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Keysight 34420A Service Manual
Keysight 34420A Service Manual

Keysight 34420A Service Manual

Nano volt/ micro ohm meter
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Summary of Contents for Keysight 34420A

  • Page 1 T h e t e s t & me a s u r e me n t e q u i p me n t y o u n e e d a t t h e p r i c e y o u w a n t . A l l t e s t I n s t r u me n t s , I n c .
  • Page 2: Service Guide

    Keysight 34420A Nano Volt/ Micro Ohm Meter Service Guide...
  • Page 3: Copyright Notice

    Declaration of Conformity where in the EULA. Keysight shall be under no obligation to update, revise or Declarations of Conformity for this otherwise modify the Software. With...
  • Page 4: Safety Symbols

    Safety Symbols The following symbols on the instrument and in the documentation indicate precautions which must be taken to maintain safe operation of the instrument. Earth (ground) terminal Frame or chassis (ground) terminal Keysight 34420A Service Guide...
  • Page 5: Safety Considerations

    Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards for design, manufacture, and intended use of the instrument. Keysight Technologies assumes no liability for the customer’s failure to comply with these requirements.
  • Page 6: Environmental Conditions

    Environmental Conditions The 34420A is designed for indoor use and in an area with low condensation. The table below shows the general environmental requirements for this instrument. Environmental condition Requirement Operating temperature Full accuracy at 0 °C to 55 °C Full accuracy to 80% RH at 40°C (non-condensing)
  • Page 7: Waste Electrical And Electronic Equipment (Weee) Directive 2002/96/ Ec

    To return this unwanted instrument, contact your nearest Keysight Service Center, or visit http://about.keysight.com/en/companyinfo/environment/takeback.shtml for more information. Sales and Technical Support To contact Keysight for sales and technical support, refer to the support links on the following Keysight websites: – www.keysight.com/find/34420A (product-specific information and support, software and documentation updates) –...
  • Page 8 The 34420A is a 71/2 digit, high performance nanovolt, micro-ohm meter. Its combination of bench-top and system features makes this meter a versatile solution for your testing requirements now and in the future. Convenient bench-top features – Built-in math operations including thermistor, thermocouple and RTD temperature measurements –...
  • Page 9: The Front-Panel At A Glance

    1 Input channel select 5 Menu operation keys 2 Measurement function keys 6 Range/number of digits displayed keys 3 Math operation keys 7 Single trigger/autotrigger/auto hold key 4 Filter select key 8 Shift / local key Keysight 34420A Service Guide...
  • Page 10: The Front-Panel Menu At A Glance

    1:PROBE TYPE ) 2: UNITS ) 3: RTD TYPE ) 4:RTD Ro ) 5:T/C TYPE ) 6: COLD JUNCT ) 7:JUNCT C: MATH MENU 1: STATS ) 2: NULL VALUE ) 3: SCALE GAIN ) 4 : SCALE OFST D: TRIGger MENU 1: READ HOLD ) 2: TRIG DELAY ) 3: N SAMPLES Keysight 34420A Service Guide...
  • Page 11 1: SECURED ) [1: UNSECURED] ) [2:CALIBRATE] ) [3: CHART ZERO] ) [4 : CHART GAIN] ) [5: INJECTED I] ) 6:CAL COUNT ) 7:MESSAGE The commands enclosed in square brackets ([ ]) in the CAL MENU are "hidden" NOTE unless the meter is UNSECURED for calibration. Keysight 34420A Service Guide...
  • Page 12: Display Annunciators

    Automatic reading hold is enabled. Filt The analog and/or the digital filter is enabled. Turns on when reading memory is enabled. To review the display annunciators, hold down the key as you turn on the Shift meter. Keysight 34420A Service Guide...
  • Page 13: The Rear Panel At A Glance

    4 Chart recorder output terminal (Analog out) 8 RS-232 interface connector Use the front-panel Input / Output Menu to: – Select the GPIB or RS-232 interface – Set the GPIB bus address – Set the RS-232 baud rate and parity Keysight 34420A Service Guide...
  • Page 14: In This Book

