Keithley 2701 Service Manual
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Keithley 2701 Service Manual

Ethernet-based dmm / data acquisition system
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Model 2701 Ethernet-Based
DMM / Data Acquisition System

Service Manual

2701-902-01 Rev. B / December 2018
*P2701-902-01B*
2701-902-01B

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  • Page 1: Service Manual

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2701-902-01 Rev. B / December 2018 *P2701-902-01B* 2701-902-01B...
  • Page 2 All rights reserved. Any unauthorized reproduction, photocopy, or use of the information herein, in whole or in part, without the prior written approval of Keithley Instruments, LLC, is strictly prohibited. These are the original instructions in English. All Keithley Instruments product names are trademarks or registered trademarks of Keithley Instruments, LLC.

  • Page 3: Safety Precautions

    Keithley products are designed for use with electrical signals that are measurement, control, and data I/O connections, with low transient overvoltages, and must not be directly connected to mains voltage or to voltage sources with high transient overvoltages.
  • Page 4 (note that selected parts should be purchased only through Keithley to maintain accuracy and functionality of the product). If you are unsure about the applicability of a replacement component, call a Keithley office for information.

  • Page 5: Table Of Contents

    Restoring factory defaults ....................1-4 Performing the verification test procedures ................. 1-5 Verification test summary ......................1-5 Test considerations ........................1-6 Model 2701 verification ......................1-6 Verifying DC voltage ......................... 1-7 Verifying AC voltage ........................1-9 Verifying DC current ........................ 1-10 Verifying AC current ........................
  • Page 6 Table of contents Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Manufacturing calibration ....................2-18 Recommended test equipment ....................2-19 Calibration card preparation ....................2-19 Unlocking manufacturing calibration ..................2-19 Measuring function generator signal amplitude ............... 2-19 Front panel manufacturing calibration ..................2-20 Remote manufacturing calibration ...................
  • Page 7 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Table of contents Handling PC boards ........................5-1 Solder repairs ..........................5-2 Static sensitive devices ......................5-2 Assembly drawings ......................5-3 Disassembly procedures ...................... 5-3 Case cover removal ........................5-3 Motherboard removal ........................
  • Page 8 Table of contents Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual :CALibration:PROTected:NDUE ....................8-7 :CALibration:PROTected:SAVE ....................8-7 DC calibration commands ....................8-8 :CALibration:PROTected:DC:STEP<step> ................8-9 AC calibration commands ....................8-10 :CALibration:PROTected:AC:STEP<step>................8-11 Manufacturing calibration commands ................8-12 :CALibration:PROTected:AC:STEP<14|15> ................8-12 :CALibration:PROTected:DC:STEP0 ..................

  • Page 9: Performance Verification

    If the instrument is still under warranty and its performance is outside specified limits, contact your Keithley representative or the factory to determine the correct course of action. If the unit is not under warranty and it fails to meet specified limits, refer to the calibration procedures in the next section.

  • Page 10: Verification Test Requirements

    Line power The 2701 requires a line voltage of 100 V/120 V/220 V/240 V ±10% and a line frequency of 45 Hz to 66 Hz or 360 Hz to 440 Hz. Note that the line frequency is automatically sensed at power-up, but the line voltage must be manually set to either 100 V/120 V or 220 V/240 V.

  • Page 11: Recommended Test Equipment

    5700A calibrator is adequate for most applications. Verification limits The verification limits stated in this section have been calculated using only the 2701 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 2701 specifications and pertinent calibration equipment specifications.

  • Page 12: Example Reading Limit Calculation

    For example, assume that you are testing the 10 kΩ range using an actual 10.03 kΩ calibration resistance value. Using 2701 one-year 10 kΩ range accuracy of ± (100 ppm of reading + 6 ppm of range), the calculated reading limits are: Reading limits = 10.03 kΩ...

  • Page 13: Performing The Verification Test Procedures

    Section 1: Performance verification Performing the verification test procedures Verification test summary Verification tests can be performed either through the 2701 front panel terminals or through plug-in modules. This section contains the following procedures: • 2701 verification — Use this procedure to test 2701 accuracy through the front panel terminals.

