Keysight Technologies 34420A Service Manual
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Keysight Technologies 34420A Service Manual

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

  • Page 1 Keysight 34420A Nano Volt/ Micro Ohm Meter Service Guide...
  • Page 2 FAR 27.401 or DFAR could result in personal injury or death. 227.7103-5 (c), as applicable in any Do not proceed beyond a WARNING technical data. notice until the indicated conditions are fully understood and met. Keysight 34420A Service Guide...

  • Page 3: 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 4: Safety Considerations

    Do not install substitute parts or perform any unauthorized modification to the NOTE product. Return the product to an Keysight Technologies Sales and Service Office for service and repair to ensure that safety features are maintained. Keysight 34420A Service Guide...

  • Page 5: 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 cond ition Requirement Operating condition – 0 °C to 55 °C Temperature Storage condition –...

  • Page 6: Waste Electrical And Electronic Equipment (Weee) Directive 2002/96/Ec

    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) – www.keysight.com/find/assist (worldwide contact information for repair and service) Keysight 34420A Service Guide...
  • Page 7 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 8: 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 9: 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 10 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 11: Display Annunciators

    Automatic reading hold is enabled. Fil t 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 12: 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 13: 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 14 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...

  • Page 15: Table Of Contents

    Front-Panel Display Formats ....... . .41 Keysight 34420A Service Guide...
  • Page 16 ......... . . 84 Gain Verification Procedure ....... 84 Keysight 34420A Service Guide...
  • Page 17 ......122 Injected Current Compensation ......122 Keysight 34420A Service Guide...
  • Page 18 ........167 Backdating Keysight 34420A Service Guide...
  • Page 19 Display and Keyboard Schematic ......185 Characteristics and Specifications Keysight 34420A Service Guide...
  • Page 20 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 21 List of Figures Figure 3-1 Applying short on JM500 ..... . .92 Keysight 34420A Service Guide...
  • Page 22 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 23 ..117 Table 5-1 Main supply voltages ......140 Keysight 34420A Service Guide...
  • Page 24 THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 25 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 26: 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 27: To Prepare The Meter For Use

    “FAIL” is displayed and the ERROR annunciator turns on. See the Service Guide for instructions on returning the meter to Keysight Technologies for service. [1] DeoxIT™ is a trademark of CAIG Laboratories, Inc., San Diego, California. Keysight 34420A Service Guide...

  • Page 28: 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 29 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 30: 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 31: To Make Input Connections

    Keysight Technologies. The conductors may require occasional cleaning to remove oxides. Cleaning the conductors is described on page 137. The connector body and cable shield are connected to earth ground. WARNING Keysight 34420A Service Guide...
  • Page 32 Quick Start Using a Custom Cable Refer to page 137 for additional information about building custom input cables. Keysight 34420A Service Guide...

  • Page 33: 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 34: 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 35: To Measure Temperature With Thermistors

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

  • Page 36: 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 37: 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 137). Keysight 34420A Service Guide...

  • Page 38: 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 39: 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 40: 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 41: 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 42: 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 43 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 slid ing support shel f, order shel f 5063-9255, and slide kit 1494-0015 (for a single instrument, also order filler panel 5002-3999). Keysight 34420A Service Guide...
  • Page 44 Quick Start THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 45 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 46: 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 47: 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 48 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 49 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 50 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 51: 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 52 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 53 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 54 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 55 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 56 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 57 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 58 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 59 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 60: 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 61: 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 62: 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 63: 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 64: 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 65: 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 66: 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 67 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 68: 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 69: 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 70: 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 71 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 72 Front-Panel Operation THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 73 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 74 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 75: Calibration Procedures

    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 76 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. Keysight 34420A Service Guide...

  • Page 77: 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 78: 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 79: 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 80: 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 81: Zero Offset Verification

    5 Select each function and range in the order shown in the table on the next page. Compare each measurement result to the test limits shown in the table. – Zero offset calibration using a multifunction calibrator is NOT possible. CAUTION – Use only the low thermal 4-wire shorting plug provided. Keysight 34420A Service Guide...

  • Page 82: 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 83 [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 84: Gain Verification

    1 year 100mV Voltage/ Channel 1 100 mV 1.8 µV 3.4 µV 4.4 µV Voltage/ Channel 1 13 µV 29 µV 39 µV 10 V Voltage/ Channel 1 10 V 30 µV 240 µV 340 µV Keysight 34420A Service Guide...

