Keithley 195 Instruction Manual Download

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Summary of Contents for 195

Page 1: ...Model 195 Instruction Manual Contains Operating and Servicing Information for the Model 195 Digital Multimeter Publication Date August 1983 Document Number 195 90 OIC...

Page 2: ...is 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 softwar...

Page 3: ...Instruction Manual Model 195 Digital Multimater 01992 Keithley Instruments Inc Cleveland Ohio U S A...

Page 4: ...nally acceaible BENCH READING RATE 3 read second IEEE488 BUS IMPL ZMENTATlON MuMIne Cad DCL LLO SIX GET GTL LINT UNL SPE SPD Unlllne Commands IFC REN EOI SRQ ATN Interface Fwuttow SHI AHl T5 TEO L4 LE...

Page 5: ...ent A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring Users of this product must be protected from electric shock at all times The responsib...

Page 6: ...ly 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 s...

Page 7: ...Clip OnTestLeadSet Model1682ARFProbe Model1683UniversalTestLeadKit Model 1685 Clamp On AC Current Probe Model 1691 General Purpose Test Lead Kit Model 1950 AC Voltage AC and DC Current Option Model700...

Page 8: ...3 1 ProgramDescription 3 3 ProgramO Clear 3 3 Program 1 Non Volatile Storage 3 3 Program2 Multiplex 3 3 Program 3 IEEEAddress and Talk Only Mode 33 Program4 LineFrequency 3 4 Program 5 Digital Calibr...

Page 9: ...lter 4 17 Triggering Tl 4 17 EOIIK 4 18 Multiplex A 4 18 Delay W 4 18 StatusWord 4 19 SRQ Mode M and Status Bvte Format 4 20 BufferCommand Qand El 4 21 DateFormat 4 22 DigitalCalibration i 4 23 Non Vo...

Page 10: ...E Introduction 7 l LineVoltageSelection 7 1 FuseReplacement 7 l LineFuse 7 1 AmpsFuse 7 2 Model 1950 AC Amps Option Installation 7 2 CaObration 7 3 Recommended Calibration Equipment 7 3 Environmental...

Page 11: ...mmandGroups 4 11 GeneralEusCommands 4 11 Default Conditions Status Upon Power Up or After SDC or DCLI 4 12 Device Dependent Command Summary 4 15 RangeCommands 4 16 Rats Commands 4 17 FilterCommends 4...

Page 12: ...3 2 IEEEBusConfiguration 4 l IEEEHandshakeSequence 4 Z CommandCode 45 SvstemTvpes 4 7 IEEE 488Connector 4 7 IEEE 488Connections 4 7 Rear Panel of Model 195 Showing IEEE Connector 4 7 ContactAssignment...

Page 13: ...d 2OODRanges Connections for Calibration of 2kD Through 20MD Ranges Location of Frequency Compensating Capacitors on Model 1950 Current Calibration Connections Calibration Jumper Locations Model195Exp...

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Page 15: ...ed on the front and rear panels to allow easy con nections in both bench and rack mounted situations The selected set of inputs is controlled by a rear panel switch 7 Trigger Input and Output The Mode...

Page 16: ...of the instrument is internally selectable Refer to Section 7 Maintenance for information on setting the line voltage 1 8 3 Line Frequency The instrument will display the programmed line frequency up...

Page 17: ...can be used with the Model 195 to make AC cur rent measurements up to 50A as well The Model 1851 con sists of a 0 0019 f 1 4teninal resistance and operates with the Model 195 by developing a small mea...

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Page 19: ...to functional groups for easier operation 1 POWER The POWER switch controls the AC power to the instrument Depressing and releasing the switch once turns the power on Depressing and releasing the swit...

Page 20: ...6 PROGRAM The PROGRAM buttons are used with the front panel programs as described in Section 3 PROM The PROM button is used as the first step in entering front panel programs 0 through 9 RECALL ENT T...

Page 21: ...nal it does not protect the unit from excessive voltage applied to the other input terminals 2 4 POWER UP PROCEDURE 6 EXTERNAL TRIGGER This BNC connector is usad to apply pulses to trigger the Model 1...