  • Page 14: Test Considerations

    • Do not use autoranging for any verification tests, because autorange hysteresis may cause the 2701 to be on an incorrect range. For each test signal, you must manually set the correct range for the 2701 using the range keys.

  • Page 15: Verifying Dc Voltage

    To verify DC voltage accuracy: 1. Connect the 2701 HI and LO INPUT jacks to the DC voltage calibrator as shown in the next figure. Make sure the INPUTS switch is set to the FRONT position.
  • Page 16 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2. Select the DC volts function by pressing the DCV key and set the 2701 to the 100 mV range. 3. Set the calibrator output to 0.00000 mV DC and allow the reading to settle.

  • Page 17: Verifying Ac Voltage

    Damage to your instrument may occur. To verify AC voltage accuracy: 1. Connect the 2701 HI and LO INPUT jacks to the AC voltage calibrator as shown in the next figure. Be sure the INPUTS switch is in the FRONT position.

  • Page 18: Verifying Dc Current

    To verify DC current accuracy: 1. Connect the 2701 AMPS and INPUT LO jacks to the calibrator as shown in the next figure. Be sure that the INPUTS switch is in the FRONT position and the calibrator is set for normal current output.

  • Page 19: Verifying Ac Current

    AC current calibrator to the 2701 input, verifying that the displayed readings fall within specified limits. To verify AC current accuracy: 1. Connect the 2701 AMPS and INPUT LO jacks to the calibrator as shown in the next figure. Be sure the INPUTS switch is in the FRONT position.

  • Page 20: Verifying Resistance

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Verifying resistance Check resistance by connecting accurate resistance values to the 2701 and verifying that its resistance readings are within the specified limits. Do not apply more than 1000 V...
  • Page 21 3. Select the 2701 4-wire resistance function by pressing the Ω4 key, then choose the SLOW integration rate with the RATE key. 4. Set the 2701 for the 100 Ω range and make sure the FILTER is on. Enable OCOMP (offset-compensated ohms) for 100 Ω range verification. (Press SHIFT then OCOMP.) 5.

  • Page 22: Verifying Temperature

    1. Connect the DC voltage calibrator output terminals to the 2701 INPUT jacks using low-thermal, shielded, 2-wire connections. Be sure the INPUTS switch is in the FRONT position. 2. Configure the 2701 for °C units, type J temperature sensor, and 0 °C simulated reference junction: Press SHIFT then SENSOR and note the unit displays the temperature units: UNITS: C.
  • Page 23 RTD temperature To verify the RTD temperature: 1. Connect the precision decade resistance box to the 2701 INPUT and SENSE jacks using four- wire connections. Be sure the INPUTS switch is in the FRONT position. 2. Configure the 2701 temperature function for °C units and RTD temperature sensor (α=0.00385): Press SHIFT then SENSOR and note the unit displays the temperature units: UNITS: C.

  • Page 24: Verifying Frequency

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Verifying frequency To verify the 2701 frequency function: 1. Connect the function generator to the 2701 INPUT jacks. Be sure the INPUTS switch is in the FRONT position. Figure 7: Connections for 2701 2.

  • Page 25: Verifying Dc Voltage

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 1: Performance verification Verifying DC voltage Check DC voltage accuracy by applying accurate voltages from the DC voltage calibrator to the 7700 input terminals and verifying that the displayed readings fall within specified limits.
  • Page 26 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2. Install the 7700 in slot 1 of the 2701, then 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.

  • Page 27: Verifying Ac Voltage

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 1: Performance verification Verifying AC voltage Check AC voltage accuracy by applying accurate AC voltages at specific frequencies from the AC voltage calibrator to the 7700 inputs and verifying that the displayed readings fall within specified ranges.

  • Page 28: Verifying Dc Current

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2. Install the 7700 in Slot 1 of the 2701, then 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.

  • Page 29: Verifying Ac Current

    Section 1: Performance verification 2. Install the 7700 in Slot 1 of the 2701, then 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.