    If you have questions relating to the operation of the meter, call NOTE 1-800-452-4844 in the United States, or contact your nearest Keysight Technologies Sales Office. Keysight 34420A Service Guide...
  • Page 15 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 16: Table Of Contents

    Front-Panel Display Formats ....... . .41 Keysight 34420A Service Guide...
  • Page 17 ......... . . 84 Keysight 34420A Service Guide...
  • Page 18 ......... .117 Keysight 34420A Service Guide...
  • Page 19 ........126 Input Connector Replaceable Parts ......126 Characteristics and Specifications Keysight 34420A Service Guide...
  • Page 20 Keysight 34420A Service Guide...
  • Page 21 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 22 List of Figures Figure 3-1 Applying short on JM500 ..... . .92 Keysight 34420A Service Guide...
  • Page 23 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 24 ....107 Table 4-1 Main supply voltages ......120 Keysight 34420A Service Guide...
  • Page 25 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 26 Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide Quick Start Quick Start To Prepare the Meter For Use If the Meter Does Not Turn On To Adjust the Carrying Handle To Make Input Connections To Measure Voltage To Measure Resistance...
  • Page 27: Quick Start

    The rear cover of this book is a fold-out Quick Reference Guide. On this cover NOTE you will find a quick summary of various meter features. Inside the rear cover is a diagram of the front panel menu options. Keysight 34420A Service Guide...
  • Page 28: To Prepare The Meter For Use

    If the self-test is successful, “PASS” is displayed on the front panel. If the test is not successful, “FAIL” is displayed and the ERROR annunciator turns on. See the Service Guide for instructions on returning the meter to Keysight Technologies for service.
  • Page 29: If The Meter Does Not Turn On

    Use the following steps to help solve problems you might experience when turning on the meter. If you need more help, see the Service Guide for instructions on returning the meter to Keysight Technologies for service. 1 Verify there is ac power to the meter.
  • Page 30 3 Rotate the line-voltage selector 4 Replace the fuse-holder assembly until the correct voltage appears in in the rear panel. the window. Install the correct fuse and verify that the correct line voltage appears in the window. Keysight 34420A Service Guide...
  • Page 31: To Adjust The Carrying Handle

    Quick Start To Adjust the Carrying Handle To adjust the position, grasp the handle by the sides and pull outward. Then, rotate the handle to the desired position. Bench-top viewing positions Carrying Position Keysight 34420A Service Guide...
  • Page 32: To Make Input Connections

    The connector and cable are an integral part of the measurement system. For NOTE the highest accuracy, use the copper cable and connectors supplied by Keysight Technologies. The conductors may require occasional cleaning to remove oxides. Cleaning the conductors is described on page 117.
  • Page 33 Quick Start Using a Custom Cable Refer to page 117 for additional information about building custom input cables. Keysight 34420A Service Guide...
  • Page 34: To Measure Voltage

    Maximum resolution: 0.1 nV (on 1 mV range) Independent NULL for each channel Channel 1 LO to Channel 2 LO isolated to 150 Vpeak. Scan mode alternates between input channels every 3 seconds or every NOTE measurement, whichever is longer. Keysight 34420A Service Guide...
  • Page 35: To Measure Resistance

    Ranges: 1 W, 10 W, 100 W, 1 kW, 10 kW, 100 kW, 1 MW Maximum resolution: 0.1 μW (on 1 ohm range). Resistance measurements use offset compensation. Offset compensation can be NOTE disabled if desired. Keysight 34420A Service Guide...
  • Page 36: To Measure Temperature With Thermistors

    Quick Start To Measure Temperature With Thermistors Thermistor type: 5 kW Keysight 34420A Service Guide...
  • Page 37: To Measure Temperature With Rtds

    Quick Start To Measure Temperature With RTDs 4-wire, type: a = .00385 (DIN/IEC 751) or a = .00391 = 4.9 W to 2.1 kW Keysight 34420A Service Guide...
  • Page 38: To Measure Temperature With Thermocouples