  • Page 85: 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 86: Mv And 10 Mv Gain Verification (Optional)

    7 ½ digits (100 PLC) Filters OFF 2 Connect the calibrator, resistive divider, and meter as shown. Source + Sense + Meter Calibrator Source - Sense - Isothermal environment 3 Measure or calculate the divider ratio. Keysight 34420A Service Guide...

  • Page 87: 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 88: 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 89: 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 90 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 91: 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 92: 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 93 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 94: 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 95: 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 96: 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 97: 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 98: 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 99: 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 100: Table 3-7 Table

    [a] Gain calibration can be performed with an input that is within 0.9 to 1.1 of range. [b] The constants calculated for these ranges are used to derive the gain calibration constants for the 1 mV and 10 mV ranges. Keysight 34420A Service Guide...

  • Page 101: 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 102 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 103: 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 104: 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 105: 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 106 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 107: 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 108 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 109 Keysight 34420A Nano Volt / Micro Ohm Meter Service Guide Theory of Operation Block Diagram Input and Protection Function Switching DC Amplifier Ohms Current Source A-to-D Converter Configuration Data Shift Register Floating Logic Earth-Referenced Logic Power Supplies Front Panel This chapter is organized to provide descriptions of the circuitry contained on each schematic shown in chapter 9.

  • Page 110: Theory Of Operation

    The A/D Converter changes the voltage from the DC Amplifier into digital information. The conversion uses a Multislope III ADC method based upon patented Keysight Technologies ADC technology. This conversion technique uses a stable Voltage Reference. The A/ D Converter digital information is used by the Main Controller to calculate the measurement.
  • Page 111 Referenced Circuitry. The Power Transformer provides the bound between floating and earth reference. The power supply also provides the line frequency reference used by the Main Controller and resets the Main Controller after power is applied. Keysight 34420A Service Guide...

  • Page 112: Input And Protection

    On the 100 V Range, relay K102 is closed to connect the input signal to the Function Switch through the 100:1 high voltage divider resistor network U102A. Both K101 and K102 are driven by relay driver U150 (on the Function Switching Keysight 34420A Service Guide...
  • Page 113 In the 2-wire ohms function, the voltage drop is measured across the Channel 1 HI and LO input terminals. In the 4-wire ohms function, the voltage is measured across the Channel 2 HI and LO input terminals. Keysight 34420A Service Guide...

  • Page 114: Function Switching

    U203, U204, and U314 form a programmable gain amplifier. This circuit is used to inject a signal via capacitors C201 and C202 that minimizes switching transients at the input terminals when the “Measure Customer” switch is opened and closed. Keysight 34420A Service Guide...

  • Page 115: Dc Amplifier

    U314B. Together with R302 through 304, and CR301, they allow a few millivolts of programmable voltage to be developed across R305. The resulting current flow is used to null the input bias current of the dc amplifier. Keysight 34420A Service Guide...
  • Page 116 Amplifier. If the peak level at the output of the dc amplifier exceeds approximately ± 14 volts, the comparator output U311A or U311B will change state. This information is sent to the CPU and will cause the reading to output as an OVLD. Keysight 34420A Service Guide...

  • Page 117: Ohms Current Source

    10 ma 11.43 kΩ 200 Ω 10 Ω 10ma 11.43 kΩ 200 Ω 100 Ω 10 ma 11.43 kΩ 200 Ω 1 kΩ 1 ma 28.57 kΩ 5 kΩ 10 kΩ .1 ma 28.57 kΩ 50 kΩ Keysight 34420A Service Guide...
  • Page 118 U310B which has a voltage gain of approximately X12. The signal from U310B is routed by K451 to comparator U452A. If the signal is larger than the “clamp voltage” set at U452 pin 3, the output ofU452 will go negative, turning on Q457 Keysight 34420A Service Guide...
  • Page 119 U452A is turning the current source off. If the current source terminals are open circuited, R467 prevents the open circuit voltage from rising above the programmed “clamp voltage”. Keysight 34420A Service Guide...

  • Page 120: A-To-D Converter

    U411, resistor network U102E, and voltage reference U403. The O or 5 Volt signal output is sent to the ASIC U501, and residue ADC U500. The ADC method used by the Keysight 34420A is called Multislope III. It is based on patented Keysight Technologies ADC technology. Multislope III is a charge balancing, continuously integrating, analog-to-digital conversion technique.
  • Page 121 Theory of Operation ADC through 30 kΩ resistors in Ul02E (pins 26 and 28). Amplifier U401B provides a precise +5 V reference for the U500 on-chip ADC. Keysight 34420A Service Guide...

