KEI 7708 User
Contents
1.2. ON SECONDARY SIDE COMPONENTS SIDE 01 SE Ea NX CN EZ Ye 19 JE Nn No V IN 19 2 J 7 s PA M4 SLL d oe cte o LL 2 r 1 515 DEDI Ll rites E 52 T y b i x NL bw i az LOW 2 NA ah EXP YS kl Nus e So e le NU 1000 0000 TE 5 A 5 E uL eo 8 5 2 2 S 5 5 E 0000 0000 0000 5 ee 2 soe Q A uw S o O gt Es ie y d Q QE 72 3 CY OO Cx C SE pr cx m Nc Sey Ne Nu NC NEP M M M 52 L5 O A O
3. Table 1 Connection log Model 7708 Channel Color Description Description Color Channel H INPUT L H SENSE L L CH21 H H CH2 L L CH22 H H CH3 L L CH23 H H CH4 L L CH24 H H CH5 L L CH25 H H CH6 L L CH26 H H CH7 L L CH27 H H CH8 L L CH28 H H CH9 L L CH29 H H CH10 L L CH30 H H CH11 L L CH31 H H 12 L L CH32 H H CH13 L L CH33 H H 4 L L CH34 H H 5 L L CH35 H H CH16 L L CH36 H H CH17 L L CH37 H H CH18 L L CH38 H H CH19 L L CH39 H H CH20 L L CH40 Performance verification The performance of the Model 7708 card is tested by verifying measurement accuracy through the card If verification limits are met through the front panel terminals of the Model 27xx they should also be met through the card WARNING information in this section is intended only for qualified service personnel Do not attempt these procedures unless you are qualified to do so NOTES Measurement accuracy through the Model 7708 card should only be verified after instrument accuracy has already been verified through the front panel terminals of the Model 27xx The procedures to verify accuracy from the front panel inputs are provided in the Model 2700 Service Manual If the Model 7708 card is still under warranty and is the cause of measur
4. CH1 Output 7 E j HI DC Voltage Calibrator n Output LILILILILILILILILLLILILILI P HLHLHLHLHLH L Hi HL AL HL C t Guz CH3 CH4 CH5 CH6 CH7 Cus Em CH10 11 CH12 CH14 ES Rs e E CHIZ CH20 CH36 H38 3 4 Hee te ee Oa 22 CH23 CH24 CH25 CH26 CH27 28 CH29 CH30 CH31 CH32 CH33 CH34 H HL HL H E HL HL HE HL HL Note Use shielded cables to minimize noise 00000000000 unum CH21 Model 7708 22 Calibration The following procedures calibrate the temperature sensors on the Model 7708 plug in modules WARNING information in this section is intended only for qualified service personnel Do not attempt these procedures unless you are qualified to do so Recommended test equipment In order to calibrate the Model 7708 you will need equipment summarized in Table 8 Table 8 Recommended equipment for Model 7708 calibration Digital Thermometer 18 to 23 0 1 Keithley 7797 Calibration Extender Board Extender board connections The Model 7708 being calibrated should be connected to the 7797 Calibration Extender Board and the extender board should then be installed in scanner Slot 1 Note that the module being calibrated will be ex
5. CH23 CH24 CH25 CH26 CH27 CH28 CH29 CH30 CH31 CH32 CH33 CH34 J HLHLHL H RE Typical connections The following examples show typical wiring connections for the following types of measurements Thermocouple connections see Figure 5 Q2 wire and thermistor connections see Figure 6 e 4 wire and RTD connections see Figure 7 Voltage AC or DC see Figure 8 Figure 5 Thermocouple connections Channel 1 LO Channels 2 39 Thermocouples HI 1 Channel 40 Figure 6 Q2 wire and thermistor connections Channel 1 LO e Resistors or Channels 2 39 2774 Thermistors Channel 40 Figure 7 Q4 wire and RTD connections Resistor or Channel 1 4 Wire RTD LO Channels 2 19 HI Resistor or Channel 20 4 Wire RTD LO HI i Channel 21 LO Channels 22 39 HI Channel 40 LO o Figure 8 Voltage connections DC or AC HI lt i i 1 i oee DC Voltage Voltage a lt 7 i Channel 40 DW EE gt Channels 2 39 Connection log Make a copy of Table and affix it to the cover of the Model 7708 Use this to record connection information and channel descriptions as needed
6. K41 K20 K43 5543 cus cg44 CR45 Bae aie FUN el T 21 1 Sg E 9 EE CE cm CR5 cm cm CRT cm p CR10 cn CR11 p CR12 p CR13 p CR14 OO OS OS OS amp 9 a D C A SHADED AREAS DENOTE vol SMT NOT POPULATE e Ke K3 K4 K5 K6 KT K8 K9 K10 K11 K12 K13 K14 lv C fs 2 R23 E QUUD OEC EX Seley en ene O O Of U 2 dre 118 T e 019 E Ll Ew CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8 CH9 CH1 CH11 CH12 CH14 c3 x H L k 10 L L H L Hs s Ua L L L L 101 102 103 104 113 us CH15 CH16 CHIT CH18 19 CH20 D Wr d si L H L H H L 5 Dle 40 000 olp a N C P a FON fs a a EEN KON Lx ES Cone he Iu LY SA LY Sy Iu Iu 4 4 4 4 A uw P Ns Koy 7 Xu aa 25 p r3 a CH35 CH36 CH3 H38 CH39 CH4 JE 2 Hee HL H L H L g o TETOS 106 107 108 IU U12 ro coq LN x TE109 TE110 TELLI TE112 ES a CH21 CH22 CH23 CH24 CH25 CH26 27 CH28 CH 29 CH30 CH32 CH33 CH34 H L H L L H L H L H L H L H H L
7. 5 2 EN S MEA EV 7 o m EM O 9 5 5 5 gt e nnnn o nnnn o nnnn SELI O UUUU 510 MER iae C le e VY gl cum 2 NM 5 S ay ___ 2 jo g 27 T EN EN N d M a IS EN la 1 TP1 E YS X YY 7 X 4 Ne wu oy _ ER V S 59 c S 1 5 Lo A An s 5 S 5 a 1 Sa ai M gt 9 E Y o o 4 9 EO o 2 m 21 42 S oq 2 aane S8 S8 5705 E 8 rm rm rm rm rm rm rm LP en D Pee ou d S EE 55 1 i 1 i 1 1 1 1 1 1 1 E 1 1 1 1 i 1 1 1 i 1 o 8 790 qa RB e ja R19 0000 5 E gt gt S 55 N 0000 C20 0000 0000 4 C14 Cll R108 CIO RT lt Tp gt m Rios 2 So G G amp Pl R V MATION 5 POOL Ds Edad es QU IR NO REVISION ENG DATE arnar CHG D R1 FROM R 418 69 8K 2
8. ANG 005 EXCLUDES FINISHED HOLE SIZES DO NOT SCALE DRAWING AND BOARD LAYER CONSTRUCTION CONFIDENTIAL PROPRIETARY 3 2 PG 1 OF 2 051 227 N X
9. RMS 10V RMS 5ppm steady state and burst modulation General Radio 1433 T Precision Decade Resistance Box 10Q to 400Q 0 02 Miscellaneous Equipment Double banana plug to double banana plug shielded cables 2 BNC to double banana plug shielded cable NOTE The Fluke 5725A amplifier is necessary only if you wish to verify the 750V AC range at 50kHz Verification at 220V and 50kHz using only the 5700A calibrator is adequate for most applications Performance verification procedures NOTE The following procedures check one channel or one channel pair and CH21 of the Model 7708 card To check other channels or channel pairs modify the procedures by connect ing the verification equipment to the appropriate channel or channel pair and then closing that channel Verifying DC voltage Check DC voltage accuracy by applying accurate voltages from the DC voltage calibrator to the Model 7708 input terminals and verifying that the displayed readings fall within specified limits CAUTION Do not exceed 300V DC between plug in module INPUT and L terminals or between any adjacent channels Follow these steps to verify DC voltage accuracy 1 Connect the Model 7708 CH1 H and L INPUT terminals to the DC voltage calibrator as shown in Figure 9 NOTE Use shielded low thermal connections when testing the 100 and ranges to avoid errors caused by noise or thermal effects Connect the
