the input signal 1 Disconnect all input signals from the instrument 2 Remove the two screws securing the top cover and remove the cover from the instrument 3 Select the amps function and place the instrument on the 2pA range 4 Enable zero check but leave zero
230. m Component Required Condition ________ Remarks Set to 115 230 as required Check for continuity Plugged into live receptacle power on 120V 120 15 15V 15V 5 240 240V 13 27 5V 27 5 15 Line voltage selection Remove to check Referenced to 110V common Referenced to V source common Referenced to digital common Referenced to analog common Referenced to analog commen Referenced to analog common Referenced to bootstrap common Referenced to preamp out 7 15 ranging amplifier or associated control circuits are not func converter and display circuits are operating properly The tioning properly operation of these circuits should be verified before attemp ting to troubleshoot the analog circuitry 7 7 7 A D Converter and Display Use the procedure listed in Table 7 13 to make sure the A D Table 7 11 Relay Configuration m 2 Function Range K309 K310 K308 K311 K312 K307 K303 K304 K305 k306 K301 K302 Volts x x x X Ohms x x x x x x X X X X X X X X X X X X X X x x X X Amps X X X X x X X X X Coulombs 200 pC 2 nC 20 nC External 200mC Feedback 2 V 20 V Zero Check 772571 Relay Energized These relays may also energized depending on range and function X XX X XX gt x gt x X gt x X gt x X x X gt x gt x gt gt 7 16 Table 7 12 Ranging Amplifier Gains
231. matic Diagram Dwg No 617 106 Sheet 2 of 3 8 23 8 24 92 8 S2 8 JO 12945 90L 19 5 pueog 6 8 3 5 00562 1901 2198 Ee rum ment cos H3HIOA MARE VA mezcal OU1VW3H2S sun seve EVA m A SA Gee p Ge LN384ND SONV IVE s 11133810 39075 9v 3402 391 419 08 339 4313081233 20 ZlOld S21 VIA NNOD XYIYL 30 e CT3IHS OL eas r NO Z Soor lt 3NOZ a GA SSA A 2 39 d OL c AS LY 00109 2 OSA AZ eS solar 301 O 9 3NOZ VS 2 OL seis VA I 92 E 39 OF Wie l 4 YOZZ yi 23 3NOZ 991 219 as r gt 93130419313 30 HLIM SILVA AS O h e x IN lI DY 3102 i 2 39vd OL v 3NOZ z OL v L 0832 7 viva ST CORA 772 725 55515 TIA EA FWA BAIS NACEN sos 22252 LAD Se EUN EGEE i Des Foray A AA HSALYSANOD 7 Co 0617 106 H zi 3 a 2 v PAGE 3 OF 3 46102 ORINA 82 8 L2 8 9LL ZL9
232. measuring functions selection of instrument ranges and such items as zero check zero and suppression and front panel triggering VOLTS The VOLTS button places the instrument in the DC volts measuring mode When VOLTS is pressed the indicator next to the button turns on showing that the instrument is set for that mode Note that the Model 617 will be in this mode when it is first turned on Pressing SHIFT VOLTS will place the instrument in the external feedback mode as described in paragraph 2 12 OHMS Pressing OHMS places the unit in the resistance measuring function The indicator next to the OHMS button will be illuminated when the instrument is in this mode Note that there are two ways to measure resistance with the Model 617 Pressing OHMS alone will cause the instrument to measure resistance using the constant current method Press ing the SHIFT button before pressing OHMS places the in strument in the mode of resistance measurement as described in paragraph 2 8 The V I indicator will light when the instrument is in this mode COUL The Model 617 may be set up to measure charge by pressing the COUL button The indicator next to the COUL button will illuminate when the instrument is set for this mode AMPS Pressing AMPS switches the instrument to the current measuring function The AMPS indicator will turn on when the instrument is in this mode RANGE These two buttons allow you to increment or decrement th
233. mmands are those multiline commands that re quire no addressing All devices equipped to implement such commands will do so simultaneously when the command is transmitted As with all multiline commands these com mands are transmitted with ATN true LLO Local Lockout LLO is sent to instruments to lock out their front panel controls DCL Device Clear DCL is used to return instruments to some default state Usually instruments return to their power up conditions SPE Serial Poll Enable SPE is the first step in the serial polling sequence which is used to determine which device has requested service SPD Serial Poll Disable SPD is used by the controller to remove all devices on the bus from the serial poll mode and is generally the last command in the serial polling sequence 3 4 3 Addressed Commands Addressed commands are multiline commands that must be preceded by the device listen address before that instrument will respond to the command in question Note that only the addressed device will respond to these commands SDC Selective Device Clear The SDC command performs essentially the same function as the DCL command except that only the addressed device responds Generally in struments return to their power up default conditions when responding to the SDC command GTL To Local The command is used to remove instruments from the remote mode With some instruments GTL also unlocks fro
234. mode and select the 2nC range Enable zero correct Disable zero check enable suppress and set the DC calibrator output to 1 0000V Verify that the display reads between 0 995 and 1 005nC Enable zero check and set the calibrator output to 0 0000V Table 5 2 Limits for Amps Verification 19 000V 19 000V 19 000V 19 000V 19 000V 1 900V 1 94 1 9V 1 9V Values in parenthesis are nominal values determine these values Bol Reading Value 189 28 C 18 970 to 19 030mA 1 8967 to 1 9033mA 189 70 to 190 304A 18 970 to 19 0304A 1 8967 to 1 90334A 189 51 to 190 49nA 18 951 to 19 049nA 1 8947 to 1 9053nA 186 95 to 193 05pA 18 689 to 19 311pA 1 8630 1 9370pA See text for methods to 5 3 NOTE GREEN LEFT DISCONNECTED KER OB CHASSIS A A a CHASSIS GROUND AND LO CONNECTED 6011 CABLE REMOVE SHORTING LINK Figure 5 2 Connections for Amps Verification 200nA to 20mA Ranges mes 6147 MODEL 617 SHIELDED FIXTURE FIGURE 5 1 6147 ADAPTER n _ 100M2 2014 109 2nA 1060 200pA 10069 2pA and 20pA NOTE SHORTING LINK IN PLACE MODEL 617 Figure 5 3 Connections for Amps Verification 2pA to 20nA Ranges BNC CABLE POMONA 4530 C POMONA 3283 1000pF STANDARD SHORTING LINK IN PLACE AIR CAPACITOR Figure 5 4 Connections for Coulombs Verifications
235. mp 4 c 9 4 4 4 5 9 8 0 9898599599858 ot omo s a mov mo 4 q q n s q 442424246 or v t q q q 3 3 3 k n q q 4 vos or og q q n S 3 4 Making Current Making Charge Measurements Resistance Measurements 43404404 42 9 o po o9 v s vo 4 o oe 9 OR v s v o 9 9 9 4 e Using the Ohms Function As Current Source discussion Using the Voltage Source Basic Operating Procedure om mor q e s q q n n 4 q lt 44 a 5 44 4 44 44404 40404 9 6 404040004 404 4 40 9 9 9 42040404 04040040422 Resistance Measurements Analog Outputs 2V Analog Output Preamp Using External Feedback Electrometer Input Circuitry q lt 9 4 s q q s 444 o4 vo 4 o9 8 3 O9 od o Por mom m 4444 4 4 wor Fo e n 9 n q 3 4 a
236. mple if a charge of 12nC is seen after 10 second interval the current is 12nC 10 1 2nA Using Data Store at a 10 second rate can ease data taking 5 As an alternative to the above procedure connect a chart recorder to the 2V ANALOG OUTPUT paragraph 2 9 and graph the measured charge Since the current is given I dQ dt the current at any point is equal to the slope of the graph at that point after applying the appropriate scaling factor 100pC V 200pC range 1nC V 2nC range 10nC V 20nC range CAUTION Connecting PREAMP OUT COM or 2V ANALOG OUTPUT to earth while floating input may damage the instrument Charge Measurement Considerations primary considera tion when making charge measurements is the input offset current of the integrating amplifier Any such current is in tegrated along with the input signal and reflected in the final reading The Model 617 has a maximum input offset current of 5 X 10 15A at 23 C This value doubles every 10 C This input offset current translates into a charge of 5 10 15C per second at a temperature of 23 C This value must be sub tracted from the final reading to obtain the correct value When using an external voltage source the input current should be limited to less than 1mA by placing a resistor in series with the high input lead The value of this resistor should be at least R 1000V in ohms where V is the voltage across the capacitor or the compliance of the
237. n consent or misuse of any product or part This warranty also does not apply to fuses software non rechargeable batteries damage from battery leakage or problems arising from normal wear or failure to follow instructions THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES NEITHER KEITHLEY INSTRUMENTS INC NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT INDI RECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS INC HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES SUCH EXCLUDED DAMAGES SHALL INCLUDE BUT ARE NOT LIMITED TO COSTS OF REMOVAL AND INSTALLATION LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON OR DAMAGE TO PROPERTY KEITHLEY Keithley Instruments Inc 28775 Aurora Road Cleveland 44139 216 248 0400 Fax 216 248 6168 http www keithley com CHINA Keithley Instruments China Yuan Chen Xin Building Room 705 12 Yumin Road Dewai Madian Beijing 100029 8610 62022886 Fax 8610 62022892 FRANCE Keithley Instruments SARL BP 60 3 All e des Garays 91122 Palaiseau C dex 33 1 60 11 51 55 Fax 33 1 60 11 77 26 GERMANY Keithley Instruments GmbH Landsberger Strasse 65 D 82110 Germering Muni
238. n occur when an invalid command such as is transmitted this command is invalid because the in strument has no command associated with that letter Similarly an IDDCO error occurs when an invalid option is sent with a valid command For example the command T9X has an invalid option because instrument has no such trigger mode HP 85 Programming Example To demonstrate a bus er ror send an IDDC with the following statements REMOTE 727 END LINE OUTPUT 717 H1X END LINE When the second statement is executed the bus error message appears on the display for about one second Model 8573 Programming Exampie in the follow ing statements to demonstrate a bus error by sending an IDD V 1 CALL IBSRE BRDO V return CMD H1X CALL IBWRT M617 return The bus error message will be displayed for about one second when the second statement is executed 3 11 2 Number Error number error occurs when an out of range value is sent to the instrument when programming the voltage source or when sending calibration values over the bus Under these conditions the instrument wil display the following error message n Err The command string will be accepted but calibration or voltage values will remain unchanged HP 85 Programming Example Enter the following lines to display a number error REMOTE 727 END LINE OUTPUT 727 D1V125X END LINE When the second statement is executed the i
239. nal connections Any leakage current through cables and test fixtures can be minimized if care is taken To cancel these effects set up the measurement exactly as desired but leave the resistor under test disconnected Program the voltage source to the desired value and turn on its output With the instrument in the amps mode enable suppress to null the leakage current Turn off the source connect the resistor and re enable the voltage source Place the instrument in the V I ohms mode and ceed with the measurement High megohm resistors are somewhat curious devices often exhibiting characteristics somewhere between those of an in sulator and a normal resistor Because of these unique traits the measured value of such a resistor will often vary with ap plied voltage Such variation in resistance is known as the voltage coeffi cient The Model 617 can be used to characterize such resistance changes by measuring the resistance with a number of different applied voltages Once the variations are known the voltage coefficient of the resistor being tested can be calculated The method for determining the voltage coeffi cient of these resistors is discussed in Section 4 2 9 ANALOG OUTPUTS The Model 617 has two analog outputs on the rear panel The 2V ANALOG OUTPUT provides a scaled 0 2V output with a value of 2V corresponding to full range input The PREAMP OUT is especially useful in situations requiring buffering These two
240. nal pull up resistor is used a mechanical switch may be used Note however that de bouncing circuitry will probably be required to avoid im proper triggering CAUTION Do not exceed 30V between digital com mon and chassis ground or instrument damage may occur 2 Place the instrument in the one shot trigger mode by press ing SHIFT and then TRIG in that order The instrument will indicate that it is in the one shot mode by illuminating the SGL indicator 3 To trigger the instrument apply a pulse to the External Trigger input The instrument will process a single reading each time the pulse is applied Note that the instrument may also be triggered by pressing TRIG 4 To return the instrument to the continuous mode press the SHIFT and TRIG buttons in sequence NOTES 1 External triggering can be used to control the fill rate in the data store mode See paragraph 2 12 for details 2 The Model 617 must be in the appropriate trigger mode to respond to external triggering the unit will be in this mode upon power up See paragraph 3 10 14 for details 3 trigger overrun occurs the instrument is triggered while processing a reading from a previous trigger it will ignore the trigger and display the following t Err 2 13 2 Meter Complete The 617 has an available output pulse that can be used to trigger other instrumentation A single TIL compatible negative going pulse with a minimum duration of 10psec
241. nction with the elec trometer section to make resistance measurements as high as 10160 EXTERNAL TRIGGER INPUT This BNC connector can be used to apply external trigger pulses to the Model 617 to trig ger the instrument to take one or more readings depending on the selected trigger mode PREAMP PREAMP OUT ON GUARD A IFOLLOWS v GUARO iNPUT 100 1 16 250 INTERNAL LO INPUT OPO TRIAX 250V PEAK A V SOURCE OUTPUT 103V MAX CAUTION 00 NOT FLOAT INPUT LO WITH PREAMP OUT COM CONNECTED TO EARTH 2 GUARD 2V ANALOG OUTPUT IEEE 488 INTERFACE ADDRESS ENTERED WITH FRONT PANEL PROGRAM PREAMP OUT 2 ANALOG OUTPUT METER COMPLETE OUTPUT EXTERNAL TRIGGER INPUT IEEE COMMON v LINE VOLTAGE SELECTED INTERNAL 105 125V 210 250 Q D LINE RATING 50 60H2 SLOWBLOW 25VA 114 90 125 180 250V Figure 2 2 Model 617 Rear Panel METER COMPLETE OUTPUT This BNC connecter pro vides an output pulse when the Model 617 has completed a reading it is useful for triggering other instrumentation Chassis Ground This jack is a 5 way binding post that is connected to instrument chassis ground It is intended for use in situations requiring an accessible chassis ground terminal A shorting link is supplied and connected to the CHASSIS GROUND terminal 2 6 2 V 0 GUARD
242. nd string from keyboard 40 OUTPUT 727 A Send command string to 617 50 GOTO 20 Repeat 60 END To run the program press the HP 85 RUN key At the com mand prompt type in the desired calibration command and press return For example to perform NVRAM storage type in LIX and press return Model 8573 Programming Example Use the program below to send calibration commands to the Model 617 from an IBM computer equipped with a Keithley Model 8573 IEEE 488 interface The lines below are to be added to the DECL BAS program as described in the Model 8573 Instruc tion Manual PROGRAM COMMENTS 10 NAS GPIBO CALL IBFIND Find board descrip NA BRDO tor 20 NAS DEVO CALL IBFIND Find instrument 617 96 30 1 CALL IBSRE BRD0 V 40 27 CALL IBPAD descriptor Send remote enable Set primary address M617 96 V to 27 50 INPUT CALIBRATION COM Input command MAND A string 60 IF A EXIT THEN 90 Check if program is to be halted Send command string to instrument 70 CALL IBWRT M617 AS 80 GOTO 50 Repeat 90 V 0 CALL IBONL Close the board file BRDO 6 V 96 100 CALL 617 90 Close the instrument file After entering the program run it by pressing the F2 function key on the computer At the command prompt type in the desired calibration command and press the return key For example type in L1X to perform NVRAM storage To exit the program clean
