Keysight Technologies 34420A Service Manual

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Keysight 34420A Nano Volt/ Micro Ohm Meter

Service Guide

Notices

CAUTION

WARNING

duced in any form or by any means (including electronic storage and retrieval or translation into a foreign language) without prior agreement and written consent from Keysight Technologies as governed by United States and international copyright laws.

Trademarks

Microsoft® and Windows® are U.S. registered trademarks of Microsoft Corporation. All other brand and product names are trademarks or registered trademarks of their respective companies.

Manual Part Number

34420-90010

Edition

Edition 3, September 2018

Printed in:

Printed in Malaysia

Published by:

Keysight Technologies Bayan Lepas Free Industrial Zone, 11900 Penang, Malaysia

Technology Licenses

The hard ware and/or software described in this document are furnished under a license and may be used or copied only in accordance with the terms of such license.

Declaration of Conformity

Declarations of Conformity for this product and for other Keysight products may be downloaded from the Web. Go to http://www.keysight.com/

go/conformity. You can then search by

product number to find the latest Declaration of Conformity.

U.S. Government Rights

The Software is “commercial computer software,” as defined by Federal Acquisition Regulation (“FAR”) 2.101. Pursuant to FAR 12.212 and 27.405-3 and Department of Defense FAR Supplement (“DFARS”) 227.7202, the U.S. government acquires commercial computer software under the same terms by which the software is customarily provided to the public. Accordingly, Keysight provides the Software to U.S. government customers under its standard commercial license, which is embodied in its End User License Agreement (EULA), a copy of which can be found at http://www.keysight.com/

find/sweula. The license set forth in the

EULA represents the exclusive authority by which the U.S. government may use, modify, distribute, or disclose the Software. The EULA and the license set forth therein, does not require or permit, among other things, that Keysight: (1) Furnish technical information related to commercial computer software or commercial computer software documentation that is not customarily provided to the public; or (2) Relinquish to, or otherwise provide, the government rights in excess of these rights customarily provided to the public to use, modify, reproduce, release, perform, display, or disclose commercial computer software or commercial computer software documentation. No additional government requirements beyond those set forth in the EULA shall apply, except to the extent that those terms, rights, or licenses are explicitly required from all providers of commercial computer software pursuant to the FAR and the DFARS and are set forth specifically in writing elsewhere in the EULA. Keysight shall be under no obligation to update, revise or otherwise modify the Software. With respect to any technical data as defined by FAR 2.101, pursuant to FAR

12.211 and 27.404.2 and DFARS

227.7102, the U.S. government acquires no greater than Limited Rights as defined in FAR 27.401 or DFAR

227.7103-5 (c), as applicable in any technical data.

Warranty

THE MATERIAL CONTAINED IN THIS DOCUMENT IS PROVIDED “AS IS,” AND IS SUBJECT TO BEING CHANGED, WITHOUT NOTICE, IN FUTURE EDITIONS. FURTHER, TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, KEYSIGHT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, WITH REGARD TO THIS MANUAL AND ANY INFORMATION CONTAINED HEREIN, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. KEYSIGHT SHALL NOT BE LIABLE FOR ERRORS OR FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES IN CONNECTION WITH THE FURNISHING, USE, OR PERFORMANCE OF THIS DOCUMENT OR OF ANY INFORMATION CONTAINED HEREIN. SHOULD KEYSIGHT AND THE USER HAVE A SEPARATE WRITTEN AGREEMENT WITH WARRANTY TERMS COVERING THE MATERIAL IN THIS DOCUMENT THAT CONFLICT WITH THESE TERMS, THE WARRANTY TERMS IN THE SEPARATE AGREEMENT SHALL CONTROL.

Safety Information

A CAUTION notice denotes a hazard. It calls attention to an operating procedure, practice, or the like that, if not correctly performed or adhered to, could result in damage to the product or loss of important data. Do not proceed beyond a CAUTION notice until the indicated conditions are fully understood and met.

A WARNING notice denotes a hazard. It calls attention to an operating procedure, practice, or the like that, if not correctly performed or adhered to, could result in personal injury or death. Do not proceed beyond a WARNING notice until the indicated conditions are fully understood and met.

2 Keysight 34420A Service Guide

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 3

Safety Considerations

WARNING

NOTE

Read the information below before using this instrument.

The following general safety precautions must be observed during all phases of operation, service, and repair of this instrument. 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.

Only qualified, service-trained personnel who are aware of the hazards involved should remove the cover from the instrument.

For continued protection against fire, replace the line fuse only with a fuse of the specified type and rating.

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

4 Keysight 34420A Service Guide

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

Temperature

Humidity

Operating condition – 0 °C to 55 °C Storage condition – –40 °C to 75 °C

Operating condition – Up to 80% RH at 40°C (non-condensing)

Keysight 34420A Service Guide 5

Waste Electrical and Electronic Equipment (WEEE) Directive 2002/ 96/EC

This instrument complies with the WEEE Directive (2002/96/EC) marking requirement. This affixed product label indicates that you must not discard this electrical or electronic product in domestic household waste.

Product category:

With reference to the equipment types in the WEEE directive Annex 1, this instrument is classified as a “Monitoring and Control Instrument” product.

The affixed product label is as shown below.

Do not dispose in domestic household waste.

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)

– www.keysight.com/find/assist

(worldwide contact information for repair and service)

6 Keysight 34420A Service Guide

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

– Two channel input allows ratio and difference functions for voltage

measurements

– Highly visible vacuum-fluorescent display

– Portable, ruggedized case with non-skid feet

Flexible system features

– GPIB (IEEE-488) interface and RS-232 interface are standard

– SCPI (Standard Commands for Programmable Instruments) and Keithley 181

compatibility

– Readings at up to 250 per second

Keysight 34420A Service Guide 7

The Front-Panel at a Glance

1 Input channel select

2 Measurement function keys

3 Math operation keys

4 Filter select key

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5 Menu operation keys

6 Range/number of digits displayed keys

7 Single trigger/autotrigger/auto hold key

8 Shift / local key

The Front-Panel Menu at a Glance

The menu is organized in a top-down tree structure with three levels.

A: MEASurement MENU

1: DIG FILTER ) 2: INTEGRATE ) 3: OCOMP W ) 4: LOW POWER W ) 5: LOW VOLT W )

6: LoV LIMIT W

B: TEMPerature MENU

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 9

E: SYStem MENU

NOTE

1: RDGS STORE ) 2: SAVED RDGS ) 3: ERROR ) 4: TEST ) 5: CHART OUT ) 6: CHART SPAN )

7: CHART NULL ) 8: DISPLAY ) 9: COMMA ) 10: PRESET ) 11: REVISION

F: Input/Output MENU

1: GPIB ADDR ) 2: INTERFACE ) 3: BAUD RATE ) 4: PARITY ) 5: LANGUAGE

G: CALibration MENU

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" unless the meter is UNSECURED for calibration.

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Display Annunciators

Adrs Rmt Man Trig OC Off Null Stats Scale ERROR Shift Ch1 Ch2 Ch1 - Ch2 Ch1 / Ch2 W LP 2W LoV Hold Filt Mem

Turns on during a measurement. Meter is addressed to listen or talk over the GPIB interface. Meter is in remote mode (using remote interface). Meter is using manual ranging (autorange is disabled). Meter is waiting for a single trigger or external trigger. Offset compensation is turned off. A null value is being used. Math statistics operations are being used. Math scaling operations are being used. Hardware or remote interface command error(s) detected. "Shift" key has been pressed. Meter input is on Channel 1. Meter input is on Channel 2. Meter is indicating the difference between inputs on channel 1 and channel 2. Meter is indicating the ratio of the inputs on channel 1 and channel 2. Meter is measuring resistance (Ohms). Meter is using low power Ohms. Meter is using 2-wire Ohms (annunciator off indicates a 4-wire measurement). Meter is using voltage limited Ohms. Automatic reading hold is enabled. The analog and/or the digital filter is enabled. Turns on when reading memory is enabled.

To review the display annunciators, hold down the Shift key as you turn on the meter.

Keysight 34420A Service Guide 11

The Rear Panel at a Glance

1 Chassis ground

2 Power-line fuse-holder assembly

3 Power-line voltage setting

4 Chart recorder output terminal

(Analog out)

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

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5 Voltmeter complete output terminal

6 External trigger input terminal

7 GPIB (IEEE-488) interface

connector

8 RS-232 interface connector

In This Book

NOTE

Quick Start Chapter 1 prepares the meter for use and helps you get familiar

with a few of its front-panel features.

Front-Panel Operation Chapter 2 introduces you to the front-panel menu and

describes some of the meter's menu features.

Calibration Procedures Chapter 3 provides calibration, verification, and

adjustment procedures for the meter.

Theory of Operation Chapter 4 describes block and circuit level theory related

to the operation the meter.