10. 8 CHAN ANA MULTIPLEXER DG408DY 844 013 U31 U38 CENTIGRADE TEMP SENSOR LM35DM 906 014 RETRIG MULTIVIB 74HC123AM IC 788 016 2 5 CASCADABLE SERIAL EEPROM LSI 212 U24 IC QUAD 2 IN AND 74HCT08 837 COVER HEAT STAKE ASSEMBLY 7700 302A BOTTOM CARD COVER 7702 301C COMPRESSION SPRING SP 7 3 25 Ordering information To place an order or to obtain information concerning replacement parts contact your Keithley representative or the factory see inside front cover for addresses When ordering parts be sure to include the following information Card model number Model 7708 Card serial number Part description Component designation if applicable Keithley part number Factory service If the instrument is to be returned to Keithley Instruments for repair perform the following Call the Repair Department at 1 888 KEITHLEY for a Return Material Authorization RMA number Complete the service form at the back of this manual and include it with the instrument Carefully pack the instrument in the original packing carton Write ATTENTION REPAIR DEPARTMENT and the RMA number on the shipping label Component layout The component layout for the Model 7708 is shown at the end of this packing list 26 7708 40 Channel Differential Multiplexer w Automatic CJC GENERAL 40 CHANNELS 40 channels of 2 pole relay input All channels configur Card
11. Cu crus qui CH32 CH33 CH34 HLHLHL gpgggggouugy o 1 uem eme Note Use shielded low thermal cables to minimize noise Enable or disable calibrator external sense as indicated CH21 Model 7708 in procedure EXE 16 5 Set the Model 27xx for the 1000 range and make sure the FILTER is on Enable OCOMP offset compensated ohms for the 100Q range test Press SHIFT then OCOMP 6 Recalculate reading limits based on actual calibrator resistance values 7 Source the nominal full scale resistance values for the 100Q 10MQ ranges summarized in Table 5 and verify that the readings are within calculated limits Table 5 Limits for resistance verification Nominal Nominal reading limits Q Range resistance 1 year 18 C to 28 C Recalculated limits 100Q 100Q 99 9880 to 100 0120Q to Q 1kQ 1kQ 0 999894 to 1 000106kQ to kQ 10kQ 10kQ 9 99894 to 10 00106kQ to kQ 100kQ 100kQ 99 9890 to 100 0110kQ to kQ IMQ IMQ 0 999890 to 1 0001 10MQ to MQ 10MQ 10MQ 9 99590 to 10 00410MQ to MQ 100MQ 100MQ 99 5770 to 100 4230MQ to MQ Enable OCOMP for 100Q range Calculate limits based on actual calibration resistance values and Model 27xx one year resistance accuracy specifications See Verification limits 8 Connect the Model 7708 and CH21 terminals to the cal
12. Halsuantie 2 00420 Helsinki Finland 09 53 06 65 60 Fax 09 53 06 65 65 3 all e des Garays 91127 Palaiseau C dex 01 64 53 20 20 Fax 01 60 11 77 26 Landsberger Strasse 65 82110 Germering 089 84 93 07 40 Fax 089 84 93 07 34 Unit 2 Commerce Park Brunel Road Theale Berkshire RG7 4AB 0118 929 75 00 Fax 0118 929 75 19 1 5 Eagles Street Langford Town Bangalore 560 025 080 212 80 27 Fax 080 212 80 05 Viale San Gimignano 38 20146 Milano 02 48 39 16 01 Fax 02 48 30 22 74 New Pier Takeshiba North Tower 11 1 Kaigan 1 chome Minato ku Tokyo 105 0022 81 3 5733 7555 Fax 81 3 5733 7556 2FL URI Building 2 14 Yangjae Dong Seocho Gu Seoul 137 888 82 2 574 7778 Fax 82 2 574 7838 Postbus 559 4200 AN Gorinchem 0183 63 53 33 Fax 0183 63 08 21 c o Regus Business Centre Frosundaviks All 15 4tr 16970 Solna 08 50 90 46 00 Fax 08 655 26 10 13F 3 NO 6 Lane 99 Pu Ding Road Hsinchu Taiwan ROC 886 3 572 9077 Fax 886 3 572 9031 Copyright 2003 Keithley Instruments Inc Printed in the U S A 5 03
13. CAP 47pF 5 100V CERAMIC C 465 47P C5 CAP 4 7 10 35V TANTALUM C 476 4 7 C16 CAP 220uF 20 10V TANTALUM C 558 220 1 14 CR15 CR42 CR45 CR48 CR56 DIODE DUAL SWITCHING BAV99L RF 82 CR43 CR44 CR46 CR47 DIODE SWITCHING MMBD914 RF 83 CR101 CR104 DIODE DUAL HIGH SPEED RF 147 J1015 CONN RT ANGLE DUAL ROM RECEPT CS 1065 1 K1 K41 LATCHING RELAY SINGLE COIL RL 225 K42 K43 NON LATCHING RELAY RL 242 Q4 Q6 DIGITAL TRANS DUAL PNP TG 386 Q5 N CHANNEL P CHANNEL POWER MOSFET TG 360 Q7 DIGITAL TRANS DUAL PNP TG 385 Q25 Q27 Q29 Q31 Q33 Q35 Q37 Q39 TRANS PNP SILICON TG 388 041 043 045 047 049 051 026 028 030 032 Q34 Q36 Q38 040 TRANS NPN SILICON TG 389 042 044 046 048 050 052 RES 69 8kQ 1 1W THICK FILM R 418 69 8K R2 R5 R6 108 110 R12 RES 1kQ 1 100mW THICK FILM R 418 1K R4 RES 10kQ 1 100mW THICK FILM R 418 10K R7 R13 RES ARRAY 4 x 4 3kQ 5 100mW TF 276 4 3K R14 R55 RES 137Q 1 125mW METAL FILM R 391 137 R200 R202 RES 4700 5 125mW METAL FILM R 375 470 R203 R205 RES 4 7kQ 5 125mW METAL FILM R 375 4 7K R206 R207 RES 1kQ 5 125mW METAL FILM R 375 1K 1 106 TE112 TE113 CONN 4 JOLO BB 125 04 115 4 2 4 101 3103 107 109 CONN 8 115 8 U1 U3 U6 U8 IC 8 STAGE SHIFT STORE MC14094BD 772 07 025 POS NAND GATES INV 74 14 IC 656 U9 U10 IC DUAL OPTO IC 1358 011 012
14. E d I eem 909996066 22127229 2 i ji Comb Model 7708 Function Generator 50Q Coax Cable Function Output Verifying ratio and average Follow the procedure below to verify ratio and average CAUTION Exceeding 300V between plug in module INPUT or SENSE and L terminals may cause instrument damage Connect the Model 7708 and 21 and L terminals to the DC calibrator as shown in Figure 15 Install the Model 7708 in Slot 1 of the Model 27xx turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position Select the Model 27 DCV function and the range Close Channel by pressing the CLOSE key and keying in 101 Select the Model 27xx RATIO function press SHIFT then RATIO Set the calibrator output to 1 00000V DC and allow the reading to settle Verify that the ratio reading is between 0 9999926 and 1 000074 Press OPEN to open Channel 1 Figure 15 Connections for ratio and average verification
15. Guide 440 248 0400 Fax 440 248 6168 www keithley com Introduction The Model 7708 is a 40 channel differential multiplexer card with the following features DC and AC voltage measurement 2 wire or 4 wire measurement automatically pairs switches for four wire measurements 20 Temperature applications RTD thermistor thermocouple Built in cold junction reference Screw terminal connections Designed specifically for use with Keithley s Model 2700 2701 and 2750 system DMMs NOTE references to the Model 27xx apply to the Models 2700 2701 and 2750 WARNING Before operating the Model 27xx with an accessory card verify that the card is properly installed and the mounting screws are tightly fastened If the mounting screws are not properly connected an electrical shock hazard may be present Topic Page Introduction SPCCHICALONS M 2 leac rares e M 2 Card configuration Ib ve 3 CONMECHONS I canvas 4 Witing E Typical connections N EE EEE AETA TA 7 CONMECHON E A 9 Performance verification Venfication test r