243. ng the shield should be connected to input low SOURCE METER Rs POM cage Figure 2 5 Meter Loading Considerations 2 7 4 Guarded Operation Guarding consists of using a conductor supplied by a low im pedance source to totally surround the leads carrying a high impedance signal The output of this low impedance source is kept at the same potential as the signal itself resulting in drastically reduced leakage currents To approach the concept of guarding let us first review the unguarded circuit shown in Figure 2 6 The measured signal is represented by the voltage source and the source resistance Rs Cable leakage impedance is represented by 21 The source resistance and leakage impedance form a voltage divider that attenuates the source voltage as follows 21 Es Ee Rs Thus to keep the error due to leakage resistance under 0 1 the leakage resistance must be at least 1000 times the source resistance value Guarding the circuit miminizes these effects by driving the shield at signal potential as shown in Figure 2 7 Here uni ty gain amplifier with a high input impedance and low output impedance is used The input of the amplifier is connected to the signal while the output is used to drive the shield Since the amplifier has unity gain the potential across 2115 essen tially zero so no leakage current flows Leakage between the cable shield and ground may be considerabl
244. ng sourced through the resistor under test by the voltage source To measure from a baseline current such as fixture leakage enable suppress while in amps To display the resistance being measured press SHIFT and then OHMS in that order The V I light will turn on indi cating that the V I ohms mode is enabled If a displayed resistance overload occurs the usual display message will be indicated however if the input current exceeds the maximum input Value for the selected amps range the AMPS LED will flash as previously indicated Note that the display can be placed in either the alpha or numeric ex ponent mode as discussed in paragraph 2 5 To measure from a baseline resistance enable suppress while in V L SHIELD OPTIONAL RANGING AMPLIFIER TO A D CONVERTER 2V ANALOG OUTPUT EQUIVALENT CIRCUIT Figure 2 14 Resistance Measurement Connections 2 18 Resistance Measurement Considerations The main ad vantage of using the constant voltage method for resistance measurements is that the effects of leakage resistance and distributed capacitance are minimized Because of these fac tors the resistance range of the instrument can be greatly in creased in the case of the Model 617 to 10160 However there are certain characteristics pertaining to high resistance measurements that require discussion A primary consideration when using this mode is to match the voltage and current ranges to opt
245. nsists of the input stage output stage ranging amplifier A D converter feedback and switching elements The input stage is a propietary FET amplifier designed for high input impedance 200TQ and low input off set current less than 5 The output stage provides further amplification thus allowing the preamp output to go as high as 210V depending on the selected range and function Further control of the input and output stages are provided by the feedback and switching elements which set gain and transfer function according to the selected range and func tion In addition zero check and zero correct provide a con venient means to zero the instrument allowing cancellation of internal offsets The ranging amplifier conditions the output stage signal into a 0 2V signal for the A D converter The A D converter uses both charge balance and single slope conversion techniques The heart of the digital section is the 146805E2 CMOS pro cessor that supervises the entire operation of the instrument Additional digital circuits include the display made up of a 4 digit mantissa and 2 digit alpha or numeric exponent the IEEE 488 interface and the front panel switch matrix The switch matrix decodes front panel switch closure information that controls instrument operation from the front panel The voltage source is a fully programmable isolated unit that is also controlled by the microprocessor internal 12 bit D A converter t
246. nstrument will display the number error message for about one second This error occurs with this example because an attempt is made to program a voltage value of 125V which is outside the range of the voltage source 102 35V lt V lt 102 4V Model 8573 Programming Example display the number error enter the following lines into the IBM com puter V 1 IBSRE BRDO V 96 return CMD D1V125X CALL IBWRT M617 CMD return The number error message will be displayed for about one se cond when the second statement is executed The number er ror occurs with this example because of the attempt to pro gram a voltage of 125V which is above the range of the voltage source 102 35V lt V lt 102 4V 3 11 3 Trigger Overrun Error A trigger overrun error occurs when the instrument receives a trigger while it is still processing a reading from a previous trigger Note that only the overrun triggers are ignored and will have no effect on the instrument except to generate the message below When a trigger overrun occurs the following front panel message will be displayed for approximately one second t Err HP 85 Programming Exampie To demonstrate a trigger overrun error enter the following statements into the HP 85 keyboard REMOTE 727 END LINE OUTPUT 727 773 END LINE TRIGGER 727 TRIGGER 727 END LINE Note that the trigger overrun message is displayed with the third line above is execu
247. nt 19 A1 9E 1 In this example the nominal value for the 20V range is being used Note that only as many significant digits as necessary need be sent In this case the exact calibration point is as sumed to be 19 000 even though only the first two digits were actually sent If the calibration value is outside the allowed range 6 of nominal value a number error will occur as indicated by the following message n Err Once all functions and ranges have been calibrated perma nent storage of calibration parameters must be performed as described in paragraph 3 10 12 NOTE The proper calibration signal must be connected to the instrument before attempting calibration See Section 7 for complete details on calibrating the instrument either from the front panel or over the bus HP 85 Programming Example The following statements can be used to calibrate the instrument on the 200V range REMOTE 727 END LINE OUTPUT 727 190 END LINE When the second statement is executed calibration of the 200V range is performed assuming that the correct calibra tion value is applied to the instrument Model 8573 Programming Exampie Use the following statements to send the 200V range calibration value to the in strument V 946 1 CALL IBSRE BRDO return CMD A190X CALL IBWRT M617 CMD return 3 26 The calibration value is sent to the instrument when the second staternent is executed 3 10
248. nt V 0 2 V 1 X 10195 Note that the voltage coefficient of a particular device may apply only across the selected voltage range and may in fact vary with different voltage increments in the same approximate range MODEL 6147 TRIAX TO BNC ADAPTER MODEL 4801 CABLE 4 O HI Rx MEGOHM E NE HIGH E RESISTOR V SOURCE OUTPUT m AY auto L E 1 MODEL 6104 SHIELDED 617 SET TO OHMS TEST FIXTURE POMONA MODEL 4585 PATCH CORDS 617 PREAMP 6104 TEST FIXTURE 4801 CABLE 6147 ADAPTER 3 E HI n 1 LO LO A D CONVERTER Rx 5 L a MA Vs V SOURCE sl T EQUIVALENT CIRCUIT Figure 4 10 Configuration for Voltage Coefficient Studies 4 11 4 9 STATIC CHARGE DETECTION Electrostatic charge is a deficiency or excess of electrons on an ungrounded surface Such charges are usually generated on poor conductors of electricity such as plastics synthetic fibers and paper during handling or processing of these materials Once these charges accumulate they do not dis sipate readily because of the excellent insulating character istics of the materials involved Static charge build up can be a problem with integrated cir cuits especially with those of the CMOS variety While these devices which operate at high impedance levels often have static protection built in it is best to properly protect them during transit or storage For that reason such ICs are usuall
249. nt and its performance falls outside the specified range contact your Keithley representative or the fac tory to determine the correct course of action 5 2 ENVIRONMENTAL CONDITIONS All measurements should be made at 18 28 65 82 F and at less than 70 relative humidity unless otherwise noted 5 3 INITIAL CONDITIONS The Model 617 must be turned on and allowed to warm up for at least two hours before beginning the verification pro cedures If the instrument has been subject to extremes of temperature outside the range specified in paragraph 5 2 additional time should be allowed for internal temperatures to reach normal operating temperature Typically it takes one additional hour to stabilize a unit that is 10 C 18 F out side the specified temperature range NOTE While rated accuracy is achieved after the two hour warm up period input bias current may require ad ditional time to come to its optimum level Allow two hours for input bias current to settle to less than 10fA and eight hours to less than 5fA It is preferable in sensitive applications to leave the unit on continuously 5 4 RECOMMENDED TEST EQUIPMENT Table 5 1 lists all test equipment required for verification Alternate equipment may be used as long as the substitute equipment has specifications at least as good as those listed in the table NOTE The verification limits in this section do not in clude test equipment tolerance A shielde
250. nt panel controls if they were previously locked out with the LLO command GET Group Execute Trigger The GET command is used to trigger devices to perform a specific action that depends on device configuration for example take a reading Although GET is an addressed command many devices respond to GET without addressing Table 3 1 IEEE 488 Bus Command Summary State of command Type Command ATN Hine Comments REN Remote Enable EOI IFC Interface ATN Attention Set up for remote operation Marks end of transmission Clears Interface Defines data bus contents SRQ Multiline Universal LLO Local Lockout DCL Device Clear SPE Serial Poll Enable SPD Serial Poll Disable Addressed GTL Go To Local Group Execute Trigger UNL Uniisten UNT Untalk Unaddressed SDC Selective Device Clear i Controlled by external device Low Locks out front panel controls Low Returns device to default conditions Low Enables serial polling Low Disables serial polling Low Returns unit to default conditions Low Sends go to local Low Triggers device for reading p Removes all listeners from bus Removes any talkers from bus Device dependent Programs Model 617 for various modes Don t Care See paragraph 3 10 for complete description 34 3 4 4 Unaddress Commands The two unaddress commands are used by the controller to remove any tal
251. o 199 99mV are normally within the capabilities of the 200mV range If the instrument is in the autorange mode it will move up range if necessary 2 Setting the range lower than the stored baseline value will overrange the instrument 3 Accurate control over when the baseline is actually stored may be achieved by placing the instrument in a one shot trigger mode Once the desired baseline value is connected to the instrument the baseline can be stored by sending Nix 4 Function changes cancel baseline suppress Refer to para graph 2 11 2 for details concerning suppress 3 22 85 Programming Example To enable baseline sup pression type in the following lines REMOTE 727 END LINE OUTPUT 727 N1X END LINE When the END LINE key is pressed the second time the baseline suppression mode is enabled Model 8573 Programming Example Type the following commands into the HP 85 keyboard in order to enable baseline suppression V 1 CALL IBSRE BRDO V return CMD N1X CALL IBWRT M617 CMD return The baseline suppression mode will be enabled when the return key is pressed the second time 3 10 6 Display Mode D The two parameters associated with the display mode mand control whether the front panel display shows the elec trometer reading or the voltage source value Thus this com mand performs essentially the same function as the front panel DISPLAY button The two display command parameters
252. o minimize the slowing effects of input capacitance is to minimize the amount of capacitance in the circuit Using low capacitance cable and keeping the cable as short as possible are two ways to do so However there is a limit to the amount of capacitance reduction that can be achieved In those cases especially where high impedance levels are involved guarded operation see paragraph 2 7 4 may be necessary While input capacitance does increase rise time it can help to filter out some noise present at the input by effectively reduc ing electrometer bandwidth If we assume that all input capacitance is lumped into a single element the half power 3dB point of the circuit in Figure 2 28 will be 1 f 3dB 21RsgCIN Thus if Rs has a value of 10MQ and CiN has value of 100pF the half power point will be 159Hz f 2 33 Table 2 8 Voltage and Percent Error For Various Time Constants Error 0 632 Es 36 0 86 Es 14 9 0 95 E 5 0 982 Es 1 8 0 674 0 25 0 09 0 033 0 012 0 005 0 993 Es 0 9975 Es 0 999 Es 0 99966Es 0 9999 Es 0 99995Es ReCin CIRCUIT 0 632 RSCIN B EXPONENTIAL RESPONSE Figure 2 28 Input Capacitance Effects 2 14 7 Source Resistance As shown in Table 2 9 a minimum value of source resistance is recommended for each AMPS range The reason for this can be understood by examining Figure 2 29 Considering ef fects on
253. o obtain and display instrument status the error condition word and the data condition word 3 33 PROGRAM COMMENTS 10 REMOTE 727 20 DIM 25 30 OUTPUT 727 UOX 40 DISP mdlFRRCZNTOBGD QMMKYY 50 ENTER 727 A Send remote enable Send UO command Display UO word values Obtain UO status from in strument Display UO status word Send U1 command Get error condition word Display error condition word 60 DISP 70 OUTPUT 727 80 ENTER 727 A 90 DISP A 80 PRINT RD 90 CMD U1X CALL IBWRT M617 CMD 100 RD SPACE 25 CALL IBRD Get error condition Display status word Send U1 command M617 76 RD word 110 PRINT RD Display error condi tion word 120 CMD U2X CALL IBWRT M617 CMD 130 RD SPACES 25 CALL IBRD Get data condition Send U2 command M617 RD word 140 PRINT RD Display data condi tion word 150 SPACESQS CALL IBRD 617 RD 160 PRINT RD Get normal reading 100 OUTPUT 727 U2X 110 ENTER 727 4 120 DISP 5 Send U2 command Get data condition word Display data condition 170 0 CALL IBONL Display normal reading Close the board file word Get normal reading Display normal reading 130 ENTER 727 A 140 DISP 5 150 END After entering the program run it by pressing the HP 85 RUN key The program will place the unit in remote line 10 send the UO command line 30 and then obtain and displa