Service Chapter 5 provides guidelines for returning your meter to Keysight

Technologies for servicing, or for servicing it yourself.

Replaceable Parts Chapter 6 contains a detailed parts lists of the meter.

Backdating Chapter 7 describes the differences between this manual and

older issues or this manual.

Schematics Chapter 8 contains the meter's block diagram, schematics,

disassembly drawings, and component locator drawings.

Characteristics and Specifications Chapter 9 lists the meter's specifications

and describes how to interpret these specifications.

If you have questions relating to the operation of the meter, call 1-800-452-4844 in the United States, or contact your nearest Keysight Technologies Sales Office.

Keysight 34420A Service Guide 13

THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK.

14 Keysight 34420A Service Guide

Safety Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Waste Electrical and Electronic Equipment (WEEE) Directive

2002/96/EC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Product category: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Sales and Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

The Front-Panel at a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

The Front-Panel Menu at a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Display Annunciators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

The Rear Panel at a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

In This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

1Quick Start

Quick Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

To Prepare the Meter For Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

If the Meter Does Not Turn On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

To Adjust the Carrying Handle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

To Make Input Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

To Measure Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

To Measure Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

To Measure Temperature With Thermistors . . . . . . . . . . . . . . . . . . . . .35

To Measure Temperature With RTDs . . . . . . . . . . . . . . . . . . . . . . . . . . .36

To Measure Temperature With Thermocouples . . . . . . . . . . . . . . . . . .37

To Select a Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

To Set the Number of Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

To Set the Integration Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Front-Panel Display Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Keysight 34420A Service Guide 15

To Rack Mount the Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

2 Front-Panel Operation

Front-Panel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Front-Panel Menu Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

A Front-Panel Menu Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

To Select an Input Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

To Select a Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

To Set or Change the Number of Digits . . . . . . . . . . . . . . . . . . . . . . . . 62

To Set the Integration Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

To Trigger the Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Null (Relative) Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

To Use Math (Stats) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

To Set the Number of Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Chart Output (Analog Output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

To Unsecure the Meter for Calibration . . . . . . . . . . . . . . . . . . . . . . . . . 70

3 Calibration Procedures

Keysight Technologies Calibration Services . . . . . . . . . . . . . . . . . . . . . 75

Calibration Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Time Required for Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Automating Calibration Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 75

Recommended Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Test Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Performance Verification Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Quick Performance Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Performance Verification Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Zero Offset Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Zero Offset Verification Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Gain Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Gain Verification Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

16 Keysight 34420A Service Guide

1 mV and 10 mV Gain Verification (Optional) . . . . . . . . . . . . . . . . . . . .86

1 mV and 10 mV gain verification procedure . . . . . . . . . . . . . . . . . .86

Injected Current Verification (Optional) . . . . . . . . . . . . . . . . . . . . . . . . .88

Injected Current Verification Procedure . . . . . . . . . . . . . . . . . . . . . .88

Chart Output Verification (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . .89

Chart Output Verification Procedure . . . . . . . . . . . . . . . . . . . . . . . . .89

Calibration Security Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91

To Unsecure the Meter Without the Security Code . . . . . . . . . . . . .92

Calibration Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Calibration Message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95

Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Aborting a Calibration in Progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97

Zero Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Zero Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Gain Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Gain Adjustment Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Gain Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Injected Current Calibration (Optional) . . . . . . . . . . . . . . . . . . . . . . . .101

Internal Temperature Reference Calibration (Optional) . . . . . . . . . . .103

Chart Output Calibration (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . .104

Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

4 Theory of Operation

Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110

Input and Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Function Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114

DC Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115

Ohms Current Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117

A-to-D Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120

Configuration Data Shift Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .122

Injected Current Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . .122

Keysight 34420A Service Guide 17

Chart Recorder Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Floating Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

Earth-Referenced Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

5Service

Operating Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Types of Service Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Repackaging for Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Electrostatic Discharge (ESD) Precautions . . . . . . . . . . . . . . . . . . . . . 134

Surface Mount Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

To Replace the Power-Line Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Input Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Cleaning the Connector Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Self-Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Power-On Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Complete Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Performing Individual Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

6Replaceable Parts

Replaceable Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

To Order Replace Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

Backdating and Part Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

Input Connector Replaceable Parts . . . . . . . . . . . . . . . . . . . . . . . . 147

34420-66501 Main PC Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

34420-66502 Display and Keyboard PC Assembly . . . . . . . . . . . . . . . 164

34420A Mainframe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Manufacturer's List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

7Backdating

18 Keysight 34420A Service Guide

8Schematics

Mechanical Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172

34420-66501 Component Locator . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

34420-66502 Component Locator . . . . . . . . . . . . . . . . . . . . . . . . . . . .174

Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175

Input and Protection Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176

Function Switching Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177

DC Amplifier Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178

Ohms Current Source Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

A/D Converter Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

Configuration Data Shift Registers Schematic . . . . . . . . . . . . . . . . . .181

Floating Logic Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182

Earth Referenced Logic Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . .183

Power Supply Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184

Display and Keyboard Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185

9 Characteristics and Specifications

Keysight 34420A Service Guide 19

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20 Keysight 34420A Service Guide

List of Figures

Figure 3-1 Applying short on JM500 . . . . . . . . . . . . . . . . . . . . . . .92

Keysight 34420A Service Guide 21

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22 Keysight 34420A Service Guide

List of Tables

Table 3-1 Zero Offset Verification Procedure . . . . . . . . . . . . . . . . 82

Table 3-2 Gain Verification Procedure . . . . . . . . . . . . . . . . . . . . .84

Table 3-3 1 mV and 10 mV gain verification procedure . . . . . . . 87

Table 3-4 Gain calibration procedure . . . . . . . . . . . . . . . . . . . .100

Table 3-5 System error messages . . . . . . . . . . . . . . . . . . . . . . .105

Table 3-6 Self-test error messages . . . . . . . . . . . . . . . . . . . . . .106

Table 3-7 Calibration error messages . . . . . . . . . . . . . . . . . . . .107

Table 4-1 Amplifier gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115

Table 4-2 2-wire or 4-wire resistance measurements . . . . . . . .117

Table 5-1 Main supply voltages . . . . . . . . . . . . . . . . . . . . . . . . .140

Keysight 34420A Service Guide 23

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24 Keysight 34420A Service Guide

Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide

1 Quick Start

Quick Start 26 To Prepare the Meter For Use 27 If the Meter Does Not Turn On 28 To Adjust the Carrying Handle 30 To Make Input Connections 31 To Measure Voltage 33 To Measure Resistance 34 To Measure Temperature With RTDs 36 To Measure Temperature With Thermocouples 37 To Select a Range 38 To Set the Number of Digits 39 To Set the Integration Time 40 Front-Panel Display Formats 41 To Rack Mount the Meter 42

1 Quick Start

Shift

DCV

Shift

NOTE

Quick Start

This chapter helps you prepare the meter for use and contains exercises designed to get you started with the meter, its menus, and the front panel.

The front panel has two rows of keys to select various functions and operations. Most keys have a shifted function printed in blue above the key. To perform a

shifted function, press (the Shift display annunciator will turn on). Then, press the key that has the desired label above it. For example, to select the

temperature measurement function, press .

If you accidentally press , just press it again to turn off the Shift annunciator.

The rear cover of this book is a fold-out Quick Reference Guide. On this cover you will find a quick summary of various meter features. Inside the rear cover is a diagram of the front panel menu options.

26 Keysight 34420A Service Guide

To Prepare the Meter For Use

Shift

The following steps help you verify that the meter is ready for use.

1 Check the list of supplied items.

Verify that you have received the following items with your meter. If any item is missing, contact your nearestKeysight Technologies Sales Office.

– One low thermal input cable.

– One low thermal four-wire shorting plug.

– One power cord.

–This User’s Guide.

–One Service Guide.

–One folded Quick Reference card.

– Certificate of Calibration with removable calibration label.

– One bottle of DeoxIT™ contact cleaner.

2 Connect the power cord and turn the meter on.

The front panel display will light up while the meter performs its power-on self-test. The GPIB bus address is displayed. The meter is left in 61/2 digit resolution, channel 1 input, and digital filter on.

Quick Start 1

[1]

To view the display with all annunciators turned on, hold down as you turn on the meter.

3 Perform a complete self-test.

The complete self-test performs a more extensive series of tests than those performed at power-on. Hold down Shift as you press the power switch to turn

on the meter; continue to hold for more than 5 seconds. The self-test will begin when you release the key.

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.

[1] DeoxIT™ is a trademark of CAIG Laboratories, Inc., San Diego, California.

Keysight 34420A Service Guide 27

1 Quick Start

NOTE

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.

First verify that the meter’s power switch is in the “On” position. Make sure the

power cord is firmly plugged into the power module on the meter’s rear panel.

Verify that the power source is energized.