Page 22: ...normal operating mode and begin displaying read ings The instrument will be in the following modes IEEEStatus Local Function and Range 1OOOVDC Resolution 5 digits Filter Off Zero Off 7 Ifanyofthetests...

Page 23: ...nction affects the integration period and the aamplea averaged per reading In DCV DCA and OHMS modes the nominal integration period is 16 66ma 60Hz or 2Oms 150Hz corresponding to the S2 rate mode lSee...

Page 24: ...rminal may be larger than the displayed value when using the zaro mode For exampla if a 16OVDC baseline is stored an applied voltage of 17 W will result in a displayed value of only 25V 4 If desired p...

Page 25: ...RGM and TRIG 19 buttons in sequence The TRIG light will go out end the display decimal point will flesh at the conversion rate NOTES 1 The PRGM TRIG button sequence actually enters front panel Program...

Page 26: ...ggered after it com pletes its reading 2 7 4 Triggering Example As en example of using external input end output triggering assume the Model 195 is to be used in conjunction with e Keith Modal 230 Pro...

Page 27: ...itive value If the negative source terminal is connected to the HI terminal the display will show a negative value The Model 195 can make DC voltage measurements between 1OOnVand 1OOOV The nominal ben...

Page 28: ...ess the OHMS button and seleot a range consistent with the expected resistance If desired use autoranging Set the display resolution as desired 4 If readings are to be made on the 2ODor 2OOil ranges u...

Page 29: ...tointerpret the reading For example assume the display reads ss fcllanrs The scurce value is 195 000mV 2 9 4 DC Current Measurements With the Model 1950 option installed the Model 195 is capable of D...

Page 30: ...y ineccurete The Model 195 because of its TRMS True Root Mean Square measuring capabilities with the Modal 1950 option provides aqoureta AC measure ments for a wide variety of AC input weveforms 2 9 1...

Page 31: ...ue of 5V and an RMS value of 7 07V Here the average responding meter gives a reading of 5 55V 5x 1 111 while the Model 195 gives a TRMS reading of 5V 2 9 2 Crest Factor The crest factor of a wavefon i...

Page 32: ......

Page 33: ...ed with most or all the programs are listed in Table 32 Note that many of the programs have additional m gee which are covered separately with each progrsm description Table 3 2 General Front Panel Pr...

Page 34: ...be stored in non volatile RAM 10 Constants are to be entered by the operator when prompted to do so by the instrument When entering a numerical con stant A The constant is entered by pressing the numb...

Page 35: ...r an input as follows j5torl 4 To perform NV storage press ENT The data entered in Program 3 4 5 and 8 will be stored in the non volatile RAM and the instrument will return to normal operation NOTES 1...

Page 36: ...displayed upon power up Table 3 3 Program 3 IEEE Parameters _I Value 1Description O 30 1Priman address O 30 40 I I Talk only mode with prefix Example NDVC 1 23456E 2 41 Talk onlv mode without orefix 1...

Page 37: ...the 2VDC range the operator would key in the following sequence PRGM 5 1 9 5 0 0 ENT NOTES 1 Program 5 doss not automatically store the calibration con stants in NVRAM Program 1 must be used to perfo...

Page 38: ...tion of the RECALL button Hold the RECALL but ton in to scroll the readings 13 To obtain an average up to the displayed address of step 9 during the recall process press 3 The instrument will ra spond...

Page 39: ...ll perform a RAM and ROM teat simultaneously with the display teat for a few seconds Upon completion of the test an appre priats message sss Table 3 5 will be displayed The instru ment will then promp...

Page 40: ...s for a calibration input enter the value of mx IO x m 2 5 Disconnect the mx signal and connect the b value 6 Disable then enable the zero mode All subsequent readings will be scaled according to the...

Page 41: ...h date and most com mands Five bus management linea and three handshake linsa round out the complement of signal lines Since the bus is of parallel design all devices connectsd to the bus have the sem...

Page 42: ...revious byte transfer If these conditions are not met the source must then wait until the NRFD and NDAC lines have the correct status If the source is a controller NRFD and NDAC must remain stable for...