    Reference: external thermistor, external fixed value, or internal thermistor. Channel 2 only. When using the internal thermistor as the temperature reference, you should NOTE make a custom cable to connect the thermocouple wire directly to the input terminals (see page 117). Keysight 34420A Service Guide...
  • Page 39: To Select A Range

    (auto or manual) for each channel independently. When manually ranging, the selected range is local to the active channel; the meter remembers the range when you switch between channels. Keysight 34420A Service Guide...
  • Page 40: To Set The Number Of Digits

    – The number of digits shown is dependent upon integration time and filter settings. The meter will not allow you to show more digits than the practical measurement capability of the meter. You can, however, reduce the number of digits shown. Keysight 34420A Service Guide...
  • Page 41: To Set The Integration Time

    4½). Integration Time is local to the selected function. This means that you can select NOTE the integration time for each function independently. The meter remembers integration time when you switch between functions. Keysight 34420A Service Guide...
  • Page 42: Front-Panel Display Formats

    -045.230 mV 5½ digits are displayed. “½” digit 7 digits This is the 1 ohm range, 0.133,256,7 W 7½ digits are displayed. “½” digit O.VLD mV This is an overload indication on the 1 mV range. Keysight 34420A Service Guide...
  • Page 43: To Rack Mount The Meter

    Instructions and mounting hardware are included with each rack-mounting kit. Any System II instrument of the same size can be rack-mounted beside the 34420A meter. Remove the carrying handle, and the front and rear rubber bumpers, before rack-mounting the meter.
  • Page 44 To rack mount two instruments side-by-side, order lock-link kit 5061-9694 and flange kit 5063-9212. To install one or two instruments in a sliding support shelf, order shelf 5063-9255, and slide kit 1494-0015 (for a single instrument, also order filler panel 5002-3999). Keysight 34420A Service Guide...
  • Page 45 Quick Start THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 46 Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide Front-Panel Operation Front-Panel Operation Front-Panel Menu Reference A Front-Panel Menu Tutorial To Select an Input Channel To Select a Range To Set or Change the Number of Digits To Set the Integration Time...
  • Page 47: Front-Panel Operation

    It does, however, give you a good overview of the front-panel menu and the most common front-panel operations. See Chapter 3, “Features and Functions”, of the Keysight 34420A User’s Guide for a complete discussion of the meter’s capabilities and operation.
  • Page 48: Front-Panel Menu Reference

    Sets the nominal (0°C) value for the RTD in use. 5: T/C TYPE Selects the type of thermocouple in use. 6: COLD JUNCT Sets the source of the temperature reference junction. 7: JUNCT TEMP Allows direct entry of reference junction temperature. Keysight 34420A Service Guide...
  • Page 49 1: READ HOLD Selects the reading hold sensitivity band. 2: TRIG DELAY Specifies a time delay between the trigger and the start of the measurement. 3: N SAMPLES Sets the number of samples taken per trigger. Keysight 34420A Service Guide...
  • Page 50 Selects either the GPIB or RS-232 remote interface. 3: BAUD RATE Sets the baud rate for RS-232 operation. 4: PARITY Selects even, odd, or no parity for RS-232 operation. 5: LANGUAGE Selects interface language, either SCPI or Keithley 181. Keysight 34420A Service Guide...
  • Page 51 Reads the first 11 characters of a calibration string, if any, entered from the remote interface. [1] The commands enclosed in square brackets ( [ ] ) are “hidden” unless the meter is UNSECURED for calibration. Keysight 34420A Service Guide...
  • Page 52: A Front-Panel Menu Tutorial

