Keithley -
Contents
1. 1 1 1 1 17 1 1 11 21 11 1 aM 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 8 W 20 2 1 1 8 1 1 517 4185 1 1 10 10 10 10 1 6 1 2 1 2 1 2 1 2 1 2 2 1 8 1 2 W 1 2 1 2 W 1 2 lt Type MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF MtF WWVa WW MtF Comp Comp Comp r 28 RESISTORS Cont d Mfr Code 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 07716 91637 91637 91637 91637 91637 91637 91637 91637 91637 91637 91637 07716 71450 07716 01686 91637 91637 91637 91637 91637 91637 07716 01121 01121 01121 01121 Mfr Desig CEC CEC CEC CEC CEC CEC CEC TO CEC TO CEC TO CEC TO CEC TO CEC TO CEC TO 656 0 Ins 115 CEA 7009 MFF MFF MFF MFF 2 CEA EB EB EB EB REPLACEABLE PARTS Keithley Part No R942. AMPLIFIER INST UMENTS SCHEMATIC KEITHLEY SERVICE FORM Model __ No Date Name Phone Company Address City sl I e State uci 9 5 5 Zn List all control settings and describe problem Attach 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 What power line voltage is used Variation Frequency Ambient Temperature _ Variation F Rel Humidity _____________ Any additional information If special modifications have been made by the user please describe below Be sure to include your name and phone number on this service form 35
3. 0 075 pA OUTPUT to Measure current Repeat for OUTPUT 1000 nA Range Set decade dials Current reading should to 9 9 9 Set range to 1000 nA be 999 nA 7 5 nA Set OUTPUT to Measure current Repeat for OUTPUT 100 nA Range Set decade dials Current reading should to 9 9 9 Set range to 100 nA be 99 9 nA 0 75 nA Set OUTPUT to Measure current Repeat for OUTPUT k Includes 0 32 accuracy of the Model 160 see Table 5 1 Includes 0 22 accuracy of the Model 160 see Table 5 1 17 wr EAP AES nnt i 4 3 j iactu Vase WRT WX v MODEL 225 Para Specification 6 3 or Adjustment TABLE 6 1 Cont d Description CALIBRATION Measurement Figure b Line Regulation NOTE Line voltage 115V Amb Temp 25 Rel Humidity 50 Link between LOW and GROUND FILTER OFF Load Regulation NOTE Line voltage 115V Amb Temp 25 Rel Humidity 50 Link between LOW and GROUND FILTER OFF 4 Noise Check Modulation f Inductive Loading 8 Drift Check 0676 Verify line regulation Set OUTPUT to STANDBY Set decade dials to 9 9 9 Connect load re sistor between front panel LOW and OUT as shown in Figure 18 Set COMPLIANCE to 100 Set FINE to 0 Set range to 100 mA Set line voltage to 105 V Set OUTPUT to Measure voltage at load Repeat
4. DIODES Circuit Mfr Mfr Keithley Fig Desig Type Code Desig Part No Ref D101 Not Used p102 Silicon 01295 1N645 RF 14 14 0103 Silicon 01295 1N645 RF 14 14 D104 Silicon 01295 1N645 RF 14 14 D105 Not Used D106 Silicon 01295 18645 RF 14 14 D107 Silicon 01295 1N645 RF 14 14 D108 Silicon 01295 1N645 RF 14 14 D109 Silicon 01295 1N645 RF 14 14 D110 Silicon 01295 1N645 RF 14 14 DILL Silicon 01295 1N645 RF 14 14 D112 Silicon 01295 1N645 RF 14 14 D113 Silicon 01295 1N645 RF 14 14 0114 Not Used 115 Not Used 0116 zener 6 24 12954 1N827A 22 8 16 117 Silicon 01295 18914 RF 28 14 D118 Silicon 01295 1N914 RF 28 15 D119 Silicon 01295 1N914 28 14 D120 Silicon 01295 18914 RF 28 14 121 24555A 14 Selected from Keithley Part No TG 39 NPN transistor connected base to emitter 22 0675 25 MODEL 225 REPLACEABLE PARTS MISCELLANEOUS PARTS Circuit Mfr Mfr Keithley Fig Desig Description Code Des g Part No Ref DS101 Pilot Light LIMIT 91802 2100 PL 38 2 DS201 Pilot Light Decimal 91802 2140 PL 47 2 DS202 Pilot Light Decimal 91802 2140 PL 47 2 05203 Pilot Light Decimal 91802 2140 PL 47 2 F201 117V Fuse Slow Blow 1 4A 75915 313 250 FU 17 2 F201 234V Fuse 3AG Slow Blow 1 8A 11400 MDL FU 20 2 Fuse Holder 75915 342012 3 2 201 Power Cord 6 feet 93656 4638 13 00 5 2 Strain relief for P201 28520 SR 5P 1 CC 4 2 QA201 Integrated Circuit 07263 65R7723393A723C 16 14 2 QA202 Linear Integrated Cir
5. Switch Board Component Layout 228 Mother Board Component Layout Switch 5101 3 6 6 6 6 6 7 2E 13 13 14 14 eo Chassis Top View m M Accuracy Check Regulation Check Modulation Check Inductive Load Check H Current Mode vs Voltage Mode Waveforms N N Top Cover Assembly w Bottom Cover Assembly 0676 111 MODEL 225 CAUTION iv CAUTION IF THE DECADE CURRENT DIALS ARE SET TO 0 0 0 and if the Output Selector switch is not at STANDBY a COMPLIANCE VOLTAGE up to 100 volts may be present at the output terminals For maximum operator safety the Model 225 Current Source should always be set to STANDBY mode when no current output is needed The Output Selector switch S105 should also be set to STANDBY prior to changing current dial settings and or Voltage Compliance This will ensure that no transient currents will be generated WARNING This instrument is not approved for use in hazardous locations as defined in the National Electrical Code Classes I II and III Class I Those locations in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures Class II Those locations that are hazardous because of the presence of combustible
6. East Sumiyoshi 24 Bldg Room 201 2 24 2 Sumiyoshi cho Naka ku Yokohama 231 81 45 201 2246 Fax 81 45 201 2247 NETHERLANDS Keithley Instruments BV Avelingen West 49 4202 MS Gorinchem Postbus 559 4200 AN Gorinchem 01830 35333 Fax 01830 30821 SWITZERLAND Keithley Instruments SA Kriesbachstrasse 4 8600 D bendorf 01 821 9444 Fax 01 820 3081 2 CONTENTS MODEL 225 CONTENTS Section Page 8 5 1 GENERAL DESCRIPTION OPERATION CIRCUIT DESCRIPTION 550 1 5 CALIBRATION REPLACEABLE PARTS 8 ii 3 0675 MODEL 225 ILLUSTRATIONS ILLUSTRATIONS Figure No Title Page Front Panel Front Panel Controls Rear Panel Controls Connections Resistive Load Current Sink Capacitive Load Inductive Load Floating Supply Volt Limit Characteristic F Modulation s a s eee vx o Block Diagram n n ng won Component Layout PC 227
7. Tepro Electric Corp 5 St Paul Se Rochester N Y 14604 General Electric Semiconductor Products Dept Syracuse 13201 Arrow Hart amp Hegeman Electric Co 103 Hawthorne St Hartford Conn 06106 Motorola Semiconductor Prod Inc 5005 E McDowell Rd Phoenix Ariz 85008 Tansistor Electronics Inc 1000 West Road Bennington Vt 05201 Union Carbide Corp Electronics Div New York N Y 10017 Components Inc Ar zona Div Phoenix Ariz 85019 Varian Assoc EIMAC Div 301 Industrial Way San Carlos Calif 94070 Transistor Electronics Corp Hwy 169 Co Rd 18 Minneapolis Minn 55424 Fairchild Camera amp Inst Corp 313 Frontage Road Mountain View Calif IRC Inc 2850 Mt Pleasant Burlington Iowa 52601 GL Electronics Div of GL Industries Inc Westville N J 08093 Gulton Industries Inc Alkaline Battery Div Metuchen N J Burgess Battery Co Div of Servel Inc Freeport Ill Burndy Corp Richards Ave Norwalk Conn 06852 CTS of Asheville Inc Mills Gap Road Skyland N C IRC Inc Greenway Road Boone N C 28607 Electro Scientific Indus Inc 13645 NW Science Park Dr Portland Or 97229 National Semiconductor Corp Commerce Drive Danbury Conn 06813 Transitron Electronic Corp 144 Addison St East Boston Mass Clarostat Mfg Co Inc Lower Washington St Dover N H 03820 Dickson Electronics Corp 302 S Mells Fargo Ave Scottsdale
