Agilent Technologies 34401A Wartungshandbuch

Agilent TechnologiesAgilent 34401A 6 ½ Digit MultimeterService Guide

Display Annunciators Adrs Rmt Man Trig Hold Mem Ratio Math ERRORRear Shift 4W Turns on during a measurement. Multimeter is addressed to listen

Front/Rear Selection Referring to the front/rear schematic on page 9-8, the purpose of thiscircuitry is to select either the front terminals or the re

Function Switching The purpose of the Function Switching section (schematic shown onpage 9-9) is to connect the Input HI terminal to the various measu

DC AmplifierThe DC Amplifier circuit (schematic shown on page 9-10) is used byevery measuring function except frequency and period. Analog switchU101B

In the DC current function, a current is applied between the Input I andLO terminals. Ranging is accomplished by relay K102 and amplifier gainswitchin

Ohms Current Source The ohms current source (schematic shown on page 9-10) flows from theInput HI terminal to the Input LO terminal for both the 2-wir

AC Circuit Referring to the schematic shown on page 9-11, the multimeter usesa true RMS ac-to-dc converter to measure ac voltages and currents.The ac-

The programmable capacitance is implemented by varying the signallevel across a compensating capacitor. In the x0.2 configuration, lowfrequency gain i

A-to-D Converter The analog-to-digital converter (ADC) is used to change dc voltages intodigital information (schematic shown on page 9-12). The circu

Each analog-to-digital conversion begins when the multimeter istriggered. The ADC starts by clearing the integrator slope count in U501.At the end of

Floating Logic Referring to the schematic shown on page 9-13, the floating commonlogic controls operation of the entire instrument. All measurementcon

The Rear Panel at a Glance 1 Chassis Ground 2 Power-Line Fuse-Holder Assembly 3 Power-Line Voltage Setting 4 Front and Rear Current Input

The counter register is used to capture either ADC slope count at theCOMP input or frequency count at the FREQIN input. The COMP inputfunctions as bot

The main processor has an on chip 10-bit successive approximation ADCwith two selectable inputs: FLASH and FREQRNG. The FLASH input isused to sample

Power Supplies Referring to the schematic shown on page 9-15, the multimeter uses twotypes of power supplies: floating supplies and earth referenced

Front Panel The front panel circuits (schematic shown on page 9-16) consist ofvacuum fluorescent display control, display high voltage drivers, andkey

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6Service 6

ServiceThis chapter discusses the procedures involved for returning a failedmultimeter to Agilent for service or repair. Subjects covered include thef

Operating ChecklistBefore returning your multimeter to Agilent for service or repair, checkthe following items:Is the multimeter inoperative? Verify t

Types of Service Available If your multimeter fails within one year of original purchase, Agilentwill repair or replace it free of charge. If your uni

• If your failed unit was “in-warranty,” your replacement unit willcontinue the warranty time clock to the end of your one year standardwarranty. You

In This Book Specifications Chapter 1 lists the multimeter’s specifications anddescribes how to interpret these specifications.Quick Start Chapter

Electrostatic Discharge (ESD) Precautions Almost all electrical components can be damaged by electrostaticdischarge (ESD) during handling. Component d

To Replace the Current Input Fuses The front and rear current input terminals are protected by two seriesfuses. The first fuse is a 3 A, 250 Vac, fast

Pass/Fail Output (continued) Installation Procedure The assembly drawings and schematics are located in chapter 9,“Schematics.”1 Unscrew the two rear

Troubleshooting Hints This section provides a brief check list of common failures. Beforetroubleshooting or repairing the multimeter, make sure the fa

Troubleshooting Hints(continued) Current input is inoperative Verify that the rear panel 3 A, 250 V current fuse is functional.Verify that the interna

Readings are inaccurateInaccurate readings are normally caused by either invalid calibration orby non-linear measuring circuits. If recalibration does

Self-Test Procedures Power-On Self-Test Each time the multimeter is powered on, a small set of self-tests areperformed. These tests check that the min