  • Page 30: Verifying Resistance

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2. Install the 7700 in slot 1 of the 2701, then 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.
  • Page 31 Section 1: Performance verification 2. Install the 7700 in slot 1 of the 2701, then 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.

  • Page 32: Verifying Temperature

    Section 1: Performance verification Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 9. Disable external sense on the calibrator. 10. Set the 2701 for the 100 MΩ range. 11. Source a nominal 100 MΩ resistance value and verify that the reading is within calculated limits for the 100 MΩ...
  • Page 33 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 1: Performance verification Thermocouple temperature To verify the thermocouple temperature: 1. Connect the DC voltage calibrator output terminals and ice point reference to the 7700 CH1 H and L INPUT terminals using low-thermal shielded connections, as shown in the next figure.
  • Page 34 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2. Install the 7700 in slot 1 of the 2701, then 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.

  • Page 35: Verifying Frequency

    2. Install the 7700 in slot 1 of the 2701, then 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.

  • Page 36: Verifying Ratio And Average

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual 2. Install the 7700 in Slot 1 of the 2701, 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.

  • Page 37: Calibration

    Comprehensive calibration ............2-4 Manufacturing calibration ............2-18 Model 7700 calibration ............2-21 Introduction Use the procedures in this section to calibrate the 2701. Calibration procedures include: • Comprehensive calibration: Usually the only calibration required in the field. • Manufacturing calibration: Usually only performed at the factory (unless the unit has been repaired).

  • Page 38: Warm-Up Period

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Warm-up period Allow the 2701 Ethernet-Based DMM / Data Acquisition System to warm up for at least two hours before performing calibration. If the instrument has been subjected to temperature extremes (those outside the ranges stated above), allow extra time for the instrument’s internal temperature to stabilize.

  • Page 39: Calibration Considerations

    • Always let the source signal settle before calibrating each point. • If an error occurs during calibration, the 2701 will generate an appropriate error message. 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.

  • Page 40: Front Panel Calibration Code

    4. Press ENTER to confirm the code. 5. The 2701 allows you to define a new calibration code. Use the up and down range keys to toggle between yes and no. Choose N if you do not want to change the code. Choose Y if you want to change the code.

  • Page 41: Calibration Cycle

    ABORT CAL? Press EXIT to abort calibration at this point or press any other key to return to the calibration process. The 2701 will not respond to any remote programming commands while the ABORT CAL? message is displayed. 2701-902-01 Rev. B / December 2018...

  • Page 42: Front Panel Calibration

    Preparing the Model 2701 for calibration To prepare the 2701 for calibration: 1. Turn on the 2701 and allow it to warm up for at least two hours. 2. Start the calibration process: Access the calibration menu by pressing SHIFT then TEST, then display TEST: CALIB using the up or down range key.

  • Page 43: Front Panel Short And Open Calibration

    Section 2: Calibration Front panel short and open calibration At the 2701 prompt for a front panel short, perform the following: 1. Connect the 8610 low-thermal short to the instrument front panel INPUT and SENSE terminals as shown in the next figure. Make sure the INPUTS button is not pressed in so that the front inputs are selected.
  • Page 44 Wait until the 2701 finishes each step. The unit will display CALIBRATING while calibrating. If your calibrator cannot output the values recommended in the next table, use the left and right arrow keys and the up and down range keys to set the 2701 display value to match the calibrator output voltage.
  • Page 45 Set the calibrator to the indicated value and place the unit in operate. (If the calibrator cannot output the exact resistance value, use the 2701 left and right arrow keys and the range keys to adjust the display to agree with the actual calibrator resistance.
  • Page 46 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual DC current calibration To perform DC current calibration: 1. Connect the calibrator to the AMPS and INPUT LO terminals of the 2701 as shown in the next figure. Figure 19: Connections for DC and AC current calibration 2.
  • Page 47 AC voltage calibration To perform AC voltage calibration: 1. Connect the calibrator to the 2701 INPUT HI and LO terminals as shown in the next figure. Figure 20: Connections for AC voltage calibration 2. Perform the calibration steps summarized in the next table. For each step: Set the calibrator to the indicated value and make sure the calibrator is in OPERATE.
  • Page 48 After the 700 VAC at 1 kHz point has been calibrated, the unit will prompt you for 100 mA at 1 kHz. To perform AC current calibration: 1. Connect the calibrator to the AMPS and INPUT LO terminals of the 2701 as shown in DC current calibration (on page 2-10).

