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Agilent 4338B Milliohmmeter
Service Manual
SERIAL NUMBERS
This manual applies directly to instruments with serial number pre x JP1KD.
For additional important information about serial numbers, read
\Instruments Covered by This Manual" in Chapter 1 of this manual.
Agilent Part No. 04338-90033
Printed in JAPAN March 2001
Notice
The information contained in this document is subject to change without notice.
This document contains proprietary information that is protected by copyright. All rights are
reserved. No part of this document may be photocopied, reproduced, or translated to another
language without the prior written consent of the Agilent Technologies.
Agilent Technologies Japan, Ltd.
Component Test PGU-Kobe
1-3-2, Murotani, Nishi-ku, Kobe-shi,
Hyogo, 651-2241 Japan
Copyright Agilent Technologies Japan, Ltd.
c 1996, 2000, 2001
Manual Printing History
August 1996 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : First Edition (part number: 04338-90033)
June 2000 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : Second Edition (part number: 04338-90033)
March 2001 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : Third Edition (part number: 04338-90033)
iii
Safety Summary
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 speci c
WARNINGS elsewhere in this manual may impair the protection provided by the equipment.
In addition it violates safety standards of design, manufacture, and intended use of the
instrument.
The Agilent Technologies assumes no liability for the customer's failure to comply with these
requirements.
Note 4338B complies with INSTALLATION CATEGORY II and POLLUTION DEGREE 2
in IEC1010-1. 4338B is INDOOR USE product.
Ground The Instrument
To avoid electric shock hazard, the instrument chassis and cabinet must be connected to a
safety earth ground by the supplied power cable with earth blade.
DO NOT Operate In An Explosive Atmosphere
Do not operate the instrument in the presence of
ammable gasses or fumes. Operation of any
electrical instrument in such an environment constitutes a de nite safety hazard.
Keep Away From Live Circuits
Operating personnel must not remove instrument covers. Component replacement and internal
adjustments must be made by quali ed maintenance personnel. Do not replace components
with the power cable connected. Under certain conditions, dangerous voltages may exist even
with the power cable removed. To avoid injuries, always disconnect power and discharge
circuits before touching them.
DO NOT Service Or Adjust Alone
Do not attempt internal service or adjustment unless another person, capable of rendering rst
aid and resuscitation, is present.
DO NOT Substitute Parts Or Modify Instrument
Because of the danger of introducing additional hazards, do not install substitute parts or
perform unauthorized modi cations to the instrument. Return the instrument to a Agilent
Technologies Sales and Service Oce for service and repair to ensure that safety features are
maintained.
Dangerous Procedure Warnings
Warnings , such as the example below, precede potentially dangerous procedures throughout
this manual. Instructions contained in the warnings must be followed.
Warning Dangerous voltages, capable of causing death, are present in this
instrument. Use extreme caution when handling, testing, and adjusting
this instrument.
iv
Certi cation
Agilent Technologies certi es that this product met its published speci cations at the time
of shipment from the factory. Agilent Technologies further certi es that its calibration
measurements are traceable to the United States National Institute of Standards and
Technology, to the extent allowed by the Institution's calibration facility, or to the calibration
facilities of other International Standards Organization members.
Warranty
This Agilent Technologies instrument product is warranted against defects in material and
workmanship for a period of one year from the date of shipment, except that in the case of
certain components listed in General Information of this manual, the warranty shall be for the
speci ed period. During the warranty period, Agilent Technologies Company will, at its option,
either repair or replace products that prove to be defective.
For warranty service or repair, this product must be returned to a service facility designated by
Agilent Technologies. Buyer shall prepay shipping charges to Agilent Technologies and Agilent
Technologies shall pay shipping charges to return the product to Buyer. However, Buyer shall
pay all shipping charges, duties, and taxes for products returned to Agilent Technologies from
another country.
Agilent Technologies warrants that its software and rmware designated by Agilent
Technologies for use with an instrument will execute its programming instruction when
property installed on that instrument. Agilent Technologies does not warrant that the operation
of the instrument, or software, or rmware will be uninterrupted or error free.