2 Verify the power-line voltage setting.

The line voltage is set to the proper value for your country when the meter is

shipped from the factory. Change the voltage setting if it is not correct. The

settings are: 100, 120, 220, or 240 Vac (for 230 Vac operation, use the 220 Vac

setting).

See the diagram on the next page to verify or change the setting.

To replace the 250 mAT 250 V fuse, order part number 2110-0817. This fuse is used for all power line voltage settings.

28 Keysight 34420A Service Guide

Quick Start 1

1 Remove the power cord. Remove

the fuse holder assembly from the rear

3 Rotate the line-voltage selector

until the correct voltage appears in the window.

2 Install the fuse. Remove the

line-voltage selector from the assembly.

4 Replace the fuse-holder assembly

in the rear panel.

Install the correct fuse and verify that the correct line voltage appears in the window.

Keysight 34420A Service Guide 29

1 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

30 Keysight 34420A Service Guide

To Make Input Connections

NOTE

WARNING

Using the Cable Provided

Align the front panel connector and cable conductors, press in.Tighten coupling nut.

Quick Start 1

Keysight 34420A Service Guide 31

The connector and cable are an integral part of the measurement system. For 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 137.

The connector body and cable shield are connected to earth ground.

1 Quick Start

Using a Custom Cable

Refer to page 137 for additional information about building custom input cables.

32 Keysight 34420A Service Guide

To Measure Voltage

NOTE

Channel 1 Ranges: 1 mV, 10 mV, 100 mV, 1 V, 10 V, 100 V Maximum resolution: 0.1 nV (on 1 mV range)

Channel 2 Ranges: 1 mV, 10 mV, 100 mV, 1 V, 10 V 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.

Quick Start 1

Scan mode alternates between input channels every 3 seconds or every measurement, whichever is longer.

Keysight 34420A Service Guide 33

1 Quick Start

NOTE

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 disabled if desired.

34 Keysight 34420A Service Guide

To Measure Temperature With Thermistors

Thermistor type: 5 kW

Quick Start 1

Keysight 34420A Service Guide 35

1 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

36 Keysight 34420A Service Guide

To Measure Temperature With Thermocouples

NOTE

Thermocouple types: B, E, J, K, N, R, S, T

Reference: external thermistor, external fixed value, or internal thermistor. Channel 2 only.

Quick Start 1

When using the internal thermistor as the temperature reference, you should make a custom cable to connect the thermocouple wire directly to the input terminals (see page 137).

Keysight 34420A Service Guide 37

1 Quick Start

NOTE

To Select a Range

You can let the meter automatically select the range using autoranging or you can select a fixed range using manual ranging.

– Autoranging is selected at power-on and after a remote interface reset.

–Autorange thresholds:

Down range at <10% of range Up range at >120% of range

– If the input signal is greater than the present range can measure, the meter will

give an overload indication (“OVLD”).

– When making difference or ratio measurements, an overload on either channel

will give an overload indication (“OVLD”).

For voltage measurements, ranging is local to the selected channel. This means that you can select the ranging method (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.

38 Keysight 34420A Service Guide

To Set the Number of Digits

You can set the display to show 4½, 5½, 6½, or 7½ digits. In this book, the most significant digit (leftmost on the display) is referred to as the “½” digit, since it can only be a “0” or “1”. The number of digits displayed also depends upon the

integration time set, see page 40.

Quick Start 1

– The number of digits is set to 6½ digits at power-on and after a remote

interface reset.

– 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 39

1 Quick Start

NOTE

To Set the Integration Time

Integration time is specified in Number of Power Line Cycles (NPLC). You can set the NPLC to 0.02, 0.2, 1, 2, 10, 20, 100, or 200.

– You can set the integration time to one of three fixed values by choosing the

number of digits displayed, see page 39.

– You can set the integration time in the MEASure menu using the INTEGRATE

command.

– The Integration Time is directly related to the maximum number of digits the

meter will display.

NPLC

0.02 4½ 5½

0.2 5½ 6½

16½ 7½

26½ 7½

10 6½ 7½

20 7½ 7½

100 7½ 7½

200 7½ 7½

Filter Off

Max Digits Shown

Filter On

Max Digits Shown

– You can always show fewer digits than the maximum allowed (the minimum

number of digits shown is 4½).

Integration Time is local to the selected function. This means that you can select the integration time for each function independently. The meter remembers integration time when you switch between functions.

40 Keysight 34420A Service Guide

1.021,651 V

-045.230 mV

0.133,256,7 W

O.VLD mV

-H.DDD,DDD,D EFF

6 digits

“½” digit

5 digits

“½” digit

7 digits

“½” digit

Front-panel display format

This is the 1 V range,

This is the 100 mV range,

This is the 1 ohm range,

This is an overload indication on the 1 mV range.

6½ digits are displayed.

5½ digits are displayed.

7½ digits are displayed.

– H D E F

Negative sign or blank (positive) “½” digit (0 or 1) Numeric Digits Exponent (m, k, M) Measurement units

Front-Panel Display Formats

Quick Start 1

Keysight 34420A Service Guide 41

1 Quick Start

To Rack Mount the Meter

You can mount the meter in a standard 19-inch rack cabinet using one of three optional kits available. 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.

To remove the handle, rotate it to the vertical position and pull the end s outward.

To remove the rubber bumper, stretch a corner and then slide it off.

42 Keysight 34420A Service Guide

Quick Start 1

To rack mount a single instrument, order adapter kit 5063-9240.

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 43

1 Quick Start

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44 Keysight 34420A Service Guide

Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide

2 Front-Panel Operation

Front-Panel Operation 46 Front-Panel Menu Reference 47 A Front-Panel Menu Tutorial 51 To Select an Input Channel 60 To Select a Range 61 To Set or Change the Number of Digits 62 To Set the Integration Time 63 To Trigger the Meter 64

2 Front-Panel Operation

Front-Panel Operation

This chapter assumes you are familiar with the meter and menu operations. You should also understand how to make connections for the various types of measurements. If you are not familiar with this information, please read Chapter 1,

"Quick Start" starting on page 25.

This chapter does not give a detailed description of every front-panel key or menu 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.

46 Keysight 34420A Service Guide

Front-Panel Menu Reference

A: MEASurement MENU

1: DIG FILTER ) 2: INTEGRATE ) 3: OCOMP W ) 4: LOW POWER W ) 5: LOW VOLT W )

6: LoV LIMIT W

1: DIG FILTER Selects the digital filter speed. Can be set to FAST,

MEDIUM, or SLOW.

2: INTEGRATE Sets the measurement integration time.

3: OCOMP W Enables or disables offset compensation for resistance

measurements.

4: LOW POWER W Enables or disables low power ohms measurements.

5: LOW VOLT W Enables or disables voltage limited resistance

measurements.

6: LoV LIMIT W Sets the voltage limit for voltage limited resistance

measurements.

Front-Panel Operation 2

B: TEMPerature MENU

1:PROBE TYPE ) 2: UNITS ) 3: RTD TYPE ) 4:RTD Ro ) 5:T/C TYPE ) 6: COLD JUNCT ) 7:JUNCT

1: PROBE TYPE Selects thermocouples, thermistors, or RTDs as the

temperature probe.

2: UNITS Sets the measurement units to either °C, °F, or Kelvins.

3: RTD TYPE Sets the type of RTD in use.

4: RTD Ro 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 47

2 Front-Panel Operation

C: MATH MENU

1: STATS ) 2: NULL VALUE ) 3: SCALE GAIN ) 4 : SCALE OFST

1:STATS Recalls the values of minimum, maximum, standard

2: NULL VALUE Selects independent null settings for voltage on channels 1

3: SCALE GAIN Sets the gain for linear scaling of the data.

4: SCALE OFST Sets the offset for linear scaling of data.

D: TRIGger MENU

1: READ HOLD ) 2: TRIG DELAY ) 3: N SAMPLES

1: READ HOLD Selects the reading hold sensitivity band.

2: TRIG DELAY Specifies a time delay between the trigger and the start of

3: N SAMPLES Sets the number of samples taken per trigger.

deviation, average, peak-to-peak, and number of readings.

and 2, resistance, and temperature functions.

the measurement.

48 Keysight 34420A Service Guide

Front-Panel Operation 2

E: SYStem MENU

1: RDGS STORE ) 2: SAVED RDGS ) 3: ERROR ) 4: TEST ) 5: CHART OUT ) 6: CHART SPAN )

7: CHART NULL ) 8: DISPLAY ) 9: COMMA ) 10: PRESET ) 11: REVISION

1: RDGS STORE Enables or disables reading memory.

2: SAVED RDGS Recalls readings stored in memory (up to 1024 readings).

3: ERROR Retrieves errors from the error queue (up to 20 errors).

4: TEST Performs a complete self-test or individual self-tests.

5: CHART OUT Enables or disables the chart recorder output (Analog Out).

6: CHART SPAN Sets the chart recorder output range (Analog Out).

