Keithley 660A, Instruction Manual

Page 1: ...INSTRUCTION MANUAL MODEL 660A GUARDED DC DIFFERENTIAL VOLTMETER...

Page 2: ...representative or the factory DDD 216 795 2666 You will be given assistance and shipping instructions REPAIRS AND RECALIBRATION Keithley Instruments maintains a complete re pair service and standards...

Page 3: ...Kelvin Varley Divider 14 4 4 Null Detector 14 4 5 Guarding 15 5 SERVICING 17 5 l General 17 5 2 Servicing Schedule 17 5 3 Parts Replacement 17 5 4 Troubleshooting L7 Section Page 6 CALIBRATION 21 6 l...

Page 4: ...ssis ground line frequency rejection greater than 45 db Also full guarding minimizes leakage problems L 2 OPERATING MODES The Model 660A can be used as a potentiometer or as a conventional vacuum tube...

Page 5: ...M STABILITY Will operate within stated Limit of error for one year TFXPERATURECOEFFICIENT Does not exceed 0 002 per OC REPEATABILITY Within 0 005 MAXIMUMNULL SENSITIVITY LOO microvoltb full scale with...

Page 6: ...weight 24 pounds l 5 ACCESSORIES a Model 6601A High Voltage Divider is a LOO L divider which extends the range of the Model 660A to 5000 volts The divider accuracy is O Ol and its input resistance is...

Page 7: ...EL 660A DIFFERENTIAL VOLTMETER PIGURE 2 Model 660A Front Panel Controls and Terminals Circuit Designations refer to Replaceable Parts List and the Schematic Diagram J FIGURE 3 Model 660A Rear Controls...

Page 8: ...sly variable f METER ZERO Control The METER ZERO Control adjusts the meter needle to zero The Control is needed on only the 0 1 and l O millivolt null ranges on the other ranges the needle will normal...

Page 9: ...RO Control Then return the NULL Switch to VTVM The stability of the Model 660A is such that no adjustment should be required in eight hours after a 30 minute warm up 2 4 OPERATING PROCEDURES a The Mod...

Page 10: ...Leave the RANGE Switch at the last setting used in the VTVM operation If the VTVM reading is negative reverse the POLARITY Switch position 2 Set the first two Reference Voltage Dials to the first two...

Page 11: ...ls on the Model 660A rear panel c Set the Reference Voltage Dials to 10 millivolts to apply an accurate lo millivolt potential to the null detector on the LO millivolt null range This will provide a f...

Page 12: ...compared to the shunt resistance across the null detector meter The LR drop across the divider will cause the meter to be off up to 6 depending upon the Reference Voltage Dial settings On the lOO mil...

Page 13: ...odel 660A input resistance is lolo ohms 2 S THERMALEMF PRECAUTIONS Observe standard thermocouple techniques to reduce thermal emf errors for measurements using the most sensitive null ranges Since the...

Page 14: ...l setting and multiply the difference by 50 to obtain the value of the resistor in megohms c For resistances between 10 000 megohms and 100 000 megohms set the NULL Switch to 1 volt adjust the Referen...

Page 15: ...FERENTIAL VOLTMETER If measurements are made on the 1 to loo volt null ranges the input resistance R is 50 megohms Equation 4 becomes Rx 5 10 7 1 This is thebasis for simplified calculations in paragr...

Page 16: ...lly guarded to avoid leakage NOTE Refer to Schematic Diagram 18269E for cir it designations INPUT GUARDED TERMINALS NULL DETECTCIR KELVIN VARLEV REFERENCE DlVlDER VOLTAGE SUPPLY FIGURE 7 Simplified Mo...

Page 17: ...preceeding string Between the two contacts of the first Reference Voltage Switch S3003 the total resistance is 40 kilohms 80 kilohms in para llel with the 80 kilohms total resistance of the four rema...

Page 18: ...uarding is accomplished by floating the null detector and the input circuitry at a voltage equal to the input voltage from a low impedance source This full guarding eliminates leakage between the inpu...

Page 19: ...ner diode D3003 only from Keithley Instruments Inc or its representative Re fer to paragraph 5 6 for instructions to replace the zener 5 4 TROUBLESHOOTING a The following procedures are for repairing...

Page 20: ...ly dur ing warm up Zener diode D3003 is un Return the instrument for stable factory check out Light modulator E3002 is Check light modulator by re defective placing easurements out of toler Out of cal...

Page 21: ...e Reference Voltage Dials to zero and short the input terminals Attach an oscillo scope to the junction of capacitor Cl016 and resistor R1035 from pin 6 of V1002 Figure 8 shows the wave form if potent...

Page 22: ...tificate Electra Scientific Industries Model RV7 22 Voltage divider for range calibration ecade Voltage Divider terminal linearity hl ppm certificate corrected to 0 2 ppm Slectro Scientific Industries...

Page 23: ...calibration for the Kelvin Varley divider its accuracy can only be verified The divider accuracy depends upon matching resistors and switches At manufacture each resistor within the first two Referenc...

Page 24: ...is adusted until the voltmeter indicates a null Model LC 875B r 9 9 m Extender P 5 and 0 5 v on1 Model RV722 NOTP The accuracy of the Model 660A calibration will be no greater than the accuracy of the...

Page 25: ...Divider to corresponding voltages Use the 9 9 megohm extender for the 5 and 0 5 volt outputs See Figure 9 The difference read on the null detector is the correction factor for each of the three voltag...