16. Hub L E we me co CX X yw cea SEY 63 065 Cy cy CY x KT 52 Roy Noe 2 5 2 2 wos LS Gy eA a 5 4 NU 0004 016 2 K21 22 K23 K24 K25 K26 K21 K28 K29 K30 K31 K32 K33 K34 ma eS e E co ET Exe t J D Sus L 3 E gol sL bi tl el I tt d 2 ure mE a Eg Eg SS aS OS Se OS OES ES DEI do rm amp rmn rn Erm rm pos 4 y R6 i Loe THe 1L 111041 i Lud LO crosl 1 51 1 e _ LHe R56 ete LHe m 6 Mesto 9 fesse t3 or ace D ENS d EN a ae nt St ix 1 i m CA OOOOOUD D000000D 2DDDUU D0DUDD i u25 U24 Ul U3 U6 04 019 vis Res ners 09 010 DEN DC M3 NS wu AN C A ON ESE ie E FOR COMPONENT INFORMATION 5 PRODUCTI Sd pud T Iu UNLESS OTHERWISE SPECIFIED DATE SCALE ae CAN KEIIHLE DIMENSIONS ARE IN INCHES TITLE CON TOLERANCES DECIMALS ANGULAR DRN APPP KEITHLEY INSTRUMENTS INC Row ao M LM APPR M B CLEVELAND OHIO 44139 PONENT LAYOUT LING
17. complete Model 7708 calibration 23 Remote Model 7708 calibration 1 Connect the Model 7708 to the 7797 Calibration Extender Board see Extender board connections above With the power off install the Model 7708 7797 combination in Slot 1 and select the rear inputs with the INPUTS switch Allow three minutes for thermal equilibrium Accurately measure and record the cold temperature of the Model 7708 card surface at the center of the card 4 Press in and hold the Model 27xx OPEN key while turning on the power Enable calibration by sending the CODE command For example the default command is CAL PROT CODE KI0027xx Initiate calibration by sending the following command CAL PROT CARD1 INIT Calibrate the Model 7708 with the following command CAL PROT CARDI STEPO temp Here temp is the cold calibration temperature C measured in Step 3 Send the following commands to save calibration and lock out calibration CAL PROT CARDI SAVE CAL PROT CARDI LOCK Replaceable parts This section contains replacement parts information and the component layout drawing for the Model 7708 Parts list Replaceable parts for the Model 7708 are listed in Table 9 24 Table 9 Model 7708 parts list Circuit Designation Description Keithley Part No C4 C7 C9 C11 C14 C200 C201 0 1 20 50V CERAMIC C 418 1 C203 C213 C2 C6 C17 C20 C23 C25 C202
18. qualified service personnel Do not attempt to perform this procedure unless qualified to do so Figure 2 shows how to access the screw terminals on the Model 7708 Channel designations for the screw terminals are contained in Figure 3 WARNING Do not exceed the maximum specifications for the Model 7708 module Refer to the end of this packing list for specifications Figure 2 Screw terminal access LOCK 100000000 cR Figure 3 Model 7708 screw terminal channel designations CH1 thru CH14 HL HL Cable tie holes CH35 CH36 CH37 CH38 CH39 HL L HL HEHEHEHEHE L INPUT SENSE CH21 CH22 CH23 CH ki HLHL ANAL HALAL ALAL and Y 24 CH25 CH26 CH27 CH28 CH2 CH30 CH31 CH32 CH33 CH34 INPUT SENSE Cable tie holes CH21 CH34 CH15 4 CH20 CH35 42 CH40 Wiring procedure WARNING information in this section is intended for qualified service personnel Do not attempt to perform this procedure unless qualified to do so Use the following procedure to wire the Model 7708 m
19. source signal settle before taking a reading WARNING Observe the following safety precautions when performing these tests Some of the procedures in this section may expose you to dangerous voltages Use standard safety precautions when such dangerous voltages are encountered to avoid personal injury or death caused by electric shock The maximum common mode voltage voltage between any plug in module terminal and chassis ground is 300V DC or 300V RMS Exceeding this value may cause a breakdown in insulation creating a shock hazard Verification limits The verification limits stated in this section have been calculated using only the Model 27xx one year accuracy specifications and they do not include test equipment uncertainty If a particular measurement falls slightly outside the allowable range recalculate new limits based on both Model 27xx specifications and pertinent calibration equipment specifications Example reading limit calculation The following is an example of how reading limits have been calculated Assume you are testing the 10V DC range using a 10V input value Using the Model 27xx one year accuracy specification for 10V DC of 30ppm of reading 5ppm of range the calculated limits are Reading limits 10V 10V x 30ppm 10V x 5ppm Reading limits 10V 0 0003 0 00005 Reading limits 10V 0 00035V Reading limits 9 99965V to 10 00035V Calculating resistance reading limits Resistance read
20. uL B1 250 TO R 418 140K KK 11 10 0 25306 REVISED ARTWORK NO COMPONENTS CHG D LM ELS 2 5 01 ADDED AND DELETED SEV ERAL PARTS ELS SHADED SMT BOTTOM AREAS DENOTE NOT POPULATE metes De os ot KEITHL E CLEVELAND INSTRUMENTS 44139 OHIO CONFIDENTIAL PROPRIET ARY UNLESS OTHERWISE SPECIFIED DIMENSTONS ARE IN INCHES TOLERANCES DECIMALS ANGULAR t 4 16 ANG 005 FINISHED HOLE SIZES LAYER CONSTRUCTION EXCLUDES AND BOARD TREGE COMPONE DRAWING LAYOUT QSIF 227A Specifications are subject to change without notice All Keithley trademarks and trade names are the property of Keithley Instruments Inc All other trademarks and trade names are the property of their respective companies KEITHLEY Keithley Instruments Inc Sales Offices BELGIUM CHINA FINLAND FRANCE GERMANY GREAT BRITAIN INDIA ITALY JAPAN KOREA NETHERLANDS SWEDEN TAIWAN 28775 Aurora Road Cleveland Ohio 44139 440 248 0400 Fax 440 248 6168 1 888 K EITHLEY 534 8453 www keithley com Bergensesteenweg 709 B 1600 Sint Pieters Leeuw 02 363 00 40 Fax 02 363 00 64 Yuan Chen Xin Building Room 705 12 Yumin Road Dewai Madian Beijing 100029 8610 82251886 Fax 8610 82251892