8. checked with an actual output load connected Clipping of the output signal may occur de pending on the compliance voltage setting The modulation feature is especially useful when making dynamic impedance measurements on semi conductor devices etc 0972 12 CIRCUIT DESCRIPTION SECTION 3 3 1 GENERAL The Model 225 is an all solid state current source which is composed of various circuits as shown in Figure 12 These circuits include the following types a High Gain Operational Amplifier A3 b Differential Voltage Sensing Amplifier c Kelvin Divider with Precision l volt Reference d Voltage Compliance Amplifier A2 e Compliance Voltage Control f Compliance Voltage Suppies 130 V Series Regulators h Range Resistor Controls i Power Supplies j Modulation Circuit 3 2 THEORY OF OPERATION The Model 225 can deliver currents from 10 7 to 10 1 amperes with a compliance voltage up to 100 volts The current source utilizes a high gain differential amplifier A3 which controls the current through the range resistor The differential voltage sensing amplifier Al senses the OUT voltage with respect to a voltage reference kelvin varley divider network permits adjustment of current in decade steps The voltage compliance amplifier A2 senses the voltage at a point ahead of the range resistor with respect to the compliance voltage control potential The compliance voltage supplies allow
9. current from 50 Hz to 500 Hz Input Z approximately 500 ohms FILTER For operation with inductive loads up to 100 millihenries having greater than 10 6L R ratio Limits shunt output impedance to 1 microfarad shunted by greater than 1010078 ENVIRONMENT 50 relative humidity limit at 25 CONNECTORS Output front and rear panels BNC POWER 105 125 210 250 volts switch se lected 50 60 Hz 25 watts DIMENSIONS WEIGHT 5527 high x 834 10 deep net weight 8 pounds wide x 225 CURRENT SOURCE 4 VOLTAGE OUTPU Sern anes N supaypak Se 0 9 T STANDBY FILTER Low out Wie 3 IN mil le t Atte NODS GENERAL DESCRIPTION SECTION 1 1 1 GENERAL The Model 225 is current source with full scale ranges from 1077 to 10 1 ampere 1 2 FEATURES range GENERAL DESCRIPTION MODEL 225 c Accuracy The three decade dials adjust the out put current to 05 of full range and 5 of reading d Polarity The OUTPUT SELECTOR Switch provides polarity selection without changing connections to the a Resolution The three decade dials plus a Trim load potentiometer provides a resolution of 02 of full e Floating Capability The instrument LOW be floated up to 500 volts above chassis b Compliance Voltage A front panel Compliance Control provides an adjustable maximum compliance
10. dust Class III Those locations that are hazardous because of the presence of easily ignitable fibers or flyings 0676 MODEL 225 0571 SPECIFICATIONS SPECIFICATIONS OUTPUT D C Current 107 ampere full range to 107 ampere in seven decade ranges 3 digit line readout Voltage 100 volts maximum Compliance limit continuously variable from 10 to 100 volts Polarity Positive or negative Floating 500 volts maximum off chassis ground less than 5 ppm of full range change in output current per volt RESOLUTION Three significant figuresfrom 107 to 107 ampere Trim potentiometer permits 0 02 of full range or better resolution ACCURACY 0 5 of reading 0 05 of full range STABILITY 0 02 ot reading 0 005 of full range on the 10 to 10 4 ampere range 0 1 of reading 0 02 of range on the 10 7 ampere range the first hour or in sub sequent 8 hour periods after a 1 hour warm up and at reasonably constant ambient tem perature NOISE Less than 0 01 rms of full range above 5 Hz LOAD REGULATION 0 005 offuilrange from no load to full load on the 10 to 10 5 pere range 0 05 on the 107 ampere range with FILTER LINE REGULATION 0 005955 of full range for 10 change in line voltage OVERLOAD PROTECTION Voltage limitedto com pliance voltage setting of polarity selected Automatic recovery from overload MODULATION Transformer input permits modu lation of
11. for OUTPUT Set line voltage to 125V Verify load regulation Set OUTPUT to STANDBY Set decade dials to 9 9 9 Set FINE to 0 Set range to 100 mA Set COMPLIANCE to 100 Set line voltage to 115 V Connect load resistor between front panel LOW and OUT as shown in Figure 18 Set OUTPUT to Measure volt age at load Repeat for OUTPUT Set OUTPUT to STANDBY Set decade dials to 9 9 9 Set FINE to 0 Set range to 100 mA Set COMPLIANCE to 100 Connect load resistor Set OUTPUT to Measure rms noise using Voltmeter D Repeat for OUTPUT Set range to 100 mA Set decade dials to 5 0 0 Set FINE to 0 Set COMPLIANCE to 100 Connect Oscilla tor H to MODULATE input Connect Oscilloscope and load resistor to OUT as shown in Figure 19 Set Oscillator for 30 V 100 Hz Waveform should be a 400 mV p p mod ulated wave Set range to 100 mA Set decade dials to 9 9 9 Set FINE to 0 Set COMPLIANCE to 100 Set FILTER to ON Connect inductive load 1 wR in series with 1 kQ as shown in Figure 20 Set OUTPUT to Connect Oscilloscope H and measure ripple Voltage should be less than 100 mV p p Set FILTER to OFF No oscillations should occur Set range to 1000 pA Set decade dials to 9 9 9 Set FINE to 0 Set OUTPUT to STANDBY Warm up 225 for 1 Hr Connect Recorder to OUT Set OUTPUT to Adjust FINE for 1 V deflection on recorder Total drift for lst hour should not exceed 250 mV with less
12. than 100 18 18 Voltage change should not exceed 50 pV Voltage change should not exceed 50 Voltage change should 18 not exceed 50 pV Noise should be less than 10 mV rms 400 mV p p 19 20 15 CALIBRATION MODEL 225 TABLE 6 2 Calibration Procedures Para Specification Sub Test Schematic 6 4 or Adjustment Description Measurement Assembly Figure Point Part Power Supplies NOTE Calibrate power supply DC voltmeter and os cilloscope must be 12 VOLTS DC Measure 12V supply Adjust for volt PC 228 14 16 12 2462035 floated for measure with respect to range switch shaft age of 12V Poten ment of 12V supplies common Adjust potentiometer R226 0 01V Ripple tiometer Line Voltage 117V for 12V should be less R226 Link between LOW and than 3 mV p p GROUND LINE SWITCH 117V 12 VOLTS DC Measure 12V supply Voltage should 228 14 16 12V 24203 with respect to range switch be 12V 0 shaft common Ripple should be less than 3 mV NOTE If 234V power is used set LINE SWITCH to 234V 10 VOLTS DC Measure 10V with Voltage should 228 14 16 10 242031 respect to LOW Ripple should be be 10 41V less than 20 mV p p 10 VOLTS DC Measure 10V with Voltage should 228 14 16 10 24203 respect to LOW Ripple should be be 10V less than 20 mV b Amplifier Zero Set range to nA Set decade dials Adjust for 0 228 14 16 24204
13. volt f Modulation The output current can be modulated over a frequency range from 50 to 500 Hz age from 10 to 100 volts Control Power Switch 5202 OUTPUT SELECTOR Switch 8105 VOLTAGE COMPLIANCE Control 8117 LIMIT Indicator 05101 Range Switch S101 Selector Switches 102 103 5104 FINE Control R138 FILTER Switch S106 Control or Terminal Power Cord 201 LINE VOLTAGE Switch 5201 FUSE F201 OUT Receptacle 7105 LOW Terminal J201 GROUND Terminal 3420 MODULATE Receptacle J101 Shorting Link 2 TABLE 1 1 Front Panel Controls Functional Description Controls line power to instrument Decimal point serves as a pilot lamp Selects positive or negative polarity or standby position Sets the maximum compliance voltage which can be developed at the OUT terminal When lighted the instrument is in Voltage mode Selects the full scale range The decimal point is auto matically positioned by the Range switch Selects the magnitude of current in 3 decade positions Adjusts current When set to the switch connects a 1 uF capacitor at the OUT terminal TABLE 1 2 Rear Panel Controls and Terminals Functional Description Provides line power to instrument Sets instrument for 117 or 234 V line operation Slow Blow 117 V 1 4A 234 V 1 84 Output high connection Output low connection Ground chassis connection Connection to modul