    – To turn off the menu at any time without saving changes, press any function If you become confused or get lost at any point during the tutorial, simply turn NOTE off the menu and start over again with step 1 for that example. Keysight 34420A Service Guide...
  • Page 53 NOT saved. Press (Menu Enter) to save changes made on the parameter level. Auto/Man VOLTS ONLY - The requested function is only available for voltage measurements. UNAVAILABLE - The action requested is NOT allowed in the present configuration. Keysight 34420A Service Guide...
  • Page 54 2 Move across to the SYS MENU choice on this level. There are six menu group choices available on the menus level. Each choice has a letter prefix for easy identification (A: , B: , etc.). E: SYS MENU Keysight 34420A Service Guide...
  • Page 55 The first parameter choice is ON for the COMMA command (the comma setting is stored in non-volatile memory and ON is the factory setting). 6 Move across to the OFF choice. There are two parameter choices for COMMA. Keysight 34420A Service Guide...
  • Page 56 This returns you to the COMMA command, which was the last command used before you exited the menu in the Example 1. 9: COMMA 2 Move down to the COMMA parameter choices. The first parameter choice is OFF (the current setting from Example 1). Keysight 34420A Service Guide...
  • Page 57 6½ digits displayed. Connect the four-wire short to the meter input. 1 Turn on the menu. On/Off Shift You enter the menu on the menus level. The MEAS MENU is your first choice on this level. A: MEAS MENU Keysight 34420A Service Guide...
  • Page 58 For this example, you will first set the null value to –0.300000 volts. 0.000,000,0 V ˄ When you see the flashing “ ^ ” on the left side of the display, you can abort the edit and return to the “commands” level by pressing ∧ Keysight 34420A Service Guide...
  • Page 59 You decrement or increment each digit independently. Neighboring digits are not affected. – 0.300,000,0 V 9 Move the flashing cursor over to the units location. Notice that the units are flashing on the right side of the display. – 0.300,000,0 V Keysight 34420A Service Guide...
  • Page 60 NULL on. You can then edit this number as described. This is the end of the front-panel menu tutorial. The remainder of the chapter NOTE discusses several of the most common front-panel operations. Keysight 34420A Service Guide...
  • Page 61: To Select An Input Channel

    Channel Scan mode alternates between input channels every 3 seconds or every NOTE measurement, whichever is longer. If you are using the scan mode, turn off all the input filters (both digital and analog). Keysight 34420A Service Guide...
  • Page 62: To Select A Range

    (auto or manual) for each channel independently. When manually ranging, the selected range is local to the active channel; the meter remembers the range when you switch between channels. Keysight 34420A Service Guide...
  • Page 63: To Set Or Change The Number Of Digits

    – The number of digits shown is dependent upon integration time and filter settings. The meter will not allow you to show more digits than the practical measurement capability of the meter. You can, however, reduce the number of digits shown. Keysight 34420A Service Guide...
  • Page 64: To Set The Integration Time

    4½). Integration Time is local to the selected function. This means that you can select NOTE the integration time for each function independently. The meter remembers integration time when you switch between functions. Keysight 34420A Service Guide...
  • Page 65: To Trigger The Meter

    Ext Trig terminal. The meter is triggered on the negative edge of a TTL pulse. The front-panel key is disabled when in remote. Single Keysight 34420A Service Guide...
  • Page 66: Null (Relative) Operation

    – Since an independent null value is stored for each input channel, difference or ratio functions also use these null values. Additionally, when using the difference function, an additional difference null can be applied (the difference null is only available from the front panel). Keysight 34420A Service Guide...
  • Page 67: To Use Math (Stats)

    The scaling math operation is described in the Keysight 34420A User's Guide. This discussion applies to stats (statistics) operations only. Enable the statistics by pressing the key.
  • Page 68 Front-Panel Operation view the statistics taken. After viewing the stored statistics, press Shift (Menu On/Off) to return to the measurement and continue taking statistics. Keysight 34420A Service Guide...
  • Page 69: To Set The Number Of Samples

    CONFigure and MEASure? commands automatically set the sample count to 1. – Front Panel operation: set the number of samples per trigger in the 3: N SAMPLES command under the TRIGger menu. – Remote operation: use the following command: SAMPle:COUNt {<value>|MIN|MAX} Keysight 34420A Service Guide...
  • Page 70: Chart Output (Analog Output)

    – The chart output state (including the span and null values) is stored in non-volatile memory. – span cannot have a negative value. – The chart output has a voltage “rollover” to prevent the loss of data, see the Keysight 34420A User’s Guide. Keysight 34420A Service Guide...
  • Page 71: To Unsecure The Meter For Calibration

