Keithley 1801 Instruction Manual Download Page 57

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Service Information

5-3

9. Make sure that the thermal isolation enclosure lid is

in place, and allow two minutes for thermals to settle.

10. Adjust the current offset control (I ZERO) for a

Model 2001 front panel reading of 0µV ± 0.1µV

11. Disconnect the low-thermal resistor when the offset

adjustment is complete.

INPUTS

41V

PEAK

V ZERO

I ZERO

CAUTION:

NO INTERNAL OPERATOR SERVICEABLE PARTS,
SERVICE BY QUALIFIED PERSONNEL ONLY.

KEITHLEY

2mV

PEAK

Low-thermal

Shorting Strap

1801 NANOVOLT PREAMP

Offset Voltage Adjustment

Figure 5-1
Connections for offset voltage adjustment

INPUTS

41V

PEAK

V ZERO

I ZERO

CAUTION:

NO INTERNAL OPERATOR SERVICEABLE PARTS,
SERVICE BY QUALIFIED PERSONNEL ONLY.

KEITHLEY

2mV

PEAK

1801 NANOVOLT PREAMP

Offset Voltage Adjustment

10k

Ω

Low-thermal

Resistor

Figure 5-2
Connections for offset current adjustment

Summary of Contents for 1801

Page 1: ...Model 1801Nanovolt Preamp Instruction Manual A G R E A T E R M E A S U R E O F C O N F I D E N C E...

Page 2: ...NSEQUENTIAL 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 I...

Page 4: ...new Revision is created all Addenda associated with the previous Revision of the manual are incorporated into the new Revision of the manual Each new Revi sion includes a revised copy of this print h...

Page 5: ...s 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 befor...

Page 6: ...nt 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...

Page 7: ...mpatibility 1 3 1 10 Optional accessories 1 3 2 Installation 2 1 Introduction 2 1 2 2 Card configuration 2 2 2 2 1 Preamplifier module 2 2 2 2 2 Power supply card 2 3 2 3 Power supply card preparation...

Page 8: ...entials 3 18 3 4 2 Source resistance noise 3 20 3 4 3 Magnetic fields 3 21 3 4 4 Electromagnetic interference EMI 3 22 3 4 5 Ground loops 3 22 3 4 6 Shielding 3 22 4 Performance Verification 4 1 Intro...

Page 9: ...g 5 12 5 5 1 Troubleshooting equipment 5 12 5 5 2 Troubleshooting access 5 12 5 5 3 Troubleshooting procedure 5 12 6 Replaceable Parts 6 1 Introduction 6 1 6 2 Parts lists 6 1 6 3 Ordering information...

Page 10: ...ons for AC voltage measurements 3 10 Figure 3 4 Connections for 4 wire resistance measurements 3 12 Figure 3 5 Connections for frequency measurements 3 13 Figure 3 6 Connections for differential tempe...

Page 11: ...rformance Verification Table 4 1 Recommended test equipment for performance verification 4 2 Table 4 2 Limits for DC volts verification 4 5 Table 4 3 Limits for AC voltage verification 4 6 5 Service I...

Page 12: ...el 2001 by a factor of 10 000 Low noise Excellent noise rejection ensures minimal noise effects on the measurement Low thermal input connections Copper to copper input connections are used to minimize...

Page 13: ...pping carton and inspect for physical damage Report any such damage to the shipping agent immediately Save the packing carton in case the unit must be shipped in the future NOTE Be careful not to thro...

Page 14: ...ision level may also be displayed by using the front panel MENU GENERAL SERIAL selection If an earlier version is displayed Ann contact your Keithley sales representative regarding an upgrade to your...

Page 15: ...ation Covers connect ing the power supply cable to the card and routing the output leads through the cable clamp 2 4 Card installation and removal Gives the proce dure to install the power supply card...

Page 16: ...en LO and chassis ground is 41V peak Exceeding these limits may result in damage Offset Adjustments V ZERO and I ZERO are externally accessible adjustments for nulling voltage and current offsets resp...

Page 17: ...p provides a strain relief for the output leads and power cable Output Leads The two output leads are terminated with banana plugs intended to connect to the multimeter input jacks Red is HI and black...

Page 18: ...ded to that of the Model 1801 2001 Typ ical common mode current levels for a DMM or chart recorder are several micro amps or higher Power Connections Output Connections To Preamp Figure 2 3 Power and...

Page 19: ...Figure 2 4 Typical analog output connections so pry out the two fasteners then remove the cover plate 2 Slide the power supply card edges into the guide rails inside the multimeter 3 With the ejector...

Page 20: ...le to the power supply card and multimeter Lock card Ejector Arms 2 Unlock card Figure 2 5 Power supply card installation 2 5 1 Power supply connections After installing the power supply in the multim...