Page 43: ...tes 4 ATN Attention The controller sends ATN while transmit ting addresses or multiline commands Device dependent commends are Sent with the ATN line high false 5 SRQ Service Request The SRD commend i...

Page 44: ...to place the instrument in the DCV mode The IEEE 488 bus treats device dependent commands as data in that ATN is high false when the commands are transmitted 4 5 COMMAND CODES Each multiline command i...

Page 45: ...V v Figure 4 3 Command Code e tn...

Page 46: ...the primary address must be properly program med as described in this section 4 7 1 Typical Controlled Systems The IEEE 488 bus is a parallel interface system As a result ad ding more devices is simpl...

Page 47: ...r on each end The Keithley Model 7006 3 or 7008 6 cable is ideal for this purpose Once the connections are made the screws should be tightened securely For the location of the connector on the rear pa...

Page 48: ...the address unchanged simply Press 5NT To change the address enter a new value between 0 and 36 and press ENT CAUTION NOTES The voltage between IEEE common and ground must not exceed 30V or damage to...

Page 49: ...tware is being used with the interface Often the user may incorrectly suspect that a hardware pro blem is causing fault when it was the software that was caus ing the problem all along 4 8 2 HP85 BASI...

Page 50: ...odel 195 talker capabilities exist only after the instrument has been addressed to talk 4 L Listener Function The ability for the Model 195 to receive devicedependent data over the bus from other devi...

Page 51: ...e remote enable command is sent to the Model 195 by the controller to set the instrument up for remote operation Generally this should be done before attempting to program the instrument over the bus...

Page 52: ...are locked out The GTL command se ouence is automatically sent bv the HP 85 with the following statment LOCAL 716 END LINE Note that the REMOTE light on the front panel turns off Front oanel control o...

Page 53: ...e the instrument in the one shot on GET trigger mode with the following statement OUTPUT 716 T3X END LINE When the END LINE key is pressed the decimal point will stop flashing indicating the instrumen...

Page 54: ...vice dependent commands Generally the X character is the last byte in the command string The execute character also controls instrument operation in the T4 and T5 trigger modes as described in paragra...

Page 55: ...es averaged 4 digits Line cycle integration 8 reading samples averaged 4 digits Line cycle integration 16 reading samples averaged 4 digits IOOms integration period 1 reading sample averaged 5 digits...

Page 56: ...acter YfCR LF CR LF YILF CR LF CR Y X None Hn n number of front panel bunon D Display ASCII message X Execute other device dependent commands Table 4 12 Range Commands Programming Example Select the a...

Page 57: ...he display shows only l OOOOVDC 9 Once zero is enabled the baseline will be stored when the next A D conversion is triggered Zeroed readings will then be displayed with each subsequent triggered conve...

Page 58: ...ing front panel control sequence A0 Enable multiplex routines O L _ n PRGM 9 Al Disable multiplex routines 2 A LLO command will inhibit front panel triggering in the T6 Upon power up or after a DCL or...

Page 59: ...may be transmitted 4 The self test IJ byte is set to 2 after passing the self test JI command and 1 if the test fails This byte will be set to zero upon power up 5 The returned terminator character Y...

Page 60: ...e 4 16 SRQ Mask Commands Sets Bit Command Number Conditions to Generate SRQ Ml 80 LSBI Reading Done Overflow M2 Bl IDDC IDDCO or No remote M4 82 Buffe full M8 83 Buffer l 2 full Ml6 84 Self test faile...

Page 61: ...byte bits in order on the CRT The SRQ tB8 error 85 and IDDCO IBO bits are set because line 30 of the program attempted to program the instrument with an illegal command option K5l Table 4 17 Status B...

Page 62: ...ntervals 5 minute intervals 10 minute intervals 30 minute intervals 1 hour intervals NOTES 1 Buffer operation can also be controlled from the front panel as described in paragraph 3 5 8 2 The Model 19...

Page 63: ...layed in each mode on the CRT Note that a umber of seconds pass in the G2 and G3 modes since the in strument must first assemble the entire buffer before trsnsmit ting it to the computer 4 10 16 Digit...

Page 64: ...tests ENTER 716 AS DISP AS calibration vslue Enter first reading with old calibration constants Displsv reading on CRT Programming Example Enter the fallowing statements in OUTPUT 716 VO 1OOOOX Progr...