Limitation Of Warranty
The foregoing warranty shall not apply to defects resulting from improper or inadequate
maintenance by Buyer, Buyer-supplied software or interfacing, unauthorized modi cation or
misuse, operation outside the environmental speci cations for the product, or improper site
preparation or maintenance.
No other warranty is expressed or implied. Agilent Technologies speci cally disclaims the
implied warranties of merchantability and tness for a particular purpose.
v
Exclusive Remedies
The remedies provided herein are buyer's sole and exclusive remedies. Agilent Technologies
shall not be liable for any direct, indirect, special, incidental, or consequential damages,
whether based on contract, tort, or any other legal theory.
Assistance
Product maintenance agreements and other customer assistance agreements are available for
Agilent Technologies products.
For any assistance, contact your nearest Agilent Technologies Sales and Service Oce.
Addresses are provided at the back of this manual.
vi
Safety Symbols
General de nitions of safety symbols used on equipment or in manuals are listed below.
Instruction manual symbol: the product is marked with this symbol when it is
necessary for the user to refer to the instruction manual.
Alternating current.
Direct current.
On (Supply).
O (Supply).
Frame or chassis terminal
This Warning sign denotes a hazard. It calls attention to a procedure, practice,
condition or the like, which, if not correctly performed or adhered to, could
result in injury or death to personnel.
This Caution sign denotes a hazard. It calls attention to a procedure, practice,
condition or the like, which, if not correctly performed or adhered to, could
result in damage to or destruction of part or all of the product.
Note denotes important information. It calls attention to a procedure,
practice, condition or the like, which is essential to highlight.
vii
Documentation Map
Operation Manual
Operation Manual (Agilent Part Number: 04338-90030 for English edition, 04338-97030 for
Japanese edition) explains speci cations, basic measurement explanations, and how to verify
conformance to published speci cations.
Service Manual
Service Manual (Agilent Part Number: 04338-90043) explains how to adjust, troubleshoot, and
repair the 4338B.
How To Use This Manual
This is the Service Manual for the 4338B Milliohmmeter. This manual contains adjustments and
repair information, and consists of the following four chapters.
Chapter 1 General Information
Chapter 1 gives general information for servicing the 4338B. This chapter lists the
recommended equipment for adjustments and troubleshooting.
Chapter 2 Adjustments
Chapter 2 describes the adjustments, required to ensure that the 4338B is within its published
speci cations after it has been repaired, or it fails the performance tests.
Chapter 3 Assembly Replacement
Chapter 3 provides the information on replacing the 4338B assemblies. The information
includes replaceable assembly lists, and removal and installation procedures.
Chapter 4 Troubleshooting
Chapter 4 provides the information on troubleshooting the 4338B. The information includes
theory of operation and information on faulty assembly isolation.
Appendix A Manual Changes
Appendix A contains manual changes and provides information for using this manual with
4338Bs manufactured before the printing date of the manual.
Appendix B Default Jumper and Switch Settings
Appendix B describes the settings of the jumpers and switches on the 4338B A2 CPU Board
Assembly. The information is required when the A2 assembly is replaced.