7: CHART NULL S Sets the chart recorder output offset (Analog Out).

8: DISPLAY Enables or disables the front panel display.

9: COMMA Enables or disables a comma separator between digits in

the display.

10: PRESET Returns the meter to factory default settings.

11: REVISION Displays the meter’s firmware revision code.

F: Input / Output MENU

1: GPIB ADDR ) 2: INTERFACE ) 3: BAUD RATE ) 4: PARITY ) 5: LANGUAGE

1: GPIBADDR Sets the GPIB bus address (0 to 30, default 22).

2: INTERFACE 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 49

2 Front-Panel Operation

G: CALibration MENU

1: SECURED ) [1: UNSECURED] ) [2:CALIBRATE] ) [3: CHART ZERO] ) [4 : CHART GAIN] )

[5: INJECTED I] ) 6:CAL COUNT ) 7:MESSAGE

[1]

1: SECURED The meter is secured against calibration; enter code to

unsecure.

1: UNSECURED The meter is unsecured for calibration; enter code to

secure.

2: CALIBRATE Performs a calibration of meter; must be UNSECURED.

3: CHART ZERO Performs a calibration of the chart recorder output zero

level.

4: CHART GAIN Performs a calibration of the chart recorder output gain.

5: INJECTED I Performs a calibration to minimize the injected current.

6: CAL COUNT Reads the total number of times the meter has been

calibrated.

7: MESSAGE 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.

50 Keysight 34420A Service Guide

A Front-Panel Menu Tutorial

∧

∧ ∧

∧

Shift

∧

Shift∧Auto/Man

Shift

∧

NOTE

This section is a step-by-step tutorial which shows how to use the front-panel menu. We recommend that you spend a few minutes with this tutorial to get comfortable with the structure and operation of the menu.

The menu is organized in a top-down tree structure with three levels (menus, commands, and parameters). You move down or up the menu tree to

get from one level to the next. Each of the three levels has several horizontal choices which you can view by moving left or right .

Front-Panel Operation 2

–To turn on the menu, press

–To turn off the menu, press

(Menu On/Off).

(Menu On/Off), or press any of the

function or math keys on the top row of front-panel keys.

–To execute a menu command, press .

–To recall the last menu command that was executed, press

(Menu

Recall).

–To turn off the menu at any time without saving changes, press any function

key

If you become confused or get lost at any point during the tutorial, simply turn off the menu and start over again with step 1 for that example.

Keysight 34420A Service Guide 51

2 Front-Panel Operation

∧

∧ ∧

∧∧∧∧∧

∧

Shift∧∧

Auto/Man

Shift

∧

Auto/Man

Messages Displayed During Menu Use

TOP OF MENU -You pressed while on the menus level; this is the top level of the menu and you cannot go any higher.

To turn off the menu, press Shift (Menu On/Off). To move across the choices on a level, press or . To move down a level, press .

MENUS - You are on the menus level. Press or view the choices.

COMMANDS - You are on the commands level. Press or to view the command choices

within the selected menu group.

PARAMETER - You are on the parameter level. Press or to view and edit the parameter for the selected command.

MENU BOTTOM - You pressed while on the parameter level; this is the bottom level of the menu and you cannot go any lower.

To turn off the menu, press (Menu On/Off). To move up a level, press .

ENTERED - The change made on the parameter level is saved. This is displayed after you press Auto/ Man (Menu Enter) to execute the command.

MIN VALUE - The value you specified on the parameter level is too small for the selected command. The minimum value allowed is displayed for you to edit.

MAX VALUE - The value you specified on the parameter level is too large for the selected command. The maximum value allowed is displayed for you to edit.

EXITING - You will see this message if you turn off the menu by pressing (Menu On/Off) or a front-panel function/math key. You did not edit any values on the parameter level and changes were NOT saved.

NOT ENTERED - You will see this message if you turn off the menu by pressing (Menu On/Off) or a front-panel function/math key. You did some editing of parameters but the changes were

NOT saved. Press

VOLTS ONLY - The requested function is only available for voltage measurements. UNAVAILABLE - The action requested is NOT allowed in the present configuration.

(Menu Enter) to save changes made on the parameter level.

52 Keysight 34420A Service Guide

Front-Panel Operation 2

-0.824,153 V -0.824153 V

With comma separator

(factory setting)

Without comma separator

Shift

∧

On/Off

A: MEAS MENU

∧∧∧

∧

E: SYS MENU

Menu Example 1

The following steps show you how to turn on the menu, move up or down between levels, move across the choices on each level, and turn off the menu.

In this example, you will turn off the display comma separator.

The meter can display readings on the front panel with or without a comma separator. The following steps show how to disable the comma.

1 Turn on the menu.

You enter the menu on the menus level. The MEAS MENU is your first choice on this level.

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.).

Keysight 34420A Service Guide 53

2 Front-Panel Operation

∧

1: RDGS STORE

∧∧∧∧∧∧∧

∧

9: COMMA

∧

OFF

3 Move down to the commands level within the SYS MENU.

The RDGS STORE command is your first choice on this level.

4 Move across to the COMMA command on the command s level.

There are eleven command choices available in the SYS MENU. Each choice on

this level has a number prefix for easy identification (1: , 2: , etc.).

5 Move down a level to the COMMA parameter choices.

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.

54 Keysight 34420A Service Guide

Front-Panel Operation 2

Auto/Man

ENTER

ENTERED

Shift

∧

Recall

9: COMMA

∧

OFF

7 Save the change and turn off the menu.

The meter beeps and displays a message to show that the change is now in effect. You are then exited from the menu. The meter will no longer show commas in the display.

Menu Example 2

The following exercise demonstrates how to use the menu recall feature as a shortcut to set the COMMA command back to its original setting. You must

perform the steps in Menu Example 1 before you start this example.

1 Use menu recall to return to the COMMA command.

This returns you to the COMMA command, which was the last command used before you exited the menu in the Example 1.

2 Move down to the COMMA parameter choices.

The first parameter choice is OFF (the current setting from Example 1).

Keysight 34420A Service Guide 55

2 Front-Panel Operation

∧

Auto/Man

ENTER

ENTERED

Shift

∧

On/Off

A: MEAS MENU

3 Move across to the ON choice.

Set the parameter back to its original value.

4 Save the change and turn off the menu.

The meter beeps and displays a message to show that the change is now in

effect. You are then exited from the menu.

Menu Example 3

Some commands in the menu require that you enter a numeric parameter value. The following steps show you how to enter a number in the menu. For this example, you will set the null value for channel 1 to –30 millivolts.

Make sure the meter has channel 1 selected, is in the dc voltage function, and has 6½ digits displayed. Connect the four-wire short to the meter input.

1 Turn on the menu.

You enter the menu on the menus level. The MEAS MENU is your first choice

on this level.

56 Keysight 34420A Service Guide

Front-Panel Operation 2

∧

C: MATH MENU

∧

1: STATS

∧

2: NULL VALUE

∧

0.000,000,0 V

∧

2 Move across to the MATH MENU choice on this level.

There are six menu group choices available on this level.

3 Move down to the commands level within the MATH MENU.

The STATS command is your first choice on this level.

4 Move across to the NULL VALUE command.

5 Move down to edit the NULL VALUE parameter.

The null value should be 0.000000 V when you come to this point in the menu for the first time. For this example, you will first set the null value to –0.300000 volts.

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 57

2 Front-Panel Operation

∧∧– 0.000,000,0 V

∧

– 0.000,000,0 V

∧∧∧

– 0.300,000,0 V

∧∧∧

∧

∧∧∧

– 0.300,000,0 V

6 Make the number negative.

The left most character on the display toggles between +, –, and

7 Move the flashing cursor over to edit the second digit.

Notice that the digit to the right of the decimal point is flashing.

8 Increment the digit until “3” is displayed.

You decrement or increment each digit independently. Neighboring digits are

not affected.

9 Move the flashing cursor over to the units location.

58 Keysight 34420A Service Guide

Notice that the units are flashing on the right side of the display.

Front-Panel Operation 2

∧

– 030.000,00 mV

Auto/Man

ENTER

ENTERED

Null

Shift

∧

NOTE

10 Decrease the displayed number by a factor of 10.

Notice that the position of the decimal point changes and the displayed number increases by a factor of 10 and the mV annunciator is on.

11 Save the change and turn off the menu.

The meter beeps and displays a message to show that the change is now in effect. You are then exited from the menu.

You will be returned to the normal measurement display, and, if you have installed the four-wire short, the display will show a positive measurement in the approximate amount of the null value just entered.

The Null annunciator is on in the display.

Keep in mind that null is turned on and - 0.03 volts is used as the null value for measurements. To clear the null value, press .