  • Page 122: Configuration Data Shift Register

    Chart Recorder Output The Chart Recorder Output circuit is also shown on the Configuration Data Shift Register schematic. The circuit discussion is given in the “Earth-Referenced Logic” on page 126. Keysight 34420A Service Guide...

  • Page 123: Floating Logic

    The counter register is used to capture the ADC slope count at the COMP input. The COMP input functions as both a clocked comparator and the slope counter input for the ADC. In both cases the counter register captures the lower 8 bits of a Keysight 34420A Service Guide...
  • Page 124 (FXRO) and to measure the input power line frequency (LSENSE). Frequencies from 55 Hz to 66 Hz are measured as 60 Hz. All other line input frequencies are assumed to be 50 Hz. Keysight 34420A Service Guide...
  • Page 125 11-bit frame at a rate of 187.5 k bits/second. When the RS-232 interface is selected, data is sent across the isolated link at 93.75 k bits/second. The 11-bit data frame is configured for one start bit, eight data bits, one control bit, and one stop bit. Keysight 34420A Service Guide...

  • Page 126: Earth-Referenced Logic

    Chart Recorder Output. U700 programs DAC U610 to output a voltage in the range of± 3Vdc, in direct proportion to the measured input voltage on a given range. A full 3 Vdc output represents a 120% full scale input voltage. Keysight 34420A Service Guide...

  • Page 127: Power Supplies

    The GPIB (IEEE-488) and RS-232 interfaces along with other input/output circuits are powered from this supply. A -5V supply is obtained from U609 and U611 to power the DAC, U610, to provide the chart recorder (analog) output. Keysight 34420A Service Guide...

  • Page 128: Front Panel

    U602 port pins P0.0 through P0.4 to poll each key column for a key press. Column read-back data are read by the microprocessor at port pins P1.0 through P1.3 for decoding and communication to the floating logic circuits. Keysight 34420A Service Guide...

  • Page 129: 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 130: 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 131: Types Of Service Available

    Contact your nearest Keysight Service Center. They will arrange to have your meter repaired or replaced. Express Exchange (U.S.A. only) You can receive a replacement Keysight 34420A via overnight shipment for low downtime. 1 Call 1-800-258-5165 and ask for “Express Exchange.”...
  • Page 132 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 133: Repackaging For Shipment

    Repackaging for Shipment For the Express Exchange Service described on the previous page, return your failed Keysight 34420A to the designated Keysight Service Center using the shipping carton of the exchange unit. A shipping label will be supplied. Keysight will notify you when your failed unit has been received.

  • Page 134: 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 135: 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 136: 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 137: Input Connector

    Service Input Connector Keysight 34420A Service Guide...

  • Page 138: 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 139: 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 5-1. Keysight 34420A Service Guide...
  • Page 140 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 141: 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 142 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 143 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 144 Service THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...

  • Page 145: Replaceable Parts

    Keysight 34420A Nano Volt / Micro Ohm Meter Service Guide Replaceable Parts 34420-66501 Main PC Assembly 34420-66502 Display and Keyboard PC Assembly 34420A Mainframe Manufacturer's List This chapter contains information ordering replacement parts for your meter. The parts lists are divided into the following four groups: –...

  • Page 146: To Order Replace Parts

    3 Provide the instrument model number and serial number. Backdating and Part Changes Always refer to Chapter 7, "Backdating" before attempting repair or before ordering replacement parts. Parts changes are documented in the backdating chapter. Keysight 34420A Service Guide...

  • Page 147: Input Connector Replaceable Parts

    Replaceable Parts Input Connector Replaceable Parts Use the following Keysight Technologies part numbers to obtain replacement input connectors and cables. Contact your nearest Keysight Technologies Sales Office for replaceable parts. Keysight part number Description 34104A Low thermal input connector (blank)