21. 708 module does not support amps measurements System channel operation cannot be used to close channels while an amps function DCI or ICI is selected If an amps function DCI or ACI is selected and you attempt to close a system channel the message NO AMPS CHAN will be displayed briefly For remote programming error 222 Parameter data out of range is generated Example SYST PRES Restores system preset defaults SENS FUNC CURR DC Selects DCI function ROUT CLOS 0101 Attempts to close system channel 101 Generates error 222 If a system channel is already closed and you attempt to select the DCI or ACI function the message INVALID FUNC will be displayed briefly For remote programming error 221 Settings conflict is generated Example SYST PRES Restores system preset defaults ROUT CLOS 0101 Close system channel 101 SENS FUNC CURR DC Attempts to select DCI function Generates error 221 Making amps measurements In order to perform amps measurements you must use the front panel inputs of the 27xx main frame You can still use the 7708 module for other aspects of the test such as controlling a bias supply for DUT but you must use multiple channel operation to close channels Example NOTE order to use the front panel inputs make sure the INPUT switch is in the out position SYST PRES Restores system preset defaults ROUT MULT CLOS 0101 Closes channel 101 SENS F
22. A 1 5 Eagles Street Langford Town Bangalore 560 025 080 212 80 27 Fax 080 212 80 05 ITALY Viale San Gimignano 38 20146 Milano 02 48 39 16 01 Fax 02 48 30 22 74 JAPAN New Pier Takeshiba North Tower 13F 11 1 Kaigan 1 chome Minato ku Tokyo 105 0022 81 3 5733 7555 Fax 81 3 5733 7556 KOREA 2FL URI Building 2 14 Yangjae Dong Seocho Gu Seoul 137 888 82 2 574 7778 Fax 82 2 574 7838 NETHERLANDS Postbus 559 4200 AN Gorinchem 0183 63 53 33 Fax 0183 63 08 21 SWEDEN c o Regus Business Centre Frosundaviks All 15 41 16970 Solna 08 50 90 46 00 Fax 08 655 26 10 TAIWAN 13F 3 NO 6 Lane 99 Pu Ding Road Hsinchu Taiwan ROC 886 3 572 9077 Fax 886 3 572 903 1 5 03 Safety Precautions The following safety precautions should be observed before using this product and any associated instrumentation Although some in struments and accessories would normally be used with non haz ardous voltages there are situations where hazardous conditions may be present This product is intended for use by qualified personnel who recog nize shock hazards and are familiar with the safety precautions re quired to avoid possible injury Read and follow all installation operation and maintenance information carefully before using the product Refer to the manual for complete product specifications If the product is used in a manner not specified the protection p
23. Input i able to 4 pole LO RELAY TYPE Latching electromechanical ACTUATION TIME lt 3ms Card Sense Specified for Model 2700 firmware revision BO2 or later l0 Cold junction 1 Ref x4 HI CAPABILITIES Channel 1 CHANNELS 1 40 Multiplex one of 40 2 pole or one of 20 4 pole signals i T EUNDI into DMM Configuration supports dual 1x20 independent multi Channels 2 19 Backplane plexers i isolation HI Channel 20 INPUTS MAXIMUM SIGNAL LEVEL Channels 1 40 300V DC or rms 1A switched 60W 125VA maximum Poe Closed oe Backplane 1 1 see Note SAFETY Conforms to European Union Directive 73 23 EEC EN61010 1 Backplane CAT T i HI Channel 21 CONTACT LIFE typ gt 105 operations at max signal level 2108 operations cold switching CONTACT RESISTANCE 20 at end of contact life CONTACT POTENTIAL lt 500nV typical per contact 1uV max i Channels 41 43 in this schematic lt 500nV typical per contact pair max 1 refer to the designations used for OFFSET CURRENT lt 100 P control and not actual available channels CONNECTOR TYPE Screw terminal 20 AWG wire size For more information refer to the ISOLATION BETWEEN ANY TWO TERMINALS gt 10 0 lt 200 ISOLATION BETWEEN ANY TERMINAL AND EARTH gt 10 Q lt 400 Channels 42 and 43 can be individually CROSS TALK 1MHz 500 Load 40dB controlled using ROUTe MULTiple if the INSERTION LOSS 500 Sour
24. JO O0 00 J CJ 3 EM 00 r 0 7 7 LH L INPUT SENSE dum du Model 7708 Calibrator Output AC Voltage lt Shielded Cable Set the Model 27xx for the 100mV range make sure that REL is disabled Source 1kHz and 50kHz AC voltages for each of the ranges summarized in Table 4 and make sure that the respective Model 27xx readings fall within stated limits 6 Press the OPEN key to open Channel 1 Table 4 ACV reading limits 1kHz reading limits 50kHz reading limits ACV range Applied AC voltage 1 year 18 C to 28 C 1 year 18 C to 28 C 100mV 100 0000mV 99 910 to 100 090mV 99 830 to 100 170mV 1V 1 000000V 0 99910 to 1 00090V 0 99830 to 1 00170V 10V 10 00000V 9 9910 to 10 0090V 9 98300 to 10 0170V 100V 100 0000V 99 910 to 100 090V 99 830 to 100 170V 750V 300 000V 299 60 to 300 40V 299 27 to 300 73V Tf the 5725A amplifier is not available change the 300V 50kHz step to 220V 5OkHz Reading limits for 220V 50kHz 219 36 to 220 64 Verifying resistance Check resistance by connecting accurate resistance values to the Model 7708 and verifying that its resistance readings are within the specified limits CAUTION not apply more than 300V between plug in module INPUT or SENSE and L termina
25. KEITHLEY Model 7708 40 Channel Differential Multiplexer with Automatic CJC User s Guide PA 744 Rev 8 03 GR Bee MEAS U Ree ONFIDENCE 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 original 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 EXPRES
26. SED OR IMPLIED INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE THE REMEDIES PRO VIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES NEITHER KEITHLEY INSTRUMENTS INC NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT INDIRECT 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 LIM ITED 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 Ohio 44139 440 248 0400 Fax 440 248 6168 1 888 KEITHLEY 534 8453 www keithley com Sales Offices BELGIUM Bergensesteenweg 709 B 1600 Sint Pieters Leeuw 02 363 00 40 Fax 02 363 00 64 CHINA Yuan Chen Xin Building Room 705 12 Yumin Road Dewai Madian Beijing 100029 8610 82251886 Fax 8610 82251892 FINLAND Halsuantie 2 00420 Helsinki Finland 09 53 06 65 60 Fax 09 53 06 65 65 FRANCE 3 all e des Garays 91127 Palaiseau C dex 01 64 53 20 20 Fax 01 60 11 77 26 GERMANY Landsberger Strasse 65 82110 Germering 089 84 93 07 40 Fax 089 84 93 07 34 GREAT BRITAIN Unit 2 Commerce Park Brunel Road Theale Berkshire RG7 4AB 0118 929 75 00 Fax 0118 929 75 19 INDI