14. with the FILTER Switch OFF but is 1 x 1010 ohms with the FILTER Switch There fore the maximum output impedance is 2 x 10 on 100 nA and 1000nA ranges with the FILTER Switch OFF The effective output impedance R can be determined by the following equations 0676 MODEL 225 TABLE 2 2 Output Impedance Output Impedance x x x x x x x With Filter switch set to off For the 100 mA range Ry 1030 and X regulation 0 005 Ry Since 4 regulation 100 x Ro t 100 Ry REG 100 x 1000 9 0 005 The Model 225 will deliver the dialed current for load resistance from 0 ohms to Ryay The value of Ryay is determined by the dialed current I and the compliance voltage setting Vc where RMAX Vc I If the load resistance exceeds RMAX then the Model 225 will automatically switch into Volt age Limit mode indicated by the LIMIT lamp DS101 Then Ro or R 2 x 1079 f Floating Operation The instrument can be floated up to 500 volts off chassis ground with less than 5 of full range change in output current per volt off ground For floating operation the shorting link on the rear panel must be removed this case two coaxial cables should be used to connect to output high and low The outer shell of the front panel OUT and LOW receptacles are always at chassis ground for safety when floating the instrument A filter capaci tor C217 05 HF is connected between the LOW and
15. 106 are current limiting transistors which shut down the output transistors during a change in the selected polarity h Range Resistor Controls The Range Switch S101 selectes full range current from 1077 to 1071 amperes Range resistors R184 thru R190 are selected such that for each selected current the voltage drop across the Range resistor R is 1 volt for full range 0571 14 CIRCUIT DESCRIPTION i Power Supplies The remaining power supplies provide power to the amplifier stages and voltage references 1 10 volts Diodes D211 thru D214 form a full wave rectifier which provides unregulated voltages for the 10 volt regulator stages Capacitors C207 and C208 provide filtering Transistors Q209 and Q210 and reference zeners D205 and D206 form the 10 volt regulators This supply provides bias voltages for the voltage LIMIT indicator circuit 2 12 volts This supply provides power to the amplifier stages and reference diode D116 The supplies consist of a full wave rectifier Diodes D215 thru D218 an integrated circuit QA201 and a linear operational amplifier QA202 The voltage developed by QA201 is 24 volts This output is split to form separate 12 volt supplies These supplies are referenced to the output high Po tentiometer R226 provides adjustment of the 24 volt output Modulation Circuit The modulation circuit consists of transformer 101 which is connected so that the voltage feedback to amplifie
16. 2 2 1 1 8 W MtF 07716 CEA R88 402 14 R113 100 0 10 1 2 W Comp 01121 EB R1 100 14 8114 15 1 1 8 W MtF 07716 CEA 888 15 14 RIL5 5 49 1 1 8 MtF 07716 CEA R88 5 49K 14 R116 2 20 2W WWVar 71450 1NS 115 RP50 2K 8 14 R117 50 kQ 10 3W wuvar 12697 58 RP80 50K 14 R118 5 1 kf 5 3W WW 44655 200 R173 5 1K 14 R119 22 kQ 10 1 2 W Comp 01121 EB R1 22K 14 R120 10 10 1 2 W Comp 01122 EB R1 10K 14 R121 1 20 24 71450 INS 115 5 0 5 14 R122 8 2 10 1 2 W Comp 01121 EB R1 8 2K 14 R123 390 2 10 1 2 W Comp 01121 EB 1 390 14 R124 390 Q 10 1 2 W Comp 01121 EB 81 0 14 R125 4 7 kQ 10 1 2 W Comp 01121 EB Rl 4 7K 14 R126 20 kQ 1 1 8 W MtF 07716 CEA R88 20K 14 R127 20 kQ 1 1 8 W MtF 07716 CEA R88 20K 14 8128 20 kQ 1 1 8 W MtF 07716 CEA R88 20K 14 R129 20 1 1 8 W 07716 R88 20K 14 R130 2 2 10 1 2 W Comp 01121 EB R1 2 2K 14 R131 20 kQ 1 1 8 W MtF 07716 CEA R88 20K 14 R132 20 kQ 1 1 8 W MtF 07716 CEA R88 20K 14 R133 49 9 1 1 8 W 07716 888 49 9 14 R134 20 1 1 8 W MtF 07716 CEA R88 20K 14 R135 20 1 1 8 W MtF 07716 CEA R88 20K 14 R136 100 1 07716 R88 100K 14 R137 499 Q 1 1 8 W MtF 07716 CEA R88 499 14 R138 500 9 1 1 2 W Var 71450 GC T450 RP91 500 14 R139 95 3 2 1 1 2 W 07716 R94 95 3 13 R140 100 Q 10 1 2 W Comp 01121 EB 1 100 15 R141 182 1 1 8 W 07716
17. 214 Silicon 01295 1N645 RF 14 14 D215 Silicon 01295 1N645 RF 14 14 D216 Silicon 01295 1N645 RF 14 14 D217 Silicon 01295 1N645 RF 14 14 D218 Silicon 01295 1N645 RF 14 14 0777 27 30 REPLACEABLE PARTS MODEL 225 RESISTORS Circuit Mfr Mfr Keithley Fig Desig Value Rating Type Code Desig Part No Ref R201 4 7 10 1 2 W Comp 01121 EB R1 4 7k 14 R202 6 8 10 1 2 W Comp 01121 EB R1 6 8k 14 R203 2 kQ 0 1 1 2 W WW 54294 SP23D18 62 2 8 22 14 8204 4 7 10 1 2 W Comp 01121 RI 4 7k 14 8205 2 2 kQ 10 1 2 W Comp 01121 R1 2 2k 14 R206 1 kQ 10 1 2 W Comp 01121 EB 1 1 1 14 8207 2 0 1 1 2 WW 54294 SP23D18 867 2 1 AK 14 R208 2 2 KR 10 1 2 W Comp 01121 EB Rl 2 2k l4 R209 56 kQ 10 1 2 Comp 01121 EB R1 56k 14 R210 10 10 1 2 W Comp 01121 81 101 14 R211 10 10 1 2 Comp 01121 EB R1 10k 14 R212 47 kQ 10 1 2 W Comp 01121 EB 1 47 14 8213 56 10 1 2 W Comp 01121 EB R1 56k 14 R214 87 KR 10 1 2 W Comp 01121 R1 47k 14 R215 1 kQ 10 1 2 W Comp 01121 EB 1 1 14 R216 1 10 1 2 Comp 01121 amp 1 1 14 R217 Not Used R218 Not Used R219 Not Used R220 Not Used 8221 Not Used R222 Not Used R223 1 8 8 10 1 2 W Comp 01121 EB R1 1 8k 14 R224 12 Q 10 1 2 W Comp 01121 EB R1 12 l4 R225 6 04 1 1 8 W 07716 R88 6 04k 14 R226 1 kQ 20 2 W WW 71450 185115 50 1 R 14 R227 2 21 K9 1 1 8 W MtF 07716 CEA R8
18. 40 2 R94 40 2 R94 40 2 R94 40 2 R94 40 2 R94 40 2 R127 200 8127 0 127 0 R127 200 R127 200 R127 200 R127 200 R127 200 R127 200 R127 200 R127 200 8169 11 RI69 1K R169 1K 169 4 8169 11 8169 16 R169 1K 169 1 R169 1K RL69 1K 169 1 888 450 50 20080 4 888 895 0 8169 10 169 1 R169 10K R169 100K RL69 1M 7161 4 R88 681 R1 100K R1 10 1 220 81 220 REPLACEABLE PARTS MODEL 225 SWITCHES Circuit Mfr Keithley Fig Desig Description Code Part No Ref 5101 Rotary Switch less components Range 80164 SW 284 2 Knob Assembly Range Switch 80164 2 5102 Rotary Switch less components first Decade Switch 80164 SW 282 2 Knob Assembly first Decade Switch 80164 23603A 2 8103 Rotary Switch less components second Decade Switch 80164 50 282 2 Knob Assembly second Decade Switch 80164 23603A 2 104 Rotary Switch less components third Decade Switch 80164 54 282 2 Knob Assembly third Decade Switch 80164 23603A 2 5105 Rotary Switch OUTPUT SELECTOR Switch 80164 5 3 2 Knob OUTPUT SELECTOR Switch 5106 Toggle Switch FILTER 80164 54 309 2 5201 Slide Switch LINE 80164 54 151 2 5202 Toggle Switch Power 80164 54 4 2 26 29 0571 MODEL 225 REPLACEABLE PARTS POWER SUPPLY 200 SERIES CAPACITORS Circuit Mfr Mfr Keithley Fig Desig Value Rating Type Code Desig Part No Ref 2201 Not Used C202 3 HF 400 V My 13050 5 1 11
19. 7 5 14 C203 001 uF 600 CerD 72982 001 022 001 14 C204 001 600 72982 001 C22 001M 14 C205 140 uF 150 V EMC 56289 Type 630 C183 140M 14 C206 140 uF 150V EMC 56289 Type 630 C183 140M 14 C207 100 uF 40V EAL 73445 04 0 0150 14 14 C208 100 uF 40V EAL 73445 C437AR G100 C150 100M 14 C209 001 uF 600V CerD 72982 ED 001 C22 001M 14 210 001 uF 6004 CerD 72982 ED 001 C22 001M 14 C211 100 uF 40V EAL 73445 C437AR G100 C150 100M 14 C212 4 7 uF 20V ETT 17554 TSD1 20 475 179 4 7 14 C213 100 pF 600V CerD 72982 ED 100 22 100 14 C214 02 uF 600v CerD 72982 ED 02 C22 02M 14 C215 10 uF 20V ETT 17554 TSD2 20 106 179 10 14 C216 10 uF 20V ETT 17554 TSD2 20 106 C179 10M 14 C217 05 uF 600V My 56289 6PS 550 C62 05M 14 C218 150 pF 600V CerD 72982 70 0 C22 150P 14 C219 470 pF 1000V CerD 71590 471 C64 470P DIODES Circuit Mfr Mfr Keithley Fig Desig Type Code Desig Part No Ref D201 Silicon 01295 1N645 RF 14 14 D202 Silicon 01295 1N645 RF 14 14 D203 Zener 12954 1N709 DZ 21 14 0204 2 12954 14709 02 1 14 D205 Zener 12954 14715 DZ 22 14 D206 Zener 12954 1N715 DZ 22 14 0207 Rectifier lA 800V RTC 04713 154006 1 8 14 0208 Rectifier 800 04713 1N4006 RF 38 14 D209 Rectifier 1A 800V Rf Sa 04213 1 4006 RF 38 14 0210 Rectifier 1A 800V 04713 1N4006 RF 38 14 D211 Silicon 01295 1N645 RF 14 14 D212 Silicon 01295 1N645 RF 14 14 D213 Silicon 01295 14645 RF 14 14 D