Hint You can use the menu recall feature to save steps when entering the null

value. First, press on the front panel and then press

(Menu

Recall). The meter will jump to the 2: NULL VALUE command. Press . The null value in the display is the first reading taken after you turned 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 discusses several of the most common front-panel operations.

Keysight 34420A Service Guide 59

2 Front-Panel Operation

Channel

Shift

Channel

NOTE

To Select an Input Channel

For voltage measurements, you have two independent input channels.

–Pressing toggles the display between Channel 1 and Channel 2.

– Pressing (Scan) creates an alternating Channel 1 and Channel 2

display. Press again to cancel.

Scan mode alternates between input channels every 3 seconds or every measurement, whichever is longer. If you are using the scan mode, turn off all the input filters (both digital and analog).

60 Keysight 34420A Service Guide

To Select a Range

NOTE

You can let the meter automatically select the range using autoranging or you can select a fixed range using manual ranging.

Front-Panel Operation 2

– Autoranging is selected at power-on and after a remote interface reset.

– Autorange thresholds:

Down range at <10% of range Up range at >120% of range

– If the input signal is greater than the present range can measure, the meter will

give an overload indication (“OVLD”).

– When making difference or ratio measurements, an overload on either channel

will give an overload indication (“OVLD”).

Keysight 34420A Service Guide 61

2 Front-Panel Operation

To Set or Change the Number of Digits

integration time set, see page 63.

– The number of digits is set to 6½ digits at power-on and after a remote

interface reset.

– 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.

62 Keysight 34420A Service Guide

To Set the Integration Time

NOTE

Integration time is specified in Number of Power Line Cycles (NPLC). You can set the NPLC to 0.02, 0.2, 1, 2, 10, 20, 100, or 200.

– You can set the integration time to one of three fixed values by choosing the

number of digits displayed, see page 62.

– You can set the integration time in the MEASure menu using the INTEGRATE

command.

– The Integration Time is directly related to the maximum number of digits the

meter will display.

Front-Panel Operation 2

NPLC

0.02 4½ 5½

0.2 5½ 6½

16½ 7½

26½ 7½

10 6½ 7½

20 7½ 7½

100 7½ 7½

200 7½ 7½

Filter Off

Max Digits Shown

Filter On

Max Digits Shown

– You can always show fewer digits than the maximum allowed (the minimum

number of digits shown is 4½).

Keysight 34420A Service Guide 63

2 Front-Panel Operation

Single

To Trigger the Meter

You can trigger the meter from the front panel using single trigger or autotrigger.

– Autotriggering is enabled when you turn on the meter. Notice that the

* (sample) annunciator turns on during each measurement.

– Single triggering takes one reading each time you press and then waits

for the next trigger. Continue pressing this key to trigger the meter.

Using an External Trigger

The external trigger mode is also enabled by pressing . It is like the single trigger mode except that you apply a trigger pulse to the rear-panel Ext Trig terminal. The meter is triggered on the negative edge of a TTL pulse.

The front-panel key is disabled when in remote.

64 Keysight 34420A Service Guide

Null (Relative) Operation

Null

When making null measurements, also called relative, each reading is the difference between the input signal and a stored null value. You could, for example, make a more accurate two-wire ohms measurement by shorting the test

leads and pressing to remove the test lead resistance.

Reading = measurement – null value

– The null value is adjustable and you can set it to any value between 0 and ±

120% of the highest range, for the present function.

– The null value is stored in volatile memory; the value is cleared when power

has been off or after a remote interface reset.

– Each function and channel has an independent null value. For voltage

measurements, each input channel has an independent null. Temperature measurement null is applied to all temperature measurements (if you change the probe type, null is still enabled and applied). The null for resistance measurements applies to both 2-wire and 4-wire measurements.

– The null value is stored in the meter’s Null Register. There are two ways you

can specify the null value. First, you can enter a specific number into the register from the front-panel menu or from the remote interface. Any previously stored value is replaced with the new value. If you are operating the meter from

the front panel, entering a null value also turns on the null function.

The second way to enter the null value is to let the meter store the first reading in the register. Press the key to make the displayed measurement the null

value and enable the Null operation. After you enable null, the first reading displayed will be zero. If you entered a number into the register, as described in the paragraph above, the first reading does not overwrite the stored value.

– 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).

Front-Panel Operation 2

Keysight 34420A Service Guide 65

2 Front-Panel Operation

Stats

Shift

∧

Stats

Shift

∧

To Use Math (Stats)

There are two math operations available, only one of which can be enabled at a time. The meter can either scale the readings as they are taken, or can keep statistics on a group of reading. The selected math operation remains in effect until you disable it, change functions, turn off the power, or perform a remote interface reset.

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. Read the statistics gathered in the MATH menu under the STATS command.

After viewing the stored statistics, press (Menu On/Off) to return to the measurement and continue taking statistics.

After you enable statistics, the first reading that the meter takes is stored as both the minimum and maximum value. The minimum is replaced with any subsequent value that is less. The maximum is replaced with any subsequent value that is greater.

All values are stored in volatile memory; the meter clears the values when stats is turned on, when power has been off, or after a remote interface reset or preset.

When enabled, the following statistics are available:

MIN minimum reading

MAX maximum reading

AVER arithmetic average of all readings

STD DEV standard deviation of all readings

PEAK-PEAK peak to peak value of minimum and maximum

COUNT the total number of readings

Hint You can use the menu recall feature to save steps when using the math

operations. After pressing on the front panel, press (Menu Recall). The meter will jump to the 1:STATS command and you can press to

66 Keysight 34420A Service Guide

Front-Panel Operation 2

Shift

∧

view the statistics taken. After viewing the stored statistics, press (Menu On/Off) to return to the measurement and continue taking statistics.

Keysight 34420A Service Guide 67

2 Front-Panel Operation

To Set the Number of Samples

Normally, the meter takes one reading (or sample) each time it receives a trigger from the selected trigger source (if the meter is in the wait-for-trigger state). You can, however, instruct the meter to take multiple readings for each trigger received.

– Number of samples: 1 to 50,000. The default is 1 sample per trigger.

– The sample count is stored in volatile memory; the meter sets the sample

count to 1 when power has been off or after a remote interface reset. The

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}

68 Keysight 34420A Service Guide

Chart Output (Analog Output)

Shift

Null

Shift

∧

reading chart null–()

span

----------------------------------------- chart output voltage=

You can use the Chart Output (Analog Output) connector on the rear panel to run a strip chart recorder or similar instrument. The connector provides an output voltage proportional to the measured voltage.

– Enable the chart output under the 5: CHART OUT command in the SYStem

menu.

Set the chart span under the 6: CHART SPAN command in the SYStem menu.

Set the chart offset under the 7: CHART NULL command in the SYStem menu.

You can also press (Chart Null) to null the chart output voltage based upon the displayed reading. This action places a null value in the Chart

Offset register. Pressing 7: CHART NULL command where you can manually edit the null value.

– The output can range from –3.00 V to +3.00 V.

– When chart output is disabled (Off), the output is set to 0 V.

– The output impedance is 1 kW.

– The output voltage is related to the input signal as follows:

Front-Panel Operation 2

(Menu Recall) will take you to the

Note that reading includes the results of measurement unit conversion, filtering, null, and any math operation performed on the measurement.

– 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 69

2 Front-Panel Operation

A: MEAS MENU

∧

G: CAL MENU

1: SECURED

Shift

∧ ∧

NOTE

^000000: CODE

^034420: CODE

To Unsecure the Meter for Calibration

The meter can use a calibration security code to prevent unauthorized or accidental calibration. This procedure shows you how to unsecure the meter for calibration.

1 Turn on the menu.

2 Move across to the CAL MENU choice on this level.

3 Move down a level to the SECURED command.

If the display shows UNSECURED, you do not need to perform this procedure to perform calibration.

4 Move down to the ''parameters” level.

5 Enter the security code.

6 Save the change and exit.

70 Keysight 34420A Service Guide

Front-Panel Operation 2

NOTE

The security code is set to “KT34420” when the meter is shipped from the factory. The security code is stored in non-volatile memory and does not change when the power has been off or after a remote interface reset.

To enter the security code from the front panel, enter only the six digits. To enter the security code from the remote interface, you may use up to 11 characters.

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.

Additional information about the calibration security feature is given on page 91.

Keysight 34420A Service Guide 71

2 Front-Panel Operation

THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK.

72 Keysight 34420A Service Guide

Keysight 34420A Nano Volt/Micro Ohm Meter Service Guide

3 Calibration Procedures

Keysight Technologies Calibration Services 75 Recommended Test Equipment 77 Test Considerations 78 Performance Verification Tests 79 Zero Offset Verification 81 Gain Verification 84 1 mV and 10 mV Gain Verification (Optional) 86 Injected Current Verification (Optional) 88 Chart Output Verification (Optional) 89 Calibration Security Code 91 Calibration Count 94 Calibration Message 95 Calibration Procedure 96 Aborting a Calibration in Progress 97 Zero Calibration 98 Gain Calibration 99 Injected Current Calibration (Optional) 101 Internal Temperature Reference Calibration (Optional) 103 Chart Output Calibration (Optional) 104 Error Messages 105

This chapter contains procedures for verification of the meter's performance and adjustment (calibration).