viii
Contents
1. General Information
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Instruments Covered by This Manual . . . . . . . . . . . . . . . . . . . . . 1-1
Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
2. Adjustment
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Safety Consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Adjustment Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Adjustable Components . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Factory-Selected Components . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
EEPROM Write Protect Switch . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Related Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Adjustment Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Program Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Making a Working Copy . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Program Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Adjustment Procedure References . . . . . . . . . . . . . . . . . . . . . . 2-5
Resistance Measurement Adjustment . . . . . . . . . . . . . . . . . . . . 2-5
Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
3. Assembly Replacement
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Restored Exchange Assemblies . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Replacing the A2 CPU Board Assembly . . . . . . . . . . . . . . . . . . . . 3-2
Replaceable Assembly List . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Replaceable Mechanical Parts List . . . . . . . . . . . . . . . . . . . . . . . 3-5
Disassembly Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Tools and Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Cover Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
A1 Main Board Removal . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Removal Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
A2 CPU Board Assembly Removal . . . . . . . . . . . . . . . . . . . . . 3-10
Removal Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
A5 AC Inlet Board Assembly Removal . . . . . . . . . . . . . . . . . . . . 3-10
Removal Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Keyboard Assembly Removal . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Removal Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
LCD Assembly Removal . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Removal Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
BNC Connector Removal . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Removal Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Contents-1
4. Troubleshooting
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
After Service Product Safety Checks . . . . . . . . . . . . . . . . . . . . . 4-2
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Overall Measurement Theory . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Overall Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Analog Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Signal Source Section . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Range Resistor and Current Sense Ampli er Sections . . . . . . . . . . . . 4-7
Voltage Sense Ampli er and Process Ampli er Sections . . . . . . . . . . 4-8
Digital Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
Power Supply Section . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Check Procedure References . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Check 1, DC-DC Converter Output Voltage . . . . . . . . . . . . . . . . 4-13
Check 2, LCD Displays Anything? . . . . . . . . . . . . . . . . . . . . . 4-14
Check 3, LCD Operates Correctly? . . . . . . . . . . . . . . . . . . . . 4-14
Check 4, Any Error Message on LCD? . . . . . . . . . . . . . . . . . . . 4-14
Check 5, CPU Related Error Message? . . . . . . . . . . . . . . . . . . . 4-14
Check 6, CPU Power LED Lights? . . . . . . . . . . . . . . . . . . . . . 4-14
Check 7, Any Error Code on LED? . . . . . . . . . . . . . . . . . . . . 4-15
Check 8, CPU Fuse High Lead Voltage . . . . . . . . . . . . . . . . . . . 4-16
Check 9, Fuse and Line Switch . . . . . . . . . . . . . . . . . . . . . . 4-16
Check 10, DC-DC Converter Input Voltage . . . . . . . . . . . . . . . . . 4-17
Check 11, DC-DC Converter Open Output Voltages . . . . . . . . . . . . . 4-18
Check 12, Transformer Secondary Voltage . . . . . . . . . . . . . . . . . 4-19
A. Manual Changes
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Manual Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
B. Default Jumper and Switch Settings
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
Jumper and Switch Settings . . . . . . . . . . . . . . . . . . . . . . . . . B-1
Index
Contents-2
Figures
1-1. Serial Number Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
2-1. Adjustment Program Flow . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2-2. Range Resistor Adjustment Setup . . . . . . . . . . . . . . . . . . . . . . 2-5
3-1. Cover Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
4-1. Voltage Current Ratio Measurement Principle . . . . . . . . . . . . . . . . 4-3
4-2. 4338B Overall Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . 4-4
4-3. Analog Section Block Diagram . . . . . . . . . . . . . . . . . . . . . . . 4-5
4-4. Signal Source Section Block Diagram . . . . . . . . . . . . . . . . . . . . 4-6
4-5. Range Resistor and Current Sense Amp. Block Diagram . . . . . . . . . . . 4-7
4-6. Voltage Sense Amp. and Process Amp. Block Diagram . . . . . . . . . . . . 4-8
4-7. Digital Section Block Diagram . . . . . . . . . . . . . . . . . . . . . . . 4-9
4-8. Power Supply Section Block Diagram . . . . . . . . . . . . . . . . . . . . 4-10
4-9. Troubleshooting Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
4-10. DC-DC Converter Output Voltage Check . . . . . . . . . . . . . . . . . . . 4-13
4-11. CPU Board Assembly LED Light Sequence . . . . . . . . . . . . . . . . . . 4-15
4-12. Location of High Lead of A2F1 Fuse . . . . . . . . . . . . . . . . . . . . 4-16
4-13. Test Pin Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
4-14. DC-DC Converter Output Connector . . . . . . . . . . . . . . . . . . . . 4-18
4-15. Transformer Secondary Voltage Check . . . . . . . . . . . . . . . . . . . 4-19
B-1. Jumper and Switch Settings . . . . . . . . . . . . . . . . . . . . . . . . B-1
Tables
1-1. Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1-2. Required Language Extensions . . . . . . . . . . . . . . . . . . . . . . . 1-2
2-1. Related Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
3-1. Replaceable Major Assembly List . . . . . . . . . . . . . . . . . . . . . . 3-3
3-2. A2 CPU Board Assembly, Replaceable Assembly List . . . . . . . . . . . . . 3-4
3-3. Replaceable Assembly List . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3-4. Replaceable Mechanical Parts List 1 . . . . . . . . . . . . . . . . . . . . . 3-5
3-5. Replaceable Mechanical Parts List 2 . . . . . . . . . . . . . . . . . . . . . 3-6
3-6. Replaceable Mechanical Parts List 3 . . . . . . . . . . . . . . . . . . . . . 3-7
3-7. Replaceable Mechanical Parts List 4 . . . . . . . . . . . . . . . . . . . . . 3-8
4-1. DC-DC Converter Output Voltage (Connected) . . . . . . . . . . . . . . . . 4-13
4-2. DC-DC Converter Open Output Voltages . . . . . . . . . . . . . . . . . . . 4-18
A-1. Manual Changes by Serial Number . . . . . . . . . . . . . . . . . . . . . A-1
Contents-3
1
General Information
Introduction
This chapter provides information on instruments covered by this manual and required
equipment for the adjustment and troubleshooting.