20. 8 23396C 245638 245610 17148 17149 54 171478 192068 192058 0972 Sag MODEL 225 REPLACEABLE PARTS FIGURE 22 Top Cover Assembly FIGURE 23 Bottom Cover Assembly 0571 24 21 REPLACEABLE PARTS MODEL 225 REPLACEABLE PARTS LIST AMPLIFIER 100 SERIES PC 228 CAPACITORS Circuit Mfr Mfr Keithley Fig Desig Value Rating Type Code Desig Part No Ref clot 0068 uF 600V CerD 72982 0068 C22 0068M 14 c102 0022 600 CerD 72982 ED 0022 C22 0022M 14 C103 22 uF 50 84411 601 C41 22M 14 C104 02 uF 600y CerD 72982 ED 02 C22 02M 14 C105 4 7 uF 20V ETT 17554 501 20 475 0179 44 14 C106 4 7 uF 20v ETT 17554 TSD1 20 475 0179 4 6 14 C107 1 HF 200 13050 107 21 C66 1M 14 C108 1 uF 200v My 13050 107 21 C66 1M 16 C109 02 600 72982 0 02 C 22 02 C110 33pF 1000 71590 DD 330 C 64 33p CONNECTORS Circuit Mfr Mfr Keithley Fig Desig Description Code Desig Part No Ref J101 Receptacle BNC MODULATE Mil UG 1094 u 02660 31 221 cs 15 2 J102 Not Used 3103 Receptacle BNC Front Panel OUT Mil No UG 1094 U 02660 31 221 08 15 2 J104 Receptacle BNC Rear Panel OUT Mil No Uc 1094 U 02660 31 221 CS 15 2 J105 Receptacle BNC Front Panel LOW Mil No UG 1094 U 02660 31 221 CS 15 2 J201 Binding Post GROUND 58474 DF21BC BP 11B 2 J202 Binding Post Rear Panel LOW 58474 DF21GC 8 116 2
21. 8 2 21k 14 R228 20 ka 1 1 8 W 07716 R88 20k 14 R229 20 kQ 1 1 8 W 07716 888 14 R230 10 kQ 10 1 2 W Comp 01121 EB R1 10k 14 R231 120 Q 10 1 2 W Comp 01121 EB R1 120 14 amp 232 100 ka 10 1 2 Comp 01121 EB R1 100k 14 TRANSISTORS Circuit Mfr Mfr Keithley Fig Desig Code Desig Part No Ref Q201 04713 2N3905 TG 53 14 Q202 04713 MM4003 TG 59 l4 Q203 04713 2N3905 TG 53 l4 Q204 PNP 92 Case MOT 2N5087 TG 61 14 Q205 04713 283905 TG 49 14 Q206 02735 40346 TG 44 14 Q207 02735 40346 TG 44 14 Q208 04713 MM4003 16 59 14 0209 02734 40317 TG 43 14 Q210 02734 40319 TG 50 14 28 0675 31 REPLACEABLE PARTS CODE TO NAME LIST CODE TO NAME List of Suggested Manufacturers Reference Federal Supply Code for Manufacturers Cataloging Handbook H4 2 Aerovox Corp 740 Belleville Ave New Bedford Mass 02741 Film Capacitors Inc 100 Eighth St Passaic N J Allen Bradley Corp 1201 South 2nd St Milwaukee Wisc 53204 Texas Instruments Inc Semiconductor Components Div Dallas Texas 75231 RCL Electronics Inc 195 McGregor St Manchester N H 03102 Varo inc Electrokinetics Div Santa Barbara Calif 93102 Amphenol Corp 2801 South 25th Ave Broadview Ill 60153 Radio Corp of America Defense Electronic Products Camden N J Radio Corp of America Receiving Tube Div Somerville N J Hopkins Engineering Co 12900 Foothill Blvd San Fernando Calif 91342
22. 888 1 14 R142 182 1 1 8 W MtF 07716 CEA R88 182K 14 R143 10 kQ 10 1 2 W Comp 01121 EB R1 10K 14 R144 500 2 20 3 4 W Cermet 73138 77PR500 8 64 500 KP 14 145 49 9 k0 1 1 8 W 07716 888 49 9K 14 R146 49 9 k2 1 1 8 W MtF 07716 CEA 888 49 9 14 R147 10 kQ 10 1 2 W Comp 01121 EB RL 10K 14 R148 40 2 0 1 1 2 W 07716 R94 40 2 13 R149 40 2 2 1 1 2 W 07716 89 2 13 R150 40 2 0 1 1 2 W 07716 amp 94 40 2 13 R151 40 2 2 1 1 2 W MtF 07716 CEC R94 40 2 13 R152 40 2 Q0 1 1 2 W MtF 07716 CEC R94 40 2 13 24 0571 27 MODEL 225 MODEL 225 Circuit Desig R153 8154 R155 R156 R157 R158 R159 R160 R161 R162 R163 R164 R165 R166 R167 R168 R169 8170 Riv R172 R173 R174 R175 RL76 R177 R178 R179 80 R181 R182 R183 R184 R185 6186 RL87 R188 R189 R190 R191 R192 R193 R194 RI95 0774 Value o 2 12 9 5 2 e e 2 tv N t2 242 200 ki 2 k3 1 200 2 4 99 10 2 100 3 1 k 10 k 100 k 1 M2 10 M 681 2 100 k 10 220 2 220 2 Rating 1 1 1 1 1 1 1 2 W 1 2 W 1 2 W 1 2 W 1 2 1 2 1 4 1 2 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 0
23. Ariz Potter Co Highway 51 N Wesson Miss 39191 Solitron Devices Inc 256 Oak Tree Road Tappan N Y 10983 Midwec Corp 602 Main Oshkosh Nebr 69154 Cornell Dubilier Electric Corp 50 Paris Street Newark N J 39570 Sprague Electric Co Box 1509 Visalia Calif 93278 ITT Semiconductors Div of Corp Lawrence Mass 01841 Daven Div of Edison 104 McGraw Edison Co Livingston N J Teledyne Systems Co Communications Div Los Angeles Calif 90066 Components Inc Smith St Biddeford Ma 04005 General Reed Co 174 Main St Metuchen N J 08840 General Radio Co 22 Baker Ave West Concord Mass 01781 Hathaway Instruments Inc 5800 E Jewell Ave Denver Colorado 80222 Heyman Mfg Co 147 N Michigan Ave Kenilworth N J Richey Electronics Inc 1307 Dickerson Rd Nashville Tenn 37213 Leeds and Northrup 4901 Stenton Ave Philadelphia Pa 19144 Mallory R and Co Inc 3029 E Washington St Indianapolis Ind 46206 Ohmite Mfg Co 3601 Howard St Skokie 111 60076 Sangamo Electric 1301 North Lith Springfield 111 62705 Shallcross Mfg Co 24 Preston St Selma N C Sprague Electric Co North Adams Massachusetts Superior Electric Co The 383 Middle St Bristol Conn 06012 Union Carbide Corp 270 Park Ave New York N Y 10017 Victoreen Instrument Co 5806 Hough Ave Cleveland Ohio 44103 Allied Control Co
24. Cleveland Ohio 44114 Resistance Products Co 914 S 13th St Harrisburgh Pa 17104 Continental Wirt Electronics Corp Philadelphia Pa Keithley Instruments Inc 28775 Aurora Road Cleveland Ohio 44139 Bourns Inc 6135 Magnolia Ave Riverside Calif 92506 Grayhill Inc 561 Hillgrove Ave La Grange 111 60525 International Rectifier Corp 1523 East Grand Ave El Segundo Calif Switchcraft Inc 5527 Elston Ave Chicago Ill 60630 General Instrument Corp Capacitor Division Darlington S C 29532 Smith Herman H Inc 812 Snediker Ave Brooklyn N Y 11207 Burroughs Corp Electronic Components Div Plainfield N J 07061 Electronic Devices inc Brooklyn New York Arco Electronics inc Community Drive Great Neck N Y 11022 TRW Capacitor Div 112 W First St Ogallala Nebr Sarkes Tarzian Inc E Hillside Dr Bloomington Ind 480 Radio Corp of America Electronic Components amp Devices Harrison N J Philco Corp Lansdale Div Church Rd Lansdale Pa 19446 Mallory Capacitor 3029 East Washington Indianapolis Ind 46206 Mallory Battery Co Tarrytown New York Dale Electronics Inc 0 Box 609 Columbus Nebr 68601 Elco Corp Willow Grove Pennsylvania Gremar Mfg Co Inc 7 North Ave Wakefield Mass Industrial Devices Inc 982 River Rd Edgewater N J 07020 Honeywell Inc Micro Switch Div Freeport 111 61032 Sylvania Electri
25. E to 0 0 0 Set OUTPUT to STANDBY 0 1 mV Poten Set COMPLIANCE to 100 Connect tiometer Digital Voltmeter between test R144 points shown in Figure 16 Adjust potentiometer Rl44 for zero Reference Set range to mA Set decade dials Adjust for PC 228 14 16 24204E to 9 9 9 Set FINE to 10 Set OUT 1 0V 0 5 Poten PUT to STANDBY Set COMPLIANCE nV tiometer to 100 Connect Digital Voltmeter 8182 between test points shown in Figure 16 Adjust potentiometer R182 for 1 0 0 5 Set OUTPUT to STANDBY Voltage change must not exceed 1 4 Bias Set range to n Set decade dials Adjust for 228 14 16 2420457 to 9 9 9 Set FINE to 10 Set voltage be COMPLIANCE to 100 Set OUTPUT to tween 27 mV STANDBY Connect Digital Volt to 40 mV meter between test points shown in Figure 16 Adjust potentiometer R121 for voltage between 27 mV to 40 mV This sets current thru transistors 0101 0102 16 0571 US pol s MODEL 225 CALIBRATION TABLE 6 2 CONT D Specification Sub Test Schematic 6 4 or Adjustment Description Measurement Assembly Figure Point Part No e Compliance Set range to Set decade dials Adjust for 228 14 16 COMMON 24204 to 9 9 9 Set FINE to 10 Set voltage of Poten COMPLIANCE to 100 Set OUTPUT to 101 V 10 tiometer STANDBY Connect Digital Volt R116 meter A between range switch shaft 12V common and L