  • Page 49: Remote Calibration

    1. Connect the 2701 to the ethernet or connect the unit to a computer through the RS-232 port. 2. Turn on the 2701 and allow it to warm up for at least two hours before performing calibration. 3. Unlock the calibration function by sending :CAL:PROT:CODE 'KI002701'.

  • Page 50: Short And Open Calibration

    2. Send the :CAL:PROT:DC:STEP1 command. 3. After the 2701 completes this step, remove the low-thermal short and then send the :CAL:PROT:DC:STEP2 command. Be sure to minimize movement near front Input terminals. Excessive movements can cause capacitive coupling errors.
  • Page 51 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 2: Calibration 2. Perform the calibration steps summarized in the next table. For each step: Set the calibrator to the indicated voltage and make sure the unit is in operate. Use the recommended voltage, if possible.
  • Page 52 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual DC current calibration To perform DC current calibration: 1. Connect the calibrator to the AMPS and INPUT LO terminals of the 2701 as shown in DC current calibration (on page 2-10).
  • Page 53 700 VAC at 1 kHz 700.000 V, 1 kHz AC current calibration To perform AC current calibration: 1. Connect the calibrator to the AMPS and INPUT LO terminals of the 2701 as shown in DC voltage calibration (on page 2-8).

  • Page 54: Programming Calibration Dates

    Section 2: Calibration Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Programming calibration dates Program the present calibration date and calibration due date by sending the following commands: :CAL:PROT:DATE <year>, <month>, <day> :CAL:PROT:NDUE <year>, <month>, <day> For example, the following commands assume calibration dates of 12/15/1999 and 12/15/2000...

  • Page 55: Recommended Test Equipment

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 2: Calibration Recommended test equipment The next table summarizes the test equipment required for the manufacturing calibration steps. In addition, you will need a calibrator and a signal generator to complete the comprehensive calibration steps.

  • Page 56: Front Panel Manufacturing Calibration

    Comprehensive calibration (on page 2-4). 8. Connect the function generator to the 2701 front panel INPUT jacks as shown in the next figure. Select the front input jacks with the INPUTS switch. Figure 21: Function generator connections for manufacturing calibration 9.

  • Page 57: Remote Manufacturing Calibration

    Comprehensive calibration (on page 2-4). 7. Connect the function generator to the 2701 INPUT jacks. Select the front input jacks with the INPUTS switch. 8. Set the generator to output a 1 V RMS, 3 Hz sine wave, then send :CAL:PROT:AC:STEP14 <Cal_voltage>.

  • Page 58: Recommended Test Equipment

    After turning on the power during the calibration procedure, complete the procedure as quickly as possible to minimize card heating that could affect calibration accuracy. Allow the 2701 to warm up for at least two hours. Front panel Model 7700 calibration To calibrate the 7700 from the front panel: 1.
  • Page 59 3. Accurately measure and record the cold temperature of the 7700 card surface at the center of the card. 4. Press and hold the 2701 OPEN key while turning on the power. 5. Enable calibration by sending the :CODE command. The default command is :CAL:PROT:CODE 'KI002701'.

  • Page 60: Routine Maintenance

    The information in this section deals with routine maintenance and includes procedures for setting the line voltage, replacing the 2701 line and front terminal AMPS fuses, and replacing the amps fuses for the 7700 plug-in module. Replacement of the 2701 non-volatile RAM battery and module relay closure count is also covered.
  • Page 61 Section 3: Routine maintenance Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual The power line fuse is located in the power module next to the AC power receptacle. See the next figure. Figure 22: Power module 2701-902-01 Rev. B / December 2018...
  • Page 62 Operating the 2701 with the wrong line voltage selected may result in instrument damage. 4. Install the fuse holder assembly into the power module by pushing it in until it locks in place.