254. obtain and display 100 readings on the computer CRT PROGRAM 10 DIM AS 25 20 REMOTE 727 30 OUTPUT 727 QOX COMMENTS Send remote enable Enable data store at conversion rate 40 SPOLL 727 Serial poll the 617 50 IF NOT BIT S 1 THEN 40 If not full wait 60 OUTPUT 727 B1G2X Set read mode to data store Loop 100 times Get a reading 70 FOR I 1 100 80 ENTER 727 90 DISP Display it 100 NEXT I Loop back and get next reading 110 END After entering the program press the HP 85 RUN key The program will enable data store line 30 wait for memory to 3 24 fill lines 40 and 50 turn on the data store output line 60 and then request and display all 100 readings lines 70 100 Model 8573 Programming Exampie To demonstrate data store operation load the modified DECL BAS file and enter the program lines below PROGRAM COMMENTS 10 NAS GPIBO CALL IBFIND Find the board NAS BRDO descriptor 20 NA DEVO CALL IBFIND Find the instrument NAS M617 descriptor 30 V 27 CALL IBPAD Set primary address M617 96 to 27 40 1 CALL IBSRE BRDO V 96 50 CMD Q0X CALL IBWRT M617 CMD 60 CALL IBRSP M617 SB 70 IF SB AND 2 0 THEN 60 80 CMD B1G2X CALL IBWRT M617 90 FOR I 1 TO 100 100 RD SPACES 25 C ALL Send remote enable Enable data store at conversion rate Get status byte If not full wait Turn on data store L
255. odel 617 is placed in the ohms mode constant current values between InA and 100 are available at the INPUT jack high and low terminals as shown in Table 4 1 Input high sources the current These currents can be used to plot the I V current voltage characteristics over a substan tial range R displayed resistance MODEL 6147 TRIAX MODEL 4801 TO BNC ADAPTER BNC CABLE A AA KEFFHLEY MODEL 6104 SHIELDED TEST FIXTURE 617 SET TO OHMS EQUIVALENT CIRCUIT 617 PREAMP 6104 SHIELD CABLE 6147 ADAPTER 7 in uid 2 m HI LO GND VS Figure 4 6 Diode Characterization 4 7 Figure 4 6 shows the basic circuit configuration for using the Model 617 in this manner A decade current I is forced through the diode under test The current will develop a for ward voltage drop Vr across the diode The voltage across the diode can be calculated by multiplying the displayed resis tance by the test current see Table 4 4 For example assume that a resistance reading of 50 is measured with the instru ment on the 200kQ range The voltage across the diode is 104A 50kQ 0 5 Figure 4 7 shows several examples for typical diodes The curves were drawn from data obtained in the manner just described WARNING Up to 300V may be present between the high and low terminals in ohms 4 6 CAPACITOR LEAKAGE MEASUREMENTS n important parameter associated with ca
256. of the calibration jumper W101 during the calibra tion program As with the Meter Complete output protection of the Exter nal Trigger input is necessary to protect the device from over voltage inputs External Trigger protection components in clude R101 CR102 and CR103 A D control information is fed out the PB3 and PBS ter minals through U102B A pulse width modulation scheme is used with 18 and 50 pulses representing logic 0 and logic 1 respectively 200usec pulse is used to strobe data into the A D and serial parallel control circuits Note that this infor mation is used to control the A D converter as well as to con trol the input preamplifier through relays set the ranging amplifier gain and to control the three phases of the measure ment cycle Isolation is provided by opto isolator U122 Because of this isolation scheme input signa common can be floated up 500V above chassis ground while digital com mon remains within 30V of ground In a similar fashion A D data is routed in from the A D con verter through opto isolator U121 The MPU reads this data 6 12 through the TIMER terminal As data pulses come in an in ternal 8 bit timer is incremented until 256 counts have occur red When all counts have been taken an internal interrupt is generated which causes to MPU to read the timer data A separate software counter is then decremented and the pro cess repeats Because of this data input sch
257. oftware all along 3 8 2 Interface BASIC Programming Statements Many of the programming instructions covered in this section use examples written with Hewlett Packard Model 85 BASIC and Model 8573 Interface statements These computers and interfaces were chosen for these examples because of their versatility in controlling the IEEE 488 bus This section covers those HP 85 and Model 8573 statements that are essential to Model 617 operation A partial list of HP 85 and Model 8573 statements is shown in Table 3 6 85 statements have a one or three digit argu ment that must be specified as part of the statement The first digit is the interface select code which is set to 7 at the fac tory The last two digits of those statements requiring a 3 digit argument specify the primary address Those statements with a 3 digit argument listed in the table shown a primary address of 27 the default primary address of the Model 617 For a different address you would of course change the last two digits to the required value For example to send GTL command to a device using primary address of 22 the following statement would be used LOCAL 722 Some of the statements have two forms the exact configura tion depends on the command to be sent over the bus For ex ample CLEAR 7 sends a DCL command while CLEAR 727 sends the SDC command to a device with a primary address of 27 The Model 8573 statements which are also listed in T
258. om mands are derived from an instrument s primary address The primary address may have any value between 0 and 30 and is generally set by rear panel DIP switches or programmed in from the front panel of the instrument The actual listen ad dress value sent out over the bus is obtained by ORing the primary address with 20 For example if the primary ad dress is 27 1B the actual listen address is 3B 3B 1B 20 In a similar manner the talk address is obtained by ORing the primary address value with 40 With the present example the talk address derived from a primary address of 27 decimal would be 5B 958 1B 40 The IEEE 488 standards also include another addressing mode called secondary addressing Secondary addresses lie in the range of 60 7F Note however that many devices do not use secondary addressing Once the device is properly addressed appropriate bus tran sactions are set to take place For example if an instrument is addressed to talk it will usually place its data byte on the bus one byte at a time The listening device frequently the con troller will then read this information 3 3 IEEE 488 BUS LINES The signal lines on the IEEE 488 bus are grouped into three different categories data lines management lines and hand shake lines The data lines handle bus data and commands while the management and handshake lines ensure that proper data transfer and bus operation takes place Each bus l
259. on where a circuit designer must measure the gate to source voltage of a precision JFET amplifier that has a gate impedance of 100MQ Further assume that the re quired accuracy of this measurement is 1 The set up for this measurement is shown in Figure 4 4 The gate source voltage is represented by while the effective gate impedance is represented as Rs The input resistance of the voltmeter is given as Ryn METER METER CALAS DORT us 100MQ RIN 49 EQUIVALENT CIRCUIT Rin HI MEASUREMENT CONFIGURATION Figure 4 4 Measuring High Impedance Gate Source Voltage The percent error due to voltmeter loading in this circuit can be given as ERROR 100 Rs Rw Suppose for example a typical DMM with a 10M input resistance were used to make this measurement The error because of meter loading would be 100MQ ERROR 100 91 error 100MQ 10 0 Even if a DMM with an input resistance of 10 2 were used the error would still be 100MQ ERROR x 100 9 1 error 100M 160 Such a large error would not be tolerable in this case because of the 1 accuracy requirement However since the Model 617 has an input resistance of 20070 its error in this example would be 100MQ 96 ERROR x 100 0 00005 error 100MQ 20070 which would be dominated by the instrument s specified ac curacy Thus the input impedance of the Model 617 would be more than
260. onstants If a RAM memory error occurs the following message will re main on the display The instrument will be completely inoperative If this error occurs it should be assumed that a problem exists within the instrument The problem should be rectified before using the instrument If a calibration error occurs the two exponent decimal points will flash The instrument will be functional under these con ditions but calibration is not accurate Use the calibration procedures in paragraph 7 4 of this section to calibrate the in strument Note that this error may also indicate a defective 7 7 3 Self Diagnostic Program The self diagnostic program can be used to test the front panel LEDs access the software revision level and enter a special mode to allow signal tracing through the instrument Enter the diagnostic program as follows 1 Turn off the instrument for at least three seconds if it is presently turned on 2 Press and hold the TRIG button and then turn on power 3 The instrument will then turn on all front panel LEDS and display segments The instrument will remain in this con figuration as long as the TRIG button is held in The display should appear as follows 1 8 8 8 8 8 8 4 The software revision level will then be displayed when the TRIG button is released A typical example is El 7 14 Power supply and DC voltage checks analog signal tracing continuity static logic l
261. ont panel or over the IEEE 488 bus To calibrate the instrument from the front panel perform the following procedures omitting paragraph IEEE 488 Bus Digital Calibration To calibrate the Model 617 over the IEEE 488 bus perform the following procedures omit ting paragraph Front Panel Digital Calibration Calibration Jumper A jumper located on the mother board disables enables front panel and TEEE 488 bus calibration When the jumper is in the disabled position permanent NVRAM storage of calibration constants will not take place However tem porary calibration values may be entered and used even if NVRAM calibration storage is disabled Note however that calibration parameters will be lost once power is turn ed off unless they are stored in NVRAM The calibration jumper location and the disabled enabled positions are indicated in Figure 6 WARNING Turn off the instrument and disconnect the line cord before removing the top cover to reposi tion the calibration jumper Required Equipment The following items one of each are necessary to calibrate the Model 617 1 Keithley Model 263 Calibrator Source 2 Keithley Model 196 System DMM 0 015 3 Fluke Model 343A DC Voltage Calibrator 190V 0 002 4 Triax to Triax cable supplied with 263 5 Keithley Model CA 18 1 Dual Banana to Banana cable NOTE The following additional equipment will be necessary if calibration is to be performed over t
262. oop 100 times Get a reading IBRD M617 RD 110 PRINT RD Display the reading 120 NEXT I Go back and get another 130 0 CALL IBONL Close the board file BRDO V 96 140 CALL IBONL M617 96 V Close the instrument file Press the IBM F2 key to run the program Data store is enabl ed line 50 the program waits for memory to fill lines 60 and 70 the output is turned on line 80 and all 100 readings are then requested and displayed lines 90 120 3 10 9 Voltage Source Value The voltage source value command allows you to program the built in voltage source of the Model 617 to between 102 35V and 102 4V in 50mV increments Normally the voltage source output is updated at the beginning of each electrometer conversion every 160msec however you can force an immediate update by applying an appropriate trigger stimulus to force the start of a new conversion see paragraph 3 10 14 for more information on triggering The voltage source value is programmed by sending the V command letter followed by maximum of 5 digits senting the voltage value The unit will round off the pro grammed values to 50mV minimum increments Either nor mal or scientific representation may be used as indicated below Vnnn nn normal convention Vn nnnnE n scientific notation Upon power up or after a DCL or SDC the source output will be programmed to 00 00V Some equivalent examples of these two
263. or location 2 Tighten the screws securely but do not overtighten them 3 8 3 Add additional connectors from other instruments as re quired 4 Make sure the other end of the cable is properly connected to the controller Some controllers have an IEEE 488 type connector while others do not Consult the instruction manual for your controller for the proper connecting method INSTRUMENT INSTRUMENT INSTRUMENT CONTROLLER Figure 3 6 IEEE 488 Connections NOTE The IEEE 488 bus is limited to a maximum of 15 devices including the controller Also the maxi mum cable length is limited to 20 meters or 2 meters times the number of devices which ever is less Failure to heed these limits may result in erratic bus operation Custom cables may be constructed by using the information in Table 3 5 and Figure 3 8 Table 3 5 lists the contact assignments for the various bus lines while Figure 3 8 shows contact assignments CAUTION The voltage between IEEE 48B common and chassis ground must not exceed 30V or in strument damage may occur IEEE 488 INTERFACE ADORESS ENTERED VWITH FRONT PANEL PROGRAM o ul 3 7 617 Table 3 5 IEEE Contact Designations Contact IEEE 488 Number Designation Type 3 7 3 Primary Address Programming The Model 617 must receive a listen command before is will respond to addressed commands Similarly
264. ource Connections i ya ERR aX A rad d 2 14 Resistance Measurement 6 2 2 2 15 Typical 2V Analog Output Connections 2 16 Typical Preamp Qut CODDECBOIS s xoc pa ERIT 2 17 Electrometer Input Circuitry Amps 2 2 18 Shielded Fixture Construction os bu Red 2 19 Transdiode Logarithmic Current Configuration 2 20 Non Decade Current Ganso 2 21 Equivalent Input Impedance with Zero Check 2 22 External Trigger Pulse Specifications i vierges e 2 23 Meter Complete Pulse Specifications D ERI dE ERA 2 24 External Triggering Example 2 2 25 Multiple Ground Points Create Ground 2 26 Eliminating Ground Loops ded EHE ee o gt 2 27 Leakage Resistance Effects iced 2 28 Input Capacitance Effects Own RP i da bs 2 29 Simplified Model of Source Resistance and Source Capacitance Effects 3 1 IEEE Bus Configuration
265. ow lt 1sec on power on MPU Reset then goes high 4V 5 U109 4 655kHz clock Data Strobe 6 110109 6 655kHz clock Address strobe 7 0109 37 Variable pulse train A D Data 8 0102 pin 6 Variable pulse train A D Control 9 14102 pin 8 Variable pulse train Voltage supply control 10 U102 pin Negative going pulse every 350msec Meter complete Table 7 17 Display Board Checks Step em Component Required Condition Power on 200V DC range zero check on Voltages referenced to digital common 5V supply Segment drivers U201 pin 9 U201 U202 pins 11 18 U204 pins 11 18 U205 pins 15 18 U209 pins 10 15 P1016 pin 14 5V 5 Variable pulses Variable pulses Digit drivers 1msec negative going pulse every 10msec Depress COUL R ZERO CHECK TRIG or DATA ON button Depress AMPS R SHIFT SUPPRESS Vt or RECALL button Depress VOLTS OHMS AUTO ZERO CORRECT DISPLAY PROGRAM or OPERATE button Pulse present when button depressed P1016 pin 15 Pulse present when button depressed P1016 pin 16 Pulse present when button pressed Table 7 18 Voltage Source Checks Remarks Voltages referenced to voltage source common except as noted Step Item Component Required Condition Power on V Source OV 2 U132 pin 9 82kHz clock Voltage sou