Instruments Covered by This Manual
Agilent Technologies uses a two-section, nine character serial number which is printed on
the serial number label (Figure 1-1) attached to the instrument's rear panel. The rst ve
characters are the serial pre x, and the last ve digits are the sux.
Figure 1-1. Serial Number Label
An instrument manufactured after the printing date of this manual may have a serial
number pre x that is not listed on the title page. This unlisted serial number pre x indicates
the instrument is dierent from those described in this manual. The manual for this new
instrument may be accompanied by a yellow Manual Changes supplement or have a dierent
manual part number. This sheet contains \change information" that explains how to adapt the
manual to the newer instrument.
In addition to change information, the supplement may contain information for correcting
errors (Errata) in the manual. To keep this manual as current and accurate as possible, Agilent
Technologies recommends that you periodically request the latest Manual Changes supplement.
The supplement for this manual is identi ed by this manual's printing date and its part number,
both of which appear on the manual's title page. Complimentary copies of the supplement are
available from Agilent Technologies. If the serial pre x or number of an instrument is lower
than that on the title page of this manual, see Appendix A, Manual Changes . For information
concerning, a serial number pre x that is not listed on the title page or in the Manual Change
supplement, contact the nearest Agilent Technologies oce.
General Information 1-1
Required Equipment
Table 1-1 lists the required equipment for adjusting and troubleshooting the 4338B. Table 1-2
lists the required language extensions to be used with the adjustment program.
Table 1-1. Required Equipment
Equipment Requirements Recommended Model Qty. Use
Multimeter DC V Accuracy: < 1% 3458A 1 T1
Standard Resistors No Substitute 42030A 1 A2
Open Termination No Substitute 42090A3 1 A
Short Termination No Substitute 42091A3 1 A
Computer No Substitute HP 9000 series 200 or 3004 1 A
RAM 4M bytes
Operating System BASIC 5.1 or higher 98616A 1 A
Adjustment Program No substitute Agilent PN 04338-65005 1 A
1 Troubleshooting
2 Adjustment
3 This model is also included in the 42100A, Four Terminal Pair Resistor Set
4 Excluding the 9826A
Table 1-2. Required Language Extensions
Name Ver. Name Ver. Name Ver. Name Ver.
CLOCK 5.0 CS80 5.01 GRAPH 5.2 KBD 5.1
COMPLEX 5.1 EDIT 5.1 GRAPHX 5.2 MAT 5.1
CRTA 5.1 ERR 5.1 GPIB 5.0 MS 5.1
CRTX 5.1 FGPIB 5.0 IO 5.1 PDEV 5.0
1 This language extension depends on the mass storage type used.
1-2 General Information
2
Adjustment
Introduction
This chapter describes the adjustment required to ensure the 4338B is within its published
speci cations after it has been repaired. The adjustment should be performed along
with periodic maintenance to keep the 4338B in optimum operating condition. If proper
performance cannot be achieved after adjustment, proceed to Chapter 4.
Note To ensure proper results and correct instrument operation, a 30 minute
warm-up and stabilization is required before performing the adjustment.