    If the display shows UNSECURED, you do not need to perform this procedure to NOTE perform calibration. 4 Move down to the ''parameters” level. ^000000: CODE 5 Enter the security code. ^034420: CODE 6 Save the change and exit. Keysight 34420A Service Guide...
  • Page 72 Use the arrow keys to move left or right between digits. Use the up or down arrow keys to change the digits. To re-secure the meter (following calibration), perform this procedure again. NOTE Additional information about the calibration security feature is given on page Keysight 34420A Service Guide...
  • Page 73 Front-Panel Operation THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 74: Calibration Procedures

    Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide Calibration Procedures Keysight Technologies Calibration Services Recommended Test Equipment Test Considerations Performance Verification Tests Zero Offset Verification Gain Verification 1 mV and 10 mV Gain Verification (Optional) Injected Current Verification (Optional) Chart Output Verification (Optional)
  • Page 75 Calibration Procedures new correction factors are stored in non-volatile memory until the next calibration adjustment is performed. (Non-volatile memory does not change when power has been off or after a remote interface reset.) Keysight 34420A Service Guide...
  • Page 76: Keysight Technologies Calibration Services

    Keysight Technologies Calibration Services When your meter is due for calibration, contact your local Keysight Technologies Service Center for a low-cost recalibration. The Keysight 34420A is supported on automated calibration systems which allow Keysight Technologies to provide this service at competitive prices. Calibrations to MIL-STD-45662 are also available at competitive prices.
  • Page 77 The meter must be unsecured prior to initiating the calibration procedure. For further information on programming the meter, see Chapter 4 in the Keysight 34420A User's Guide.
  • Page 78: Recommended Test Equipment

    Temperature Measurement Device (RTD or ± 0.2° C none thermistor) 6 1/2 Digit Digital Multimeter (DMM) 10 Vdc ± 0.01% Keysight 34401A [a] Q = Quick verification P = Performance verification Tests O = Optional Verification Tests T = Troubleshooting Keysight 34420A Service Guide...
  • Page 79: Test Considerations

    – Assure that low noise connections are made to the meter and calibrator. Chapter 7 of the Keysight 34420A User's Guide describes low noise input connections. – Allow 5 minutes for thermal offset stabilization after handling the input connector or shorting plug before making measurements or performing calibrations.
  • Page 80: Performance Verification Tests

    You can perform many tests individually (or all tests at once) using the TEST command in the SYS MENU. You can also perform a self-test from the remote interface. See Chapter 4 in the Keysight 34420A User's Guide. – If the self-test is successful, “PASS” is displayed on the front panel.
  • Page 81: Quick Performance Check

    90 day test limits. You should use the 24-hour test limits only for verification within 24 hours after performing the adjustment procedure. After acceptance, you should repeat the performance verification tests at every calibration interval. If the meter fails performance verification, adjustment or repair is NOTE required Keysight 34420A Service Guide...
  • Page 82: Zero Offset Verification

    2 Read “Test Considerations” on page 78. 3 Apply the low thermal 4-wire shorting plug (Keysight PN 34103A) to the meter's input terminal. Ensure the connector coupling nut is properly tightened. 4 Allow 5 minutes for the thermal shorting plug and input connector to temperature stabilize.
  • Page 83: Zero Offset Verification Procedure

    20 mΩ 20 mΩ 20 mΩ 4-wire Ohms 100 kΩ 300 mΩ 400 mΩ 400 mΩ 4-wire Ohms 1 MΩ 3 Ω 4 Ω 4 Ω Low Power Ohms 1 Ω 2 μΩ 2 μΩ 2 μΩ Keysight 34420A Service Guide...
  • Page 84 [a] This value includes 100 nV for NULL off, see the specifications in datasheet. [b] For 2-wire Ohms with Null ON (within ± 1°C of NULL), add 2 mΩ to the listed specification. If null is not used, add 0.2 Ω to the listed specification. Keysight 34420A Service Guide...
  • Page 85: Gain Verification

    78. 3 Connect a multifunction calibrator to the meter's input terminals using the low thermal input cable provided (Keysight PN 34102A). Ensure the connector coupling nut is properly tightened. 4 Allow 5 minutes for the input connections to temperature stabilize.
  • Page 86: Table 3-3 Table