27. UNC CURR DC Selects DCI function Legal operation Card configuration Description Figure shows a simplified schematic diagram of the Model 7708 module As shown the Model 7708 has channels that are grouped into two banks of twenty channels forty channels total Backplane isolation is provided for each bank Each bank also includes separate cold junction reference points The first bank contains channels 1 through 20 while the second bank contains channels 21 through 40 Each channel of the 40 channel multiplexer card is wired with separate inputs for HI LO providing fully isolated inputs Although the Model 7708 relays are the latching type relays hold their state even after power has been removed all relay states are set to open a few seconds after either a power cycle or a RST command is issued Connections to DMM functions are provided through the card backplane connector Figure 1 Simplified schematic of Model 7708 Input LO Sense LO Cold junction i x4 HI o oTf o Channel 1 LO o 1 1 e Channels 2 19 o of o Channel 20 LO o o O N 2 Pole Open 4 Pole Closed quu e M AE SEA see Notes Cold junction Ref x5 Channel 21 HI 43 see Note Backplane isolation 0 a Input 42 27
28. ce 500 Load lt 0 35dB below 1MHz module is not to be connected to the 3dB below 2MHz audeo COMMON MODE VOLTAGE 300V between any terminal and chassis COLD JUNCTION 1 0 C 18 28 C Mainframe Temp 1 5 C 0 18 C amp 28 50 C Mainframe Temp ENVIRONMENTAL OPERATING ENVIRONMENT Specified for 0 C to 50 C Specified to 80 R H at 35 C STORAGE ENVIRONMENT 25 C to 65 WEIGHT 0 52kg 1 16 Ib Specifications are subject to change without notice SBG 11 7 00 Rev B LTR ECA NO REVISION ENG DATE CHG D FROM R 418 69 8K ON 25075 TO R 418 140K 06 ARTWORK NO COMPONENTS CHG D LM ELS 2 5 01 D 28251 ADDED AND DELETED SEVERAL PARTS ELS 14 25 03 PORT MGR du COMPONENTS QUOS 06
29. ect the line cord and all test cables To maintain protection from electric shock and fire replacement components in mains circuits including the power transformer test leads and input jacks must be purchased from Keithley Instru ments Standard fuses with applicable national safety approvals may be used if the rating and type are the same Other components that are not safety related may be purchased from other suppliers as long as they are equivalent to the original component Note that se lected parts should be purchased only through Keithley Instruments to maintain accuracy and functionality of the product If you are unsure about the applicability of a replacement component call a Keithley Instruments office for information To clean an instrument use a damp cloth or mild water based cleaner Clean the exterior of the instrument only Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument Products that consist of a circuit board with no case or chassis e g data acquisition board for installation into a computer should never require cleaning if handled according to in structions If the board becomes contaminated and operation is af fected the board should be returned to the factory for proper cleaning servicing Model 7708 KEITHLEY 40 Channel Differential Multiplexer with Automatic CJC Keithley Instruments Inc 28775 Aurora Road UU Cleveland Ohio 44139 User 5
30. ement inaccuracy contact your Keithley representative or the factory to determine the correct course of action Model 7708 verification test procedures include DC volts AC volts Resistance Temperature Frequency Ratio and average Verification test requirements Be sure that you perform the verification tests Under the proper environmental conditions After the specified warm up period Using the correct line voltage After restoring factory defaults With the INPUTS switch in the REAR in position Also make sure to use the proper calibration equipment Table 2 and the reading limits provided with the verification procedures Environmental conditions Conduct your performance verification procedures in a test environment that has An ambient temperature of 18 28 65 to 82 F A relative humidity of less than 80 unless otherwise noted Warm up period Allow the Model 27xx to warm up for at least two hours before conducting the verification procedures If the instrument has been subjected to temperature extremes those outside the ranges stated above allow additional time for the instrument s internal temperature to stabilize Typically allow one extra hour to stabilize a unit that is 10 18 F outside the specified temperature range Also allow the test equipment to warm up for the minimum time specified by the manufacturer Line power The Model 27xx requires a l
31. equireMents 4 err ri repe rrr He i TEREE E A EE E EREE ENEE E aE 10 11 Verification a EEE a eN E aE aa ER eE 11 Recommended test equipment 12 Performance verification prOCedUures iioi etii cor ee e 13 Calibration Recommended test equipment 2 ite edere erre 23 Extender E 23 Model 7708 23 Replaceable parts PAGS 24 Ordering in to sro M E ENEE 26 Factory Service M 26 Component layout is 26 744 Rev 8 03 Specifications The specifications for the Model 7708 switching card are located at the end of this User s Guide Operating instructions Switching card operation is covered in the Model 27xx User s Manual The Model 7708 operates the same as the Model 7700 switching card with the following differences The Model 7708 has 40 channels the Model 7700 has 20 channels The Model 7708 does not have any amps channels the Model 7700 has two amps channels Amps measurements The 7
32. esistance measurements respectively For that reason it is not necessary to independently verify the accuracy of temperature measurements As long as the DC volts and resistance functions meet or exceed specifications temperature function accuracy is automatically verified However tem perature verification procedures are provided below for those who wish to separately verify temperature accuracy Thermocouple temperature 1 101 Figure 13 nals using low thermal shielded connections as shown in Figure 13 Install the Model 7708 in Slot 1 of the Model 27xx turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position Select the temperature function by pressing the TEMP key Close Channel 1 by pressing the CLOSE key and keying in Connections for thermocouple temperature verification H HLH LHL CHL HL A ch cH2 Cu Cui CHS 15 16 CH17 CH18 CH19 CH20 HL H CH7 CH8 cin CH35 CH36 CH37 CH38 CH39 40 L HL HL HL Model 7708 Notes This setup and reading limits table does not include errors from ice point thermocouple wire and connections HI and LO connections from the calibrator and Model 7708 must be electrical