Page 26: ...equal to the correction factor at 5 volts 5 0 5 volt Range Calibration Set the Model 660A controls as follows RANGE Switch 0 5 Reference Voltage Dials 4 9 9 9 10 NULL Switch 0 1 MV POLARITY Switch Ad...

Page 27: ...nd the standard cell are detected by the Model 150A and are recorded on a recorder Refer to Figure 11 for the block diagram of the test circuit d In using the test circuit the following points are imp...

Page 28: ...it reads more than 20 microvolts adjust the 500 V CAL potentiometer R3025 Figure 20 shunting the divider NOTE Any adjustment of potentiometer R3025 requires all other ranges to be calibrated 3 After...

Page 29: ...ETER FIGURE 13 Top View of Model 660A Chassis Front panel faces to the right Location of components printed circuits and switches is shown Refer to the Replaceable Parts List for circuit designations...

Page 30: ...CALIBRATION FIGURE 14 Bottom View of Model 660A Chassis Front panel faces to the right Reference A in the photograph designates the location of resistors R3031 R3033 R3034 R3036 R3037 and R3039 Figur...

Page 31: ...CALIBRATION MODEL 660A DIFFERENTIAL VOLTMETER FIGURE 15 Component Locations on Printed Circuit Board PC93 1 FIGURE 16 Component Locations on Printed Circuit Board PC105 30 1066R...

Page 32: ...URE 17 Capacitor Modulator Diode and Tube Locations on Printed Circuit Board PC93 2 Refer to Figure 18 for resistor location FIGURE 18 Resistor Locations on Printed Circuit Board PC93 2 Refer to Figur...

Page 33: ...CALIBRATION MODEL 660A DIFFERmTIAL VOLTMETER FI XJRE 19 Capacitor Modulator Diode and Tube Locations on Printed Circuit Board PC92 Refier to Figure 20 for the resistor locations 32 1065R...

Page 34: ...MODEL 660A DIFFERENTIAL VOLTMETER CALIBRATION F 1 IGURF 20 Resistor Locations on Printed Circuit Board PC92 ocation of other components Refer to Figure 19 for the 1065R 33...

Page 35: ...CALIBRATION MODEL 660A DIFFERENTIAL VOLTMETER 34 GIJRE 21 Component Locations of Model 6601A Circuit designations refer to Schematic Diagram 16321B 1065R...

Page 36: ...nknown voltage to the Divider INPUT and use the Model 660A as out lined in paragraph 2 4 NOTE The input cable to the Model 6601A must be able to withstand 5000 volts Use of normal leads will maintain...

Page 37: ...lower be used in the rack enclosure in which the Model 660A is mounted The instrument specifications state a 0 002 per C temperature coefficient A temperature rise of 5 C 9 OF will cause a 0 01 error...

Page 38: ...t All structural parts and those parts coded for Keithley manufacture 80164 must be ordered from Keithley Instruments Inc In ordering a part not listed in the Replaceable Parts List completely describ...

Page 39: ...13 0 0022 pf 1000 CerD 72982 85125V222P C22 0022M Cl014 10 pf 15 ETB 56289 TE1155 C3 10M Cl015 0047 iJ f 1000 CerD 72982 811Z5V472P C22 0047M Cl016 1 0 I lf 600 v MY 13050 24009 C12 1M Cl017 4 Pf 250...

Page 40: ...08804 PL 2 13 Neon Lamp Mfg No NE 2P 08804 PL 2 13 Light Modulator 80164 Model 1513 16 Light Modulator 80164 Model 1513 16 Light Modulator 80164 Model 1514 17 Light Modulator 80164 Model 1512 Light M...

Page 41: ...0164 80164 80164 80164 80164 80164 80164 80164 80164 04009 80164 80164 80164 80164 80164 118 14828A 19185A SW 4 116 14838A 2 2 SW 203 14838A 2 TR 67 13 RESISTORS Mfg Mfg Keithley Fig Desig Value Ratin...

Page 42: ...l 2 w lO l 2 w lO l 2 w l l 2 w 30 l 2 w l l 2 w K Nominal value factory set 1065R wwvar 71450 AW RP19 15K 2 DCb 79727 CFE 15 R12 ZOOK 16 DCb 79727 CFE 15 R12 470K 16 Comp 01121 EB Rl 1M 16 camp 0112...

Page 43: ...l 4 w 0 1 l 4 w l l 2 w l 2 w l l 2 w lO 5 w DCb 79727 CFE 15 R12 150K DCb 79727 CFE 15 R12 180K camp 01121 EB Rl 100K Comp 01121 EB Rl 100K Comp 01121 EB Rl 220K camp 01121 EB Rl 220 Comp 01121 HB R4...

Page 44: ...4 13 R3057 to R3067 R3068 to R3078 R3079 R3080 1 6 kn 80164 5 13 320 n 750 cl O l L 2 w ww 01686 I l 2 w DCb 79277 lO 4 w WWVsr 12697 7044 R67 320 CFE 15 RlZ Jr 58M RP49 750 13 13 13 VACUUMTUBES Circu...

Page 45: ...116 116 Pll6 AW P 36 CFE 15 R91 2M 22 R91 2M 22 R91 2M 22 R91 2M 22 R91 2M 22 RP3 200 22 R90 100K 22 R12 1K 22 _ _ _ _ _ __ ___ 00011 Sylvania Electric Products Inc Buffalo Operations of Sylvania Elec...

Page 46: ...Sprague Electric Co North Adams Mass 58474 Superior Electric Co The Bristol Corm 71400 Bussmann Mfg Div of McGraw Edison Co St Louis MO 79727 Continental Wirt Electronics Corp Philadelphia Pa 80164 K...

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