Self-test procedures are numbered in the order in which they areexecuted. The order is designed to build confidence from a small kerneltowards progres

607 Rundown too noisy This test checks the gain repeatability betweenthe integrating ADC and the U500 onchip ADC. The gain test (606), isperformed ei

615 Ohms 10 uA source failed This test configures to the 10 V dc rangewith the internal 10 M 100:1 divider U102A connected across the input.The 10 µA

ContentsChapter 1 SpecificationsDC Characteristics 12AC Characteristics 14Frequency and Period Characteristics 16General Information 18Product Di

622 Frequency counter failed This test configures for the 100 mV acrange. This test immediately follows test 621. With C301 holding acharge from test

7Replaceable Parts 7

Replaceable PartsThis section contains information for ordering replacement parts foryour Agilent 34401A Multimeter. The parts lists are divided into

34401-66501 – Main PC Assembly (A1)Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Numbe

Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number C506 0160-6497 Capacitor-Fxd 0.1 uF ±

Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number J704 1252-2266 1 Connector-Rect D-Sub

Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number R130 0699-1394 2 Resistor 14.7K ±1% .

Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number R430 0699-1503 1 Resistor Zero Ohm 2

Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number U201 1826-2420 IC-Op Amp LP Dual 8-P

34401-66512 – Display Assembly (A2)Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number C60

Chapter 4 Calibration Procedures Agilent Calibration Services 61Calibration Interval 61Time Required for Calibration 61Automating Calibration Pr

Agilent 34401A Mainframe Reference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr. Part Number A1 34401-66

Manufacturer’s ListMfr. Code Manufacturer’s Name Manufacturer’s Address Zip Code 00779 AMP Inc Harrisburg, PA U.S.A. 17111 01121 Alle

136

8Backdating 8

Backdating The table below lists all 34401A changes with prior serial numbers. This information is provided for backdating purposes only.Approx. Effe

34401-66522 Display Assembly Replaceable Parts ListReference Agilent Part Mfr. Designation Number Qty Part Description Code Mfr.

34401-66522 Display Assembly Component LocatorChapter 8 BackdatingAgilent 34401A Multimeter140

34401-66502 Schematic141Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inches Binder Edge (RH Page) Fo

9Schematics 9

Schematics• Mechanical Disassembly 9-3• Component Locator Diagram – Main Board (34401-66501) 9-5• Component Locator Diagram – Front Panel (34401-665

Chapter 6 Service Operating Checklist 111Types of Service Available 112Repackaging for Shipment 113Electrostatic Discharge (ESD) Precautions 11

Mechanical Disassembly9-3Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inches Binder Edge (RH Page) F

Mechanical Disassembly9-4Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold HereBinder Edge (LH Page) Foldout Cut

Component Locator DiagramMain PC Board (34401-66501)9-5Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inche

Component Locator DiagramFront-Panel PC Board (34401-66512)9-6Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold H

Agilent 34401A Block Diagram9-7Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inches Binder Edge (RH Page)

34401-66501 (sheet 1 of 8)Front/Rear Selection Schematic9-8Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold Here

34401-66501 (sheet 2 of 8)Function Switching Schematic9-9Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inc

34401-66501 (sheet 3 of 8)DC Amplifier and Ohms Schematic9-10Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold He

34401-66501 (sheet 4 of 8)AC Circuit Schematic9-11Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inches Bi

34401-66501 (sheet 5 of 8)A/D Converter Schematic9-12Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold HereBinder

Contents10

34401-66501 (sheet 6 of 8)Floating Logic Schematic9-13Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inches

34401-66501 (sheet 7 of 8)Earth-Referenced Logic Schematic9-14Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold H

34401-66501 (sheet 8 of 8)Power Supplies Schematic9-15Fold HereFold HereFold HereFold Here Binder Edge (RH Page) Foldout Cut Size = 9 x 19 inches

34401-66512 (sheet 1 of 1)Display and Keyboard Schematic9-16Fold HereFold HereBinder Edge (LH Page) Foldout Cut Size = 9 x 19 inchesFold HereFold Her