26. GROUND binding posts to minimize line frequency pickup The LOW to GROUND isolation is approximately 107 ohms typ cal example of floating operation is shown in Figure 9 In this example the Model 225 can be used with a voltage supply such as Keithley Model 240A to extend the maximum compliance voltage to 600 volts The Model 225 can be adjusted for a compliance voltage of 500 100 volts dc The maximum current is 10 milli amperes for the Model 240A 2 3 PRELIMINARY PROCEDURES a Power Check the 117 234V Switch for proper line voltage setting Check the fuse for proper rating Set the Power Switch to off before connecting the power cord b Connections The output load should be connected as described in paragraph 2 1 0972R 10 OPERAT LON c Control Settings The output current is selected by three decade switches and a seven position Range Switch Refer to the discussion of the front panel controls in paragraph 2 4 before power is turned on 2 6 FRONT PANEL CONTROLS Power Switch 202 This switch controls the line power to the instrument OUTPUT SELECTOR Switch 5105 This switch has four positions designated STANDBY STANDBY and The and positions set the output current polarity The two STANDBY positions divert the out put current as shown in Figure 5 The output load is not disconnected at any position of the switch The shunting effect should be considered since a smal
27. Inc 2 East End Ave New York N Y Beiden Mfg Co 415 So Kilpatrick Chicago 111 60644 Birnbach Radio Co Inc 147 Hudson St New York N Y Cambridge Thermionic Corp 430 Concord Avenue Cambridge Mass Bussmann Mfg Div of McGraw Edison Co St Louis Mo CTS Corp 1142 W Beardsley Ave Elkhart Ind ITT Cannon Electric Inc 3208 Humbolt St Los Angeles Calif 90031 Centralab Div of Globe Union Inc Milwaukee Wisc 53212 Cinch Mfg Co and Howard B Jones Div Chicago 111 60624 Dialight Corp 60 Stewart Ave Brooklyn N Y 11237 G C Electronics Co 400 S Wyman Rockford Ill 61101 General Instrument Corp Capacitor Division Newark N J 07104 Erie Technological Prods Inc 644 M 12th St Erie Pa 16512 Beckman Instruments Inc Helipot Division Fullerton Calif 92634 Amperex Electronic Co Div of North American Philips Co Inc Hicksville N Y Elco Resistor Co 1158 Broadway New York N Y Signalite Inc 1933 Heck Ave Neptune N J 07753 Johnson E F Co 297 Tenth Ave S W Waseca Minn 56093 REPLACEABLE PARTS CODE TO NAME L st Cont nued IRC Inc 401 North Broad St Philadelphia Pa 19108 Littlefuse Inc 800 E Northwest Hwy Des Plaines 111 60016 Mallory Controls Div of Mallory P amp Inc Frankfort Ind Miller J W Co 5915 S Main St Los Angeles Calif 3 Mueller Electric Co 1583 E 3150 St
28. Instruction Manual Mode 225 Current Source Publication Date August 1976 Keithley Instruments Inc Cleveland Ohio U S A Document Number 29039 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 written 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 EX
29. Multimeter Digital Electrometer Voltmeter Differential Voltmeter True RMS Oscilloscope Variac Power Line Monitor Oscillator Recorder Load Fixture Inductive Load Fixture TABLE 5 1 Test Equipment Specification Voltage 0 1 of reading Current 0 2 of reading except 0 3 of reading on 100 mA 1 A ranges 001 V to 100 V 10149 input resist ance 0 5 V to 500 V 100 W null 0 1 mV to 300 V rms Freq Resp 10 to 4 MHz DC 450 kHz 1 mV div 0 130 V rms 105 130 V rms 100 Hz sine wave 1 mA for full scale deflection 1 kQ 10 Q Resistors 1 mH Inductance 16 Manufacturer and Model No Keithley Model 160 Keithley Model Keithley Model 662 Keithley Model 124 Tektronix Model 503 General Radio Wavetek Keithley Model 370 See Text See Text Accuracy check General General General General General Line Regulation General Modulation Check Drift Check Load Regulation Inductive Load Check 11 CALIBRATION MODEL 225 SECTION 6 CALIBRATION 6 1 GENERAL This section contains procedures for checking the instrument in order to verify operation NOTE within specifications If proper facilities and equipment are not 6 2 TEST EQUIPMENT Refer to Table 5 1 for recom available contact a Keithley representative mended test equipment for servicing and calibrating or the Sales Service Department Cleveland this instrument Ohio Keit
30. OW Connect load resistor Adjust potentiometer R116 for 101 10 f Voltage Limit Lamp Set range to mA Set decade dials to 9 9 9 Set FINE to 10 Set COMPLIANCE to 10 Set OUTPUT to STANDBY Connect Oscilloscope E to OUT Oscilloscope Settings 2mV div 5mS Trigger INTERNAL Input AC COUPLED Connect load resistor Set OUTPUT 228 14 16 24203E to Adjust potentiometer R203 Poten such that the LIMIT lamp turns on tiometer when the 225 changes from current R203 mode to voltage mode NOTE To determine the crossover point between current and voltage modes adjust the COMPLIANCE con trol until the oscilloscope r pple waveform changes as shown in Figure 21 Set OUTPUT to Adjust potentiometer PC 228 24203E R207 such that the LIMIT lamp turns Poten on when the 225 changes from current tiometer mode to voltage mode R207 0571 17 CALIBRATION MODEL 225 FIGURE 17 Accuracy Check FIGURE 18 Regulation Check OSCILLOSCOPE DSCILLATOR jj OSCILLOSCOPE OUTPUT lt IOOMY PP FIGURE 19 Modulation Check FIGURE 20 Inductive Load Check 2MS div CURRENT MODE swy diy VOLTAGE FIGURE 21 Current Mode Vs Voltage Mode Waveforms 18 21 0676 7 sor MODEL 225 SECTION 7 7 1 REPLACEABLE PARTS LIST This section contains a list of components used in this instrument for user reference The Rep
31. PRESSED 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 Test Instrumentation Group Keithley Instruments Inc 28775 Aurora Road Cleveland Ohio 44139 216 248 0400 Fax 216 248 6168 CHINA Keithley Instruments Inc Holiday Inn Lido Office Building 4040 Beijing China 100004 8610 436 2871 2860 8610 436 2871 FRANCE Keithley Instruments SARL 3 All e des Garays 60 91122 Palaiseau C dex 01 60 11 51 55 Fax 01 60 11 77 26 GERMANY Keithley Instruments GmbH Landsberger Str 65 82110 Germering 089 849307 0 Fax 089 84930759 GREAT BRITAIN Keithley Instruments Ltd The Minster 58 Portman Road Reading Berkshire RG30 15 01734 575666 Fax 01734 596469 ITALY Keithley Instruments SRL Viale S Gimignano 38 20146 Milano 02 48303008 Fax 02 48302274 JAPAN Keithley Instruments Far
32. SISSVHO 100 6023 1041802 13 1 3 rav dui titan A 0117 08 0 Qvuv 30214 WHO 0001 43A1408389S 301 71081 03 13NYd 18084 031081 23111 9260 303011 5 5 NI 38 TWHS 302 3 151533 3 3 lt 34384 153091 1145 71 eS 9 pesi HYH DILUWJHO2S JtOZpZ AMA 335 6600006000600 6 0 3 1025 9 05 AS 3811 107 Quo VOLTAGE 7 COMPLIANCE 50K AnJ TRANSIENT ABSORBER VOLTAGE LIMIT Qa ft i SEE Dw6 2420356 SCHEMATIC POWER SUPPLY 2 HERMES ay NOTES 1 ALL RESISTANCE amp CAPACITANCE SHALL BE DESIGNATED IN OHMS MICROFARADS UNLESS OTHERWISE NOTED HIGHEST REFERENCE DESIGNATION aaa 2 FRONT PANEL CONTROL quo ozo 55 3 9 INTERNAL SCREWDRIVER ADJ M MEGOHM 5 5166 jasc e 1111 5 1000 OHM oF PICOFARAD 6 111121 7 CLOCKWISE ROTATION 8 f REAR PANEL CONTROL SCHEMATIC DESIGNATION NOT USE D 7 02 dios owe pus Rios DIMENSIONAL TOLERANCES oxx RO J MODULATE FRONT PANEL OuTPUT REAR PANEL OUTPUT FRONT PANEL Low UNLESS OTHERWEEE SPECIFIED