33. ge sources with high transient over voltages Measurement Category II connections require protection for high transient over voltages often associated with local AC mains connections Assume all measurement control and data I O connections are for connection to Category I sources unless other wise marked or described in the Manual Exercise extreme caution when a shock hazard is present Lethal voltage may be present on cable connector jacks or test fixtures The American National Standards Institute ANSI states that a shock hazard exists when voltage levels greater than 30V RMS 42 4V peak or 60VDC are present A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring Operators of this product must be protected from electric shock at all times The responsible body must ensure that operators are pre vented access and or insulated from every connection point In some cases connections must be exposed to potential human con tact Product operators in these circumstances must be trained to protect themselves from the risk of electric shock If the circuit is capable of operating at or above 1000 volts no conductive part of the circuit may be exposed Do not connect switching cards directly to unlimited power circuits They are intended to be used with impedance limited sources NEVER connect switching cards directly to AC mains When con necting sources to switching cards install pro
34. ibrator as shown in Figure 12 9 Disable external sense on the calibrator 10 Set the Model 27xx for the 100M range 11 Source a nominal 100MQ resistance value and verify that the reading is within calculated limits for the 100 range 12 Press the OPEN key to open Channel 1 Figure 12 Connections for resistance verification 100MX range My sa 9 18 LH CH9 cui cinta En ena H Eo CH4 5 6 CH7 CH8 15 16 CH17 CH18 CH19 CH20 HL LHLH HL CH35 CH36 Hui cns CH40 E L L HL Lr BE H L INPUT SENSE 1 1f 22 CH23 CH24 CH25 CH26 CH27 28 CH29 CH30 CH31 CH32 CH34 HL HL H L H L HL H L H L HL HL HL HL NN 1 Qu qum MM TTT i Model 7708 LL x lt Output Hi Calibrator Output 2 Wire Resistance Output LO 6 C cot O O Note Use shielded cables to minimize noise Disable calibrator external sense mode Verifying temperature Thermocouple thermistor and RTD temperature readings are derived from DC volts and r
35. iguration process Set the decade resistance box to each of the values shown in Table 7 and verify that the temperature readings are within the required limits Open Channel 1 when finished Table 7 Plug in module four wire RTD temperature verification reading limits Applied resistance Reading limits 1 year 18 to 28 22 800 100 000 313 590 190 06 to 189 94 C 0 06 to 0 06 C 599 94 to 600 06 C Based on a 0 00385 See text 20 Verifying frequency Follow the steps below to verify the Model 27xx frequency function Connect the function generator to the Model 7708 and L INPUT terminals See Figure 14 Install the Model 7708 in Slot 1 of the Model 27xx then turn on the power and allow the unit to warm up for one hour before proceeding Be sure the front panel INPUTS switch is set to the REAR position 3 Set the function generator to output a IKHz RMS sine wave Select the Model 27xx frequency function by pressing the FREQ key Close Channel 1 by pressing the CLOSE key and 1 2 101 5 Verify that the Model 27xx frequency reading is between 0 9999kHz 1 0001kHz Figure 14 Connections for frequency verification 7 008000000 1 CH2 CH3 CH5 CH6 CH7 CH8 En En 15 16 CH17 CH18 19 CH20 Cras CHa Car Qus ns
36. ine voltage of 100V 120V 220V 240V 10 and a line frequency of 47 5Hz to 63Hz Note that the line frequency is automatically sensed at power up but the line voltage must be manually set to either 100V 120V or 220V 240V as described in Section 3 of the Model 27xx Service Manual Factory defaults Before performing the verification procedures restore the instrument to its factory defaults as follows 1 Press SHIFT and then SETUP The instrument will display the following prompt RESTORE FACT 2 Using either range key select FACT then restore the factory default conditions by pressing ENTER INPUTs switch In order to connect the Model 7708 card to the meter of the Model 27xx the INPUTs switch must be in the REAR in position The INPUTS switch is located on the front panel of the Model 27xx multimeter near the input terminals Test considerations When performing the verification procedures e sure to restore factory defaults as outlined above Make sure that the equipment is properly warmed up and connected to the correct input terminals Also make sure that the INPUTS switch is in the REAR in position Do not use autoranging for any verification tests because autorange hysteresis may cause the Model 27xx to be on an incorrect range For each test signal you must manually set the correct range for the Model 27xx using the range keys Make sure the calibrator is in operate before you verify each measurement Always let the
37. ing limits must be recalculated based on the actual calibration resistance values supplied by the equipment manufacturer Calculations are performed in the same manner as shown in the preceding example except of course that you should use the actual calibration resistance values instead of the nominal values when performing your calculations For example assume that you are testing the 10kQ range using actual 10 03kQ calibration resistance value Using Model 27xx one year 10kQ range accuracy of 100ppm of reading 6ppm of range the calculated reading limits are Reading limits 10 03kQ 10 03kQ x 100ppm 10kQ x 6ppm Reading limits 10 02894kQ to 10 03106kQ Recommended test equipment Table 2 summarizes recommended verification equipment You can use alternate equipment as long as that equipment has specifications at least as good as those listed in Table 2 Keep in mind however that calibrator uncertainty will add to the uncertainty of each measurement Table 2 Recommended verification equipment Fluke 5700A Calibrator DC voltage AC voltage 1kHz 50kHz Resistance 100mV 14ppm 100mV 200ppm 100Q 17ppm 1 0 7 1 0 82 1kQ 12ppm 10 5 10 82 10 11 100V 7ppm 100 90 100kQ 13ppm 1000 9 700V 85ppm 1MQ 18ppm 10MQ 37ppm 100MQ 120ppm Fluke 5725A Amplifier AC Voltage 50kHz 700V 375ppm Keithley 3930A or 3940 Frequency Synthesizer
38. l or between any adjacent channels or instrument damage could occur Follow these steps to verify resistance accuracy Using shielded Teflon or equivalent cables in a 4 wire configuration connect the Model 7708 CH1 H and L INPUT termi nals and CH21 H and L SENSE terminals to the calibrator as shown in Figure 11 Install the Model 7708 in Slot 1 of the Model 27xx turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position 3 Set the calibrator for 4 wire resistance with external sense on Select the Model 27 4 wire resistance function by pressing the 94 key Close Channel by pressing the CLOSE key 1 and keying in 101 Figure 11 Connections for resistance verification 1000 to ranges CH1 Output Sense I Resistance Calibrator zi Output 000000000000 3 CNIXCH2 CH3 CH4 CH5 CH6 CH8 CH9 10 CH11 12 CHI3 14 CH35 CH36 CH37 CH38 CH39 CH40 E H L H L H L HL HL HL E 15 16 CH17 CH18 eno HLHLHLHL L E e m n m JO EE H L INPUT SENSE 1 2 1 ee en i25