Safety Consideration
This chapter contains NOTEs, CAUTIONs, and WARNINGs which must be followed to ensure
operator safety and to maintain the instrument in a safe and serviceable condition. The
adjustment covered in this chapter should be performed only by a quali ed person who is
aware of the hazards.
Warning Any interruption of the protective ground conductor (inside or outside
the instrument) or disconnection of the protective ground terminal can
make the instrument dangerous. Intentional interruption of the protective
ground system for any reason is prohibited.
Required Equipment
Table 1-1 lists the equipment required to perform the adjustment. Use only calibrated
standards when adjusting the 4338B.
Adjustment 2-1
Adjustment Tools
No hand tools are required for the adjustment.
Adjustable Components
There are no adjustable components, such as variable capacitors or variable resistors, in the
4338B. Adjustment is performed by updating the adjustment data stored in the EEPROM.
Factory-Selected Components
No factory-selected components are used in the 4338B
EEPROM Write Protect Switch
There are no EEPROM write protect switches in the 4338B.
Related Adjustment
There is only one adjustment for the 4338B. Table 2-1 lists the adjustment that must be
performed if an assembly has been replaced.
Table 2-1. Related Adjustment
Assembly Replaced Required Adjustment
A1 Main Board Assy Resistance Measurement Adjustment
A2 CPU Board Assy without ROM None1
A5 AC Inlet Board Assy None
LCD Assembly None
DC-DC Converter Unit None
Keyboard Assembly None
1 If the EEPROM, A2U1, is replaced, the Resistance Measurement Adjustment is required.
2-2 Adjustment
Adjustment Program
The adjustment program listed in Table 1-1 is required for the adjustment. Using the program,
the computer controls the 4338B to obtain the adjustment data, and stores the data in the
4338B internal EEPROM, A2U1.
The adjustment program runs on the computer listed in Table 1-1. The program should be
installed into your computer according to the procedure described in \Program Installation". To
start the program after it has been installed, refer to \Program Execution".
Figure 2-1 shows the adjustment program
ow. The following lists the brief explanation for
each menu item.
Figure 2-1. Adjustment Program Flow
INITIAL SETUP de nes the standards' calibration values. Update the standard's calibration
values if necessary.
Resistance obtains the data to adjust the actual measurement resistance to the
Measurement standards' value, and writes the data both to the 4338B internal EEPROM
Adjustment and to the unit-serial-number dependent le on the disk. This adjustment
should be performed if the Impedance Measurement Accuracy performance
test fails.
Rewrite EEPROM writes the adjustment data, which is stored in the unit-serial-number
dependent le, to the EEPROM.
Note Make sure that the correct line frequency (50 or 60Hz) has been selected in the
\UUT: 4338B" window preceding the Main Menu. This selection will improve
the adjustment data accuracy.
Adjustment 2-3
Program Installation
The adjustment program must be installed in the computer using the following procedures.
Making a Working Copy
Copy the content of the adjustment program disk to a working disk or to the harddisk to
prevent the program le from accidental deletion or destruction. Use the working disk or
harddisk and store the original disk in a safe place.
Program Execution
Perform the following steps to start the adjustment program.
Note Install the program prior to execution. Refer to \Program Installation".
1. Turn on the computer and bring up the BASIC system. Refer to the Table 1-2 for the
required language extensions.
2. Set the Mass Storage Unit Speci er to the drive/directory where the adjustment program
exists using the MSI command.
3. Load the program, \ADJ4338B" by pressing LOAD "ADJ4338B" 4Return5 (or 4Enter5).
4. Execute the program by pressing RUN.
Note In the program, the 4338B is referred as \UUT".
Note If the adjustment being performed follows right after EEPROM replacement,
change switch A2SW1-1 to \CLOSE", so that the 4338B will ignore the self test
errors at power-on. (Return the switch to \OPEN" when the adjustment has
been completed.) Refer to Figure B-1 for the switch location.
2-4 Adjustment
Adjustment Procedure References
This section provides supplemental information for the adjustment which is performed by the
program. Connection instructions and some additional explanations are provided. Use this
chapter as a reference when performing the adjustment.