266. ows the instrument to trigger other devices 2 13 1 External Trigger The Model 617 may be triggered on a continuous or one shot basis For each of these modes the trigger stimulus will de pend on the selected trigger mode which is further described in paragraph 3 10 In a continuous trigger mode the instru ment takes a continuous series of readings A trigger stimulus in continuous triggers a new reading In a one shot mode only a single reading is taken each time the instrument is trig gered The EXTERNAL TRIGGER INPUT requires a falling edge pulse at TTL logic levels as shown in Figure 2 22 The low logic level should be between 0 0 8V and the high level should be 2 5V The minimum pulse width for reliable trig gering is approximately 10usec Connections to the rear panel EXTERNAL TRIGGER INPUT jack should be made with a standard BNC connector If the instrument is in the external trigger mode it will be triggered to take readings while in either a continuous or one shot mode when the negative going edge of the external trigger pulse occurs TRIGGERS ON LEADING EDGE TTL HIGH 2V 5V TTL LOW lt 0 8V L 105 MINIMUM Figure 2 22 External Trigger Pulse Specifications To use the external triggering proceed as follows 1 Connect the external trigger source to the rear panel BNC EXTERNAL TRIGGER INPUT connector The shield outer part of the connector is connected to digital com mon Since an inter
267. pacitors is their leakage currents Once the leakage current is known the in sulation resistance can be calculated Ideally a capacitor should have no leakage current and thus infinite leakage re sistance However capacitors like all practical devices are not ideal so these parameters can become important especially to circuit design and component engineers The amount of leakage current in a given capacitor depends on its dielectric as well as the applied voltage Ceramic dielectric capacitors typically have leakage currents in the nA to pA range while polystyrene and polyester dielectric devices ex hibit much lower leakage currents generally in the fA range These values are for test voltages in the 100V range The basic configuration for this test is shown in Figure 4 8 The Model 617 voltage source is used to impress a voltage across the capacitor C The resulting leakage current is then measured by the electrometer section of the Model 617 The resistor R is necessary to limit current to a safe value in case the capacitor is shorted and it also helps to reduce noise Typically a value of about 1MQ should be used although that value can be decreased for larger capacitor values However values under 10kQ are not recommended Refer to paragraph 2 14 8 At the start of the test the Model 617 should be placed in the amps mode and on the 20mA range The voltage source is then programmed to the desired voltage and the output
268. perate in an interlocked sequence This method ensures reliable data transmission regardless of the transfer rate Generally data transfer will occur at a rate determined by the slowest active device on the bus One of the three handshake lines is controlled by the source the talker sending information while the remaining two lines are controlled by accepting devices the listener or listeners receiving the information The three handshake lines are DAV Data Valid source controls the state of the DAV line to indicate to any listening devices whether or not data bus information is valid NRFD Not Ready For Data The acceptor controls the state of NRED It is used to signal to the transmitting device to hold off the byte transfer sequence NDAC Not Data Accepted NDAC is also controlled by the accepting device The complete handshake sequence for one data byte in shown in Figure 3 2 Once data is placed on the data lines the source checks to see that NRED is high indicating that all active devices are ready At the same time NDAC should be low from the previous byte transfer If these conditions are not met the source must wait until NDAC and NRFD have the correct status 1f the source is a controller NRFD and NDAC must be stable for at least 100nsec after is set true Because of the possibility of a bus hang up many controllers have time out routines that display messages in case the transfer sequence
269. ppres sion mode is enabled with the appropriate command the in strument will internally store the baseline value with the next triggered conversion All subsequent readings will be the dif ference between the stored baseline value and the actual signal level For example if 100mV is stored as a baseline that value will be subtracted from the following readings See paragraph 2 11 2 for a complete description To use baseline suppression perform the following steps 1 Cancel baseline suppression by sending NOX if already enabled 2 Select a range and function consistent with the expected measurement 3 Connect the signal to be used as a baseline to the instru ment input WARNING The voltage present on the input terminals may be larger than the displayed value For example if 150VDC baseline is stored an applied voltage of 175 will result in a displayed reading of only 25V 4 Enable baseline suppression by sending N1X over the bus The baseline will be stored when the command is executed 5 Disconnect the baseline signal from the instrument and connect the signal to be measured in its place Subsequent readings will be the difference between the baseline and the applied signal NOTES 1 Baseline suppression reduces the dynamic range of the measurement For example if the stored baseline value is 100mV on the 200mV range an input voltage of 100mV or more would overrange the instrument even though voltages up t
270. primary purpose of this stage is to provide low leakage characteristics of the input preamplifier Stage operation centers around a dual JFET Q308 Resistors R314 R342 R351 and R352 provide a means to balance the circuit with help of jumper W303 Depending on circuit off set jumper W303 should be placed in one of three positions A Bor C Signal input is applied to the gate of the left JFET section through R334 The characteristics of the right JFET section re main constant since its voltage stays constant Because of the variation in the characteristics of the current through R335 varies developing a proportional output signal that is applied to the next stage 6 3 2 Gain Stage Input preamplifier gain is provided by a single IC operational amplifier U309 as shown in Figure 6 5 The input signal from the input stage is applied to the inverting and noninver ting terminals of the op amp while the output from the IC is applied to the output stage The feedback capacitor C319 is one of several components that provides stability by limiting the bandwidth of the amplifier 6 3 3 Output Stage The output stage takes on one of two configurations depen ding on the selected function In the volts and ohms modes the output is optimized for voltages as high as 210V while a different configuration one necessary for high current is used in amps and coulombs 6 3
271. pter below is required to connect the Model 6104 to the Model 617 Model 6105 Resistivity Chamber The Model 6105 is a guarded test fixture for measuring voltage and surface resistivities The unit assures good electrostatic shielding and high insulation resistance The complete system requires the use of an external high voltage supply such as the Model 247 as well as the Model 617 Volume resistivity up to 1090 cm and surface resistivity up to 10180 can be measured in accor dance with ASTM test procedures Sheet samples 64 to 102mm 2 X 4 in diameter and up to 6 4mm 1 4 thickness can be accommodated Excitation voltages up to 1000V may be used Model 6146 Triax Tee Adapter The Model 6147 allows the simultaneous connection of two triaxial cables to the single triaxial input of the Model 617 Model 6147 Triax to BNC Adapter The Model 6147 allows the Medel 617 input to be connected to accessories having BNC connectors Model 6171 and 6172 3 Lug to 2 Lug Adapters The Model 6171 is a 3 lug male to 2 lug female triaxial adapter while the Model 6172 is a 2 lug male to 3 lug female triaxial adapter 1 3 Model 7008 IEEE 488 Cables The Model 7008 cables are designed to connect the Model 617 to the IEEE 488 bus and are available in two similar versions The Model 7008 3 is 0 9m 3 ft in length while the Model 7008 6 is 1 8m 6 ft long Each cable is terminated with a standard IEEE 488 con nector on each end and ea
272. put of U142B when all zeroes appear on the digital inputs of the DAC The voltage source output stage is made up of U143 Q101 Q102 Q111 Q112 and associated components This circuit is essentially an operational amplifier with a gain of 10 0143 provides the circuit gain while the transistors provide the necessary output capability Transistors Q111 and Q112 and resistors R123 R124 R126 and R127 form a complementary common emitter amplifier Current limiting is accomplished via Q101 Q102 and sensing resistors R124 and R126 Current limit threshold detection is performed by comparators U144A and U144B shown in Figure 6 16 U143 along with the output stage form a compound op amp which is connected to R157 and 159 in an inverting X10 gain configuration Com pliance at the output is 110V The accurate reference voltage needed by the DAC is pro vided by U134 101 and associated components VR101 provides a stable 6 3V reference voltage while 17134 is a con stant current source that keeps zener voltage variations to a minimum The output of the reference source is also used by the protection circuit to keep erroneous voltages from appear ing at the voltage source output terminals 2MQ VDAC ce INVERTING r SIMPLIFIED COMPOUND OP AMP Figure 6 16 Simplified Schematic of Voltage Source Output Stage 6 13 The protection circuit is made up of CR116 144 K
273. r In very complex applications a larger computer could be us Tape drives or disks could be used to store any data generated by the instruments CONTROLLER A SIMPLE SYSTEM CONTROLLER INSTRUMENT MODEL 617 INSTRUMENT B ADDITIONAL INSTRUMENTATION Figure 3 4 System Types 3 7 3 7 2 Bus Connections The Model 617 is to be connected to the IEEE 488 bus through a cable equipped with standard IEEE 488 connectors an ample of which is shown in Figure 3 5 The connector is designed to be stacked to allow a number of parallel connec tions Two screws are located on each connector to ensure that connections remain secure Current standards call for metric threads as identified by dark colored screws Earlier versions had different screws which are silver colored Do not attempt to use these type of connectors with the Model 617 which is designed for metric threads Figure 3 5 IEEE 488 Connector A typical connecting scheme for the bus is shown in Figure 3 6 Each cable normally has the standard connector on each end These connectors are designed to be stacked to allow a number of parallel connections on one instrument NOTE To avoid possible damage it is recommended that you stack no more than three connectors on any one instrument Connect the Model 617 to the cable as follows 1 Line up the connector on the cable with the connector on the rear panel of the instrument See Figure 3 7 for connec t
274. r location and the disabled enabled positions are indicated in Figure 7 2 Note that the jumper is in the disabled position as shipped from the factory Description ________ Specifications 19V 1 9V 19V 190V 0 002 0 01596 DC accuracy 100M9 0 03596 10060 3 0 0896 100 10 0 0 03 1000pF 0 1 Hewlett Packard ENABLED 7 i DISABLED 343A 9520 R289 100M R289 1G R319 100G 08 62 16384A x 3823 4530 C 4801 6147 POWER CALIBRATION CONNECTOR JUMPER ofoo MOTHER BOARD FRONT OF INSTRUMENT Figure 7 2 Calibration Jumper Location 7 3 7 4 5 Front Panel Calibration Use the basic procedure below for each of the calibration points listed in the following paragraphs Zero correction must be performed on the range being calibrated 1 Turn off the instrument for at least three seconds if it is presently turned on 2 Press and hold the PROGRAM SELECT button and then turn on power 3 The instrument powers up as normal but the CAL pro gram is accessible in the program menu 4 Select the function and range to be calibrated volts amps ohms coulombs 5 Enable zero check and zero correct the instrument by enabling zero correct 6 Connect the calibration signal to the instrument Disable zero check 7 Enter the front panel calibration program by pressing PROGRAM SELECT repeatedly until the following message is displayed CAL 8
275. ramming Example Using the front panel con trols place the instrument in the amps mode and cancel autorange Enter the following statement into the HP 85 CLEAR 727 END LINE After END LINE is pressed the instrument returns to the power up default conditions listed in Table 3 10 Model 8573 Programming Example Place the instru ment in the amps function and cancel autorange with the front panel controls Now enter the following statement into the IBM PC CALL IBCLR M617 return After the return key is pressed the instrument returns to the default conditions listed in Table 3 10 3 9 7 GET Group Execute Trigger GET may be be used to trigger the Model 617 to take readings if the instrument is placed in the appropriate trigger mode more information on trigger modes may be found in para graph 3 10 14 To send GET the controller must perform the following Steps 1 Set ATN true 2 Address the Model 617 to listen 3 Place the GET command byte on the data bus HP 85 Programming Example Type in the following statements into the HP 85 keyboard to place the instrument in remote and enable the correct trigger mode for this demonstration REMOTE 727 END LINE OUTPUT 727 T3X END LINE Now send the GET command with the following statement TRIGGER 727 END LINE 3 16 When the END LINE key is pressed the instrument will pro cess a single reading Model 8573 Programming Example in
276. ransforms the digital control information in to analog voltages that set the voltage output to a maximum of 102 4V 102 35V with 50mV resolution Because of the diversity of circuitry within the Model 617 a number of power supply voltages are required The voltage source requires both 15V and 110V supplies while the analog section requires 5V input stage and 210V and 24V supplies output stage Additional supplies include a separate 5V and 9 1V supply for A D circuits and a separate 5V supply for digital circuitry In order to ensure proper isolation two separate power transformers are used one for the digital and voltage source power supplies and the other for analog power supplies 6 3 INPUT PREAMPLIFIER The input preamplifier provides the high input impedance and high output voltage capability necessary for the volts and ohms functions and the low input impedance and high cur rent output capability needed for the amps and coulombs functions A simplified block diagram of the input preamplifier is shown in Figure 6 2 The circuit is essentially made up of three sec tions an input stage which provides the necessary input im pedance functions a gain stage which provides the needed amplification and an output stage which supplies the re quired voltage or current drive capability Additional feed back and switching elements configure the amplifier accord ing to the selected measuring function 6 2 FEED
277. rce clock 3 Ul32 15 Variable pulse train Voltage source data 4 Program 102 4V output OPERATE on 5 U141 pins 4 15 All high 15V DAC inputs 6 Program 102 35V output OPERATE on 7 U141 pins 4 15 All low DAC Inputs 8 Ul41 pin 7 10 235V Current voltage converter 9 V SOURCE HI and 102 35V Voltage source output LO Outputs OPERATE ON Current voltage converter Voltage source output Program 102 4V output 10 24V 102 4V U142 pin 7 V SOURCE Hi and LO outputs OPERATE off Pin 4 high 5 15 low U141 pins 4 15 DAC inputs when output at OV Table 7 19 Input Stage Balancing Number Counts W303 in position B and Positon of R314 Fully Clockwise W303 1400 to 2800 A 200 to 1400 B 1200 to 200 C 7 21 7 22 SECTION 8 REPLACEABLE PARTS 8 1 INTRODUCTION This section contains replacement parts information schematic diagrams and component layout drawings for the Model 617 Electrometer Also included is an exploded view drawing showing the general mechanical layout of the instru ment along with part numbers 8 2 ELECTRICAL PARTS LISTS Electrical parts for the Model 617 mother board electrometer board and the display board are listed in Tables 8 2 through 8 4 respectively Parts in each table are listed alphabetically in order of circuit designation 8 3 MECHANICAL PARTS Mechanical parts are shown in F