33. a 100 volt compliance at the output These supplies deliver power to the load up to a max imum of 10 watts 100 V x 0 1 A The series regu lators are driven by the high gain differential amp lifier A3 The range resistor is selected by the RANGE Switch for currents of 1077 to 10 l ampere full range The remaining power supplies are used to bias the operational amplifiers and reference zener KV Divider FIGURE 12 8 13 MODEL 225 CIRCUIT DESCRIPTION 3 3 CIRCUITRY a High Gain Operational Amplifier This amplifier is composed of matched emitter followers 0111 and 0114 a differential rpn gain stage trans istors 0112 and 0113 a differential npn gain stage transistors 0109 and 0110 an emitter follower transistor Q115 and a second npn gain stage Q116 and 0117 b Differential Voltage Sensing Amplifier Al This amplifier is composed of a matched pair of FET S transistors 0118 and Q118B These devices have a low temperature coefficient 5 ppm C and low typical offset current less than 10 pA The offset current however doubles every 10 C approximately Potentio meter R144 provides zero adjustment for the differen tial pair Kelvin Varley Divider with Precision i Volt Reference 1 1 Volt Reference The voltage reference util izes a 9 volt zener diode 0116 The zener is stable to 20 ppm An accurate divider composed of R181 and R183 divides the 9 volts down to l volt Pot
34. ation transformer Provides connection between LOW and GROUND Paragraph 2 4 2 4 2 4 Paragraph 0571 MODEL 225 GENERAL DESCRIPTION 226 CURRENT SOURCE BFINE QUI 4 ZA 180 Range Switch 1 Selector 101 Switches FINE Control R138 STANDBY eu TER FILTER Switch S106 OUT J103 HLBKY FNS 1 Power VOLTAGE OUTPUT Switch COMPLIANCE SELECTOR 202 R117 105 FIGURE 2 Front Panel Controls Shorting Link J202 y 3201 301 J104 FIGURE 3 Rear Panel Controls 0571 3 OPERATION SECTION 2 2 1 CONNECTIONS a Output Connectors 1 Front Panel he connectors on the front panel are BNC type receptacles Keithley part no CS 15 The OUT receptacle J103 provides connec tion to the Model 225 Output High The center terminal is Output High while the outer shield is connected to chassis ground Connections to the output load can be made using the OUT receptacle when the Model 225 is not floating For a more complete discussion of floating operation refer to paragraph 2 2 f The LOW receptacle J105 provides a connection to the Model 225 Output Low The center terminal is Output Low while the outer shield is connected to chassis ground 2 Rear Panel The OUT receptacle on the rear panel is also a BNC type Connections can be made to either the front panel receptacle or the rear panel receptacle with satisfactory resul
35. c Products Inc Semiconductor Products Div Woburn Mass Electric Cord Co 1275 Bloomfield Ave Caldwell N J Raytheon Co Industrial Operation Components Div Quincy Mass Tung Sol Electric Inc Newark New Jersey Tru Ohm Products Memcor Components Div Huntington Ind 46750 Magnecraft Electric Co 5579 North Lynch Chicago 111 Gordos Corp 250 Glenwood Ave Bloomfield N J 07003 Dage Electric Co Inc Hurricane Road Franklin Ind Raytheon Components Div Semiconductor Operation Mountain View Calif Plastic Capacitors Inc 2620 N Clybourn Ave Chicago 11 T 1 50 vp 11 p agog 3euaow 870 24 r sut C 3 aN ee SInOAVI LNSNOdWOO SCC 5 142 04 T 311031000 CHASSIS LAYOUT TO PIN II TO PIN 10 14 FIGURE 15 Component Layout Switch 5101 MODEL 225 0675 12 12 31 20 ADJ PC 227 L4 J202 Ty S r CR0SSOVER ADJ se VOLT FRONT PANEL FIGURE 16 Chassis Top View dEOCc bc x ANYIRA DILYWFHOS SLNZANBLSNI 33 3 7 4405 MIMO 3 2308 01 WNN s csse If _ See zozr mot IN INT 39 0 az ONS
36. cuit 04713 MC1439G 16 13 2 T101 Modulation Transformer 80164 TR 125 TR 125 2 T201 Power Transformer 80164 TR 124 TR 124 2 TRANSISTORS Circuit Mfr Mfr Keithley Fig Desig Code Desig Part No Ref 0101 80164 40318 24560A 14 0102 04713 MM3003 TG 58 14 0103 07263 2 3565 76 39 14 9104 04713 MM4003 TG 59 14 Q105 80164 40318 24560A 14 Q106 07263 283638 TG 33 14 0107 04713 2N3905 TG 53 15 0108 04713 2N3905 16 53 14 9110 04713 283905 16 53 14 011158 80164 A 642L TG 64 14 Q113 07263 283565 TG 39 14 Qli4 80164 A 642L TG 64 14 0115 07263 2113565 TG 39 14 Q116 07263 2N3638 TG 33 14 0117 07263 2N3638 TG 33 14 Q118A 80164 2N5452 24670 14 0118 80164 285452 24670 14 9119 04713 2N3903 TG 49 14 Specially selected transistor order singly Matched pair order as a pair xk Matched pair with heat sink order as a pair 0972 26 23 REPLACEABLE PARTS RESISTORS Circuit Mfr Mfr Keithley Fig Desig Value Rating Type Code Desig Part No Ref R101 12 10 1 2 W Comp 01121 EB 81 6 14 R102 3 9 Q 10 1 2 W Comp 01121 EB 81 9 15 R103 18 2 10 1 2 W Comp 01121 EB 71 8 15 R104 100 2 10 1 2 W Comp 01121 EB R1 100 14 R105 180 Q 10 Comp 01121 cB R76 180 14 R106 470 Q 10 1 2 W Comp 01121 81 470 14 R107 3 9 Q 10 1 2 W Comp 01121 EB 1 9 15 R108 27 9 10 1 2 W Comp 01121 EB 81 7 15 R109 Not Used R110 37 4 kQ 1 1 8 W 07716 CEA R88 37 4K 14 111 402 2 1 1 8 07716 R88 402 14 R112 40
37. e instrument can be used to deliver current to a resistive load from 0 ohms to where Ryay Vc Io and is the compliance voltage setting 2 Capacitive Load The instrument can also be used to charge a capacitive load as shown n F gure 7 The capacitor will be charged to the compliance voltage set on the front panel 3 Inductive Load The instrument can be used to deliver current to an inductive load When the ratio of load inductance L to load resistance is greater than 1076 the FILTER Switch must be set to ON for stability The FILTER Switch connects a 1 pF capa citor across the output as shown in Figure 8 r INDUCTIVE b gt 10 8 FIGURE 8 Inductive Load 11 STANDBY WHEN CLOSE FIGURE 5 f MODEL 225 Resistive Load FIGURE 6 Current Sink FIGURE 7 Capacitive Load R WAND Ve E Vo FIGURE 9 Floating Supply MODEL 225 0972 MODEL 225 OPERATION c Constant Voltage Mode The Model 225 be 4 justed for a compliance voltage from 10 to 100 volts CURRENT MODE EOE The voltage limiting will occur if the load resistance is such that IgRy The instrument will auto matically switch into a constant voltage mode the LIMIT lamp will be lighted such that the output volt age will not exceed the compliance setting If the Model 225 is used as a current sink an output voltage of 130 volts could be dev
38. eloped regardless of the com Pliance setting The voltage limiting characteristic can be shown as in Figure 10 2 6 MODULATION For convenience in making dynamic measurements the Model 225 has a MODULATE input J101 m oe current can be modulated in the 50 to 500 FIGURE 10 Volt Limit Characteristic Circuitry The Model 225 uses a transformer coupled input with 500 ohms impedance b Characteristics The peak to peak modulation can be adjusted up to a maximum of 40 of full range from 50 100 Hz decreasing to about 8 of full range at 500 Hz with a 10 volt rms sine wave input The modulation circuit is not calibrated so that the user must check with a known load resistance Within a selected range the modulation is independent of decade dial setting The capacitance of the output cables can affect the modulated current signal so that the modulation calibration should take into account this capacitance Voltage Compliance The setting of the voltage ion compliance can cause clipping of the modulated cur FIGURE 11 Modulation rent as shown in Figure 11 NOTE When the 225 output is modulated the average value or dc level is determined by the dial set tings The output is essentially a sine wave at the input drive frequency The peak to peak modulation amplitude depends on both the magni tude and frequency of the drive signal so that the exact modulation waveform will have to be