  • Page 63: Replacing The Front Terminal Amps Fuse

    Release pressure on the jack and its internal spring will push the fuse carrier out of the socket. 3. Remove the fuse and replace it with the same type: 3 A, 250 V, fast-blow, Keithley part number FU-99-1.

  • Page 64: Replacing Model 7700 Plug-In Module Amps Fuses

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 3: Routine maintenance Replacing Model 7700 plug-in module amps fuses The information in this section is intended only for qualified service personnel. Do not perform these procedures unless you are qualified.

  • Page 65: Replacing Non-Volatile Ram Battery

    9. Re-install the circuit board into the plastic housing, then close the top cover. Replacing non-volatile RAM battery The 2701 has a rechargeable lithium ion battery for non-volatile RAM. Use the procedure below to replace the battery, if required. Refer to...

  • Page 66: Plug-In Module Relay Closure Count

    J900. Plug-in module relay closure count The 2701 keeps an internal count of the number of times each module relay has been closed. This count will help you determine if and when any relays require replacement (see module contact life specifications).

  • Page 67: Reading Relay Closure Count

    :ROUT:CLOS:COUN? (@101:110) Resetting relay closure count The 2701 must be in the manufacturing calibration mode to reset the closure count. To do so, press and hold the OPEN key while turning on the power, then send the :CAL:PROT:CODE code to unlock calibration (KI002701).

  • Page 68: Setting Count Update Interval

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 3: Routine maintenance Setting count update interval Relay closure counts are updated in temporary RAM every time a channel is closed regardless of how it was closed: by a SCPI command, front panel control, or during a scan. These counts are permanently written to the EEPROM on the card only at a user-settable time interval (which has a factory default of 15 minutes) or whenever the counts are queried.
  • Page 69 Circuit troubleshooting ............4-13 Introduction This section of the manual will assist you in troubleshooting and repairing the 2701. Included are self-tests, test procedures, troubleshooting tables, and circuit descriptions. It is left to the discretion of the repair technician to select the appropriate tests and documentation needed to troubleshoot the instrument.

  • Page 70: Troubleshooting

    Power-on self-tests RAM and EPROM tests During the power-on sequence, the 2701 will perform a checksum test on its EPROM and test its RAM. If the RAM tests fails, the instrument will lock up. 2701-902-01 Rev. B / December 2018...

  • Page 71: Flash Memory Tests

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Flash memory tests After the RAM and EPROM tests, the instrument will perform a checksum test on flash memory. If a failure occurs, the unit will perform the comprehensive tests summarized in the next table. If a failure occurs, an error message will be displayed, and the unit will automatically enter the firmware upgrade mode (as indicated by "FW UPGRADE"...

  • Page 72: Disp Test

    Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual DISP test The display test allows you to verify that each segment and annunciator in the vacuum fluorescent display is working properly. To run the display test: 1.

  • Page 73: Power Supply

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Power supply The following information provides some basic circuit theory that can be used as an aid to troubleshoot the power supply. A block diagram of the power supply is shown in the next figure.

  • Page 74: Display Board

    Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual AC power is applied to the AC power module receptacle. Power is routed through the line fuse and line voltage selection switch of the power module to the power transformer. The power transformer has a total of four secondary windings for the various supplies.
  • Page 75 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Microcontroller U401 is the display board microcontroller that controls the display and interprets key data. The microcontroller uses three internal peripheral I/O ports for the various control and read functions.

  • Page 76: Digital Circuitry

    Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Display DS401 is the display module, which can display up to 12 alpha-numeric characters and includes the various annunciators. The display uses a common multiplexing scheme with each character refreshed in sequence. U402 and U403 are the drivers for the display characters and annunciators.