Page 21: ...ut connection information specific to the type of measure ment function refer to paragraph 3 3 in Section 3 CAUTION Turn off the Model 2001 Multimeter power before connecting or discon necting the cab...

Page 22: ...panel switch 1801 NANOVOLT PREAMP INPUTS HI LO 41V PEAK V ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK DUT HI LO Low Thermal Input...

Page 23: ...one hour to achieve rated accuracy 2 6 2 Minimum operating distance The Model 1801 preamplifier module should be kept a minimum of two feet away from the Model 2001 Multi meter and other instrumentati...

Page 24: ...he presence of the Model 1801 by display ing the following message if the preamplifier is disabled Preamp OFF If however the preamplifier is enabled at power on the unit will display the following mes...

Page 25: ...llowing message to indicate that the preamplifier is enabled Preamp ON 5 To disable the preamplifier repeat steps 1 through 4 but select DISABLE in the PREAMP CONTROL menu The unit will display the fo...

Page 26: ...eamplifier Input calibration constants NOTE Press CHAN key to access CONFIGURE PREAMP menu See Section 5 for calibration information Table 3 3 Preamp ON OFF states Mode Preamp ON Preamp OFF DCV Range...

Page 27: ...te that only the FAST response filter is available with the ACV and FREQ functions 4 Press EXIT to return to normal display Filter frequency response curves Each of the preamplifier filters exhibits s...

Page 28: ...curves 0 10 20 30 40 50 60 70 80 90 100 0 001 0 01 0 1 1 10 100 1k 10k 100k dB Gain Frequency Hz NOTE Response curves are for preamplifier only Number corresponds to conditions listed in Table 3 4 1 2...

Page 29: ...setup is recalled the Model 1801 operating state assumes the condition dictated by the recalled setup If the setup was stored with the Model 1801 disabled the preamplifier will be disabled when the s...

Page 30: ...preamplifier state SLOW MED or FAST Notes 1 Angle brackets are used to indicate parameter type Do not include brackets in programming message 2 Upper case letters indicate command short form Example...

Page 31: ...ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTE Use only clean copper to copper connect...

Page 32: ...the ends of the leads together Allow suffi cient time for thermal offsets and noise to stabilize 4 Press the REL key The display will read zero 5 Remove the short and connect the input leads to the si...

Page 33: ...ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTE Use only clean copper to copper connect...

Page 34: ...es in ambient temperature given in Appendix A To zero rel the Model 1801 follow the steps below 1 Disable rel if presently enabled by pressing the REL key The REL annunciator should be off 2 Select th...

Page 35: ...TERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTES 1 Use only clean copper to copper connections 2 Sense voltage i...

Page 36: ...VZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTE Use only clean copper to copper connec...

Page 37: ...eady known Note that differential thermocouples can only be mea sured with the Model 1801 installed and enabled other wise pertinent setup menus will not be available Also a differential thermocouple...

Page 38: ...nge and cursor keys then press ENTER and go on to step 11 8 If you selected USER SPECIFIED SLOPE in step 6 the instrument will prompt you to enter the thermo couple slope in V C as follows SLOPE 00020...

Page 39: ...CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK a Input Connections T1 T2 Thermocouples connected in differential configuration Note Connect leads...

Page 40: ...abled the temperature bar graph display limits are reduced to reflect the 50 C tem perature range of the Model 1801 regardless of the normal range of the selected thermocouple type Otherwise the tempe...

Page 41: ...ucer Sense subsystem Temperature path Differential path Select thermocouple type type J K T E R S B USER Return thermocouple type J K T R R S B USER Select thermocouple slope value slope in V C 0 is i...

Page 42: ...ns are taken Figure 3 7 Thermal EMF generation Nanovolt Preamplifier T2 HI LO T1 A B A EAB QAB T1 T2 The thermal EMF developed by dissimilar metals A and B in a series circuit is Temperature of the A...

Page 43: ...fsets can be minimized by using the Model 2001 relative feature to null them out To do so place the instrument on the range to be used for the measurement and short the end of the connecting cable nea...

Page 44: ...of the connecting cables 2 mini mize the exposed circuit area and 3 keep test leads and magnetic field sources stationary As shown in Figure 3 9a a large loop area generates a relatively large voltag...

Page 45: ...to other instrumentation with more than one signal return path such as power line ground As shown in Figure 3 10 the resulting ground loop causes current to flow through the instrument LO signal leads...

Page 46: ...d bus VG Input voltage to the preamplifier is EIN ES I R Resistance of input LO connection typically around 100m Current passing through input LO connection due to ground voltages VG in the ground bus...