1Specifications 1

DC Characteristics DC Characteristics Accuracy Specifications ± ( % of reading + % of range ) [ 1 ] Function Range [ 3 ]Test Current or Burden Vo

DC Characteristics Function DCV, DCI, andResistanceDigits 61⁄2 61⁄2 51⁄2 51⁄2 41⁄2 Readings/s 0.6 (0.5) 6 (5) 60 (50) 300 1000 A

ii 34401A Service GuideNotices© Agilent Technologies, Inc. 1991 - 2007No part of this manual may be reproduced in any form or by any means (including

AC Characteristics AC Characteristics Accuracy Specifications ± ( % of reading + % of range ) [ 1 ]Function Range [ 3 ] Frequency24 Hour [ 2 ]23°C

AC Characteristics Measurement Noise Rejection [ 8 ] AC CMRRTrue RMS AC Voltage Measurement Method: Crest Factor:AC Filter Bandwidth: Slow Medium

Frequency and Period CharacteristicsFrequency and Period Characteristics Accuracy Specifications ± ( % of reading ) [ 1 ]Function Range [

Frequency and Period CharacteristicsFrequency and Period Measurement Method: Voltage Ranges:Gate Time: Reciprocal-counting technique.AC-coupled input

General Information General Information General Specifications Power Supply: Power Line Frequency:Power Consumption:Operating Environment:Storage Envi

Product DimensionsProduct Dimensions348. 3 mm88. 5 mm212.6 mm261.1 mm379.4 mm103.8 mmTOPProduct DimensionsAll dimensions areshown in millimeters. 1Ch

To Calculate Total Measurement Error Each specification includes correction factors which account for errorspresent due to operational limitations of

Understanding the “ % of range ” Error The range error compensatesfor inaccuracies that result from the function and range you select.The range error

Interpreting Multimeter Specifications This section is provided to give you a better understanding of the terminologyused and will help you interpret

Resolution Resolution is the numeric ratio of the maximum displayed value dividedby the minimum displayed value on a selected range. Resolution isofte

34401A Service Guide iiiSafety InformationGeneralDo not use this product in any manner not specified by the manufacturer. The protec-tive features of

Transfer Accuracy Transfer accuracy refers to the error introduced by the multimeterdue to noise and short-term drift. This error becomes apparent whe

Configuring for Highest Accuracy Measurements The measurement configurations shown below assume that themultimeter is in its power-on or reset state.

26

2Quick Start 2

Quick Start One of the first things you will want to do with your multimeter is tobecome acquainted with its front panel. We have written the exerc

To Prepare the Multimeter for Use The following steps help you verify that the multimeter is ready for use.1 Check the list of supplied items.Verify

If the Multimeter Does Not Turn OnUse the following steps to help solve problems you might encounterwhen turning on the multimeter. If you need more h

See rear panel for proper fuse rating.Agilent Part Number: 2110-0817 (250 mAT)100, 120, 220 (230) or 240 Vac 1 Remove the power cord. Remove the

To Adjust the Carrying HandleTo adjust the position, grasp the handle by the sides and pull outward.Then, rotate the handle to the desired position.

To Measure Voltage Ranges: 100 mV, 1 V, 10 V, 100 V, 1000 V (750 Vac)Maximum resolution: 100 nV (on 100 mV range)AC technique: true RMS, ac-

iv 34401A Service GuideWARNINGIEC Measurement Category II. The HI and LO input terminals may be connected to mains in IEC Cate-gory II installations f

To Measure Current Ranges: 10 mA (dc only), 100 mA (dc only), 1 A , 3 AMaximum resolution: 10 nA (on 10 mA range)AC technique: true RMS, ac-co

To Test Continuity Test current source: 1 mAMaximum resolution: 0.1 Ω (range is fixed at 1 kohm)Beeper threshold: 1 Ω to 1000 Ω (beeps below ad

To Select a Range You can let the multimeter automatically select the range usingautoranging or you can select a fixed range using manual ranging. •

To Set the Resolution You can set the display resolution to 41⁄2, 51⁄2, or 61⁄2 digits either tooptimize measurement speed or noise rejection. In th

To Make Null (Relative) Measurements Each null measurement, also called relative, is the difference between astored null value and the input signal.R

To Store Minimum and Maximum Readings You can store the minimum and maximum readings during a seriesof measurements. The following discussion shows h

To Make dB Measurements Each dB measurement is the difference between the input signal and astored relative value, with both values converted to dBm.