  • Page 77: Real Time Clock

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Real time clock U7 is the real time clock. The clock runs from main power and switches to two 0.33 F capacitors (C43, C44) on power down and can hold the time for up to six months.
  • Page 78 Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual INPUT HI INPUT HI protection is provided by the SSP (Solid State Protection) circuit. The SSP is primarily made up of Q101 and Q102. An overload condition opens Q101 and Q102, which disconnects the analog input signal from the rest of the analog circuit.
  • Page 79 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Figure 27: Analog circuitry block diagram 2701-902-01 Rev. B / December 2018 4-11...
  • Page 80 Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Ohms open-lead sense detection There are two types of open sense lead detect. See the next figure. The first is for the INPUT HI and INPUT LO leads. For these leads, the open sense detection is implemented in hardware. A comparator circuit monitors the voltage at the INPUT HI lead output and will trip the OVLD detect circuit when the voltage level exceeds an appropriate value for the particular range.

  • Page 81: Circuit Troubleshooting

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Circuit troubleshooting Troubleshooting information for the various circuits is summarized below. See Principles of operation (on page 4-4) for circuit theory. Display board checks If the front panel DISP tests show a failure, troubleshoot the display board using the following table.

  • Page 82: Digital Circuitry Checks

    Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Digital circuitry checks Digital circuit problems can be checked using the following table. Step Item/component Required condition Remarks Power-on test RAM OK, ROM OK. Verify that RAM and ROM are functional.

  • Page 83: Analog Signal Switching States

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting Analog signal switching states The following tables provide switching states of the various relays, FETs, and analog switches for the basic measurement functions and ranges. These tables can be used to assist in tracing an analog signal from the input to the A/D multiplexer.
  • Page 84 Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Ω4 signal switching Range Q101 Q102 Q114 Q136 Q109 K101* Q113 Q105 Q104 Q108 100 Ω 1 kΩ 10 kΩ 100 kΩ 1 MΩ 10 MΩ 100 MΩ...
  • Page 85 Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 4: Troubleshooting The following tables can be used to trace the analog signal through the A/D multiplexer (U163) to the final amplifier stage. These tables show the MUX lines (S3, S4, S6, S7) that are selected for measurement during the SIGNAL phase of the multiplexing cycle.
  • Page 86 Section 4: Troubleshooting Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Ω4 signal multiplexing and gain Signal U129 U129 U129 Gain Range (U163) pin 1 pin 8 pin 9 (U166) 100 Ω S4 then S7 ×100 1 kΩ...

  • Page 87: Disassembly

    Assembly drawings ..............5-3 Disassembly procedures ............5-3 Instrument reassembly ............. 5-6 Introduction This section explains how to handle, clean, and disassemble the 2701 Ethernet Multimeter/Data Acquisition System. Use the Assembly drawings (on page 5-3) located at the end of this section to assist you when disassembling and reassembling the instrument.

  • Page 88: Solder Repairs

    Use the following precautions to avoid damaging them: Many CMOS devices are installed in the 2701. Handle all semiconductor devices as being static sensitive.

  • Page 89: Assembly Drawings

    Section 5: Disassembly Assembly drawings Use the following assembly drawings to assist you as you disassemble and reassemble the 2701. Also, refer to these drawings for information about the Keithley Instruments part numbers of most mechanical parts in the unit.

  • Page 90: Motherboard Removal

    Section 5: Disassembly Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Motherboard removal To remove the motherboard: 1. Make sure that the case cover is already removed. See Case cover removal (on page 5-3). 2. Remove the nuts securing the RS-232 and Digital I/O connectors to the rear panel. Remove these nuts.

  • Page 91: Front Panel Disassembly

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 5: Disassembly Front panel disassembly To remove the display board and the pushbutton switch pad: You must first remove the case cover, the front/rear input switch, and the front input terminal wires.

  • Page 92: Instrument Reassembly

    Section 5: Disassembly Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Power module removal To remove the power module: 1. Remove the motherboard. 2. Remove the POWER switch rod. 3. Remove the card cage. 4. Disconnect the power module ground wire. This green and yellow wire connects to a threaded stud on the chassis with a Keps nut.

  • Page 93: Input Terminal Wire Connections

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 5: Disassembly Input terminal wire connections You can use the following table during reassembly to connect the input terminal wires. Input terminal Wire color INPUT HI INPUT LO Black...