  • Page 148: 34420-66501 Main Pc Assembly

    0160-6670 CAP 3300pF 50V 5% COG 1210 04222 12105A332JATRA C400-C402 0160-5954 CAP 220PF 5% 50V 04222 08055A221JAT A C403-C404 0160-6497 CAP-FXD 0.1uF 25 V 04222 12065C104KAT A C407-C410 0160-6497 CAP-FXD 0.1uF 25 V 04222 12065C104KAT A Keysight 34420A Service Guide...
  • Page 149 08055C102KAT A C602 016Q-5967 CAP-FXD 100pF 5% 04222 08055A101JAT A C603 0160-6497 CAP-FXD 0.1uF 25 V 04222 12065C104KAT A C604 0160-5947 CAP-FXD 1OOOpF 50 V 04222 08055C102KAT A C605-C606 0160-5967 CAP-FXD 100pF 5% 04222 08055A101JAT A Keysight 34420A Service Guide...
  • Page 150 MMBF4393 DIODE-ZNR 7.5V 5% PD=.155W TC=+5.3MV CR301 1902-1512 25403 BZX84C7V5 DIODE-ZNR 15V 5% T0-236 (SOT-23) CR302-CR303 1902-1572 25403 B2X84C15L PD=.35W CR304 1906-0334 DIODE- 200V 200MA 07263 MMBF4393 CR305 1902-1565 DIODE-ZNR 4.7V 5% T0-236 (SOT-23) 25403 BZX84-C4V7 Keysight 34420A Service Guide...
  • Page 151 TUBE TVS AX 230V 15% 20A CG2-230L 71744 CG2-230L E105 1970-0100 TUBE-ELECTRON SURGE V PTCTR 23663 11484 E700 9164-0173 BEEPER 51406 PKM24-4A0-1 J101 34420-81601 CONN/CBL ASSY F 28480 34420-81601 CONNECTOR-RF BNC RCPT PC-W-STDFS J601 1250-1884 00779 227161-6 50-0HM Keysight 34420A Service Guide...
  • Page 152 HF50ACB-453215 L601 9100-1788 CORE-FERRITE CHOKE-WIDEBAND;IMP:680 02114 VK20020/4B MP1-MP2 0380-0643 STANDOFF-HEX 255-IN-LG 6-32-THD 2L446 2685 2190-0577 WASHER- NO. 10 194-IN-ID.294-IN-OD 20859 3118 P500 1252-4484 CONN-POST TYPE 2.0-PIN-SPCG 12-CONT 27264 52007-1210 P551 1252-4488 CONN-POST TYPE.156-PIN-SPCG 8-CONT 27264 26-64-4080 Keysight 34420A Service Guide...
  • Page 153 1853-0568 TRANSISTOR PD=350MW FT=40MHZ 56289 TMPT5087 Q305-Q309 1854-1014 TRANSISTOR PD=350MW FT=100MHZ 04713 MMBT6429 TRANSISTOR J-FET N-CHAN D-MODE Q310 1855-0752 27014 MMBF4392 T0-236AA Q311 1855-0715 TRANSISTOR 04713 MMBF4393 TRANSISTOR J-FET N-CHAN D-MODE Q451-Q452 1855-0752 27014 MMBF4392 T0-236AA Keysight 34420A Service Guide...
  • Page 154 11 RESISTOR 301K 1% 1206.125W TC:100 200V 09021 RK73H2BT3013F R130 0699-1380 RESISTOR 3.16K +-1%.125W TKF TC=0+-100 09021 RK73H2BT3161F R131-R132 0699-1330 RESISTOR 1OOK +·1%.125W TKF TC=0+-100 09021 RK73H2BT1003F R133 0699-2433 RESISTOR 25.5K +-1%.125W TKF TC=0+·100 09021 RK73H2BT2552F Keysight 34420A Service Guide...
  • Page 155 RESISTOR 301K 1% 1206.125W TC=100 200V 09021 RK73H2BT3013F R222-R223 0699-1391 RESISTOR 10K +-1%.125W TKF TC=0+-100 09021 RK73H2BT1002F R224 0699-1466 RESITOR 10M 10% 1206.125W 200V TC=200 19701 RM7382BT106J R226 0699-1466 RESITOR 1OM 10% 1206.125W 200V TC=200 19701 RM7382BT106J Keysight 34420A Service Guide...