Closed-Case Electronic Calibration The meter features closed-case electronic calibration. No internal mechanical adjustments are required. The meter calculates correction factors based upon the input reference value you set. The

3 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.)

74 Keysight 34420A Service Guide

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.

Calibration Interval

The meter should be calibrated on a regular interval determined by the measurement accuracy requirements of your application. A 1-year or 2-year interval is adequate for most applications. Keysight Technologies does not recommend extending calibration intervals beyond 2 years for any application.

Whatever calibration interval you select, Keysight Technologies recommends that complete re-adjustment should always be performed at the calibration interval. This will increase your confidence that the Keysight 34420A will remain within specification for the next calibration interval. This criteria for re-adjustment provides the best long-term stability. Performance data measured using this method can be used to extend future calibration intervals.

Calibration Procedures 3

Time Required for Calibration

The Keysight 34420A can be automatically calibrated under computer control. With computer control you can perform the complete calibration procedure and performance verification tests in less than 50 minutes. Manual calibrations using the recommended test equipment will take approximately 2 hours.

Automating Calibration Procedures

You can automate the complete verification and adjustment procedures outlined in this chapter if you have access to programmable test equipment. You can program the instrument configurations specified for each test over the remote interface. You can then enter readback verification data into a test program and compare the results to the appropriate test limit values.

You can also enter calibration constants from the remote interface. Remote operation is similar to the local front-panel procedure. You can use a computer to

Keysight 34420A Service Guide 75

3 Calibration Procedures

perform the adjustment by first selecting the required setup. The calibration value is sent to the meter and then the calibration is initiated over the remote interface. 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.

76 Keysight 34420A Service Guide

Recommended Test Equipment

The test equipment recommended for the performance verification and adjustment procedures is listed below. If the exact instrument is not available, substitute calibration standards of equivalent accuracy.

Calibration Procedures 3

Instrument Requirements Recommended model

Low thermal 4-wire shorting plug Low EMF four-wire short

Low thermal input connector and cable Low EMF, all copper

Multifunction Calibrator

Capacitor 1000 pF none 0

1000:1 Voltage Divider Low Thermal Noise none 0

Temperature Measurement Device (RTD or thermistor)

6 1/2 Digit Digital Multimeter (DMM) 10 Vdc ± 0.01% Keysight 34401A O,T

[a] Q = Quick verification

P = Performance verification Tests

O = Optional Verification Tests

T = Troubleshooting

DC Volts O to 100 V resistance o to 1 MΩ

± 0.2° C none 0

Keysight 34103A (provided with meter)

Keysight 34102A (provided with meter)

Fluke 5700 Q,P

Use

Q,P,O,T

[a]

Keysight 34420A Service Guide 77

3 Calibration Procedures

Test Considerations

To ensure proper instrument operation, verify that you have selected the correct power line voltage prior to attempting any test procedure in this chapter. See “To

Prepare the Meter For Use” on page 27 for more information.

For optimum performance, all test procedures should comply with the following recommendations:

– Assure that the calibration ambient temperature is stable and between 18° C

and 28° C.

– Assure ambient relative humidity is less than 80%.

– Allow a 3-hour warm-up period with the low thermal shorting plug connected

before verification or adjustment.

– 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.

– Ensure the input connector or low thermal shorting plug coupling nut is

properly tightened (torque to 20 in-lb maximum).

78 Keysight 34420A Service Guide

Performance Verification Tests

Shift

The performance verification tests use the meter's specifications listed in datasheet.

You can perform four different levels of performance verification tests:

– Self-Test A series of internal verification tests that give a high confidence that

the meter is operational.

– Quick Verification A combination of the internal self-tests and selected

verification tests.

– Performance Verification Tests An extensive set of tests that are

recommended as an acceptance test when you first receive the meter or aft.er performing adjustments.

– Optional Verification Tests Tests not performed with every calibration.

Perform these tests to verify additional specifications or functions of the meter.

Self-Test

Calibration Procedures 3

A brief power-on self-test occurs automatically whenever you turn on the meter. This limited test assures that the meter is capable of operation.

To perform a complete self-test hold down the key as you press the Power switch to turn on the meter; hold down the key for more than 5 seconds (a complete description of these tests can be found in chapter 6). The meter will automatically perform the complete self-test procedure when you release the key. The self-test will complete in approximately 10 seconds.

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.

– If the self-test fails, “FAIL” is displayed and the ERROR annunciator turns on. If

repair is required, see Chapter 5, "Service" for further details.

– If all tests pass, you have a high confidence (90%) that the meter is

operational.

Keysight 34420A Service Guide 79

3 Calibration Procedures

NOTE

Quick Performance Check

The quick performance check is a combination of internal self-test and an abbreviated performance test (specified by the letter Q in the performance verification tests). This test provides a simple method to achieve high confidence in the meter's ability to functionally operate and meet specifications. These tests represent the absolute minimum set of performance checks recommended following any service activity. Auditing the meter's performance for the quick check points (designated by a Q) verifies performance for “normal” accuracy drift mechanisms.

This test does not check for abnormal component failures.

To perform the quick performance check, do the following:

– Perform a complete self-test. A procedure is given on page 72.

– Perform only the performance verification tests indicated with the letter Q.

If the meter fails the quick performance check, adjustment or repair is required.

Performance Verification Tests

The performance verification tests are recommended as acceptance tests when you first receive the meter. The acceptance test results should be compared against the 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, ad justment or repair is required

80 Keysight 34420A Service Guide

Zero Offset Verification

CAUTION

This procedure verifies the zero performance of the meter. Verification checks are only performed for those functions and ranges with unique zero calibration constants. A low thermal 4-wire shorting plug is applied to the input of the meter for these checks.

Zero Offset Verification Procedure

1 Set the meter to the following configuration for each function, channel, and

range in the table on the next page:

7 ½ digits (100 PLC) Filters OFF

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.

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.

Calibration Procedures 3

– Zero offset calibration using a multifunction calibrator is NOT possible.

– Use only the low thermal 4-wire shorting plug provided.

Keysight 34420A Service Guide 81

3 Calibration Procedures

Table 3-1 Zero Offset Verification Procedure

Step# Function/Channel Range 24 hour 90day 1 year

1 Voltage / Channel 1 1 mV

120 nV

± Error From Zero

[a]

120 nV

[a]

120 nV

[a]

Q 2 Voltage / Channel 1 10mV

120 nV

[a]

120 nV

[a]

130 nV

3 Voltage / Channel 1 100 mV 300 nV 400 nV 400 nV

4 Voltage / Channel 1 1 V 3 µV 4 µV 4 µV

5 Voltage / Channel 1 10V 10 µV 40 µV 40 µV

Q 6 Voltage / Channel 1 100V 400 µV 500 µV 500 µV

1 Voltage /Channel 2 1 mV

Q 2 Voltage / Channel 2 10 mV

120 nV

[a]

120 nV

[a]

120 nV

[a]

130 nV

3 Voltage / Channel 2 100mV 300 nV 400 nV 400 nV

4 Voltage / Channel 2 1 V 3 µV 4 µV 4 µV

5 Voltage I Channel 2 10V 10 µV 40 µV 40 µV

7 4-wire Ohms 1 Ω 2 µΩ 2 µΩ 2 µΩ

8 4-wire Ohms 10 Ω 20 µΩ 20 µΩ 20 µΩ

9 4-wire Ohms 100 Ω 200 µΩ 200 µΩ 200 µΩ

Q 10 4-wire Ohms 1 kΩ 2 mΩ 2 mΩ 2 mΩ

[a]

11 4-wire Ohms 10 kΩ 20 mΩ 20 mΩ 20 mΩ

12 4-wire Ohms 100 kΩ 300 mΩ 400 mΩ 400 mΩ

13 4-wire Ohms 1 MΩ 3 Ω 4 Ω 4 Ω

14 Low Power Ohms 1 Ω 2 µΩ 2 µΩ 2 µΩ

82 Keysight 34420A Service Guide

Calibration Procedures 3

Table 3-1 Zero Offset Verification Procedure

± Error From Zero

Step# Function/Channel Range 24 hour 90day 1 year

15 Low Power Ohms 10 Ω 20 µΩ 20 µΩ 20 µΩ

16 Low Power Ohms 100 Ω 200 µΩ 200 µΩ 200 µΩ

17 Low Power Ohms 1 kΩ 2 mΩ 2 mΩn2 mΩ

18 Low Power Ohms 10 kΩ 40 mΩ 40 mΩ 40 mΩ

19 Low Power Ohms 100 kΩ 1.2 Ω 1.5 Ω 1.5 Ω

Q 20 Low Power Ohms 1 MΩ 3 Ω 4 Ω 4 Ω

21 Voltage Limited Ohms 10 Ω 20 µΩ 20 µΩ 20 mΩ

22 Voltage Limited Ohms 100 Ω 200 µΩ 200 µΩ 200 µΩ

Optional

[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.