To Make dBm Measurements The dBm operation calculates the power delivered to a resistancereferenced to 1 milliwatt. dBm = 10 × Log10 ( reading2 / ref

To Trigger the Multimeter You can trigger the multimeter from the front panel using single triggeror auto trigger. • Auto triggering is enabled when

To Make dcv:dcv Ratio Measurements To calculate a ratio, the multimeter measures a dc reference voltageapplied to the Sense terminals and the voltag

34401A Service Guide vIEC Measurement Category II includes elec-trical devices connected to mains at an out-let on a branch circuit. Such devices incl

Front-Panel Display Formats -H.DDD,DDD EFFFFront-panel display format. 10.216,5 VDCThis is the 10 Vdc range, 51⁄2 digits are displayed. -04

To Rack Mount the Multimeter You can mount the multimeter in a standard 19-inch rack cabinet usingone of three optional kits available. Instructions

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

3Menu Tutorial 3

Menu Tutorial By now you should be familiar with the FUNCTION and RANGE / DIGITSgroups of front-panel keys. You should also understand how to makefro

Front-Panel Menu Reference 1: AC FILTER 2: CONTINUITY 3: INPUT R 4: RATIO FUNC 5: RESOLUTION Selects the slow, medium, or fast ac filter. Sets th

1: RDGS STORE 2: SAVED RDGS 3: ERROR 4: TEST 5: DISPLAY 6: BEEP 7: COMMA 8: REVISION Enables or disables reading memory. Recalls readings stored i

A Front-Panel Menu Tutorial This section is a step-by-step tutorial which shows how to use thefront-panel menu. We recommend that you spend a few min

MESSAGES DISPLAYED DURING MENU USE TOP OF MENU You pressed while on the “menus” level; this is the top level ofthe menu and you cannot go

Menu Example 1 The following steps show you how to turn on the menu, move up or downbetween levels, move across the choices on each level, and turn of

DECLARATION OF CONFORMITYAccording to ISO/IEC Guide 22 and CEN/CENELEC EN 45014Revision: B.01 Issue Date: 18 July 2001 Document 34401A.DOCManufacturer

4 Move down to the “parameters” level.The multimeter will wait for the security code to be entered. ^000000 CODE5 Unsecure the multimeter by entering

Menu Example 2 Some commands in the menu require that you enter a numeric parametervalue. The following steps show you how to enter a number in the me

3 Move down to the “commands” level within the CAL MENU.Either SECURED or UNSECURED is the first command on this level.To perform a calibration, UNSEC

7 Decrement the first digit until “0” is displayed.You decrement or increment each digit independently. Neighboringdigits are not affected. 000.000,

58

4CalibrationProcedures 4

Calibration Procedures• Agilent Calibration Services 61• Calibration Interval 61• Time Required for Calibration 61• Automating Calibration Procedur

Agilent Calibration Services When your multimeter is due for calibration, contact your local AgilentService Center for a low-cost recalibration. The 3

Automating Calibration Procedures You can automate the complete verification and adjustment proceduresoutlined in this chapter if you have access to p

Recommended Test Equipment The test equipment recommended for the performance verification andadjustment procedures is listed below. If the exact inst

Note: Unless otherwise indicated, this manual applies to all serial numbers.The Agilent Technologies 34401A is a 61⁄2-digit, high-performancedigital m

Test ConsiderationsTo ensure proper instrument operation, verify that you have selectedthe correct power-line voltage prior to attempting any test pro

Performance Verification TestsYou can perform three different levels of performance verification tests:• Self-Test A series of internal verification