  • Page 101: Replaceable Parts

    Factory service ................. 6-1 Component layouts ..............6-2 Introduction This section contains replacement parts information and component layout drawings for the 2701 and 7700. Ordering information To place an order or to obtain information concerning replacement parts, contact your Keithley Instruments representative or the factory.

  • Page 102: Component Layouts

    Section 6: Replaceable parts Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Component layouts Component layouts for the various circuit boards are provided on the following pages. 2701-902-01 Rev. B / December 2018...

  • Page 109: Accuracy Calculations

    Section 7 Accuracy calculations In this section: Introduction ................7-1 Calculating DC characteristics accuracy ........7-1 Calculating AC characteristics accuracy ........7-2 Calculating dBm characteristics accuracy ........ 7-2 Calculating dB characteristics accuracy ........7-3 Additional derating factors ............7-4 Optimizing measurement accuracy .......... 7-4 Optimizing measurement speed ..........

  • Page 110: Calculating Ac Characteristics Accuracy

    Section 7: Accuracy calculations Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Calculating AC characteristics accuracy AC characteristics accuracy is calculated similarly, except that AC specifications are given as follows: Accuracy = ±(% of reading + % of range) As an example of how to calculate the actual reading limits, assume that you are measuring 120 V, 60 Hz on the 750 V range.

  • Page 111: Calculating Db Characteristics Accuracy

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 7: Accuracy calculations and expressing 0.998852 V as dBm: Thus, the actual reading range is 13 dBm ±0.00032 dBm. dBm and dB for other voltage inputs can be calculated in exactly the same manner using pertinent specifications, ranges, and reference impedances.

  • Page 112: Additional Derating Factors

    Section 7: Accuracy calculations Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Additional derating factors In some cases, additional derating factors must be applied to calculate certain accuracy values. For example, an additional derating factor of 0.02 ppm/V must be added to DCV specifications for voltages over 500 V.

  • Page 113: Temperature

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 7: Accuracy calculations Temperature Select 3.5 digits, 0.01 PLC, filter OFF. For all functions, turn off the display and autozero, and set the trigger delay to zero. Use the :SAMPle:COUNt and READ? bus commands.

  • Page 114: Calibration Reference

    Remote error reporting ............8-18 Detecting calibration step completion ........8-21 Introduction This appendix contains detailed information about the various 2701 remote calibration commands. For information about additional commands to control other instrument functions, refer to the 2701 User’s Manual.

  • Page 115: Command Summary

    Section 8: Calibration reference Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Command summary The following table summarizes the 2701 calibration commands. Command Description :CALibration Calibration root command. :PROTected All commands in this subsystem are protected by the calibration lock (except queries and :CODE).

  • Page 116: Miscellaneous Calibration Commands

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :STEP12 1 A AC at 1 kHz step. :STEP13 2 A AC at 1 kHz step. :STEP14 1V AC at 3 Hz step :STEP15 1V AC at 1kHz step Upper-case letters indicated short form of each command.

  • Page 117: Calibration:protected:count

    Section 8: Calibration reference Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual :CALibration:PROTected:COUNt? This query command returns the number of times that the instrument has completed calibration. Type Affected by Where saved Default value Query only Not applicable...

  • Page 118: Calibration:protected:date

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:DATE This command specifies the calibration date. Type Affected by Where saved Default value Command and query Not applicable Nonvolatile memory Not applicable Usage :CALibration:PROTected:DATE <year>,<month>,<day>...

  • Page 119: Calibration:protected:lock

    Calibration constants are locked if 1 is returned; calibration constants are unlocked if 0 is returned. If you change the 2701 calibration password and forget it, you must return the 2701 to the local Keithley Worldwide Service Center to be reset. There is no user-serviceable procedure to restore the default calibration password on the 2701.

  • Page 120: Calibration:protected:ndue

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:NDUE This command sends the next calibration due date to the instrument. Type Affected by Where saved Default value Command and query Not applicable Nonvolatile memory...