Page 65: ...X END LINE 4 10 19 Hit Button IHI The hit button command allows the user to emulate virtually any front panel control sequence Through the use of the H command the front panel programs may be entered...

Page 66: ...ing Example Enter the following statements into c No Remote the HP 86 keyboard REMOTE 716 END LINE Figure 4 13 IEEE Display Error Messages OUTPUT 716 D sp 195 sp X END LINE When the END LINE key is pr...

Page 67: ...n cluding selected S buffer and multiplex modes Shown below are several conditions along with trigger to first byte out times for data transmission over the bus as well as buffer filling rates under c...

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Page 69: ...the equipment listed in Table 51 does not have specifications at least four times better than those of the Model 195 because such equipment is not readily available In such cases the allowable range...

Page 70: ...e within the limits specified in Table 5 2 7 Switch the Model 195 to the 2OV range Set the calibrator cutput to 19 OOOVand verii that the displayed reading is within the IimitS set in Table 52 8 Chang...

Page 71: ...066kg CALmRATION RESlSTANCE Figure 5 3 Connections for Verification of 20kSl Through 20MC Ranges 5 5 3 AC Voltage Accuracy Check with Model 1950 Option AC voltage accuracy is checked by connecting a c...

Page 72: ...Table 55 4 Switch the Model 195 to the 2OOfi range and set the calibrator output to 19O OOOfi Check to see that the reading is within the limits listed in Table 55 5 Switch the Model 195 to the 2mA r...

Page 73: ...tch the Model 195 to the 2004 range Verify the reading is within the limits listed in Table 56 4 Change the Model 195 to the 2mA range and switch the calibrator output to 1 90000mA See that the displa...

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Page 75: ...If the Model 1950 op tion is installed applied voltage and current signals are con trolled or modiied into the proper fon and applied to the input switching network The multiplexer applies the variou...

Page 76: ...I l 1 Figure 6 l Basic Block Diagram...

Page 77: ...de up of U124 U129 and U140 Q118 and Q119 are turned on simul taneously for X2 gain M wLIFIER OP AMPS Figure 63 Simplified Schematic of the Input Buffer Amplifier 6 3 3 2V Reference Source Model 195 v...

Page 78: ...bsequent negative going clock pulse 02 goes high connecting L a to the integrator input Since Ica is much greater than IIN the integrator output voltage immediately ramps in the negative direction Wit...

Page 79: ...s interface IC Ull8 This IC per forms many bus functions automatically to minimize MPU overhead Buffering between the 9914 IC and the IEEE bus lines is done with bus drivers Ull9 and U120 6 4 2 Memory...

Page 80: ...II I II I 1 l II I Figure S 7 Simplified Microcomputer Block Diagram...

Page 81: ...LEDs and the function and mode switches Display information is fed from Port A of the VIA PAL PA7 Information is updated at a 1 2kHz rate which means that each segment is turned on for approximately...

Page 82: ...te the 5V digital 5V analog 15V analog and 15V analog supplies respectively Filtering for each supply is provided both at the rectifier and regulator outputs Since the 5V digital supply delivers the m...

Page 83: ...ing iormula It can be seen that the zero error is subtracted from both the signal and reference values and the ratio is then taken Multi plication by two is necessanl because of the 2V reference sourc...

Page 84: ...lect one of the two reference resistors A 2 ohms reference source is connected to one side of the known resistor and the other side of the resistor is connected to the INPUT HI VOLTS OHMS HI1 terminal...

Page 85: ...roduced into the reading By using a 4 terminal configuration as shown in Figure 6 15 the error can be reduced considerably Here most of the cur rent flows through the test leads raspresented by R and...

Page 86: ...er During the second and fourth phase the zero FET is on and the 2V reference FET is on during the third phase of the input cycle During each of the four phases the A D converter convertS the signal i...

Page 87: ...lows 1 Remove the top cover as described in the disassembly in structions in paragraph 7 7 Disconnect the instrument from the power line and from other equipment before replacing fuses 7 3 1 Line Fuse...