39. entiometer R182 is used to adjust the reference voltage to precisely 1 16 2 Kelvin Varley Divider This divider is com posed of three decade dials and a potentiometer fine control The Selector Switches 5102 103 and 104 and FINE Control R138 permit adjustment of the voltage drop across the Range resistor The di vider resistors are designated R148 through R180 These resistors have 0 1 accuracy and a tempera ture coefficient of 25 ppm 9C Series Reg Decade Range Resistor Block Diagram 0676 MODEL 225 d Voltage Compliance Amplifier 2 This ampli fier is composed of a differential gain stage trans istors 0107 and 0108 The front panel compliance con trol 8117 sets the maximum compliance voltage desires up to 100 volts The bias reference for transistor 0108 is provided by a divider string composed of re sistors R115 R116 R117 and R118 Potentiometer R116 provides an internal compliance voltage adjust ment The amplifier is biased off in the constant current mode of operation When the voltage at the series regulator output reaches the preselected com pliance limit the amplifier A2 is turned ON and the Model 225 automatically changes to a voltage limit mode The LIMIT indicator 5101 is turned on auto matically when in the voltage limit mode For pos itive polarity transistor Q108 turns on in the volt age limit mode while Q107 is turned o
40. ff The differ ence voltage is buffered by emitter follower stage 0201 and Q204 Transistor 0202 is turned on and there fore drives transistor Q207 The LIMIT indicator is connected in series with Q207 Transistor Q202 pro vides voltage level translation For negative polar ity the difference voltage between 0107 and 0108 is such that trans stors Q205 and Q206 are driven Transistors 0201 and Q204 act as buffer stages Transistor Q206 provides voltage level translation and drives Q208 The LIMIT indicator is connected in series with Q208 and is turned on Potentiometers R203 and R207 provide control of the LIMIT indicator turn on for limit and limit respectively e Compliance Voltage Control This control adjusts the maximum compl ance voltage from 10 volts to 100 volts This is accomplished by using a linear 50 kil ohm potentiometer designated R117 constant current is driven through the resistor divider The polarity is controlled by the OUTPUT SELECTOR Switch 105 f Compliance Voltage Supplies These voltage supplies provide unregulated 130 volts for the series regulators power is obtained from secondary of transformer T201 Diodes D207 thru D210 form a full wave rectifier Capacitors C203 thru C206 provide filtering of ac ripple g Series Regulators Transistors 0101 and 0105 form a complimentary symmetry output stage These transistors are rated at 300 volts 35 watts Tran sistors 0103 and 0
41. h overall Item Qty Per Keithley dimensions 5 1 2 inches high x 19 inches wide x 10 No Description Asseubly Part inches deep 1 Top Cover 1 20016B 2 Panel 1 17452B Application 3 Angle 1 17476A 4 Screw 4 n The Model 1004 converts the instrument from bench to 5 Plate 1 19126A rack mounting It is suitable for mounting one instru 6 Screw 4 ment in one half of a standard 19 inch rack 7 Angle 1 14624B 10 0571 15 mat SERVICING SECTION 5 5 1 GENERAL This section contains procedures for checkout and servicing the instrument Follow the step by step procedures for complete servicing 5 2 SERVICING SCHEDULE This instrument requires no periodic maintenance beyond the normal care required for high quality electronic equipment 5 3 PARTS REPLACEMENT Refer to the Replaceable Parts List Section 7 for information regarding com ponent specifications and part numbers Replace com ponents as ndicated using replacement parts which meet the listed specifications MODEL 225 SERVICING 5 4 TROUBLESHOOTING Test Equipment Refer to Table 5 1 for recom mended test equipment for servicing and calibrating this instrument b Troubleshooting Guide Refer to Figure 16 for voltages and test points NOTE If the instrument problem cannot be readily located or repaired contact a Keithley rep resentative or the Sales Service Department Cleveland Ohio Code Letter 0571 Instrument Type
42. hley Instruments Inc maintains a complete repair and calibration facility 6 3 CALIBRATION PROCEDURE Refer to Table 6 1 for with equipment traceable to the National step by step procedures for calibrating this instru Bureau of Standards ment TABLE 6 1 Performance Check Specification 6 3 or Adjustment Description Measurement Figure Accuracy NOTE Line voltage Verify the accuracy on each full 115V Amb Temp 25 C Rel scale range Humidity 50 Link between LOW and GROUND FILTER OFF Set OUTPUT to STANDBY Connect 17 the Digital Multimeter A to OUT receptacle as shown in Figure 17 Set COMPLIANCE to 100 Set FINE to 0 calibrated position 100 mA Range Set decade dials Current reading should be to 9 9 9 Set range to 100 mA 99 9 mA 40 85 mA Set OUTPUT to Measure current Repeat for OUTPUT 10 m Range Set decade dials to Current reading should be 9 9 9 Set range to 10 mA Set 9 99 mA 075 mA OUTPUT to Measure current Repeat for OUTPUT 1000 Range Set decade dials Current reading should be to 9 9 9 Set range to 1000 pA 999 47 5 pA Set OUTPUT to Measure current Repeat for OUTPUT 100 pA Range Set decade dials to Current reading should be 9 9 9 Set range to 100 uA Set 99 9 40 75 pA OUTPUT to Measure current Re peat for OUTPUT 10 pA Range Set decade dials to Current reading should 9 9 9 Set range to 10 pA Set be 9 99 pA
43. l voltage can be developed across the 10 milliohm shunt and therefore across the output terminal VOLTAGE COMPLIANCE Control 117 This control is a continuously variable potentiometer which can be set for a compliance voltage from 10 volts to 100 volts 4 Range Switch 5101 This switch selects the full scale range from 10 7 ampere to 107 ampere The dial is designated in terms of engineering units that is nA pA and mA The full range is determined by the position of the lighted decimal point and the designated engineering unit Selector Switches 5102 5103 5104 These switches select the magnitude of the output current in three detades The position of the dials determines the significant digits from 0 0 0 to 9 9 9 FINE Control R138 This control is the inner dial of a dual concentric control The fully clock wise position 10 represents 1 digit added to the right hand dial 5104 The fully counter clockwise position is the 0 or off position When the FINE Control is set to 0 the output current is determined only by the calibrated dials within rated specifica tion This control can be used to trim the output current to within 02 of full range although the trim dial is adjustable to within 005 of full range NOTE For example if the three decade dials were set for 9 9 9 on the 1000 u range then the FINE control could be set to 1509 clockwise to obtain current output of appr