  • Page 121: Dc Calibration Commands

    Section 8: Calibration reference Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual DC calibration commands The :DC commands perform calibration of the DCV, DCI, and ohms functions. The following table summarizes these calibration commands along with the parameter limits.

  • Page 122: Calibration:protected:dc:step

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:DC:STEP<step> This command performs the calibration procedures. Type Affected by Where saved Default value Command only Not applicable Not applicable Not applicable Usage :CALibration:PROTected:DC:STEP<n> <value> <n>...

  • Page 123: Ac Calibration Commands

    Section 8: Calibration reference Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual :CAL:PROT:LOCK Lock out calibration. Also see None AC calibration commands The :AC commands perform comprehensive (user) calibration of the ACV and ACI functions. The following table summarizes these calibration commands.

  • Page 124: Calibration:protected:ac:step

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:AC:STEP<step> This command programs the individual AC calibration steps. Type Affected by Where saved Default value Command only Not applicable Not applicable Not applicable Usage :CALibration:PROTected:AC:STEP<n> <value>...

  • Page 125: Manufacturing Calibration Commands

    Section 8: Calibration reference Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual :CAL:PROT:AC:STEP13 Perform 1 A AC at 1 kHz calibration. :CAL:PROT:AC:STEP13 Perform 2 A AC at 1 kHz calibration. :CAL:PROT:SAVE Save calibration constants to nonvolatile memory. :CAL:PROT:LOCK Lock out calibration.

  • Page 126: Calibration:protected:dc:step0

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:DC:STEP0 This command performs rear scanner terminal short-circuit calibration. Type Affected by Where saved Default value Command only Not applicable Not applicable Not applicable Usage :CALibration:PROTected:DC:STEP0...

  • Page 127: Calibration:protected:code

    Section 8: Calibration reference Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Command Description :CALibration Calibration root command. :PROTected All commands in this subsystem are protected by the calibration lock (except queries and :CODE). :CODE '<up to 8 char. string>' Send calibration code.

  • Page 128: Calibration:protected:card1:Initiate

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:CARD1:INITiate This query command starts the factory calibration procedure for the Model 7700. Type Affected by Where saved Default value Query only Not applicable Nonvolatile memory...

  • Page 129: Calibration:protected:card1:Rcount

    Usage :CALibration:PROTected:CARD1:DATE? Details These commands allow you to read back the calibration date from a 7700. The card calibration date is automatically set to the present date of the 2701 when the card is calibrated. Example :CAL:PROT:CARD1:DATE? Request the saved calibration date.

  • Page 130: Calibration:protected:card1:Save

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference :CALibration:PROTected:CARD1:SAVE This command saves the 7700 calibration to nonvolatile memory after the calibration procedure has been completed. Type Affected by Where saved Default value Command only...

  • Page 131: Calibration:protected:card1:Step0

    Also see None Remote error reporting Methods to detect and determine the nature of calibration errors are discussed in the following paragraphs. See the 2701 User’s Manual for details on status register operation. 8-18 2701-902-01 Rev. B / December 2018...

  • Page 132: Error Summary

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference Error summary The following table summarizes the 2701 calibration errors. Error number and description +400, "10 vdc zero error" +401, "100 vdc zero error" +402, "10 vdc full scale error"...

  • Page 133: Error Queue

    *7700 card only. Error queue As with other 2701 errors, any calibration error will be reported in the remote error queue. You can read this queue by using the :SYST:ERR? query. The 2701 will respond with the appropriate error message, as summarized in the previous table.

  • Page 134: Detecting Calibration Step Completion

    Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual Section 8: Calibration reference Detecting calibration step completion When sending remote calibration commands, you must wait until the instrument completes the current operation before sending a command. You can use the *OPC? (operation complete) query to help determine when each calibration step is completed.
  • Page 135 All Keithley trademarks and trade names are the property of Keithley Instruments. All other trademarks and trade names are the property of their respective companies. Keithley Instruments Corporate Headquarters • 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168 • 1-800-935-5595 • www.tek.com/keithley 12/17...

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