    [a] Channel 2 can be verified only, no channel 2 gain calibration exists. Channel 2 gain calibration is derived from channel 1 gain calibration. [b] For 2-wire Ohms with Null ON (within± 1°C of NULL), add 2 mΩ to the listed specification. If null is not used, add 0.2 Ω to the listed specification. Keysight 34420A Service Guide...
  • Page 87: Mv And 10 Mv Gain Verification (Optional)

    1 mV and 10 mV gain verification procedure 1 Set the meter to the following configuration: Channel 1 input 7 ½ digits (100 PLC) Filters OFF 2 Connect the calibrator, resistive divider, and meter as shown. 3 Measure or calculate the divider ratio. Keysight 34420A Service Guide...
  • Page 88: Table 3-5 Table

    1 mV and 10 mV gain verification procedure ± Error From Full Scale Function/Channel Range 24 hour 90day 1 year Voltage/ Channel 1 1 mV 45nV 60 nV 70 nV Voltage/ Channel 1 10mV 270nV 420 nV 530nV Keysight 34420A Service Guide...
  • Page 89: Injected Current Verification (Optional)

    2 Set the DMM to measure AC Volts rms on the 100 mV range. The DMM input impedance must be 1 MQ to perform this procedure. NOTE 3 Set the Keysight 34420A to the following configuration: Channel 1 input 7½ digits (100 PLC) Filters OFF 4 Connect the DMM, capacitor, and meter as shown.
  • Page 90: Chart Output Verification (Optional)

    10 Use menu recall to return to the 6:CHART SPAN command. Shift 11 Move to the 7:CHART NULL command. 12 Move down to the parameters level and set the value shown to 0.000,000 V. 13 Execute the command. Auto/Man ENTER Keysight 34420A Service Guide...
  • Page 91 22 Execute the command. ENTER 23 Measure the chart output with the DMM and verify that the output is: 1.000 Volt ±2 mV. 24 Restore chart null and chart span to the values set before beginning this procedure. Keysight 34420A Service Guide...
  • Page 92: Calibration Security Code

    – If you forget your security code, you can disable the security feature by adding a jumper inside the meter, and then entering a new code. See the procedure on the following page. Keysight 34420A Service Guide...
  • Page 93: To Unsecure The Meter Without The Security Code

    3 Connect the power cord and turn on the meter. Be careful not to touch the power line connections. Do not touch exposed mains. WARNING 4 Apply a short between the two exposed metal pads on JM500 as shown in Figure 3-1. Figure 3-1 Applying short on JM500 Keysight 34420A Service Guide...
  • Page 94 7 Turn off the meter and remove the power cord. Reassemble the meter. 8 The meter is now unsecured and you can enter a new security code. Be sure you take note of the new security code. Keysight 34420A Service Guide...
  • Page 95: Calibration Count

    – The calibration count increments up to a maximum of 32,767 after which it wraps around to 0. There is no way provided to program or reset the calibration count. It is an independent electronic calibration “serialization” value. Keysight 34420A Service Guide...
  • Page 96: Calibration Message

    11 characters of the message on the front panel; any additional characters are truncated. – The calibration message is stored in non-volatile memory, and does not change when power has been off or after a remote interface reset. Keysight 34420A Service Guide...
  • Page 97: Calibration Procedure

    – Perform the Zero Calibration procedure (page 81). – Perform the Gain Calibration procedure (page 84). – Secure the meter against calibration. – Note the new security code and calibration count in the meter's maintenance records. Keysight 34420A Service Guide...
  • Page 98: Aborting A Calibration In Progress

    You can abort a calibration at any time by pressing any front-panel key (except ). When performing a calibration from the remote Shift interface, you can abort a calibration by issuing a remote interface device clear message or by pressing the front-panel LOCAL key. Keysight 34420A Service Guide...
  • Page 99: Zero Calibration

    10 minutes to complete. The display will indicate the ENTER calibration progress as each channel, range, and function is calibrated. 8 Perform the Zero Offset Verification procedure (page 81) to check the results. Keysight 34420A Service Guide...
  • Page 100: Gain Calibration