Page 47: ...Ground Ground bus VG Input voltage to the preamplifier is EIN ES I R Resistance of input LO connection typically around 100m Current passing through ZCM M or G due to VG and currents in the source mag...

Page 48: ...Covers the tempera ture and humidity limits for verification 4 3 Warm up period Describes the length of time the Model 1801 should be allowed to warm up before testing 4 4 Line power Covers power lin...

Page 49: ...on limits The verification limits stated in this section have been calculated using only Model 1801 one year specifications and they do not include test equipment tolerance If a particular measurement...

Page 50: ...automatically confirmed by verifying the accuracy of the 2mV DC range which is used for temper ature measurements If the Model 1801 is out of specifications and not under warranty refer to the calibra...

Page 51: ...mode and use 2 2V range 262 Low thermal Voltage Divider Input HI HI Red Input LO LO Black b Output Connections 1801 NANOVOLT PREAMP INPUTS 41V PEAK V ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEA...

Page 52: ...ading to settle 11 Verify that the Model 2001 reading is within the lim its summarized in Table 4 2 12 Repeat steps 8 through 11 for the remaining ranges voltages and divider ratios listed in Table 4...

Page 53: ...and make sure that REL is disabled NOTE Do not use REL to null offsets when per forming AC volts tests 6 Set the calibrator output to 450 000 V AC RMS at a frequency of 100Hz and allow the reading to...

Page 54: ...ed Input LO LO Black b Output Connections 1801 NANOVOLT PREAMP INPUTS 41V PEAK V ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK a Inpu...

Page 55: ...the Model 1801 preampli fier power supply card and Model 2001 are cali brated together as a unit The normal calibration method should be used in most cases Gain constants calibration where preamplifi...

Page 56: ...follows A Press the CHAN key B Select CONTROL then press ENTER C Select ENABLE then press ENTER 4 Select the 20 V DC range and allow a two hour warm up period before proceeding with the offset adjust...

Page 57: ...LO 41V PEAK VZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK Low thermal Shorting Strap 1801 NANOVOLT PREAMP Offset Voltage Adjustment...

Page 58: ...n in Figure 5 3 Be sure that the preamplifier module is installed in the thermal isolation enclosure and that the lid is firmly in place 3 Turn on the Model 2001 and the calibrator and allow a two hou...

Page 59: ...tput to 0 20000V DC Output HI Output LO 5700A Calibrator Output DC Volts Sense LO Sense HI Sense HI LO Input Output NOTE Put calibrator in external sense mode and use 2 2V range 262 Low thermal Voltag...

Page 60: ...the process without saving calibration constants press EXIT instead 22 Press EXIT to return to normal display NOTE If an error occurs an appropriate error message will be displayed See the dis cussio...

Page 61: ...end calibration date Request calibration date Send calibration due date Request calibration due date Calculate calibration constants test if they are valid valid range 0 98 to 1 2 Save calibration con...

Page 62: ...on error messages 5 Use the GPIB MENU to set the Model 2001 primary address to the value used in the controller program default 16 6 Set the calibrator to the external sense mode and lock the unit on...

Page 63: ...ts in the new power supply card The basic procedures for reading and storing constants are explained in the following paragraphs Reading gain constants There are three gain constants that are derived...

Page 64: ...nstants are only tempo rary and will be lost when power is cycled unless the CAL UNPR PRE SAVE command is sent to permanently save them 5 3 Principles of operation The following paragraphs discuss the...

Page 65: ...ost regulation filter ing is provided by C102 and C103 To 2001 Gain Filter Switching Memory Supply 2 Preamp Power Supply 1 Common Mode Current Cancellation Circuit LO To 2001 Input HI Power Supply Car...

Page 66: ...ile working with these devices 3 Handle the devices only by the body do not touch the pins or terminals 4 Any printed circuit board into which the device is to be inserted must first be grounded to th...

Page 67: ...le square wave Referenced to digital common P1034 pin 1 2 T102 pin 6 0 2V p p rounded square wave Referenced to 3 U104 pin 1 8 5V DC 10 Referenced to 4 U105 pin 2 8 5V DC 10 Referenced to 5 U108 pin 7...

Page 68: ...number 1801 Serial number Part description Circuit description if applicable Keithley part number 6 4 Factory service If the preamplifier is to be returned to Keithley Instru ments for repair perform...

Page 69: ...R FILM RES 470 5 1 4W COMPOSITION OR FILM RES 4 7K 5 1 4W COMPOSITION OR FILM RES 26 7K 1 1 8W METAL FILM RES 649K 1 1 8W METAL FILM RES 110K 1 1 8W METAL FILM RES 1K 5 1 4W COMPOSITION OR FILM RES 33...