278. rce off mode Keep in mind that the voltage source has a maximum current output of 2mA the OPERATE LED will flash if this value is exceeded WARNING Hazardous voltage may be present on the voltage source terminals depending on the programmed value HP 85 Programming Example Enter the following state ments into the HP 85 to program and display the source and turn the output on REMOTE 727 END LINE OUTPUT 727 D1V6O1X END LINE When the command string is sent to the instrument the dis play mode is changed to view the source value the source voltage is programmed to 6V and the source output is turned on Model 8573 Programming Example Enter the following statements into the IBM computer V 1 CALL IBSRE BRDO 96 V return CMD D1V601X CALL 1BWRT M617 CMD return When the command string is sent to the instrument the dis play will change to the source mode the source value will be programmed to a value of 6V and the source output will be turned on 3 10 11 Calibration Value A One advanced feature of the Model 617 is its digital calibra tion capabilities Instead of the more difficult method of ad 3 25 justing a number of potentiometers the user need only apply an appropriate calibration signal and send the calibration value over the bus The calibration command may take on either of the following forms Ann nnn An nnnnE n Thus the following two commands would be equivale
279. rd to the front panel 7 12 Disconnect the DIP cable connected to the mother board C Remove the display board by lifting up and back until the tabs at the bottom of the case are clear and then lift the display board free 5 The instrument can be re assembled by reversing the above procedure Make sure that all boards are properly seated and secured and that all connections are properly made To ensure proper operation sheilds must be replaced and fastened securely WARNING To ensure continued protection against safety hazards power line ground the green wire connected to the AC power re ceptacle must be connected to the rear panel and mother board 7 7 TROUBLESHOOTING The troubleshooting information contained in this section is intended for qualified personnel having a basic understanding of analog and digital circuitry The individual should also be experienced at using typical test equipment as well as or dinary troubleshooting procedures The information pre sented here has been written to assist in isolating a defective circuit or circuit section Isolation of the specific component is left to the technician Note that schematic diagrams and com ponent layout drawings which are an essential aid in troubleshooting are located at the end of Section 8 WARNING The electrometer board shield is connected to the inner shield of the triaxial input which is connected either to analog com mon ung
280. rdered by using the information contained in Section 8 Parts lists as well as schematic diagrams and component layouts are located in this section 1 8 UNPACKING AND INSPECTION The Model 617 Programmable Electrometer was carefully in spected before shipment Upon receiving the instrument carefully unpack all items from the shipping carton and check for any obvious signs of physical damage that might have oc curred during shipment Report any damage to the shipping agent at once Retain the original packing material in case reshipment becomes necessary The following items are included with every Model 617 ship ment Model 617 Programmable Electrometer 617 Instruction Manual Model 6011 Triaxial Input Cable Additional accessories as ordered If an additional instruction manual is required order the manual package Keithley Part Number 617 901 00 The manual package includes an instruction manual and all perti nent addenda 1 9 GETTING STARTED The Model 617 Programmable Electrometer is a highly sophisticated instrument with many capabilities Although there are a number of complex aspects about the instrument you can use the following procedure to get your instrument up and running quickly For more detailed information you should consult the appropriate section of the manual 1 Carefully unpack your instrument as described in paragraph 1 8 2 Locate the power cord and plug it into the rear panel power jack
281. re referenced to analog and signal common Another secondary winding on T301 feeds power to com ponents that generate the 5V analog and 9V analog sup plies The 5V supply is used to power the ranging amplifier A D converter and other components such as U301 located in the analog section while the 9V supply powers the 2V reference source 5V supply components include CR311 which rectifies AC input C305 for filtering and Q309 VR302 and U306 for regulation Elements of CR311 also pro vide rectification for the 9V supply while C306 filters and VR303 regulates the output voltage Both of these supplies are referenced to analog and signal common The 5V sources supply power to much of the input preamplifier section These two supplies which are refer enced to bootstrap common utilize half wave rectification and IC regulators CR320 C316 and U308 are associated with the 5V supply and CR319 C315 and U307 perform similar functions for the 5V supply R344 and R345 are in tended to trim the 5V supply voltage to a precise value The 24V sources supply power to the preamp output stage when the circuit is configured for amps or coulombs Each supply is a simple half wave rectifier filter capacitor pair with CR323 and C317 supplying 24V and CR322 and C311 performing the same functions in the 24V supply Both these supplies are referenced to the preamplifier output 7 MAINTENANCE 7 1 INT
282. remain on the display If the instrument was not able to read the stored calibration constants and configura tion the decimal points in the two exponent digits will flash If such errors occur the instrument may be partially or com pletely inoperative Refer to Section 7 for more complete details A power up self test may be run and the software revision level may be displayed by pressing and holding the TRIG but ton when the unit is first turned on During the test all front panel LEDs and the display segments will turn on as in the ex ample below 1 8 8 8 8 The instrument will then display the software revision level when TRIG is released for example E 4 The instrument will then enter the diagnostic mode which is used as an aid in troubleshooting problems within the instru ment See Section 7 for details The power must be turned off to remove the instrument from the diagnostic mode NOTE If the instrument is still under warranty less than one year from the date of shipment and problems develop it should be returned to Keithley Instruments for repair See paragraph 1 11 for details on returning the instrument 2 1 KEITHLEY 617 PROGRAMMABLE ELECTROMETER ib 119 ELECTROMETER RANGE 24 Md AUTO aa MAX INPUT 250V ZERO CHECK Ja ZERO CORRECT Jo SUPPRESS b TRIG SGL jo STATUS TALK LISTEN REMOTE V SOURCE DISPLAY E ADJUST
283. rnal Trigger and Electrometer Compiete V GUARD SWITCH OFF Position Inner shield of triax is Input LO input capaci tance is less than or equal to 20pF ON Position Inner shield of triax is Guard fol lows Input Input capacitance is less than or equal to 2pF Use Analog Output COM for Input LO connection ENVIRONMENT Operating 0 50 C Relative Humidity 70 non condensing up to 35 C Storage 25 to 65 SHIELDING Double shielded WARMUP 2 hours to rated accuracy POWER 105 125V or 210 250V internal switch selected 90 110V available 50 60Hz 25 DIMENSIONS WEIGHT 127mm high X 216mm wide X 359mm deep 5 in X 8 in X 14 in Net weight 3 6kg 8 lbs ACCESSORY SUPPLIED Model 6011 Triaxial Input Cable ACCESSORIES AVALIABLE Model 1019A Universal Fixed Rack Mounting Kit Mode 1019S Universal Slide Rack Mounting Kit Model 6011 Triaxial Input Cable 3 ft Model 6011 20 Triaxial Input Cable 10 ft Model 6103C Voltage Divider Probe 1000 1 Model 6012 Triaxial to Coaxial Adapter Model 6104 Test Shield Model 6105 Resistivity Chamber Model 6146 Triaxial Tee Adapter Model 6147 Triaxiai to BNC Adapter Model 6171 3 Lug Male to 2 Lug Female Triaxial Adapter Model 6172 2 Lug Male to 3 Lug Female Triaxial Adapter Model 7008 3 IEEE 488 Digital Cable 3 ft Mode 7008 6 IEEE 488 Digital Cable 6 ft Model 7023 Female Triaxial Connector Model 7024 3 Triaxial Cable 3 ft
284. rument to scroll through a program menu To cancel the program mode press SHIFT and then SELECT EXIT in that order Note that the pro gram mode is cancelled by pressing SELECT EXIT after a program parameter change is made 2 4 2 Display and Indicators The operation of the 4 digit display and various indicators is described below The display updates at about three readings per second Display The Model 617 has a display made up of a 4 digit signed mantissa as well as a two digit signed exponent The exponent can be represented either in scientific notation or with an alphanumeric subsript such as The exponent dis play mode can be changed with a front panel program as described in paragraph 2 5 Note that when scientific nota tion is used the decimal point remains fixed as in 1 9999 The range is indicated by the exponent In addition the display has a number of front panel error messages as shown in Table 2 1 Display Indicators The METER SOURCE and DATA LEDs indicate what the display is actually showing When the METER LED is on the display represents an electrometer reading When the SOURCE LED is illuminated the voltage source value is being displayed A data store reading is displayed when the DATA LED is turned on Normally the display will be the the meter mode but the DISPLAY and RECALL buttons will switch the display to the source and data modes respectively 2 4 STATUS Indicators These three ind
285. s as follows NOTE Charge and current verification must be per formed before resistance verification 1 Place the instrument in the ohms mode select the 2kQ range and enable zero check 2 Verify that the display shows 0000 1 count If not enable zero correct 3 Short the input leads disable zero check and enable sup press 4 Connect the decade resistance box to the Model 617 as shown in Figure 5 6 5 Set the decade resistance box to a value of 1 900kQ and disable zero check 6 Verify that the reading is within the limits stated in Table 5 4 Enable zero check 7 Select the remaining ranges and repeat steps 5 and 6 for each range Table 5 4 Limits for Ohms Verification 2kQ 20MQ Ranges ER 189 28 C 1 900 1 8958 to 1 9042 19 00 18 971 19 029 190 0 189 52 190 48 1 900MQ 1 8952 to 1 9048 10 00MQ 9 974 to 10 026Ma 5 6 NOTE LEAVE GREEN DISCONNECTED VES BLACK CHASSIS LO 6011 CABLE SHORTING LINK REMOVED MODEL 617 Figure 5 6 Corrections for Ohms Verification 2k0 20M2 Ranges 5 5 6 Ohms Verification 200 and GO Ranges Accuracy of the 200 2GQ 2000 and 200 ranges may be verified as follows 1 Accurately measure the 100 160 and 1060 resistors with the teraohmmeter or obtain the values from Table 5 2 and record the values in Table 5 5 Calculate the allowable tolerances for each r
286. s message indicates that the IEEE address program is selected along with the presently programmed value in this case the default value of 27 is being displayed Number in parenthesis refer to signal 3 Using one of the V SOURCE ADJUST buttons scroll the ground return of referenced contact displayed address to the desired value the display will number EO and REN signal lines return on show special values for the talk only mode as described in contact 24 the next paragraph 4 Exit the program by pressing SHIFT then SELECT EXIT The new address is now in effect and it will remain pro grammed even if the power is turned off CONTACT 12 CONTACT 1 NOTE Each device on the bus must have a unique primary address Failure to observe this pre caution will probably result in erratic bus opera tion CONTACT 24 CONTACT 13 3 7 4 Talk Onty Mode The Model 617 may be placed into the talk only mode and be used with a listen only device such as a printer When in this mode the instrument will ignore commands given over the bus and merely output data as requested by the listening Figure 3 8 Contact Assignments 3 9 device When the instrument is in the talk only mode the front panel TALK LED will turn on The instrument can be placed in the talk only mode by enter ing one of the following parameters in the primary address program 40 Talk only mode with prefix on data string Example NDCV 1 2345E 01 41 Tal
287. s on the displayed value If suppress is enabled in the amps function the displayed cur rent is suppressed If suppress is enabled in the V I function the displayed resistance is suppressed To make V I measurements while suppressing current enable the sup press mode while in amps and then enable the V I mode In this case the SUPPRESS LED remains ON and the displayed resistance is calculated from the suppressed current If the suppress mode is enabled while in the V I mode and AMPS is pressed suppress is cancelled but is reapplied when the mode is reentered 2 17 Use the following procedure to measure resistance with this mode 1 Turn on the instrument and allow it to warm up for one hour to obtain rated accuracy 2 Place the instrument in the amps mode by pressing AMPS 3 For maximum accuracy select the 2pA range and zero cor rect the instrument by enabling zero check and then zero correct in that order 4 Select the desired range or use autoranging if desired 5 Connect the voltage source and INPUT jack to the measured resistance as shown in Figure 2 14 Use the Model 6011 or other similar triaxial cable to make the in put connections 6 Turn on the source output by pressing the OPERATE but ton 6011 CABLE MODEL 617 INPUT AMPLIFIER PREAMP OUT COM 7 Press the DISPLAY button to return the display to the 8 10 meter mode Disable zero check The meter will now display the current bei
288. s program is indicated by the following message IEEE 27 Along with the message the presently programmed IEEE 488 address 27 in this example will be displayed To select a new address use the V SOURCE ADJUST keys When the desired value is shown in the display press SHIFT then SELECT EXIT to return to normal operation or if a change was made simply press SELECT For complete information on using the Model 617 over the IEEE 488 bus refer to Section 3 Table 2 1 Display Error Messages Err n Err limits t See Section 3 Table 2 2 Front Panel Program Messages Program Description Displays sets IEEE primary address Sets numeric or alpha exponent Allows calibration of instrument 2 5 2 Exponent Mode Alpha or Numeric The display exponent of the Model 617 can be operated in either the alpha mode or the numeric mode In the alpha mode the exponent is given in actual units such as mA In the numeric mode the exponent is given in scientific notation Table 2 3 gives typical examples including units To select the exponent program scroll through the program menu until the following message is displayed diSP Use either of the V SOURCE ADJUST buttons to set the ex ponent to the desired mode In the numeric mode the display might show dISP 3 Bus Error Instrument programmed while not in remote or illegal command or command option sent Number Error Cal