Resistance Measurement Adjustment
This adjustment updates the data to adjust the measurement resistance to the standard values.
Equipment
Standard Resistors 42030A
Open Termination 42090A
Short Termination 42091A
Setup
This setup obtains the range resistor adjustment data and the process ampli er attenuator
adjustment data.
Figure 2-2. Range Resistor Adjustment Setup
Perform the following steps as the program instructs.
1. Connect the speci ed termination or standard resistor directly to the 4338B UNKNOWN
Connectors.
2. Repeat step 1 as instructed.
Adjustment 2-5
3
Assembly Replacement
Introduction
This chapter provides the 4338B replaceable parts lists, and the step by step disassembly
procedures for the major assemblies. Table 3-1 to Table 3-7 describe all the 4338B replaceable
parts. The gure section of Table 3-7 also shows the cable connections.
Ordering Information
To order a part listed in the replaceable parts lists, quote the Agilent Technologies part number,
indicate the quantity required, and address the order to the nearest Agilent Technologies oce.
To order a part that is not listed in the replaceable parts list, include the instrument model
number, complete instrument serial number, the description and function of the part, and the
quantity of parts required. Address the order to the nearest Agilent Technologies oce.
Restored Exchange Assemblies
Some replacement assemblies are available as either new or restored assemblies. The restored
assembly is more economical than a new assembly and, as with new assemblies, a 90-day
warranty applies through the instrument's support life. The defective assembly must be
returned for credit. For this reason, new assemblies must be ordered for spare parts. The part
numbers for both new and restored assemblies are given in the replaceable parts lists.
Note The Exchange Program may not apply in your country. Contact the nearest
Agilent Technologies oce for further details.
Assembly Replacement 3-1
Replacing the A2 CPU Board Assembly
The A2 CPU Board Assembly has a ROM for the rmware and an EEPROM for the adjustment
data and user data. Both ROM and EEPROM are mounted in sockets for easy replacement. If
the A2 assembly is replaced, the ROM and EEPROM may be transferred from the defective
assembly to the new assembly as long as the ROM and EEPROM are not defective. The
ROM transfer reduces parts cost for the repair, and the EEPROM transfer saves time from
readjusting the 4338B. For this purpose, the A2 assembly can only be ordered without the
ROM.
When the A2 assembly is replaced, make sure that the jumpers and switches on the A2
assembly are in the default position as shown in Appendix B.
Replaceable Assembly List
The replaceable electrical assemblies are listed in Table 3-1 and Table 3-3.
3-2 Assembly Replacement
Table 3-1. Replaceable Major Assembly List
Reference Agilent Part Qty. Description
Designation Number
1 04263-66505 1 A5 AC Inlet Board Assembly
2 04263-60004 1 Transformer Assembly
3 04263-80901 1 DC-DC Converter Unit
4 04263-66532 1 A2 CPU Board Assembly w/o ROM
04263-00604 1 Case Shield1
0515-1550 4 Screw M3
5 04338-66504 1 A4 Keyboard Assembly
04338-25151 1 Rubber Key
0515-1550 1 Screw M3
6 04263-61010 1 LCD Assembly
04263-25003 1 Filter Transparent
0515-1550 2 Screw M3
7 04338-66551 1 A1 Main Board Assembly
1 Included in 04263-66532
Assembly Replacement 3-3
Table 3-2. A2 CPU Board Assembly, Replaceable Assembly List
Reference Agilent Part Qty. Description
Designation Number
1 2110-1123 1 A2F1, Fuse SMT 2A
2 1818-5146 1 A2U1, EEPROM
3 04338-85031 1 A2U11, ROM Rev. 1.00
Table 3-3. Replaceable Assembly List
Reference Agilent Part Qty. Description
Designation Number
A1C500 0180-4334 1 Capacitor, 22000 F (for power supply)
A1C501 0180-4334 1 Capacitor, 22000 F (for power supply)
A5SW1 3101-3171 1 Line Switch
A5VR1 0837-0237 1 Varistor
A5VR2 0837-0237 1 Varistor
3-4 Assembly Replacement
Replaceable Mechanical Parts List
The replaceable mechanical parts are listed in Table 3-4 to Table 3-7.