44. laceable Parts List describes the individual parts giving Circuit Designation Descrip tion Suggested Manufacturer Code Number Manufac REPLACEABLE PARTS REPLACEABLE PARTS turer s Part Number and the Keithley Part Number Also included is a Figure Reference Number where applicable The complete name and address of each Manufacturer is listed in the CODE TO NAME Listing following the parts list TABLE 7 1 Abbreviations and Symbols A ampere CbVar Carbon Variable CerD Ceramic Disc CerTB Ceramic Tubular Cer Trimmer Ceramic Trimmer Comp Composition DCb Deposited Carbon Desig Designation EAL Electrolytic Aluminum ETB Electrolytic Tubular ETT Electrolytic Tantalum 7 2 ELECTRICAL SCHEMATICS AND DIAGRAMS Schematics and diagrams are included to describe the electrical circuits as discussed in Section 3 Table 7 2 identi fies all schematic part numbers included 7 3 HOW TO USE THE REPLACEABLE PARTS LIST This Parts List is arranged such that the individual types of components are listed in alphabetical order Main Chassis parts are listed followed by printed circuit boards and other subassemblies 7 4 HOW TO ORDER PARTS a Replaceable parts may be ordered through the farad Figure Glass enclosed Carbon kilo 103 micro 1075 Meg 106 Manufacturer Metal Film Mylar Number ohm pico 10 12 Printed Circuit Polystyrene Reference Tinner Copperweld volt watt Wirewound Wirewo
45. oximately 999 5 pA Since the stability specification is 02 or better of reading the useable resolution would be 2 pA If the FINE control was set to 0 then the output would be 999 0 4 5 pA g FILTER Switch S106 This switch should be used whenever the Model 225 must deliver current to an inductive load OPERATION 2 5 OPERATING CHARACTERISTICS The Model 225 Current Source has a bipolar output constant current up to the maximum compliance setting and automatic cross over to constant voltage mode Bipolar Output The Model 225 deliver or accept current and as such it has a bipolar output 1 Current Source The instrument be used as a current source with a resistive load as shown in Figure 5 In this case the Model 225 delivers a current set by the front panel controls The volt age developed across the load resistance Ry is Vy Io x Ry 2 Current Sink The instrument can be used as current sink as shown in Figure 6 this case the polarity of the current is such that current is flowing into the Model 225 The output voltage Vo E IoRy where Ig is selected by the front panel dials E is the external voltage source and RL is the load resistance b Constant Current Mode The Model 225 will de liver the dialed current for resistive capacitive and inductive loads unless the voltage required at the output terminals exceeds the compliance voltage 1 Resistive Load Th
46. r can be modulated by an external source Therefore the current output will likewise be modulated The primary of T101 is connected between the center terminal of 2101 and chassis ground 3 4 SWITCHING The OUTPUT SELECTOR Switch S105 has four positions labeled STANDBY STANDBY and The and positions connect the internal circuitry such that the polarity of the current at the OUT terminal can be changed with respect to LOW This is accomplished by reversing the polarity of the voltage references since amplifier A3 is a bipolar amplifier The two STANDBY positions permit a change of polarity to be made without developing large transients The STANDBY positions connect the high output to LOW through a 10 milliohm shunt as shown in Figure 5 Since the selected current will be shunted through the 10 milliohms up to 10 millivolts be developed between the OUT and LOW terminals with no load Resistor R193 limits the voltage drop to l millivolt for a 1 ohm load ACGESSORIES MODEL 225 SECTION 4 ACCESSORIES 4 1 GENERAL The following Keithley accessories 4 2 OPERATING INSTRUCTIONS A separate Instruction be used with the Model 225 to provide additional con Manual is supplied with each accessory giving complete venience and versatility operating information rp ppt fi ag SG OS cc ecc di Model 1004 Rack Mounting Kit Description Parts List The Model 1004 is a rack mounting kit wit
47. st possible accuracy Table 2 1 shows the total accuracy for typical dial settings The accuracy on the 1000nA range is 05 of 1000 or 0 5 plus 5 of 1000 or SnA for a total of 5 5 TABLE 2 1 Accuracy For Typical Dial Settings RANGE Setting Total Accuracy FINE Control set to 0 Decade Dial Setting Output Current 2 ud CAUTION When the OUTPUT SELECTOR is set to or and VOLTAGE COMPLIANCE is set to 100 up to 100 volts will be present at the output terminals b Stability The stability is specified in terms of the front panel dial setting or reading as well as the full range selected Since the total stability specification is the sum of the reading stability and the full range stability the user should select the lowest full range for best possible stability c Line Regulation The line regulation is stated as 005 of full range for a corresponding 10 change in line voltage d Load Regulation The load regulation is spec ified as 005 of full range for a change from no load to full load The no load to full load varia tion corresponds to an output compliance voltage change from 0 volts to 100 volts e Output Impedance The effective output imped ance of the Model 225 is a function of the load reg ulation specification and the high to low insulation resistance The output impedance for each Range set ting is given in Table 2 2 The insulation resist ance is 2 x 1012 ohms
48. ts The rear panel LOW terminal 1104 is a binding post Keithley part 116 which is connected to the center terminal of J105 on the front panel The rear panel GROUND terminal 3201 is a binding post Keithley part no BP 11B which is connected to chassis ground The shorting link supplied permits LOW to chassis ground connections b Modulate Connector The MODULATE receptacle 7101 is a BNC type connector Keithley part CS 15 This connector can be used for modulating the output current using an ac modulation signal The center terminal is connected to a transformer coupled modulation circuit while the outer shield is connected to chassis ground c Cables Connections should be made using co axial cables which are low noise types with graphite coating between dielectric and shield braid For custom length cables Keithley Part No SC 9 Low Noise Coaxial Cable should be used mating BNC connector is available by ordering Keithley part 05 44 FIGURE 4 Connections MODEL 225 OPERATION 2 2 MEASUREMENT CONSIDERATIONS Accuracy The accuracy is specified in terms of the front panel dial setting or reading as well as the full range selected The FINE current control must be set to 0 position to obtain the stated accuracies Since the total accuracy of the Model 225 is the sum of the reading accuracy and the full range accuracy the user should select the lowest full range for be
49. und Variable Sales Service Department Keithley Instruments Inc or your nearest Keithley representative b When ordering parts include the following in formation Instrument Model Number Instrument Serial Number Part Description Schematic Circuit Designation Keithley Part Number c All parts listed are maintained in Keithley Spare Parts Stock available upon request Any part not listed can be made Parts identified by the Keithley Manufacturing Code Number 80164 should be ordered directly from Keithley Instruments Inc TABLE 7 2 Schematics Description Amplifier Power Supply Assembly No PC 227 PC 228 228 Schematic 24204E 24203E 0571 22 19 REPLACEABLE PARTS TABLE 7 3 Circuit Designation Series Series Description Amplifier Power Supply MODEL 225 Circuit Designation 227 228 PC 228 TABLE 7 4 Mechanical Parts List Quantity Description Per Assembly 1 Chassis 11 Front Panel Top Cover Assembly 12 Cover Sheet Metal 13 Screws Handle Assembly 14 Handle 15 Screws 6 32 3 8 Slotted Bottom Cover Assembly 2 Cover 3 Fastener Feet Assembly 4 Feet 5 Ball 6 Screws 8 32 x 3 8 Phillips Pan Head Tilt Bail Assembly 7 Bail 8 Right Assembly 9 Left Assembly 10 Screws 6 32 x 1 4 Phillips Pan Head J U _ 20 23 Keithley Part No 24021
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