289. s repeatedly to increment or decrement the source in 50mV increments as required The value may be scrolled simply by holding the button in The scrolling rate can be increased by press ing SHIFT before pressing the appropriate ADJUST but ton The actual maximum and minimum values are 102 4V and 102 35V 4 Press OPERATE to turn the source output on The LED adjacent to this button will illuminate when the output is turned on The OPERATE LED will flash if the 2mA cur rent limit is exceeded WARNING Dangerous voltage may be present on the source terminals when the output is enabled 5 To turn the source output off simply press the OPERATE button a second time The source output will then be pro grammed to 00 00V MODEL 617 O oo OO V SOURCE OUTPUT O RL 50k2 MINIMUM 100V NOTE MAXIMUM CURRENT 2mA MAXIMUM COMMON MODE VOLTAGE 100V V SOURCE Vom 100V Figure 2 13 Voltage Source Connections 2 8 2 Resistance Measurements The voltage source can be used in conjunction with the elec trometer section of the Model 617 to measure resistances as high 25 10160 In this mode the measured resistance is automatically calculated from the applied voltage and the measured current in accordance with the familiar formula R In ohms a flashing AMPS LED indicates a current overload Display resolution depends on the selected current range The suppress function act
290. s resistors are re placed the following procedure should be used to rebalance the circuit This procedure may also be used if the offset ad justment potentiometer R314 has insufficient range The procedure involves checking the number of counts of offset with jumper W303 in position B Proceed as follows 1 Remove the top cover and electrometer board shield as described in paragraph 7 6 Power should be off at this point 2 Place jumper W303 in position B 3 Select the volts mode and 200mV range Do not use autoranging 4 Enable zero check but leave zero correct disabled 5 Set the input offset adjustment potentiometer see Figure 7 3 fully clockwise as viewed from the screw end The control is a muliturn potentiometer so considerable ad justment may be required 6 Note the number of counts shown on the display and compare the value to the ranges listed in Table 7 19 From this table you can determine which position jumper 7 17 W303 should be placed in For example if the display shows between 1200 and 200 counts jumper W303 should be placed in position C 7 Place the jumper in accordance with the results of step 6 Replace the electrometer board shield 9 Turn on the power and allow the instrument to warm up for one hour before performing the following adjustment 10 Set the input offset potentiometer R314 for a reading of 00 00 1 count on the display 11 Replace the top cover when the procedure is
291. shown in Figure 2 9 Shielding will be re quired for low level measurements Connect the shield to input low 5 Disable zero check 6 Read the current value directly from the display The expo nent may be placed either in the alpha or numeric modes as described in paragraph 2 5 Current Measurement Considerations At very low levels in the picoampere range noise currents generated in the cable or from other sources can affect measurements Currents generated by triboelectric effects are a primary cause of noise currents generated in connecting cables These currents are generated by charges created at the junction between a con ductor and an insulator because of friction Coaxial and triax ial cables are especially prone to such noise currents which are generated by cable flexing To minimize these effects the cable should be tied down firmly to minimize any flexing Also special low noise cable constructed with graphite be tween the shield and insulator is available to minimize these effects However even with low noise cables several tens of femtoamps of noise currents can be generated by cable move ment 2 11 Voltage burden is frequently a consideration when making current measurements Ideally the input voltage burden should be zero in order for the instrument to have absolutely no effect on the circuit it is measuring If the voltage burden is too high its effects can degrade measurement accuracy con siderably
292. sition 1 63 04 R 76 470 Resistor 200k 0 1 W Metal Film 3 83 E4 R 264 200k Resistor 1 87kQ 1 1 8W Composition 1 04 E4 R 88 1 87k Resistor 1000 1 1 8W Composition 1 04 E4 R 88 100 Resistor 15M9 10 Composition 3 G2 C4 76 15 Resistor 402kQ 1 1 8W Composition 1 04 E4 R 88 402k Resistor 2 2kQ 5 Y4 W Composition 3 G2 C4 R 76 2 2k Resistor 1kQ 5 W Composition 1 64 F4 76 1 Resistor 4300 596 Ya W Composition 3 G3 C4 R 76 430 Resistor 6 8kQ 596 W Composition 1 F4 F5 R 76 6 8k Resistor 100 5 W Composition 1 04 F5 R 76 100k Resistor 22kQ 5 W Composition 3 E4 B5 R 76 22k Resistor 200kQ 5 4 W Composition 1 64 F5 R 76 200k Resistor 100kQ 5 4 W Composition 1 G2 F5 R 76 100k Resistor Thick Fitm Sev F5 TF 102 2 Resistor 2MQ 0 9 4 W Metal Film 3 82 05 R 321 2M Resistor 220kQ 0 196 4W Metal Film 3 82 05 R 264 220k Resistor 20 0 1 1 10W Metal Film 3 B2 DS R 263 20k Resistor 2kQ 0 1 1 10W Metal Film 3 B2 05 R 263 2k Resistor Thick Film C5 150 Not Used Used Resistor Thick Film Sev C6 TF 172 Resistor 200kQ 596 W Composition 3 C2 05 76 200 Resistor 20 W Composition 1 E4 E5 R 76 3 3k Resistor 1kQ 596 4 W Composition 1 E4 F5 R 76 1k Resistor Thick Film Sev C5 171 Resistor 47kQ 5 34 W Composition 1 E4 R 76 47k Potentiometer 1k 1 05 65 RP 111 1k
293. sponse time 2 Reduction of electrostatic fields Moving power lines or other sources away from the experiment reduces the amount of electrostatic interference seen in the measure ment 2 14 3 Thermal EMFs Thermal EMFs are small electric potentials generated by dif ferences in temperature at the junction of two dissimilar metals Low thermal connections should be used whenever thermal EMFs are known to be a problem Crimped or cad mium soldered copper to copper connections are methods that can be used to minimize these effects 2 14 4 RFI Radio Frequency Interference RFI is a general term frequent ly used to describe electromagnetic interference over a wide range of frequencies across the spectrum RFI can be especial ly troublesome at low signal levels but it may also affect higher level measurements in extreme cases RFI can be caused by steady state sources such as TV or radio broadcast signals or it can result from impulse sources as in the case of arcing in high voltage environments In either case the effect on instrument performance can be consider able if enough of the unwanted signal is present The effects of RFI can often be seen as an unusually large offset or in the case of impulse sources sudden erratic variations in the displayed reading RFI can be minimized by taking one or more of several precautions when operating the Model 617 in such en 2 32 vironments The most obvious method is to keep the
294. ssage on the Model 617 If instead the message out is displayed then the calibration jumper is in the disable position and calibration constants will be lost when the Model 617 is turned off THE 263 TO THE 617 CF IGS AND THE EXT SOURCE 93 3 DISP SET EXT V SOURCE TO OUTPUT DISP PRESS CONT TO CONTINUE PAUSE CLEAR OUTPUT 708 190 000 TO 263 8 DISP FiRZULIS0E 12X 263 program for 190pA 3 00000000019 5 000000013 8 000018 11 018 FOR I 1 TO 4 READ R OUTPUT 727 F1R R X QUIPUT 708 R R X Lb 256 OUTPUT 708 Z101X 283 WAIT 2000 OUTPUT 727 71X 617 WAIT 1000 OUTPUT 727 COX 617 WAIT 5000 OUTPUT 727 617 617 select I range select I range output BA to 617 zero correct display disable zero check zero display with suppress OUTPUT 708 Z X 263 output programmed I to 617 IF 121 THEN 220 WAIT 15000 WAIT 2000 READ R BEEP 2 200 OUTPUT 727 WAIT 2000 OUTPUT 727 NEXT I OUTPUT 708 00X PRINT AMPS RANGES CALIBRATED NOZOCIX 617 PRINT 200pA 2 2 uA 20 PRINT WAIT 2000 8 CLEAR OUTPUT 727 F3R3Z1X 617 617 send cal value disable suppress and zero correct and enable 2 263 place in standby select 20nC range and zero correct display 617 CALIBRATION PROGRAM A 14 540 OUTPUT 708 F3R4V19E 9X 2
295. stics such as high input resistance and high sensitivity give the instrument much better capabilities than those of the ordinary DMM For example the typical input resistance for an ordinary DMM is on the order of 10MQ In contrast the Model 617 has input resistance of greater than 200TQ 2 x 10140 The Model 617 can detect currents as low as 0 1fA 10 16A while a typical DMM might be limited to current measure ments in the pA range In this section then we will discuss some possible applica tions for the Model 617 Electrometer Keep in mind that these examples are only representative of what is possible with this highly sophisticated instrument and by no means exhaust the possible uses for the unit 4 2 INSULATION RESISTANCE MEASUREMENTS At the moderate impedance levels of many circuits insulation resistance is seldom a consideration as it is generally many orders of magnitude above the highest impedance en countered in the remainder of the circuit At very high im pedance levels however insulation resistance can be a con sideration since it can lower effective circuit impedance con siderably Since typical insulation resistances run in the range of 1010 10160 their values lie above the measurement range of ordinary instruments The high resistance measurement range of the Model 617 however gives it capabilities to measure such high resistances A typical test configuration for making insulation resistance
296. t will remain at 1V on the 20V and 200V ranges Only one reading for the presently selected function can be supressed the value will be lost if the function is changed except when in the V I ohms mode The instrument can be toggled between V I ohms and amps without loosing the stored value The suppressed readings can be as small as the resolution of the instrument will allow or as large as full range Some typical examples include Suppressed Applied Displayed Reading Signal Value 10 500 V 18 600 V 8 100 V 2 556 nA c 1 8000 nA 0 7560 nA 12 600mA 4 500mA 17 100mA To use suppression perform the following steps 1 Cancel suppress if presently enabled 2 Select a range and function that is consistent with the an ticipated mesurement If current is to be suppressed in V I ohms select amps first 3 Connect the signal to be supressed to the instrument input WARNING The voitage on the input terminals may be larger than the displayed value For exam ple if a 150VDC baseline is stored an ap plied voltage of 175V will result in a dis played value of only 25V 4 Press the SUPPRESS button The triggered reading will be stored at that point If suppressing current in V I ohms press SHIFT OHMS 5 Disconnect the supressed signal from the input and connect the signal to be measured in its place Subsequent readings will be the difference between the supressed value and the applied signal 6 To return t
297. t used and are always set to 0 Note that the status byte should be read to clear the SRQ line once the instrument has generated an SRQ All bits in the status byte will be latched when the SRQ is generated Bit 6 RQS will be cleared when the status byte is read Even with SRQ disabled the status byte can be read to deter mine appropriate instrument conditions In this case bits 0 1 3 and 4 will be continuously updated to reflect current in strument status however bit 5 the error bit will latch and remain so until the Ul status word paragraph 3 10 18 is read even if no 5 occurs HP 85 Programming Example Enter the following pro gram into the HP 85 PROGRAM COMMENTS 10 REMOTE 717 Q CLEAR 7 Set up for remote operation clear instrument Program for SRQ on error Attempt to program illegal option Serial poll the instru ment Identify the bits 20 OUTPUT 727 M32X 30 OUTPUT 727 K5X 40 SPOLL 727 50 B6 B5 B4 B3 B2 B1 60 FOR 1 7 TO 0 STEP 1 70 DISP 5 1 Loop eight times Display each bit posi tion 80 NEXT 1 90 DISP 100 END Once the program is entered and checked for errors press the HP 85 RUN key The computer first places the instrument in remote line 10 and then programs the SRQ mode of the in strument line 20 Line 30 then attempts to program an illegal command option at which point the instrument generates an 5 and sets the bus error bit in its status b
298. tage 7 8 Input Stage Balancing Procedure 7 9 Handling and Cleaning Precautions Rx pep gre ding dete a a SECTION 8 REPLACEABLE PARTS 8 1 8 2 Electrical Parts LIBUS Lassana RA p orori o E gt 8 3 Mechanical Parts 8 4 ee Ree bees 8 5 Factory Services os _ _ ___ 8 6 Component Layout Drawings and Schematic Diagrarns LIST OF ILLUSTRATIONS 2 1 Model 617 Front _ _ ob d or olco 2 2 Model 617 Rear 75 __ oda 2 3 Input Connector Configuration ga eds 2 4 Connections For Voltage Measurements 2 5 Meter Loading Considerations 2 6 Uneuagrded Circuit aiat Pe hada wars ded One en qe ix eee et ee ho ee ew tne 2 7 Guarded 22 22 4 obs we dees 2 8 Guarded Input Connections 11s __ hewn ted 2 9 Current o 2 10 Voltage Burden Considerations 2 11 Coulombs r 2 12 Resistance Measurement Connections 2 2 13 Voltage S
299. ted Model 8573 Programing Example Enter the following statements into the computer to demonstrate the trigger over run message V 1 CALL IBSRE BRD0 V 96 return CMD T3X CALL IBWRT M617 96 return CALL IBTRG M617 CALL IBTRG M617 96 return The trigger overrun error message will be displayed when the third line above is executed 3 35 Table 3 15 Trigger to Reading Ready Times Time msec 96 of Step Input 204A 200nA 20nA 200pA 20pA 24A 2nA I2pA I20nC 2nC I200pC 20 9 20069 2kQ Notes 1 Conditions Input is on range HP 85 controller 2 Preamp settling time to 1296 is 2 seconds on preamp ranges 2 20 200pA and must be taken into account by the user 3 Volt time error also apply to external feedback 4 time error is the same as the applicable current range 01 365 55 2 780 10 3 36 3 12 Bus Data Transmission Times A primary consideration is the length of time it takes to ob tain a reading once the instrument is triggered to make a con version The length of time will vary somewhat depending on the selected function and trigger mode Table 3 15 gives typical times SECTION 4 APPLICATIONS 4 1 INTRODUCTION Applications for the Model 617 are many and varied and will depend on the user s needs Basically the Model 617 can be used to make many of the same measurements in the range of ordinary DMMs however special characteri
300. terization MODEL 6147 TRIAX TO BNC ADAPTER MODEL 4801 CABLE 617 SET TO AMPS studies could be performed with only a single measuring in strument rather than requiring a separate voltage source As shown in Figure 4 5 a shielded test fixture such as the Keithley Model 6104 should be used to keep the measurement quiet and stable A good quality low noise cable such as the Model 4801 connected through a Model 6147 adapter should be used to connect the current input to the instrument Forward and reverse diode currents could be measured in similar manner The forward leakage current measured with T FET UNDER IL TEST AA mu p 22 MODEL 6104 SHIELDED TEST FIXTURE POMONA MODEL 4585 PATCH CORDS 6104 SHIELD 4801 CABLE 6147 ADAPTER 617 PREAMP TZ V SOURCE Figure 4 5 Leakage Current Measurement 4 6 the built in voltage source set to less than 0 6V can 4 1 Diode Currents and Voltages measured using the Model 617 without regard to input vol tage burden High capacitance diodes such as zener devices will present no problem since the Model 617 is unaffected Diode by stray capacitance up to 0 01pF Range Current Diode Voltage V 2kQ 20kQ 100 x 10 6 IR 200 kQ V 10 x 10 6 R 2MQ V 1 10 6 R 4 5 DIODE CHARACTERIZATION 20MQ V 100 x 10 9 R 200MQ V 10 x 10 9 260 2060 20000 1 10 9 When the M