    Perform the adjustments for each function only in the order shown. 1 Read “Test Considerations” on page 78. 2 Set the meter to the following configuration for each function, channel, and range in Table 3-4: 7 1/2 digits (100 PLC) Null OFF Filters OFF Keysight 34420A Service Guide...
  • Page 101: Table 3-7 Table

    Calibration Procedures 3 Connect a multifunction calibrator to the meter's input terminals using the provided cable (Keysight PN 34102A). Ensure the connector coupling nut is properly tightened. 4 Allow 5 minutes for the input connector to temperature stabilize. 5 Select each function and range in the order shown in Table 3-4.
  • Page 102: Injected Current Calibration (Optional)

    1 Set the meter to the following configuration: 6 1/2 digits (10 PLC) Channel 1 input 2 Connect channel 1 HI and channel 2 HI leads to the rear panel chassis ground screw. On/Off 3 Turn on the menu. Shift Keysight 34420A Service Guide...
  • Page 103 8 When the calibration is finished, the display shows COMPLETED 9 The display will then show the final injected current value. You may wish to record this value. After a pause, the meter returns to the measurement mode. 3.8 nA RMS Keysight 34420A Service Guide...
  • Page 104: Internal Temperature Reference Calibration (Optional)

    5 Move down to the parameters level and set the value in the display to the measured temperature value. 6 Execute the command to begin the gain calibration. Auto/Man ENTER The temperature units shown will be the currently set temperature units NOTE (°F, °C, or Kelvins). Keysight 34420A Service Guide...
  • Page 105: Chart Output Calibration (Optional)

    9 Scroll to the 4:CHART GAIN command and go to the parameter level. 10 Edit the displayed value to match the value indicated on the DMM. Execute the command. The gain calibration takes approximately 2 seconds to perform. 11 Perform the “Chart Output Verification Procedure” on page 89. Keysight 34420A Service Guide...
  • Page 106: Error Messages

    For a more complete list of error messages and descriptions see Chapter 5 in the Keysight 34420A User's Guide. Table 3-5 System error messages...
  • Page 107 Ohms 100 mV voltage clamp failed Ohms 500 mV voltage clamp failed Low impedance DC gain ×100 failed High impedance DC gain ×100 failed Cannot calibrate precharge Unable to sense line frequency I/O Processor did not respond I/O Processor failed self-test Keysight 34420A Service Guide...
  • Page 108: Calibration Error Messages

    Precharge DAC convergence failed A/D turnover correction out of range Bias current selfcal failed Charge compensation selfcal failed Injected current selfcal failed Cal checksum failed, secure state Cal checksum failed, string data Cal checksum failed, DCV correction Keysight 34420A Service Guide...
  • Page 109 Table 3-7 Calibration error messages Error Error message Cal checksum failed, Low Power FAES Cal checksum failed, RES corrections Cal checksum failed, FAES corrections Cal checksum failed, Low Voltage FAES corrections Cal checksum failed, GPIB address Keysight 34420A Service Guide...
  • Page 110: Service

    Keysight 34420A Nano Volt / Micro Ohm Meter Service Guide Service Operating Checklist Types of Service Available Repackaging for Shipment Electrostatic Discharge (ESD) Precautions Surface Mount Repair To Replace the Power-Line Fuse Input Connector Cleaning the Connector Contacts Troubleshooting Hints...
  • Page 111: Operating Checklist

    Service Operating Checklist Before returning your meter to Keysight Technologies for service or repair check the following items: Is the meter inoperative? – Verify that the ac power cord is connected to the meter. – Verify that the front-panel Power switch is depressed.
  • Page 112: Types Of Service Available

    If your unit fails after your three year warranty expires, Keysight will repair or replace it at a very competitive price. Keysight will make the decision locally whether to repair or replace your unit.
  • Page 113 Service – If your three year warranty has expired, Keysight will bill you for the Keysight 34420A exchange price - less than a new unit price. Keysight warrants exchange units against defects for 90 days. Keysight 34420A Service Guide...
  • Page 114: Repackaging For Shipment