[b]

2-wire Ohms All

Use 4-wire Ohms specifications

[b]

Keysight 34420A Service Guide 83

3 Calibration Procedures

NOTE

Gain Verification

This procedure is used to check the “full scale” reading calibration of the meter. Verification checks are only performed for those functions, channels, and ranges with unique gain calibration constants.

Gain Verification Procedure

1 Set the meter to the following configuration:

7 ½ digits (100 PLC) Filters OFF

2 Read “Test Considerations” on page 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.

5 Select each function and range on the meter in the order shown in the table on

the next page. At each function and range apply a full scale (input with the

multifunction calibrator. Compare each measurement result to the test limits

shown in the table.

The 1 mV and 10 mV gain verification is an optional verification test (see

page 86). These range gains are internally derived from the 1OOmV, 1V,

and 1OV range calibrations.

Table 3-2 Gain Verification Procedure

± Error From Full Scale

Step# Cal ibrator Output Function/Channel Range 24 hours 90day 1 year

1 100mV Voltage/ Channel 1 100 mV 1.8 µV 3.4 µV 4.4 µV

2 1 V Voltage/ Channel 1 1 V 13 µV 29 µV 39 µV

Q 3 10 V Voltage/ Channel 1 10 V 30 µV 240 µV 340 µV

84 Keysight 34420A Service Guide

Calibration Procedures 3

Table 3-2 Gain Verification Procedure

± Error From Full Scale

Step# Cal ibrator Output Function/Channel Range 24 hours 90day 1 year

4 100 V Voltage/ Channel 1 100V 1.4 mV 3 mV 4mV

5 100mV

61 V

Q 7 10 V

Voltage/ Channel 2

81 Ω 4-wire Ohms 1 Ω 17 µΩ 52 µΩ 72 µΩ

9 10 Ω 4-wire Ohms 10 Ω 110 µΩ 420 µΩ 620 µΩ

10 100 Ω 4-wire Ohms 100 Ω 1.7 mΩ 4.2 mΩ 6.2 mΩ

Q11 1 kΩ 4-wire Ohms 1 kΩ 17 mΩ 42 mΩ 62 mΩ

12 10 kΩ 4-wire Ohms 10 kΩ 170 mΩ 420 mΩ 620 mΩ

13 100 kΩ 4-wire Ohms 100 kΩ 1.8 Ω 4.4 Ω 6.4 Ω

14 1 MΩ 4-wire Ohms 1 MΩ 23 Ω 54 Ω 74 Ω

[a]

100mV 1.8µV 3.4µV 4.4µV

[a]

1 V 13µV 29µV 39µV

10V 30µV 240µV 340µV

15 1 Ω Low Power Ohms 1 Ω 17 µΩ 52 µΩ 72 µΩ

16 10 Ω Low Power Ohms 10 Ω 170 µΩ 420 µΩ 620 µΩ

17 100 Ω Low Power Ohms 100 Ω 1.7 m

Ω 4.2 mΩ 6.2 mΩ

18 1 kΩ Low Power Ohms 1 kΩ 17 mΩ 42 mΩ 62 mΩ

19 10 kΩ Low Power Ohms 10 kΩ 190 mΩ 440 mΩ 640 mΩ

20 100 kΩ Low Power Ohms 100 kΩ 2.1 Ω 5.5 Ω 7.5 Ω

21 1 MΩ Low Power Ohms 1 MΩ 23 Ω 54Ω 74 Ω

22 10Ω Voltage Limited Ohms 10Ω 220 µΩ 520 µΩ 720 µΩ

23 100 Ω Voltage Limited Ohms 100 Ω 2.7 mΩ 5.2 mΩ 7.2 mΩ

Optional 2-wire Ohms All

[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.

Use 4-wire Ohms specifications

[b]

Keysight 34420A Service Guide 85

3 Calibration Procedures

NOTE

Calibrator

Meter

Source +

Sense +

Source -

Sense -

1 k

Isothermal

environment

1 mV and 10 mV Gain Verification (Optional)

This optional procedure checks the “full scale” gain for the 1 mV and 10 mV ranges. Because of the low voltage levels used to verify these ranges and the inherent inaccuracies of multifunction calibrators at these levels, a voltage divider is used to check these ranges.

These ranges can only be verified. The gain calibrations for these ranges are derived from the calibrations on the 100mV, JV, and 10 V ranges.

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.

86 Keysight 34420A Service Guide

Calibration Procedures 3

NOTE

4 Set the calibrator to fixed range (2.2 Volt range on range lock) and O Volt

output.

5 Null the reading on the meter.

6 Set the calibrator to 1 Volt output. Adjust the calibrator output from nominal

by the divider ratio to produce a 1 mV input to the meter.

Step 4, step 5 and step 6 should be performed quickly to minimize

thermal offsets.

7 Verify the meter reading against the table below.

8 Repeat step 4 through step 7 using the calibrator 11 Volt range and applying a

10 V output to produce a 10 mV input on the meter.

You should repeat step 4 through step 8 several times and average the results to reduce the effects of measurement noise.

Table 3-3 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 87

3 Calibration Procedures

NOTE

DMM

1 Mohm

1000 pF

Channel 1 LO

Keysight 34420A

Meter

Common

Power Line

Injected Current Verification (Optional)

This optional procedure checks the injected current level. Injected current varies with the power line configuration and frequency. You should, therefore, verify injected current using the same power line configuration as the intended use.

Injected Current Verification Procedure

1 Connect the DMM and the meter to the same power line receptacle.

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.

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.

5 Measure the rms voltage on the DMM. With the setup shown, 1 mV rms is

equivalent to 1 nA rms of injected current. Verify the measured voltage is <18

88 Keysight 34420A Service Guide

mV rms (for peak-to-peak values, multiple the measured rms voltage by 2.8).

Chart Output Verification (Optional)

Shift

∧

On/Off

∧

∧∧∧

∧

∧ ∧

Auto/Man

ENTER

Shift

∧

Recall

∧

Auto/Man

ENTER

This optional procedure checks the chart output (analog output) for zero and gain calibration. Before beginning this procedure, you should check and record any settings for the chart span and chart null (see page 63) so that these values can be restored at the end of the procedure.

Chart Output Verification Procedure

1 Set the meter to the following configuration:

6 1/2 digits (10 PLC) Channel 1 DCV Math OFF Null OFF

2 Read “Test Considerations” on page 78.

3 Connect the low thermal 4-wire shorting plug to the meter's input terminals.

4 Connect the rear panel chart output terminal to a DMM.

5 Turn on the menu.

6 Select the E:SYS menu.

Calibration Procedures 3

7 Move down to the commands level and across to the 6:CHART SPAN

command.

8 Move down to the parameters level and set the value to 1.000,000 V.

9 Execute the command.

10 Use menu recall to return to the 6:CHART SPAN command.

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.

Keysight 34420A Service Guide 89

3 Calibration Procedures

Shift

∧

Recall

∧∧∧

Auto/Man

ENTER

Shift

∧

Recall

∧

Auto/Man

ENTER

14 Use menu recall to return to the 7: CHART NULL command.

15 Move to the 5:CHART OUT command.

16 Move down to the parameters level and set the value to ON.

17 Execute the command.

18 Measure the chart output with the DMM and verify that the output is:

0 Volts ±l mV.

19 Use menu recall to return to the 5: CHART OUT command.

20 Move to the 7:CHART NULL command.

21 Move down to the parameters level and set the value to -1.000,000 V.

22 Execute the command.

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.

90 Keysight 34420A Service Guide

Calibration Security Code

NOTE

This feature allows you to enter a security code (electronic key) to prevent accidental or unauthorized calibrations of the meter. When you first receive your meter, it is secured. Before you can adjust calibration constants you must unsecure the meter by entering the correct security code. A procedure to unsecure the meter is given on “To Unsecure the Meter for Calibration” on page 70.

– The security code is set to “KT034420” when the meter is shipped from the

factory. The security code is stored in non-volatile memory, and does not change when power has been off or after a remote interface reset.

– To secure the meter from the remote interface, the security code may contain

up to 11 alphanumeric characters as shown below. The first character must be a letter, but the remaining characters can be letters or numbers. You do not have to use all 11 characters but the first character must always be a letter.