301. tes the need to build a test fixture
302. the appropriate trigger simulus is given The Model 617 has eight trigger modes as follows Continous Mode Triggered by Talk T1 One shot Mode Triggered by Talk T2 Continous Mode Triggered by GET T3 One shot Mode Triggered by GET T4 Continous Mode Triggered by X TS5 One shot Mode Triggered by X T6 Continous Mode Triggered with External Trigger T7 One shot Mode Triggered with External Trigger Upon power up or after the instrument receives a DCL or SDC command the T continous mode external trigger mode will be enabled The trigger modes are paired according to the type of stimulus that is used to trigger the instrument In the TO and T1 modes triggering is performed by addressing the Model 617 to talk In the 2 and T3 modes the IEEE 488 multiline GET command performs the trigger function The instrument execute X character provides the trigger stimulus in the T4 and 5 modes while a trigger pulse applied to the rear panel EXTERNAL TRIGGER INPUT triggers the instrument in the 6 and T7 modes NOTES 1 A trigger stimulus will abort the present reading conversion and immediately begin another 3 27 2 The front panel TRIG button will trigger the instrument regardless of the selected trigger mode unless LLO is in ef fect 3 Serial polling usually addresses the instrument to talk This talk command will trigger the instrument in the TO and T1 modes HP 85 Programming Example Place the instrument
303. the IC Chip selection is performed by the CS line 6 11 The output of the 9914 IC is in standard IEEE 488 format the eight data lines DIO1 DIO8 the three handshake lines DAV NRFD NDAC and the five management lines REN IFC SRQ and are all active low with ap proximately zero volts representing a logic one The two IEEE 488 bus drivers 17119 and 17120 are necessary to bring the drive capability of the interface up to the requirements of the IEEE 488 standard which included provisions for up to 15 devices to be connected to the bus at one time The outputs of the bus drivers are connected to J1010 which is a standard IEEE 488 connector 6 6 5 Input Output Circuitry Additional MPU functions include the control of the Meter Complete and External Trigger Input analog to digital con verter control and voltage source control At the end of its conversion cycle the Model 617 sends a pulse out the Meter Complete jack on the rear panel This function is performed by the PB2 line of the MPU through U102A configured as a buffer inverter Diodes CR104 and CR105 and resistor R102 protect the circuit output 01020 U105B and associated components process the in coming trigger signal U102D buffers and inverts the signal while U105B latches the trigger pulse The pulse is then read by the MPU through PA6 PB1 is used to reset the trigger latch once the pulse is read Note that PB1 is also used to read the status
304. the coulombs ranges an accurately known capacitor is VOLTAGE placed in the feedback loop of the amplifier so that the BURDEN voltage developed is proportional to the integral of the input current in accordance with the formula idt The voltage is scaled and displayed as charge NOTE After measuring high voltages in volts or following an overload condition in ohms it may Figure 2 10 Voitage Burden Considerations 2 13 take number of minutes for the input current to drop within specified limits Input current can be verified by placing the protection cap on the IN PUT jack and then connecting a jumper between the COM and chassis ground terminals With the instrument on the 2pA range and zero check disabled allow the reading to settle until the in strument is within specifications Use the following procedure to measure charge with the Model 617 1 Turn on the power and allow a two hour warm up period for rated accuracy 2 Place the instrument in the coulombs mode by pressing the COLL button Set V Q GUARD to OFF 6011 CABLE MODEL 617 INPUT AMPLIFIER 1000pF PREAMP OUT COM To achieve rated accuracy place the instrument on the 200pC range and zero the instrument by enabling zero check and then pressing the ZERO CORRECT button Select the desired range or use autoranging if desired Disable zero check A small amount of zero check hop sudden change in the reading
305. the follow ing statements to make sure the instrument is in the remote and correct trigger modes for purposes of this demonstration 1 CALL IBSRE BRDO 96 V return CMDS T3X CALL IBWRT M617 CMD return Now send GET to the instrument with the following state ment CALL IBTRG M617 return When the return key is pressed the instrument will process single reading 3 9 8 Serial Polling SPE SPD The serial polling sequence is used to obtain the Model 617 status byte The status byte contains important information about internal functions as described in paragraph 3 10 15 Generally the serial polling sequence is used by the controller to determine which of several instruments has requested ser vice with the SRQ line However the serial polling sequence may be performed at any time to obtain the status byte from the Model 617 The serial polling sequence is conducted as follows 1 The controller sets ATN true 2 The controller then places the SPE Serial Poll Enable command byte on the data bus At this point all active devices are in the serial poll mode and waiting to be ad dressed 3 The Model 617 is then addressed to talk The controller sets false 5 The instrument then places its status byte on the data bus at which point it is read by the controller 6 The controller then sets true and places the SPD Serial Poll Disable command byte on the data bus to end the seri
306. through PAO and PA2 of the MPU If a particular switch contact is closed 2 bit will be high if the switch is open the data bit will e low 6 7 VOLTAGE SOURCE The voltage source circuitry which is located on schematic number 617 106 page 1 consists of serial to parallel data conversion circuitry the DAC Digital to Analog Converter analog circuitry current limit circuitry and pro tection circuitry Incoming clock and data signals are fed in through opto isolators U123 and U124 respectively The 88 92kHz clock is further divided down by U132 The pulse width modulated serial data controls the reset pin of U132 The Q2 and Q3 out puts of the divider are used to control the data and strobe in puts of the serial to parallel converter ICs U131 and U140 Control information consists of 12 bit words As the bits come in they are fed into the DATA input of U131 and U140 in serial form After all bits are shifted in data is strobed into the outputs of U131 and U140 The resulting 12 bit data is then applied to the digital inputs of U141 a 12 bit DAC Digital to Analog Converter This IC converts the digital information into an analog current out put The current output of 0141 is then converted into a 10V full scale signal by U142A and U142B The circuit is configured so that 10V will appear at the output of U142B when all ones appear on the digital inputs of the DAC Con versely 10V will appear at the out
307. transfer of message data over the data bus AH Acceptor Handshake Function AH1 defines the ability of the Model 617 to guarantee proper reception of message data transmitted over the data bus T Talker Function The ability of the Model 617 to send data over the bus to other devices is provided by the T func tion Model 617 talker capabilities exist only after the instru ment has been addressed to talk or when it has been placed in the talk only mode L Listener Function The ability for the Model 617 to receive device dependent data over the bus from other devices is provided by the L function Listener capabilities of the Model 617 exist only after the instrument has been ad dressed to listen SR Service Request Function The SR function defines the ability of the Model 617 to request service from the con troller Remote Local Function The RL function defines the ability of the Model 617 to be placed in the remote or local modes PP Parallel Poll Function The Model 617 does not have parallel polling capabilities DC Device Clear Function The DC function defines the ability of the Model 617 to be cleared initialized DT Device Trigger Function The ability for the Model 617 to have its readings triggered is provided by the DT function C Controller Function The Model 617 does not have con troller capabilities TE Extended Talker Function The Model 617 does not have ext
308. ts the natural logarithm of the ratio of the measured current to the suppressed current would then be displayed Voise VREAD Vsuppress kT q In IggAp Io 2 10 6 Non Decade Current Gains In Isuppress o The Model 617 electrometer input uses internal decade resistance feedback networks for the current ranges In some kT q ln applications non decade current gains may be desirable As SUPPRESS shown in Figure 2 20 an external feedback resistor can be used to serve this purpose Limitations on the magnitude IREAD of the feedback current require that the value of be 0 026 Ae 25 greater than 1020 IsUPPRESS NOTE Note that external feedback can be temporarily calibrated The circuit topology of Figure 2 19 works for 12 using the calibration program with the calibration positive input currents only For bipolar input jumper in the disable position See Section 7 signals an external offset bias must be applied or use a PNP at RO gg Y O ZERO CURRENT a ima oer INPUT LO TO RANGING COM 1002 cbs Or AMPLIFIER PREAMP CHASSIS PONENS OUT NOTE PRESS SHIFT VOLTS ENTER EXTERNAL FEEDBACK MODE Figure 2 19 Logarithmic Current Configuration 2 25 CURRENT INPUT TOMQ 1000 PREAMP OUT CHASSIS N ZERO CHECK RANGING NOTE PRESS SHIFT VOLTS TO ENTER EXTERNAL FEEDBACK MODE Figure 2 20 Non Decade
309. ts into the IBM computer V 1 CALL IBSRE BRDO return CMD K2X CALL IBWRT M617 CMD return The Model 617 will be placed in the K2 mode when the se cond statement is executed The EOI mode will be enabled but the bus hold off will be disabled Table 3 14 Hold off Times Bus Held Off Commands On X Until NVRAM Storage Completed 13msec 617 Front End Configured 20msec Value Taken 360msec When X is recognized Note NRFD will be held off until each byte is recognized 1 60msec in continuous trigger mode 1msec in one shot trigger mode 3 10 17 Terminator Y The terminator sequence that marks the end of the instru ment s data string or status word can be programmed by sen ding the Y command followed by an appropriate ASCII character The default terminator sequence is the commonly used carriage return line feed CR LF sequence ASCII 13 LF ASCII 10 The terminator will assume this default value upon power up or after the instrument receives a DCL or SDC command The terminator sequence may be changed by sending the desired one or two characters after the Y command However the capital letters A Z cannot be used as ter minators Special command sequences will program the instrument as follows 1 Y LF CR X LF CR two terminator characters 2 YCRXLP X CR LP two terminator characters 3 YX no terminator HP 85 Programming Example To reverse the
310. turned on Once the required soak time has passed the in strument can be placed on the proper current range to make the current measurement The soak time is the period 4 8 necessary to fully charge the capacitor typically 10 Once the test is completed the voltage source should be turned off to allow the capacitor to discharge The leakage current can be directly read from the Model 617 display during the test procedure If the leakage resistance value is required instead the instrument can be placed in the V I ohms mode and the instrument will directly display the leakage resistance value with no calculations necessary on the part of the user This basic procedure could be used to test a number of capacitors on an automated basis test fixture that holds a number of capacitors could be constructed and a Keithley Model 705 or Model 706 Scanner could be used to select among the various devices to be tested For a higher degree of automation both the scanner and the Model 617 could be controlled from a computer via the IEEE 488 bus In this way measurements that would otherwise be tedious and time con suming could be conducted on a more routine basis 4 7 CAPACITANCE MEASUREMENT The coulombs function of the Model 617 provides a quick and easy method of measuring capacitance values of capacitors cables and connectors It is especially useful in cases of cables and connectors because of the very small values of charge th
311. uarded or guard guarded Thus the shield can float up to 800V above chassis ground 7 7 1 Recommended Test Equipment Success in troubleshooting complex equipment like the Model 617 depends not only on the skill of the technician but also relies on the use of accurate reliable test equipment Table 7 8 lists the minimum recommended equipment for troubleshooting the Model 617 Other equipment such as logic analyzers and capacitance meters could also be helpful especially in difficult situations COVER 30540 SHIELD BINDING POSTS RED BP 11 2 BLACK 11 0 GROUND 15 SHIELD NOT PRESENT ON REV B OR LATER BOARDS SHIELD 617 314 TRIAX INPUT CONNECTOR not shown CS 181 BNC CONNECTOR CS 249 REAR PANEL 617 309 GROUND CLIP not shown FRONT PANEL 617 319 617 301 GROUND CLIP not shown BOTTOM COVER 30541 TILT BAIL not shown 30544 PUSHBUTTONS SHIFT 228 317 4 ELECTROMETER 228 317 5 V SOURCE 228 317 6 DATA STORE PROGRAM 228 3177 POWER 29465 3 Figure 7 11 Model 617 Exploded View 7 13 Table 7 8 Recommended Troubleshooting Equipment Equipment DMM with 0 015 basic DC accuracy 10M input impedance Keithley Model 197 or equivalent Dual trace triggered sweep oscillo scope DC 50MHz bandwidth 7 7 2 Power Up Self Test Upon power up the Model 617 will automatically test the RAM memory and check for proper calibration c
312. um Electrolytic C 240 4 7 C302 Capacitor 4 7uF 350V Aluminum Electrolytic ei C 240 4 7 C303 Capacitor 104F 350V Aluminum Electrolytic E C2 C 240 10 C304 Capacitor 104F 350V Aluminum Electrolytic G3 B2 240 10 C305 1500uF 25V Aluminum Electrolytic G4 C2 314 1500 t C306 Capacitor 4704F 16V Aluminum Electrolytic G4 2 C 313 470 C307 1000pF 630V Polystyrene A2 2 C 252 1000p C308 Capacitor TOpF 1000V Ceramic Disc A4 F3 C 64 10p i C309 Capacitor 104F 25V Aluminum Electrolytic H4 C2 314 10 C310 iCapacitor 104F 25V Aluminum Electrolytic H4 C2 314 10 C311 Capacitor 470uF 50V G5 276 470 20312 Capacitor 5pF 200V Polystyrene 82 ES3 C 31 5p C313 Capacitor 104F 25V Aluminum Electrolytic H4 C3 314 10 C314 Capacitor 104F 25V Aluminum Electrolytic H4 C3 C 314 10 C315 Capacitor 1000uF 16V Aluminum Electrolytic G4 B3 C 313 1000 C316 1000uF 16V Aluminum Electrolytic G4 C 313 1000 C317 Capacitor 4704F 50V G5 276 470 C318 Capacitor 22pF 500V Polystyrene B3 C 138 22p x C319 Capacitor 0 01nF 500V Ceramic Disc 22 01 C320 Capacitor 470pF 1000V Ceramic Disc 04 G3 C 64 470p C321 Capacitor 0 02uF 500V Ceramic Disc 04 D2 C 22 02 C322 390pF 500V Polystyrene E3 E2 C 138 390 CR301 Diode Sili
313. um accuracy the zero correction process should be repeated every 24 hours when the ambient temperature changes by more than 1 C or when the function is changed ZF 1002 mA 100kQ 1 1000pF uA 100M2 1 220pF nA 10060 1 pA Ze 100kQ 1 1000pF ALL 2 0 100 1 22pF 20M9 200M2 ALL GQ CIN INPUT AMPS Cin 20pF CIN Cin INPUT 10M2 INPUT 1000pF 10MQ Cin 20pF VOLTAGE Cin 20pF COULOMBS CIN 20pF Figure 2 21 Equivalent input Impedance with Zero Check Enabled 5 1 Leave zero check enabled when connecting disconnect ing input signals or when changing functions 2 In V I ohms the display will go blank if zero check is enabled 3 Zero will automatically be scaled when the instrument is moved uprange 4 Do not move the instrument down range after zero correcting the instrument Re zero the instrument after moving downrange 2 11 2 Using Suppression The suppression mode allows a stored offset value to be sub tracted from subsequent readings When the SUPPRESS but ton is pressed the instrument will trigger a conversion and in ternally store the displayed value as a baseline The SUP PRESS LED will illuminate All subsequent readings will be the difference between the suppressed value and the actual signal level The baseline maintains its absolute value regardless of range For example if a 1V signal is suppressed on the 2V range i