    If the instrument is to be shipped to Keysight for service or repair, be sure to: – Attach a tag to the meter identifying the owner and indicating the required service or repair.
  • Page 115: Electrostatic Discharge (Esd) Precautions

    – Use a conductive wrist strap to dissipate static charge accumulation. – Minimize handling. – Keep replacement parts in original static-free packaging. – Remove all plastic, foam, vinyl, paper, and other static-generating materials from the immediate work area. – Use only anti-static solder suckers. Keysight 34420A Service Guide...
  • Page 116: Surface Mount Repair

    Surface mount components should only be removed using soldering irons or desoldering stations expressly designed for surface mount components. Use of conventional solder removal equipment will almost always result in NOTE permanent damage to the printed circuit board and will void your Keysight Technologies factory warranty. Keysight 34420A Service Guide...
  • Page 117: To Replace The Power-Line Fuse

    The power-line fuse is located within the meter's fuse-holder assembly on the rear panel (see page 28). Use a 250 mAT slow-blow fuse (Keysight part number 2110-0817). This fuse is used for all power line settings. Keysight 34420A Service Guide...
  • Page 118: Input Connector

    Service Input Connector Keysight 34420A Service Guide...
  • Page 119: Cleaning The Connector Contacts

    Because the meter uses connector contacts that are almost pure copper, they are subject to oxidation. Oxidation can cause measurement errors. See Chapter 7 of the Keysight 34420A User’s Guide for a discussion of the cause of measurement error. To help prevent the formation of oxides on the connector contacts, keep the connector engaged whenever possible.
  • Page 120: Troubleshooting Hints

    Check that the input to the supply voltage regulator is at least 1 V greater than its output. Circuit failures can cause heavy supply loads which may pull down the regulator output voltage. Check the main supply voltages as tabulated in Table 4-1. Keysight 34420A Service Guide...
  • Page 121 Be sure to check that these local supplies are active.Local supplies are included in the display and front panel, the input amplifier, and the input and protection circuits. Always check that the power supplies are free of ac oscillations using an oscilloscope. Keysight 34420A Service Guide...
  • Page 122: Self-Test Procedures

    ADC and the U500 on-chip ADC. This error is reported if the procedure can not run to completion due to a hardware failure. Rundown gain out of range This test checks the nominal gain between the integrating ADC and the U500 on-chip ADC. The nominal gain is check to ±10% tolerance. Keysight 34420A Service Guide...
  • Page 123 Ohms 100 mV voltage clamp failed This test configures the 10 V range. The 10 mA current source is connected into an open circuit and the 100 mV ohms clamp voltage is selected and measured. The result is checked for 85 mV ±35 mV. Keysight 34420A Service Guide...
  • Page 124 Bias current DAC failed This test configures the 1 V range with the input internally grounded through R227. The bias current DAC, U301, is then programmed to both extremes and a measurement taken at each. A check is made to ensure that O V is between the two measurements. Keysight 34420A Service Guide...
  • Page 125 Service THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 126: Replaceable Parts

    Keysight 34420A Nano Volt / Micro Ohm Meter Service Guide Replaceable Parts To Order Replace Parts Input Connector Replaceable Parts This chapter contains information ordering replacement parts for your meter. – Input Connector Replaceable Parts...
  • Page 127 Keysight, do the following: 1 Contact your nearest Keysight Sales Office of Keysight Service Center. 2 Identify the parts by the Keysight part number shown in the replaceable parts list. 3 Provide the instrument model number and serial number.
  • Page 128: Characteristics And Specifications

    Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide Characteristics and Specifications For the characteristics and specifications of the 34420A Nano Volt/Micro Ohm Meter, refer to the datasheet at https://literature.cdn.keysight.com/litweb/pdf/5968-0161EN.pdf.
  • Page 129 Characteristics and Specifications THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 130 This information is subject to change without notice. Always refer to the English version at the Keysight website for the latest revision. © Keysight Technologies 2003-2021 Edition 4, July 2021 Printed in Malaysia  34420-90010 www.keysight.com...