Page 1: ...1 INSTRUCTION MANUAL MODEL 155 NULL DETECTOR MICROVOLTMETER K E I T Pi LE Y I IST S T P U AP E IST TS...
Page 2: ...l be given assist ance and shipping instructions re S REPAIRS AND RECALIBRATiON Keithley Instruments maintains a complete re pair service and standards laboratory in Cleve land and hasan authorized fi...
Page 3: ...MODEL 155 CONTENTS CONTENTS Section Page j CAiiui s 2 OPERATION 5 8 4 SERVICING 5 GALIBRATION 18 6 ACCESSORIEb 7 REPLACEABLE PARTS 0373...
Page 4: ...le up to 1200 volts peak will not affect reading equivalent to 140 dB CMRR ISOLATION Greater than IO12 ohms shunted by 0 01 microfarad between chassis ground case and input low RISE TIME 10 90 Less th...
Page 5: ...the Model 1554 Power Sup ply is a convenient accessory It attaches to the rear panel of the instrument and its output may be connected to the barrier strip provided also on the rear panel A switch on...
Page 6: ...h terminal and indicates the paragraph which contains instructions on the use Control Functional Description Paragraph GUARD Provides alternate connection to ground 2 2 OUTPUT HI Provides output volta...
Page 7: ...ommon between the positive and negative internal supplies is connected directly to the OUTPUT LO Terminal Power to operate the Model 155 must be applied to the OUTPUT LO POWER INPUT and POWER INPUT Te...
Page 8: ...or sensitive meas urements other external considerations besides the Model 155 will affect the accuracy Effects not noticeable when working with higher voltages are very important with microvolt signa...
Page 9: ...s divided to a deter mined ratio by the Range Switch Resistors A MOS FET chopper converts this dc input signal to an ac signal The ac signal is amplified demodulated dc amplified and applied to the me...
Page 10: ...ampere of out put current 2 The dc amplifier is composed of three differ ential amplifiers and emitter follower The sig nal from the output of the demodulator is applied to the first differential dc a...
Page 11: ...carbon batteries The idling current of the Model 155 is approximately 500 microamperes Thus the battery life for most applications will be the same as the battery shelf life If the record er output is...
Page 12: ...155 is indeed faulty Once this is determined turn the Microvoltmeter Power Switch to OFF and gath er the tools and instruments that may be necessary to disassemble troubleshoot repair and reassemble...
Page 13: ...eres is present then there is a short circuit between the battery leads in the Power Switch 2 If the 3 milliamperes cannot be obtained then there is a shorted component loading the supplies Replace th...
Page 14: ...put fil ter b If there is a signal replace QlOl and Q102 c After repairing the fault and or replac ing QlOl and Q102 replace the gate leads NOTE Defective input FETs QlOl and Q102 may be the cause of...
Page 15: ...both cases then the fault lies in the dc amplifier circuit Find the fault and repair it 3 To localize the trouble in the dc amplifier refer to Figure 7 It shows test points within the dc amplifier cir...
Page 16: ...Switch to OFF NOTE See paragraph 2 3 also for checking the condition of the batteries 5 3 PRELIMINARY CALIBRATION PROCEDURES a Make sure that Offset Current Suppress Poten tiometer R109 is at least o...
Page 17: ...millivolt through 1 volt ranges 5 7 METER CALIBRATION a Connect the Model 241 Voltage Supply to the Model 155 input and connect the output to the Model 7050 DVM b Set the Model 155 RANGE Switch to 1 V...
Page 18: ...m across the input 5 12 DRIFT CHECK FIGURE 8 Typical 10 90 Rise Time on 100 Micro volt Range Scale is 20 mV cm vertical and 0 1 sec cm horizontal a Connect the Model 370 Recorder to the Model 155 Set...
Page 19: ...MODE REJECTION CHECK 5 14 NORMAL MODE REJECTION CHECK a Use the same setup as in paragraph 5 14 ex cept apply the signal between the high and CASE Terminals and connect the high and low Termi nals tog...
Page 20: ...113 C115 QUO Q109 cm C106 Q104 ci05 C107 Q103 I Iti i Ari 6 QlOl Q102 C122 C104 C103 C102 Q106 C109 ClOl Q105 Clio C116 Did D102 C118 D107 C112 Q117 Q116 Q118 Q119 C114 Q108 C119 Dice FIGURE 11 Compon...