39. ly isolated from each other Twisted Thermocouple Wire Make HI and LO Connections in Ice Bath Connect the DC voltage calibrator output terminals and ice point reference to the Model 7708 CH1 H and L INPUT termi Calibrator Output DC Voltage Output 4 21 COOOOOOO000009 99 OOOO0 000 OO ooo oco oo e Output LO Low Thermal Copper Connection M Ice Bath 19 4 Configure the Model 27xx for C units type temperature sensor and internal reference junction as follows a Press SHIFT then SENSOR and note the unit displays the temperature units UNITS C If necessary use the cursor and range keys to select C units b Press ENTER The unit then displays the sensor type SENS TCOUPLE c Make sure that TCOUPLE is displayed then press ENTER The unit displays the thermocouple type TYPE J d Select a type K temperature sensor then press ENTER The unit then displays the reference junction type JUNC SIM e Select INT reference junction then press ENTER 5 Source each of the voltages summarized in Table 6 and verify that the temperature readings are within limits Be sure to select the appropriate thermocouple type for each group of readings See step 3 above Open Channel 1 after the test is completed Table 6 Thermoc
40. odule Make all connections using the correct wire size up to 20 AWG Also make sure to add supplementary insulation around the harness for voltages above 42V peak see Figure 4 WARNING All wiring and supplementary insulation must be rated for the maximum voltage in the system For example if 1000V is applied to the front terminals of the Model 27xx the plug in module wiring must be rated for 1000V 1 Make sure all power is discharged from the Model 7708 module 2 Access the screw terminals see Figure 2 3 Using a small flat blade screwdriver loosen terminal screws and install wires as desired Figure 4 shows connections to channels 1 and 2 4 Route wire along wire path and secure with cable ties as shown 5 Fill in a copy of the connection log Table 1 and affix it to the module cover 6 Close and lock cover Figure 4 Wire dressing f 4 e E M Cable path z for channels 1 through 20 iaapanngn LN er ee CH3 CH5 CH6 CH7 CH8 CH9 CH10 1 CHI2 CH13 Supplementary Insulation f path for channels 21 Ll Md dh 7 through 40 LHL PUT SEN f 172720202
41. ouple temperature verification reading limits Thermocouple type Applied DC voltage Reading limits 1 year 18 C to 28 C J 7 659mV 192 33 to 187 67 C 1 0 to 1 0 C 42 280 749 0 to 751 0 C K 5 730mV 192 33 to 187 67 C OmV 1 0 to 1 0 C 54 138mV 1349 0 to 1351 0 C Voltages shown are based on ITS 90 standard RTD temperature 1 Connect the precision decade resistance box listed Table 2 to the Model 7708 21 L terminals using four wire connections See Figure 11 for similar connecting scheme Install the Model 7708 in Slot 1 of the Model 27xx turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position Select the temperature function by pressing the TEMP key Close Channel by pressing the CLOSE key and keying in 101 Configure the Model 27xx temperature function for C units and RTD temperature sensor 0 0 00385 as follows Press SHIFT then SENSOR and note the unit displays the temperature units UNITS Press ENTER and note the unit displays the sensor type SENS TCOUPLE Using the cursor and range keys set the display as follows SENS 4W RTD Press ENTER and note the unit displays TYPE PT 100 Using the cursor and range keys set the unit for the following display TYPE PT385 aes Press ENTER to complete the temperature conf
42. r 18 to 28 C 100mV 100 0000mV 99 9925 to 100 0075mV 1V 1 000000V 0 999962 to 1 000038V 10V 10 00000V 9 99965 to 10 00035V 100V 100 0000V 99 9946 to 100 0054V 1000V 300 000V 299 976 to 300 024V Source positive and negative values for each range Verifying AC voltage Check AC voltage accuracy by applying accurate AC voltages at specific frequencies from the AC voltage calibrator to the Model 7708 inputs and verifying that the displayed readings fall within specified ranges CAUTION Do not exceed 300V RMS between plug in module INPUT and L terminals or between adjacent channels or 8 x 107 V Hz input because instrument damage may occur Follow these steps to verify AC voltage accuracy 1 Connect the Model 7708 and INPUT terminals to the AC voltage calibrator as shown in Figure 10 2 Install the Model 7708 in Slot 1 of the Model 27xx turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position 3 Select the AC volts function by pressing the ACV key Close Channel by pressing the CLOSE key and then keying in 101 Figure 10 Connections for AC volts verification Amplifier Connect to Calibrator 2 Output HI ZS ALAZAN
43. rma tion and as shown on the instrument or test fixture panels or switching card When fuses are used in a product replace with same type and rating for continued protection against fire hazard Chassis connections must only be used as shield connections for measuring circuits NOT as safety earth ground connections If you are using a test fixture keep the lid closed while power is ap plied to the device under test Safe operation requires the use of a lid interlock 5 03 Ifa screw is present connect it to safety earth ground using the wire recommended in the user documentation The A symbol on an instrument indicates that the user should re fer to the operating instructions located in the manual The N symbol on an instrument shows that it can source or mea sure 1000 volts or more including the combined effect of normal and common mode voltages Use standard safety precautions to avoid personal contact with these voltages The i symbol indicates a connection terminal to the equipment frame The WARNING heading in a manual explains dangers that might result in personal injury or death Always read the associated infor mation very carefully before performing the indicated procedure The CAUTION heading in a manual explains hazards that could damage the instrument Such damage may invalidate the warranty Instrumentation and accessories shall not be connected to humans Before performing any maintenance disconn