Page 88: ...holes at the outer edge of the Model 1950 with the holes in the shield 4 Secure the Model 1950 with the long screws provided with the accessory These screws fit down through the option shield spacers...

Page 89: ...e performed in the order listed DCV Ohms ACV current 3 Calibration may also be performed over the IEEE bus see paragraph 4 10 15 7 5 1 Recommended Calibration Equipment Recommended calibration equipme...

Page 90: ...19 0000 3 OOmV 19O OOOmV 190 000 3 2 1 90000v 1 90000 o 19 oooov 19 0000 o 2oov 19o ooov 190 000 o 1ooov 99o oov 990 00 o Table 7 5 Parameters for Resistance Calibration 1 2OQ 2 2OOD r r 3 2kD 4 2OkD...

Page 91: ...adjustments C Disable ZERO and set the calibrator output to 1 OOOOV 2OOHz switch the Model 195 to the WAC range Enable ZERO adjust 309 on the Model 1950 so that the displayed reading is O OOOOV 2 cou...

Page 92: ...The instrument will ask if storage is desired as follows pzGKq 2 TO perform storage press ENT If the storage iSsuccessful the instrument will return to normal operation 3 If the calibration jumper ha...

Page 93: ...o be in serted must also be grounded to the bench or table 5 Use only anti static type solder suckers 6 Use only grounded soldering irons 7 Once the device is installed on the PC board the device is n...

Page 94: ...e circuit or cir cuit section isolation of the specific component is left to the technician 75 1 Recommended Test Equipment The success or failure in troubleshooting a complex piece of equipment like...

Page 95: ...ter one of the four FET switching phases enter a number between 1 and 4 Table 7 11 lists the FET and relay switching sequence for the various range function and n value combinations To run one of the...

Page 96: ...l Xl Xl Xl Xl Xl x10 x10 Xl Xl Xl Xl Xl Xl x10 x10 Xl Xl Xl00 Xl00 Xl Xl Ei x2 x2 x10 x10 Xl Xl z x2 x2 x10 x10 Xl Xl x2 x2 x2 x2 x10 x10 Xl Xl lultiplexer FET On Qlll Ql14 Q103 Ql14 0113 0114 0103 Q1...

Page 97: ...17 Q117 N2 N3 N4 Nl Ql17 Q117 Ql17 0117 N2 N3 N4 Nl Q117 0117 0117 Qll7 N2 N3 N4 Nl 0117 Q117 Q117 Ql17 N2 N3 N4 Nl Q117 Q117 Ql17 0117 N2 1 Q117 Q117 Q117 Input Buffer Gain Xl00 Xl00 Xl Xl Xl Xl Xl X...

Page 98: ...Qll7 N4 Q117 Nl Q119 N2 0119 N3 0117 N4 Q117 Xl 1 0114 x10 0102 x10 Q114 Xl 1 Q114 I Model 195 Relavs Model 1950 I 0506 Q506 0506 pi I Q508 52i506 Table 7 12 Program 8 Tests Test Number n Display Mes...

Page 99: ...utput of CR107 15V pad next to shield Positive output of CR108 15V pad next to shield Negative output of CR108 Measure between 5V Digital and Digital Common pads next to C14 Reference to Digital Commo...

Page 100: ...esent when button held in Not present when button released Pulse present when button held in Not present when button released I Pulse present when button held in Not present when button released Table...

Page 101: ...values TP5 on Model 195 External DC Current External DC Current Re marks Vcltaaes referenced to diaital common 5Vddsupplv MPU HALT line MPU NMI line RESET line pin 40 stays LO for about 1 second after...

Page 102: ...n 1 46 TP5 1 9VDC 47 Replace analog shield Remove Model 1950 shield 48 Range 200mADC 49 External Current 190 00mADC 50 TPl Model 1950 O lSVDC 51 Range 2VAC 52 External Voltage 1 gVAC RMS 1kHz 53 TP2...

Page 103: ...3 Part Description 4 Circuit designation including schematic and component layout numbers lif applicable 5 Keithley Part Number 8 4 FACTORY SERVICE If the instrument is to be returned to the factory...