Page 21: ...r switch R105 R103 r122 RlOl R174 r179 R147 r176 r148 R166 r162 R150 r160 r158 R154 R184 3 1 Hl mm umw ma I R143 R128 R129 R142 RllO R133 Rill R172 R135 R138 _ J r14i _ R108 ii EJ R107 R188 R168 R183...
Page 22: ...mounting kit with overall dimensions 7 inches high x 19 inches wide x 6 3 4 inches deep Application The Model 1001 converts the instrument from bench mounting to rack mounting It is suitable for moun...
Page 23: ...s OUTPUT 18 Volts Nominal ISOLATION Greater than 10 ohms to ground or line at up to 507 relative humidity and 25 C less than 0 2 picofarad coupling to line CONTROLS Switch three position LINE OFF BATT...
Page 24: ...c CMRR Greater than 120 dB at dc greater than 100 dB up to 1 kHz OUTPUT 1 volt at up to 1 milliampere 1007o over range OUTPUT ISOLATION Greater than 10 ohms shunted by less than 0 001 microfarad POWER...
Page 25: ...ired Reference volt F farad No Number W ww watt Wirewound MODEL 155 REPLACEABLE PARTS LIST Rsfsr to Schematic Diagram 22354E for circuit designations BATTERIES Circuit Desig Description Mfg Code Mfg P...
Page 26: ...P59 500K R12 4 42M R12 4 42M RP59 3 5M R13 44M 12 12 12 12 12 R106 R107 R108 R109 RllO 44 12 kfi 12 kf 1 Mfi 109 1 1 W 10 1 2 W 10 1 2 W 20 0 75W 20 1 2 W DCb Comp Comp Cermet Comp 91637 01121 01121 7...
Page 27: ...1 4 W Comp 01121 CB R76 150K 12 R158 1 5 ka 10 1 4 W Comp 01121 CB R76 1 5K 12 R159 330 ka 10 1 4 W Comp 01121 CB R76 330K 12 R160 330 ka 10 1 4 W Comp 01121 CB R76 330K 12 R161 560 ka 10 1 4 W Comp 0...
Page 28: ...9 04713 TG 62 Q107 2N5089 04713 TG 62 Q108 A642L 73445 TG 64 Q109 2N5087 04713 TG 61 QUO 2N5087 04713 TG 61 Qlll 2N5089 04713 TG 62 Q112 2N5089 04713 TG 62 Q113 2N5089 04713 TG 62 Q114 2N5089 04713 TG...
Page 29: ...4 TlOl Transformer 80164 TR 122 RESISTORS Circuit Mfg Mfg Keithley Fig Desiq Value Rating Type Code Part No Part No Ref RlOl 1 kn 10 1 2 W Comp 01121 EE Rl IK 15 R102 4 7 kn 10 1 2 W Comp 01121 EE R1...
Page 30: ...ssembly 22673B 13 2 Cover Sheet Metal 1 22585C 3 Screws 4 Handle Assembly 13 11 Handle 1 HH 18 12 Screws 6 32 x 3 8 R H Slotted 2 Feet Assembly 14 4 Feet 4 FE 5 5 Ball 4 FE 6 6 Screws 8 32 x 3 8 Phill...
Page 31: ...MODEL 155 REPLACEABLE PARTS FIGURE 13 Cover Assembly FIGURE 14 Chassis Bottom View 0472 27...
Page 32: ...p 401 North Broad Street Semiconductor Division Philadelphia Pennsylvania 19108 313 Frontage Road Mountain View California 75915 Littlefuse Inc 800 E Northwest Hwy 07716 IRC Inc Des Plaines 111 60016...
Page 33: ...Calibration Equipment at the factory I 1 Certificate of Compliance 3 DESCRIPTION OF PROBLEM Include a block diagram of instruments connected in system Recorder charts or other data would be helpful Is...
Page 34: ...5 Model 5155 10 50 Model 5155 10 50 Model 5155 101 0 50 Model 5155 101 1 Model 5155 10 13 Model 5155 10 60 60 80 2 Calibration Report This report shows only the cardinal range terminal dial etc errors...
Page 35: ...n is supplied as a supplement to this Manual in order to provide the user with the latest improvements and corrections in the shortest possible time Many users will transfer this change information di...