Quick Performance CheckThe quick performance check is a combination of internal self-test andan abbreviated performance test (specified by the letter

Zero Offset Verification This procedure is used to check the zero offset performance of themultimeter. Verification checks are only performed for thos

Caution Zero offset calibration using a multifunction calibrator is NOTrecommended. The calibrator and cabling offset can be large and unstablecausi

Gain VerificationThis procedure is used to check the “full scale” reading calibration of themultimeter. Verification checks are performed only for tho

Gain Verification Test (AC V) Configuration: AC volts 61⁄2 digit AC FILTER slow (MEAS MENU) 1 Make sure you have read “Test Conside

AC Gain Verification Test (AC I) Configuration: AC current 61⁄2 digit AC FILTER slow (MEAS MENU) 1 Make sure you have

Optional AC Performance Verification Tests These tests are not intended to be performed with every calibration.They are provided as an aid for verifyi

Calibration Security Code This feature allows you to enter a security code (electronic key) toprevent accidental or unauthorized calibrations of the m

The Front Panel at a Glance 1 Measurement Function keys 2 Math Operation keys 3 Single Trigger / Autotrigger / Reading Hold key4 Shift / Local k

To Unsecure the Multimeter Without the Security CodeTo unsecure the meter without the correct security code, follow the stepsbelow. Chapter 9, “Schema

Calibration Count The calibration count feature provides an independent “serialization”of your calibrations. You can determine the number of times tha

Calibration Procedures Before beginning any adjustment procedures, the multimeter must be inthe “UNSECURED” state. To unsecure the multimeter, see “Ca

Zero Adjustment Each time you perform a zero adjustment, the multimeter stores a newset of offset correction constants for every measurement function

Zero Adjustment (continued) 2 Select the shorted terminal set (front or rear terminal) with thefront/rear switch. Separate calibration constants ar

Gain Adjustment The multimeter stores a single new gain correction constant each timethis procedure is followed. The gain constant is computed from th

Valid Gain Adjustment Input Values Gain adjustment can be accomplished using the following input values.Gain Adjustment Procedure Adjustment for each

3 Turn on the menu ( Shift < ) and then use < or > to select F: CAL MENU. 4 Use ∨ to move down to the “commands” level and select2

Optional Gain Calibration Procedures The optional calibrations in this section are used to enhance theperformance of your Agilent 34401A Multimeter. T

500 Vdc Adjustment Procedure The 500 Vdc calibration electronically corrects the multimeter’s 100:1divider network (U101) linearity characteristic for

The Front-Panel Menu at a Glance A: MEASurement MENU 1: AC FILTER > 2: CONTINUITY > 3: INPUT R > 4: RATIO FUNC > 5: RESOLUTION

1/100th Scale AC Adjustment Procedure This calibration procedure is used to enhance the ac volts and ac currentmeasurement accuracy for <1/100th sc

Understanding the AC Signal Filter The multimeter uses three different ac filters which enable you to eitheroptimize low frequency accuracy or achieve

Understanding ResolutionResolution is expressed in terms of number of digits the multimeter canmeasure or display. You can set the resolution to 4, 5,

10.216,5 VDCThis is the 10 Vdc range, 51⁄2 digits are displayed. -045.23 mVDCThis is the 100 mVdc range, 41⁄2 digits are displayed. 113

Resolution (continued) • Front-Panel Operation: Select either the slow or fast mode for eachresolution setting. The default mode is 5 digits slow.

Error Messages The following tables are abbreviated lists of multimeter’s error messages.They are intended to include errors which are likely to be en

Error Error Message 605606701702703704705706707708709720721722 [1]723 [1]725 [2]730731732733734735736 [2]740 [3]741 [3]742 [3]743 [3]744 [3]745 [3]746

5Theory ofOperation 5

Theory of OperationThis chapter is organized to provide descriptions of the circuitrycontained on each schematic shown in chapter 9. A block diagramov

Block Diagram Referring to the block diagram on page 9-7, you will notice that themultimeter’s circuitry is divided into two major blocks: the floatin