Page 104: ...1960 7 SHIELD 7 I195308 RED BINDING POSTS BP H 21 BNC CONNECTOR INOT SHOWN BLACK BINDING POSTStBP 11 O WHITE BINDING POST IBP 11 91 r FRONT PANEL OVERLAY 196302 FRONT PANEL PUSH BUlTONB m Y 30644 BRO...

Page 105: ...n Diode lN4148 Silicon Diode lN4148 Rectifier Bridge 5A 50 PIV Rectifier Bridge 5A 50 PIV Rectifier Silicon 1 5A 400PIV Rectifier Silicon lN4006 1A 800PIV Silicon Diode 1N4148 Diode Silicon 1N4148 Dio...

Page 106: ...or Thick Film Network Resistor 22023 5 1l4W Composition Resistor lOk0 5 1 4W Composition Resistor 3305 5 ll4W Composition Resistor 1000 5 1 4W Composition Resistor 1000 5 1 4W Composition Resistor Thi...

Page 107: ...lMn 5 ll4W Composition Resistor 1MQ 5 lt4W Composition Resistor 1Mn 5 1t4W Composition Resistor 100kQ lo 1W Composition Resistor 10kn 5 1t4W Composition Resistor 680kQ 10 2W Composition Resistor l OO...

Page 108: ...4lF5 F2 2lSEV 83 2 85 83 Z SEV 83 2lF5 C3 2184 C3 2 SEV C3 2iC2 D3 2181 D3 2 F3 A4 2lG5 2 E3 IC Voltage Comparator LM311N 2183 D4 2 C2 D4 IC JFET OP Amp LF35IN 2103 D4 IC ECD Decimal Decoder CD4028AE...

Page 109: ...PNP Resistor Thick Film Network Resistor Thick Film Network Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbutton Switch Pushbut...

Page 110: ...Relay K505 D3 RL 72 Relay Reed SPST Ei K508 C3 RL 57 Relay Reed SPST c3 C3 RL 57 P1004 Cable assembly 14 Pin HZ E2 CA g 2 PI008 Connector Pin P1009 Al CS 236 Connector Pin PlOlO E2 CS 236 Connector Pi...

Page 111: ...erter AD536AK E4 83 IC 305 U508 IC JFET OP Amp LF351N D4 83 IC 178 Description Cover Bonom 3ii Tilt Collar Insulating Spacer Cover Top Panel Front Window Overlay Front Panel Binding Post Black Binding...

Page 112: ...8 10...

Page 113: ...I I I I I 10 t T I 8 I...

Page 114: ...Figure E 3 Mother Board Componet Location Drawing Dwg No 195199 sheet 2 of 21 8 13 a 14...

Page 115: ...NO TE IN3 lkLi CAR1 F i Oh Figure 9 4 Display Board Component Location Drawing Dwg No 199 110...

Page 116: ...Figure 8 S Mother Board Schematic Diagram Dwg No 195106 sheet 1 of 4 8 171818...

Page 117: ...SE ML FAEALLEL CONVEGSION r FET DRIVE Yn2C I I I I J I Figure 8 S Mother Board Schematic Diagram Dwg No 198106 Isheet 2 of 4 9 19 S 20...

Page 118: ...i I f RELAY DRIVE Figure S 5 Mother Board Schematic Diagram Dwg No 195106 sheet 3 of 4 3 2113 22...

Page 119: ...IIEEE L IEEE figure 8 5 Mother Board Schematic Diagram Dwg No 195106 sheet 4 of 4 8 2318 24...

Page 120: ...I I...

Page 121: ...FIgwe 8 7 Model 1950 AC Option Schematic Diagram Owg No 195 l 9 2719 29...

Page 122: ...es Display or output check one LIDlifts 0 Unable to zero B Unstable 0 will not read applied input 0 Overload 0 Certificate of calibration required attach any additional sheetsasnecessary Show a block...

Page 123: ...d Reading Berkshire RG2 ONL i07341 66 12 67 T x 847047 FRANCE Keithley Instruments SARL Z Sis Rue Ldon Blum S P 60 91121 Palaiseau CedexiiGl 011 51 55 Telex 600933F NETHERLANDS Keithley Instruments SV...

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