44. ro vided by the product may be impaired The types of product users are Responsible body is the individual or group responsible for the use and maintenance of equipment for ensuring that the equipment is operated within its specifications and operating limits and for en suring that operators are adequately trained Operators use the product for its intended function They must be trained in electrical safety procedures and proper use of the instru ment They must be protected from electric shock and contact with hazardous live circuits Maintenance personnel perform routine procedures on the product to keep it operating properly for example setting the line voltage or replacing consumable materials Maintenance procedures are de scribed in the manual The procedures explicitly state if the operator may perform them Otherwise they should be performed only by service personnel Service personnel are trained to work on live circuits and perform safe installations and repairs of products Only properly trained ser vice personnel may perform installation and service procedures Keithley products are designed for use with electrical signals that are rated Measurement Category I and Measurement Category II as described in the International Electrotechnical Commission IEC Standard IEC 60664 Most measurement control and data I O sig nals are Measurement Category I and must not be directly connect ed to mains voltage or to volta
45. see Note Backplane Backplane isolation Sense NOTES Channels 41 43 this schematic refer to the designations used for control and not actual available channels Channels 42 and 43 can be individually controlled using multiple channel operation ROUT MULT commands if the module is not to be connected to the internal DMM For more information on multiple channel operation see Section 2 of the Model 27xx User s Manual Channel 41 2W 4W Configuration Channel 42 Sense Isolation and Channel 43 Input Isolation are normally automatically configured by the Model 27xx However by using the ROUT MULT commands refer to Section 2 of the Model 27xx User s Manual they can be manually configured NOTE 4 wire sense leads using channels 21 40 To disconnect channels 21 40 from channels 1 20 send ROUT MULT CLOS 141 note opposite logic When automatically configured for 4 wire measurements including 4 wire temperature Ratio and Channel average the channels are paired as follows and CH21 CH8 and CH28 CH15 and CH35 CH2 and CH22 CH9 and CH29 CH16 and CH36 CH3 and CH23 CH10 and CH30 7 and CH37 CH4 and CH24 e CH11 and CH31 CH18 and CH38 CH5 and CH25 12 and CH32 19 and CH39 CH6 and CH26 CH13 and CH33 CH20 and CH40 CH7 and CH27 CH14 and CH34 Card connections WARNING information in this section is intended for
46. shield to the calibrator s output LO terminal Figure 9 Connections for DC volts verification Calibrator Output DC Voltage ZS O 60 Note Use shielded low thermal cables for 100mV and 1V ranges H ENS 2 CH3 CH4 CH5 CH6 CH8 CH9 CH10 eni E dns Em rara RT e 7708 2 Install the Model 7708 Slot 1 of the Model 27xx turn on the power and allow the unit to warm up for two hours before proceeding Be sure the front panel INPUTS switch is set to the REAR position 13 3 Select the DC volts function by pressing key and set the Model 27xx to the 100mV range Close Channel 1 by pressing the CLOSE key and then keying in 101 4 Set the calibrator output to 0 00000mV DC and allow the reading to settle 5 Enable the Model 27xx REL mode Leave REL enabled for the remainder of the DC volts verification tests 6 Source positive and negative and full scale voltages for each of the ranges listed in Table 3 For each voltage setting be sure that the reading is within stated limits 7 Press the OPEN key to open Channel 1 Table 3 DCV reading limits Range Applied DC voltage Reading limits 1 yea
47. tective devices to lim it fault current and voltage to the card Before operating an instrument make sure the line cord is connect ed to a properly grounded power receptacle Inspect the connecting cables test leads and jumpers for possible wear cracks or breaks before each use When installing equipment where access to the main power cord is restricted such as rack mounting a separate main input power dis connect device must be provided in close proximity to the equip ment and within easy reach of the operator For maximum safety do not touch the product test cables or any other instruments while power is applied to the circuit under test ALWAYS remove power from the entire test system and discharge any capacitors before connecting or disconnecting cables or jump ers installing or removing switching cards or making internal changes such as installing or removing jumpers Do not touch any object that could provide a current path to the com mon 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 The instrument and accessories must be used in accordance with its specifications and operating instructions or the safety of the equip ment may be impaired Do not exceed the maximum signal levels of the instruments and ac cessories as defined in the specifications and operating info
48. ternal to the Model 27xx to avoid card heating during calibration Model 7708 calibration NOTE Before calibrating the Model 7708 make sure that power has been removed from the card for at least two hours to allow card circuitry to cool down After turning on the power during the cali bration procedure complete the procedure as quickly as possible to minimize card heating that could affect calibration accuracy Allow the Model 27xx to warm up for at least two hours Front panel Model 7708 calibration 1 Connect the Model 7708 to the Model 7797 Calibration Extender Board see Extender board connections above 2 With the power off install the Model 7708 7797 combination in Slot 1 and select the rear inputs with the INPUTS switch Allow three minutes for thermal equilibrium 3 Accurately measure and record the cold temperature of the Model 7708 card surface at the center of the card with a digital thermometer 4 Press in and hold the Model 27xx OPEN key while turning on the power 5 Press SHIFT then TEST then display TEST CALIB with the up or down range key Press ENTER select RUN then enter the appropriate calibration code default 0027xx 6 With NEW CODE displayed use the up or down range key to display N then press ENTER 7 Using the up or down range key select CARD at the CAL RUN prompt then press ENTER 8 Setthe display value to the cold calibration temperature you measured in Step 3 then press ENTER to
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