314. used to measure the value of a high impedance voltage source as shown in Figure 2 28 The source and source resistance are represented by Es and Rs the input capacitance is and the voltage measured by the electrometer is When is first applied the voltage across the capacitance and thus at the electrometer input does not instantaneously rise to its final value Instead the capacitance charges ex ponentially in accordance with the following formula Lt VM Es 1 Note that Rs is given in megohms is in microfarads while t is in seconds Because of the charging of CiN the electrometer follows the exponential curve shown in Figure 2 28B At the end of one time constant RsCrN the voltage will reach approximately 63 of its final value At the end of two time constants 2RsC the voltage will reach about 86 of its final value and so on Generally at least five time constants should be allowed for better than 1 accuracy The amount of time that must be allowed will of course de pend on the relative values of Rs and Cry For example when measuring a voltage with a source resistance of 10GQ with an input capacitance of 100pF a time constant of 1 se cond results Thus at least five seconds must be allowed to achieve a better than 1 accuracy figure Table 2 8 sum marizes voltage values and percentage error values for ten dif ferent time constants RsCriN The most obvious method t
315. ut DC Calibrator Range Voltage Voltage 617 Reading 200mV 190 000 mV 190 00 mV 1 90000 V 1 9000 V 19 0000 V 19000 V 200 V EXT VOLTS 19000 190 000 Ohms Calibration Perform the following procedure to calibrate the ohms function of the Model 617 A 12 1 Connect the Model 263 to the Model 617 as shown in Figure 8 Note that Model 263 COMMON must be con nected to Model 617 COMMON 2 Enable GUARD on the Model 263 and set the Model 617 guard switch to the ON position 3 Place the Model 617 in the ohms function and 20GQ range 4 Zero correct the Model 617 by enabling zero check and zero correct in that order 5 Program the Model 263 to output the 10GQ resistor The actual value of that resistor will be displayed by the Model 263 6 Release zero check on the Model 617 and allow the resistor reading to settle 7 Adjust the display using the ADJUST buttons of the Model 617 to correspond to the reading on the Model 263 8 Disable guard on the Model 263 and set the Model 617 guard switch to the OFF position 9 Using Table 7 as a guide repeat steps 4 through 7 for the 200MQ 2MQ and 200k0 ranges 10 Set the Model 617 to the 20 range 11 Zero correct the Model 617 by enabling zero check and zero correct in that order 12 Set the Model 263 to the 10kQ range and press ZERO to source zero ohms to the Model 617 13 Release zero check on the Model 617 The reading
316. ved before operating the Model 617 This instrument is intended for use by qualified personnel who recognize shocK hazards and are familiar with the safety precautions required to avoid possible injury Read over the manual carefully before operating this instru ment Exercise extreme caution when a shock hazard is present at the instrument s input The American National Stan dards Institute ANSI states that a shock hazard exists when voltage levels greater than 30V rms or 42 4V peak are present good safety practice is to expect that a hazardous voltage is present in any unknown circuit before measuring Do not exceed 500V peak between input low and earth ground Do not connect PREAMP OUT COM or 2V ANALOG OUTPUT to earth ground when floating input Inspect the test leads for possible wear cracks or breaks before each use If any defects are found replace with test leads that have the same measure of safety as those supplied with the instrument For optimum safety do not touch the test leads or the instrument while power is applied to the circuit under test Turn the power off and discharge all capacitors before connecting or disconnecting the instrument Do not touch any object which could provide a current path to the common side of the circuit under test or power line earth ground Always make measurements with dry hands while standing on a dry insulated surface capable of withstanding the voltage being measured Do not exceed
317. verifying instrument accuracy with each of the four measuring func tions volts ohms amps and coulombs In addition a pro cedure to verify accuracy of the internal voltage source is also included These procedures are intended for use only by qualified personnel using accurate and reliable test equip ment If the instrument is out of specifications refer to Sec tion 7 for calibration procedures unless the unit is still under warranty WARNING The maximum common mode voltage voltage between input low and chassis ground is 500V Exceeding this value may cause a breakdown in insulation creating a shock hazard Some of the procedures in this section may expose you to dangerous 5 2 voltages Use standard safety precautions when such dangerous voltages are en countered CAUTION The maximum voltage between the high and low input terminals is 250V 10 seconds maximum on the mA ranges Instrument damage may occur if this value is exceed ed NOTE Verify the electrometer section in the order listed input current amps coulombs volts and ohms Input current may remain high for several minutes following measurement of high volts or ohms Place the 0 GUARD switch in the OFF position unless otherwise noted 5 5 1 Input Current Verification Perform input current verification as follows NOTE The following procedure must be performed at an ambient temperature of 23 1 1 Disconnect all cables from the Mode
318. ware for the Model 617 is stored 7106 27128 16K X 8 PROM Temporary storage is afforded 17107 a 6116 2K X 8 RAM IC The MPU uses the RAM for temporary storage as well as for data store readings Calibration constants the display mode and the IEEE 488 primary address are stored in the 1104 During the power up cycle NVRAM data is transferred to normal RAM to allow easier access dur ing operation While data transmission to the ROM and RAM are done in parallel NVRAM data transmission is per formed serially 6 6 3 Device Selection The 146805 processor can directly address only 8K bytes of memory The Model 617 requires greater addressing capabili ty as 16K of ROM 2K of RAM and other memory space quirements are present in the system To get around this problem device selection circuitry is incorporated with the microcomputer Device selection is performed by elements of 0111 0112 U117 and 0118 MPU lines used are part of the selection pro cess include the A10 A12 address lines the PB6 line the PB7 line and the DS line Signals generated by this circuitry in clude a line which controls the ROM chip select a signal line that controls the RAM chip select and circuitry which enables the display control and JEEE 488 bus circuits Addi tional device selection signals include the memory paging signals Two signals divide the 16K ROM area into 4K pages while the a third signal divides the 2K RAM are
319. wrist strap 3 Handle the devices only by the body do not touch the pins 4 Any printed circuit board into which the device is to be in serted must also be grounded to the bench or table 5 Use only anti static type solder suckers 6 Use only grounded tip soldering irons 7 Once the device is installed on the PC board it is normally adequately protected and normal handling can resume Table 7 7 Static Sensitive Devices Keithley Part Number TF 139 TG 166 TG 128 617 600 TG 139 TG 128 TG 177 IC 163 407 103 LSI 56 LSI 58 1C 338 LSI 60 338 351 143 51 49 IC 338 412 341 337 407 412 316 251 324 251 341 283 408 347 251 247 410 283 398 277 TG 128 617 602 TG 177 IC 251 354 354 Circuit Designation 7 11 7 6 DISASSEMBLY INSTRUCTIONS If it is necessary to troubleshoot the instrument or replace a component use the following disassembly procedure An ex ploded view of the instrument may be found in Figure 7 11 WARNING Disconnect the line cord and any test leads from the instrument before disassembly 1 Remove the top cover as follows A Remove the two screws that secure the top cover to the rear panel Grasp the top cover at the rear and carefully pull up un til the tabs at the front of the cover clear the front panel The cover may then be pulle
320. y CAL 5 A normal reading will now be displayed except that the exponent decimal points will be dislayed to indicate that the instrument is in the calibration mode With the instrument in the calibration mode perform the following procedures to calibrate the Model 617 from the front panel Amps Calibration Calibration of the amps function should be performed in the following order 200pA 20nA 204A and 20mA ranges Once these ranges are calibrated the remaining ranges are automatically calibrated Use the AMPS active function of the Model 263 to source current Proceed as follows 1 Connect the Model 263 Calibrator Source to the Model 617 as shown in Figure 9 2 Place the Model 617 in the amps function and select the 200pA range 3 On the Model 617 enable zero check and zero correct in that order 4 Program the Model 263 to output 00 000pA and release zero check on the Model 617 5 After allowing the reading to settle for a few seconds zero the display of the Model 617 by pressing SUPPRESS 6 Program the Model 263 to output 190 000pA 7 Adjust the display of the Model 617 to read 190 00pA using the ADJUST buttons of the Model 617 8 Program the Model 263 to output 00 000pA by press ing ZERO on the Model 263 9 On the Model 617 disable zero correct and suppress 10 Using Table 5 as a guide select the next electrometer range and calibrator range and repeat the basic pro cedure in steps 3 through
321. y shipped and stored in anti static tubes A primary consideration then is the degree of static protec tion afforded by the anti static tube A comparison among various tubes can be set up to test the variations in charge build up as a particular IC slides the length of the tube The charge value will of course be measured by the Model 617 being operated in the coulombs function To perform this test a test fixture called a Faraday cup will be necessary Such a fixture can be easily constructed from two cans as shown in Figure 4 11 For example the outer can could be the ubiquitous one gallon paint can while the inner cylinder could be one of slightly smaller diameter such as a quart paint can The two cans must be insulated from one another Although the type of insulator is not all that critical ceramic or Teflon insulators can be used TOP VIEW OUTER CYLINDER INNER CYLINDER CONNECTOR INSULATORS TEFLON OR CERAMIC Figure 4 11 Faraday Cup Construction For convenience a BNC connector could be mounted on the outside can The outer or shield connection will of course be connected to the outer can while the inner conductor should be connected to the inner can 4 12 To perform the test connect the Model 617 to the Faraday cup using a suitable shielded cable such as Model 4801 BNC cable A Model 6147 triax to BNC adapter will be required to make the connection With the instrument in the coulom
322. y the status word lines 50 and 60 The U1 command is then trans mitted line 70 and the error condition word is then obtained and displayed lines 80 and 90 Line 100 sends the U2 com mand and the data condition word is then obtained and displayed lines 110 and 120 To show that status is transmit ted only once a normal reading is then requested and dis played lines 130 and 140 Model 8573 Programming Example Obtain and display instrument status the error condition word and the data condition word as follows load the modified DECL BAS file from disk see the Model 8573 Instruction Manual and add the lines from the program below PROGRAM COMMENTS 10 GPIBO CALL IBFIND Find the board NA BRDO descriptor 20 NA DEVO CALL IBFIND Find the instrument NA M617 descriptor 30 V 27 CALL IBPAD Set primary address M617 V 90 to 27 40 V 1 CALL IBSRE BRDO V 90 50 CMD U0X CALL IBWRT M617 CMD 60 PRINT mdlFRRCZNTOBGD QMMKYY 70 RD SPACES 25 CALL IBRD Get status word M617 RD from instrument Send remote enable Send 00 command Identify word bytes 3 34 BRDO V 180 CALL IBONL M617 96 V Close the instrument file Press the computer F2 function key to run the program The instrument is placed in remote line 40 programmed to ac cess the UO status word line 50 and that status word is then obtained and displayed lines 70 and 80 The U1 command is
323. yte The com puter then serial polls the instrument line 40 and then displays the status byte bits in proper order on the CRT In this example the SRQ B6 and error B5 bits are set because of the attempt to program an illegal command option K5 Other bits may also be set depending on instrument status 3 29 Model 8573 Programming Example Load the modified DECL BAS file into the IBM computer see the Model 8573 Instruction Manual and add the lines below PROGRAM 10 NA GPIBO CALL IBFIND 20 NA DEVO CALL IBFIND 617 30 27 CALL IBPAD M617 V 95 40 V 1 CALL IBSRE BRDO V CALL IBCLR M617 50 CMD M32X CALL IBWRT M617 CMDS 60 CMD K5X CALL IBWRT M617 CMD 70 PRINT B7 BS B4 B2 B1 BO 80 MASK 128 90 CALL IBRSP M617 5 96 loo FORI 1 TO 8 110 IF SB AND MASK 0 THEN PRINT 0 ELSE PRINT 1 120 MASK MASK 2 130 NEXT 1 140 PRINT 150 0 CALL IBONL BRDO V 160 CALL IBONL M617 9o V 90 COMMENTS Find the board descriptor Find the instrument descriptor Set primary address to 27 Send remote enable clear instrument Program for SRQ on error Attempt to program illegal option Identify the bits Define bit mask Serial poll the instru ment Loop eight times Mask off the bits and display them Close the board file Close the instrument file To run the progr
324. yte at a time 3 17 REN must be true when sending device dependent commands to the instrument or it will ignore the command and display a bus error message General HP 85 Programming Example Device dependent commands may be sent from the HP 85 with the following statement OUTPUT 727 8 A in this case contains the ASCII characters representing the command string General Model 8573 Programming the following general syntax to send device dependent com mands from the IBM PC CALL IBWRT M617 CMD Again CMD contains the command letters to program the instrument Remember that the modified declaration file must be loaded and run before using any of the programming ex amples 3 10 1 Execute X The execute command is implemented by sending an ASCII X over the bus Its purpose is to direct the Model 617 to ex ecute other device dependent commands such as F function or R range Usually the execute character is the last byte in the command string a number of commands may be grouped together into one string however there may be certain cir cumstances where it is desirable to send a command string at one time and then send the execute character later on Com mand strings sent without the execute character will be stored within an internal command buffer for later execution When the X character is finally transmitted the stored commands will be executed assuming th

Keithley 617 - University of Virginia Demonstrations

Contents

Download Pdf Manuals

Related Search

Related Contents