A _ _ _ _ _ _ _ _ _ _ _ (11 characters)

– To secure the meter from the remote interface but allow it to be unsecured

from the front panel, use the eight-character format shown below. The first two characters must be “KT” and the remaining characters must be numbers. Only the last six characters are recognized from the front panel, but all eight characters are required. (To unsecure the meter from the front panel, omit the “KT” and enter the remaining numbers.)

K T _ _ _ _ _ _ _ _ (8 characters)

Calibration Procedures 3

If you secure the meter from the remote interface and the secure code you use does not have the first two characters “KT” and the next 6 characters as digits, you cannot unsecure the meter from the front panel.

– 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.

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3 Calibration Procedures

WARNING

To Unsecure the Meter Without the Security Code

To unsecure the meter without the correct security code, follow the steps below. A procedure to unsecure the meter is given on “To Unsecure the Meter for

Calibration” on page 70. Also see Chapter 5, "Electrostatic Discharge (ESD) Precautions" before beginning this procedure.

1 Disconnect the power cord and all input connections (both front and rear

terminals).

2 Remove the instrument cover. Refer to the disassembly drawing on page 155.

3 Connect the power cord and turn on the meter. Be careful not to touch the

power line connections.

Do not touch exposed mains.

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

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Calibration Procedures 3

5 While maintaining the short, enter any unsecure code. The meter is now

unsecured.

6 Remove the short at JM500.

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.

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3 Calibration Procedures

Calibration Count

The calibration count feature provides an independent “serialization” of your calibrations. You can determine the number of times that your meter has been calibrated. By monitoring the calibration count, you can determine whether an unauthorized calibration has been performed.

Since the value increments by one for each calibration, a complete calibration increases the value by approximately 24 counts.

– The calibration count is stored in non-volatile memory and does not change

when power has been off or after a remote interface reset. Your meter was

calibrated before it left the factory. When you receive your meter read the

calibration count to determine its value.

– 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.

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Calibration Message

You can use the calibration message feature to record calibration information about your meter. For example, you can store such information as the last calibration date, the next calibration due date, the meter's serial number, or even the name and phone number of the person to contact for a new calibration.

You can record information in the calibration message only from the remote interface. You can read the message from either the front-panel menu or the remote interface.

– The calibration message may contain up to 40 characters. The meter can

display up to 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.

Calibration Procedures 3

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3 Calibration Procedures

Calibration Procedure

The adjustment procedures use the CALibrate menu to initiate internal procedures to generate and set calibration constants. The general menu procedure is the same for all calibration setups.

Before beginning any calibration procedure the meter must be unsecured for calibration (see page 70). The following procedure is the recommended method to complete a meter calibration.

–Read “Test Considerations” on page 78.

– “To Unsecure the Meter for Calibration” on page 70.

– 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.

96 Keysight 34420A Service Guide

Aborting a Calibration in Progress

Shift

Sometimes it may be necessary to abort a calibration after the procedure has already been initiated. You can abort a calibration at any time by pressing any

front-panel key (except ). When performing a calibration from the remote interface, you can abort a calibration by issuing a remote interface device clear message or by pressing the front-panel LOCAL key.

Calibration Procedures 3

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3 Calibration Procedures

Shift

∧

On/Off

∧

Auto/Man

ENTER

Zero Calibration

A new set of zero offset correction constants are stored each time a zero calibration is performed. Each channel, function, and range has a unique offset correction. Once the procedure is started, the meter will automatically sequence through all the required input channels, functions, and ranges and store a new zero offset constant for each.

You may not perform a zero calibration for a single input channel, function or range. All zero offset constants are determined when a zero calibration is begun.

As a part of the Zero Calibration, the input amplifier bias current is minimized. This error current is dependent upon temperature. You should perform the Zero Calibration procedures whenever the meter is used in environments with temperatures greater than ±5° C from the calibration temperature.

Zero Calibration Procedure

The automatic zero calibration takes approximately 10 minutes to complete.

The procedure is outlined below. You should review “Test Considerations” on page 78 before beginning this procedure.

1 Set the meter to the following configuration:

61/2 digits (10 PLC)

Channel 1 DCV

Filters OFF

2 Connect the low thermal 4-wire shorting plug to the meter's input terminals.

Ensure the connector coupling nut is properly tightened.

3 Allow 5 minutes for the thermal shorting plug and input connector to

temperature stabilize.

4 Turn on the menu and select G:CAL menu.

5 Move to the commands level and select 2:CALIBRATE.

6 Move down to the parameters level and set the value shown to 0.000,000,0 V.

7 Execute the command to begin the automatic zero calibration. The calibration

will take approximately 10 minutes to complete. The display will indicate the

calibration progress as each channel, range, and function is calibrated.

8 Perform the Zero Offset Verification procedure (page 81) to check the results.

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Gain Calibration

NOTE

The meter stores new gain correction constants each time this procedure is followed. The gain constants are calculated from calibration values entered and from measurements made automatically by the meter.

The 1 mV and 10 mV ranges use an internally derived gain constant and do not have a separate gain calibration. The 1 mV and 10 mV gain constants are based upon measurements performed during the 100 mV, 1 V and 10 V gain calibrations. Channel 1 gain is used for both channel 1 and channel 2. No separate channel 2 gain constants are stored.

It is recommended that the calibration procedure be followed in the order given here. If you are performing adjustments for an individual function, perform the adjustments ONLY in the order shown.

Gain Adjustment Considerations

– The zero calibration procedure must have been recently performed before

beginning these gain adjustment procedures.

– When performing the 4-wire ohms gain adjustment, new gain constants are

also stored for the 2-wire ohms gain constants.

– Gain adjustments can be made with calibrator input values that are within 0.9

to 1.1 of Full Scale.

Calibration Procedures 3

Gain Calibration Procedure

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

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3 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. Apply the

input signal shown.

6 Turn on the menu and select G:CALIBRATE menu.

7 Move to the commands level and select 2:CALIBRATE.

8 Move down to the parameters level and set the value in the display to the

calibrator input value.

9 Execute the command to begin the gain calibration.

10 Repeat step 1 through step 9 for each function and gain listed in the table.

11 Perform the “Gain Verification Procedure” on page 84 to check the results.

Table 3-4 Gain calibration procedure

Step#

4 100.00000 V DCV / Channel 1 100V

5 1.000,0000 Ω 4-wire Ohms 1 Ω

6 10.000000 Ω 4-wire Ohms 10 Ω

7 100.00000 Ω 4-wire Ohms 100 Ω

8 1,000.0000 Ω 4-wire Ohms 1 kΩ

9 10,000.000 Ω 4-wire Ohms 10 kΩ

10 100,000.00 Ω 4-wire Ohms 100 kΩ

11 1,000,000.0 Ω 4-wire Ohms 1 MΩ

[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.

Calibrator Output

100.00000 mV

1.0000000 V

10.000000 V

[a]

[b]

Function/Channel Range

DCV / Channel 1 100mV

DCV / Channel 1 1 V

DCV / Channel 1 10 V

100 Keysight 34420A Service Guide

Keysight Technologies 34420A Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Safety Symbols

Safety Considerations

Environmental Conditions

Waste Electrical and Electronic Equipment (WEEE) Directive 2002/ 96/EC

Product category:

Sales and Technical Support

The Front-Panel at a Glance

The Front-Panel Menu at a Glance

Display Annunciators

The Rear Panel at a Glance

In This Book

Table of Contents

List of Figures

List of Tables

1 Quick Start

Quick Start

To Prepare the Meter For Use

If the Meter Does Not Turn On

To Make Input Connections

To Measure Voltage

To Measure Resistance

To Measure Temperature With Thermistors

To Measure Temperature With RTDs

To Measure Temperature With Thermocouples

To Select a Range

To Set the Number of Digits

To Set the Integration Time

Front-Panel Display Formats

To Rack Mount the Meter

2 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

To Trigger the Meter

Null (Relative) Operation

To Use Math (Stats)

To Set the Number of Samples

Chart Output (Analog Output)

To Unsecure the Meter for Calibration

3 Calibration Procedures

Keysight Technologies Calibration Services

Calibration Interval

Time Required for Calibration

Automating Calibration Procedures

Recommended Test Equipment

Test Considerations

Performance Verification Tests

Self-Test

Quick Performance Check

Performance Verification Tests

Zero Offset Verification

Zero Offset Verification Procedure

Gain Verification

Gain Verification Procedure

1 mV and 10 mV Gain Verification (Optional)

1 mV and 10 mV gain verification procedure

Injected Current Verification (Optional)

Injected Current Verification Procedure

Chart Output Verification (Optional)

Chart Output Verification Procedure

Calibration Security Code

To Unsecure the Meter Without the Security Code

Calibration Count

Calibration Message

Calibration Procedure

Aborting a Calibration in Progress

Zero Calibration

Zero Calibration Procedure

Gain Calibration

Gain Adjustment Considerations

Gain Calibration Procedure