  • Page 156 R324 0699-1409 RESISTOR 56.2K +-1%.125W TKF TC=0+·100 09201 RK73H2BT5622F R325 0699-2156 RESISTOR 20K +-1%.125W TKF TC=0+-100 09201 RK73H2BT2002F R327 0699-1408 RESISTOR 51.1K +-1%.125W TKF TC=0+-100 19701 9C12063AFKR R328 0699-1415 RESISTOR 100 +-1%.125W TKF TC=0+-100 09201 RK73H2BT1OOOF Keysight 34420A Service Guide...
  • Page 157 R442 0699-2127 RESISTOR 36.5K +-1%.125W TKF TC=0+-100 09201 RK73H2BT3652F R449 0699-1415 RESISTOR 100 +-1%.125W TKF TC=0+-100 09201 RK73H2BT1OOOF R451 0699-1386 RESISTOR 5.62K +-1%.125W TKF TC=0+-100 09201 RK73H2BT5621F R452-R453 0699-1408 RESISTOR 51.1K +-1%.125W TKF TC=0+-100 19701 9C12063AFKR Keysight 34420A Service Guide...
  • Page 158 R505-R506 0699-1386 RESISTOR 5.62K +-1%.125W TKF TC=0+-100 09201 RK73H2BT5621F R507 0699-1391 RESISTOR 1OK +-1%.125W TKF TC=0+-100 09201 RK73H2BT1002F RS08-R509 0699-1318 RESISTOR 1K +-1%.125W TKF TC=0+-100 09201 RK73H2BT1001F R510-R511 0699-1391 RESISTOR 1OK +-1%.125W TKF TC=0+-100 09201 RK73H2BT1002F Keysight 34420A Service Guide...
  • Page 159 0699-1389 RESISTOR 8.25K +·1%.125W TKF TC=0+-100 09201 RK73H2BT8251F R625-R630 0699-3045 RESISTOR 5.11K +·1%.1W TKF TC=0+-100 19701 9C08052A5111FKR R631 0699-1391 RESISTOR 1OK +·1%.125W TKF TC=0+-100 80031 9C12063AFKR R701 0699-3408 RESISTOR 1K +-5% 1W TKF TC=0+-200 91637 CRCW2512-102J Keysight 34420A Service Guide...
  • Page 160 U120 1990-1753 28480 1990-1753 IF=20MA-MAX IC COMPARATOR PRCN DUAL 8 PIN U121 1826-1572 18324 LM393D PLSTC-SOIC SOLID STATE RELAY LED-PXSTR U122 1990-1753 28480 1990-1753 IF=20MA-MAX IC COMPARATOR PRCN DUAL 8 PIN U123 1826-1572 18324 LM393D PLSTC-SOIC Keysight 34420A Service Guide...
  • Page 161 IC OP AMP LP DUAL 8 PIN PLSTC-SOIC 24355 AD706JR U402 1826-1991 IC OP AMP HS SINGLE 8 PIN PLSTC-SOIC 24355 AD711JR U403 1826-1249 IC V RGLTR-V-REF-FXD 6.8/7.1V T0-46 PKG 18324 LM399AH(SEL) U404 1820-5937 IC FF CM0S/74AC D-TYPE POS-EDGE-TRIG 28480 1820-5937 Keysight 34420A Service Guide...
  • Page 162 PROGPAL 28480 34401-88805 U701 1820-6974 IC-GPIB CONTROLLER IEEE-4881975/78 01295 TMS9914AFNL U702 1820-6176 IC-INTERFACE XCVR BIPOLAR BUS OCTL 01295 SN75ALS160DW U703 1820-6175 IC-INTERFACE XCVR BIPOLAR BUS OCTL 01295 SN75ALS162DW U704 1990-1552 OPTO-ISOLATOR LED-IC GATE IF=10MA-MAX 28480 1990-1552 Keysight 34420A Service Guide...
  • Page 163 27014 MC74HCT14AD U706 U706 1820-7662 IC-INTERFACE DRVR/RCVR BIPOLAR DUAL 27014 LT1180CS U751 U751 1826-2464 IC V RGLTR-FXD-POS 4.8/5.2V 3-T0-220 PKG 27014 LM340T-5-LB01 XU403 1200-1672 SOCKET-IC-DIP 4-CONT DIP-SLDR 06776 SBL·041-SP122·TG30 Y701 0410-4009 GERO-RES 12MHZ +1-0.8% 28480 0410-4009 Keysight 34420A Service Guide...