Page 70: ...R BOTTOM CABLE CLAMP SHIELDED COVER BOTTOM STRIP POLYURETHANE SHIELDED COVER TOP SHIELDED COVER TOP SHIELD SCANNER BOTTOM INSULATOR BOTTOM SHIELD TOP CARD EJECTOR PLASTIC THERMAL ENCLOSURE W PACKING M...

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Page 72: ......

Page 73: ...A Specifications A 1...

Page 74: ......

Page 75: ......

Page 76: ......

Page 77: ...5700A calibrator connect the calibrator to the IEEE 488 bus as well Be sure to use shielded IEEE 488 cables for bus connections 2 Turn on the computer the Model 2001 and the cali brator Allow the Mod...

Page 78: ...tor to external sense 0V DC output PRINT Place calibrator in operate mode PRINT PRINT Set 262 polarity to POS position PRINT Wait two minutes for thermals to settle GOSUB KeyCheck FOR I 1 TO 7 Loop fo...

Page 79: ...INPUT 2 E Err IF E 0 THEN PRINT If error is detected error PRINT Err is displayed and program PRINT Calibration aborted is halted BEEP CLOSE 1 CLOSE 2 END END IF RETURN Dly Delay routine T TIMER Lp I...

Page 80: ...s10k 200e 6 cal unpr pre fs1k 2e 3 cal unpr pre calc void keypress errcheck checkopt char date 10 int i calend if ieeeinit 1 printf Cannot initialize interface n exit 1 ieeewt remote 16 n Put 2001 in...

Page 81: ...printf Calibration completed n void keypress Wait for keypress printf Press any key to continue n while kbhit 0 getch int calend n Check for cal end int n char status 40 int stat printf Waiting for ca...

Page 82: ...tion Programs B 6 Program B 2 Calibration Program for Use with Any Suitable Calibrator Turbo C Version Continued ieeerd buf if strstr buf 1801 NULL printf Model 1801 is not installed program aborted n...

Page 83: ...range PRINT 1 OUTPUT 04 RANGELCK ON Lock range PRINT 1 OUTPUT 04 OUT 0V 0 HZ Output 0V PRINT 1 OUTPUT 04 OPER Put calibrator in operate PRINT 1 OUTPUT 04 EXTSENSE ON Enable external sense PRINT PRINT...

Page 84: ...6 SYST ERR Query error queue PRINT 1 ENTER 16 INPUT 2 E Err IF E 0 THEN PRINT If error is detected error PRINT Err is displayed and program PRINT Calibration aborted is halted BEEP CLOSE 1 CLOSE 2 END...

Page 85: ...date 10 int i calend if ieeeinit 1 printf Cannot initialize interface n exit 1 ieeewt remote 16 n Put 2001 in remote ieeewt remote 04 n Put 5700A in remote ieeewt clear n Send DCL ieeewt term lf eoi n...

Page 86: ...output 16 cal unpr pre ndue s n date ieeewt output 16 cal unpr pre save n printf Calibration completed n void keypress Wait for keypress printf Press any key to continue n while kbhit 0 getch int cal...

Page 87: ...B 4 Calibration Program for Use with Fluke 5700A Calibrator Turbo C Version Continued char buf 40 ieeewt output 16 opt n ieeewt enter 16 n ieeerd buf if strstr buf 1801 NULL printf Model 1801 is not i...

Page 88: ...preamp lter response Name SLOW MEDium FAST Returns preamp lter state SLOW MED or FAST SENSe 1 TEMPerature DTCouple TYPE type TYPE USLope value USLope RTEMperature value RTEMperature TRANsducer DTC TR...

Page 89: ...o Measure 20 V range zero Measure 2mV range full scale value 1E 3 to 2E 3 Measure 200 V range full scale value 100E 6 to 200E 6 Measure 20 V range full scale value 10E 6 to 20E 6 Send calibration date...

Page 90: ...2 Introduction 1 1 2 1 3 1 4 1 5 1 6 1 B 1 L Line power 4 2 5 2 M Magnetic fields 3 21 Manual addenda 1 2 Measurement considerations 3 18 Measurements 3 7 Minimum operating distance 2 9 Model 2001 com...

Page 91: ...ve devices 5 12 Specifications 1 2 A 1 T Thermoelectric potentials 3 18 Troubleshooting 5 12 Troubleshooting access 5 12 Troubleshooting equipment 5 12 Troubleshooting procedure 5 12 U Unpacking and i...

Page 92: ...nstable Will not read applied input Overload Calibration only Certi cate of calibration required Data required attach any additional sheets as necessary Show a block diagram of your measurement system...

Page 93: ...se 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 7500 Fax 0118 929 7519 INDIA Flat 2B Willocrissa 14 Rest Hous...

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