  • Page 164: 34420-66502 Display And Keyboard Pc Assembly

    RESISTOR 10 +-1%.125W TKF TC=0+-100 09021 RK73H2BT1OROF R618 0699-1378 RESISTOR 2.61K +-1%.125W TKF TC=0+-100 09021 RK73H2BT2611F R619 0699-1391 RESISTOR 1OK +·1%.125W TKF TC=0+·100 09021 RK73H2BT1002F U601 1826-2264 IC PWR MGT-UND-V-SEN 8 PINS P-SOIC PKG 04713 MC34064D-5 Keysight 34420A Service Guide...
  • Page 165 27014 LM339M PLSTC-SOIC U608 1820-6756 IC SHF-RGTR CMOS/74HC BIDIR 04713 MC74HC299D U609 1826-1402 IC V RGLTR-FXD-POS 4.8/5.2V 8-P-SOIC PKG 04713 MC78L05ACD W601 34401-61602 CABLE ASSY, 8.8L 28480 34401-61602 Y601 0410-4009 CERO-RES 12MHZ +1-0.8% . 28480 0410-4009 Keysight 34420A Service Guide...

  • Page 166: 34420A Mainframe

    34420-49301 34420-81902 KEYPAD, FLUBBER-SWITCH 28480 34420-81902 SCW1-7 0515-0433 SCRPHM4.0x08 TXSC 28480 0515-0433 SHD1 34420-80601 SHEILD FRONT 28480 34420-80601 SHD2 34420-80602 SHEILD-AIR 28480 34420-80602 SHD3 34420-80603 SHIELD FOR TRANSFORMER 28480 34420-80603 T901 9100-5174 POWER TRANSFORMER 28480 9100-5174 Keysight 34420A Service Guide...

  • Page 167: Manufacturer's List

    NORWOOD, MA, USA 2062 25403 NV PHILIPS ELCOMA EINDHOVEN, NE 27014 NATIONAL SEMICONDUCTOR CORP SANTA CLARA, CA, USA 95052 27264 MOLEX INC LISLE, IL, USA 28480 AGILENT DIV 01 SAN JOSE COMPONENTS SAN JOSE, CA, USA 95131 Keysight 34420A Service Guide...
  • Page 168 BRADY WH CO MILWAUKEE, WI, US 53209 91637 VISHAY ELECTRONIC COMPONENTS COLUMBUS, NE, US 68601 2L446 ADAC SCREW MACHINE PRODUCTS REDWOOD CITY, CA 94063 2M627 ROHM CORP KYOTO 615, JP S4217 NIPPON CHEMI-CON CORP OHME-SHI TOKYO JP Keysight 34420A Service Guide...

  • Page 169: Backdating

    Keysight 34420A Nano Volt / Micro Ohm Meter Service Guide Backdating This chapter normally contains information necessary to adapt this manual to instruments not directly covered by the current content. At this printing, however, the manual applies to all instruments. Therefore, no information is included in this...
  • Page 170 Backdating THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...

  • Page 171: Schematics

    Keysight 34420A Nano Volt / Micro Ohm Meter Service Guide Schematics This chapter contains a block diagram, disassembly drawings, schematics, and component locator drawings for the meter. The block diagram and schematics support the Chapter 4, "Theory of Operation". Mechanical Disassembly...

  • Page 172: Mechanical Disassembly

    Mechanical Disassembly Keysight 34420A Service Guide...

  • Page 173: 34420-66501 Component Locator

    34420-66501 Component Locator Keysight 34420A Service Guide...

  • Page 174: 34420-66502 Component Locator

    34420-66502 Component Locator Keysight 34420A Service Guide...

  • Page 175: Block Diagram

    Block Diagram Keysight 34420A Service Guide...

  • Page 176: Input And Protection Schematic

    Input and Protection Schematic Keysight 34420A Service Guide...

  • Page 177: Function Switching Schematic

    Function Switching Schematic Keysight 34420A Service Guide...

  • Page 178: Dc Amplifier Schematic

    DC Amplifier Schematic Keysight 34420A Service Guide...

  • Page 179: Ohms Current Source Schematic

    Ohms Current Source Schematic Keysight 34420A Service Guide...

  • Page 180: A/D Converter Schematic

    A/D Converter Schematic Keysight 34420A Service Guide...

  • Page 181: Configuration Data Shift Registers Schematic

    Configuration Data Shift Registers Schematic Keysight 34420A Service Guide...

  • Page 182: Floating Logic Schematic

    Floating Logic Schematic Keysight 34420A Service Guide...

  • Page 183: Earth Referenced Logic Schematic

    Earth Referenced Logic Schematic Keysight 34420A Service Guide...

  • Page 184: Power Supply Schematic

    Power Supply Schematic Keysight 34420A Service Guide...

  • Page 185: Display And Keyboard Schematic

    Display and Keyboard Schematic Keysight 34420A Service Guide...
  • Page 186 Schematics THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...

  • Page 187: 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 188 Characteristics and Specifications THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK. Keysight 34420A Service Guide...
  • Page 189 This information is subject to change without notice. Always refer to the English version at the Keysight website for the latest revision. © Keysight Technologies 2003-2018 Edition 3, September 2018 Printed in Malaysia *34420-90010* 34420-90010 www.keysight.com...

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