Table 3-4. Replaceable Mechanical Parts List 1
Reference Agilent Part Qty. Description
Designation Number
1 04263-04004 1 Cover
2 5041-9167 4 Foot
1460-1345 2 Tilt Stand
3 04338-65020 1 Front Panel Assembly
1
4 5041-9170 2 Trim Side
0515-0914 4 Screw M3 (Hidden)
5 04263-40001 1 Front Bezel
2
6 04263-00605 1 Sub Panel (Hidden)
2
0515-0914 4 Screw M3 (Hidden)
2
0515-1550 2 Screw M3 (Hidden)
2
0160-4808 4 Capacitor 470 pF (Hidden)
2
1901-1250 8 Diode (Hidden)
2
7 1250-0252 4 BNC Connector
2
2950-0035 4 Nut
2
5040-3324 4 Insulator
2
5040-3325 4 Insulator (Hidden)
2
04263-01221 4 Lug Terminal (Hidden)
2
8 1510-0130 1 Binding Post
2
2190-0067 1 Washer (Hidden)
2
2950-0006 1 Nut (Hidden)
2
9 04338-87121 1 Panel Label
2
1 The assembly consists of the parts designated by 5 through 9.
2 This part is included in the Front Panel Assembly, 3.
Assembly Replacement 3-5
Table 3-5. Replaceable Mechanical Parts List 2
Reference Agilent Part Qty. Description
Designation Number
1 04263-61615 1 GPIB Connector with
atcable1
2 2110-0565 1 Fuse Holder
2110-0202 1 Fuse 0.25 A, Slow Blow (230V)
2110-0201 Fuse 0.5 A, Slow Blow (115V)
3 0515-1551 2 Screw M3
4 04338-00102 1 Chassis
5 2190-0054 1 Washer
2950-0054 1 Nut
1 Includes two sets of screw, washer and nut.
,
3-6 Assembly Replacement
Table 3-6. Replaceable Mechanical Parts List 3
Reference Agilent Part Qty. Description
Designation Number
1 0515-2079 1 Screw M4 (on the Chassis)
2 04263-24001 2 Nut Rod (for Transformer)
2190-0586 2 Washer Spring M4
3 04263-00607 1 Plate Shield
4 04263-24002 2 Nut Rod (for DC-DC Conv.)
2190-0584 2 Washer Spring M3
5 0515-1550 7 Screw M3 (for A1 and A2)
04339-24006 4 Stando (Hidden, for A1)
6 5040-3347 2 Plate (Hidden, Chassis Reverse side)
0460-0616 150 mm 2 2 Adhesive Tape (for Plate)
7 04263-07001 2 Gasket
0515-1550 4 Screw M3
8 0370-2862 1 Button, Line Switch
04339-23001 1 Shaft, Line Switch
0535-0031 1 Nut (for Shaft)
9 04339-25002 2 Support, Line Switch Plate
0515-0914 2 Screw M3 Flat Head
10 04263-01201 1 Plate, Line Switch
11 0515-0914 5 Screw M3 Flat Head (for A5)
Assembly Replacement 3-7
Table 3-7. Replaceable Mechanical Parts List 4
Reference Agilent Part Qty. Description
Designation Number
1 04263-61608 1 Wire Assy (V Selector)
2 04263-61602 1 Cable Assembly, \A"-\A"
04339-25004 1 Core Holder
0515-1550 1 Screw M3
3 04263-61604 1 Cable Assembly, \B"-\B"
04339-25004 1 Core Holder
0515-1550 1 Screw M3
4 04263-61605 1 Cable Assembly, \C"-\C"
04339-25004 1 Core Holder
0515-1550 1 Screw M3
5 04338-61603 1 Cable Assembly
6 04339-61614 1 Wire Assy (Binding Post)
3-8 Assembly Replacement
Disassembly Procedures
This section provides the procedures to disassemble the 4338B's major assemblies. Tools and
fasteners required for the replacement are described.
Caution SUSCEPTIBLE TO DAMAGE FROM ESD.
Perform the following procedures only at a static-safety workstation and wear
a grounding strap.
Tools and Fasteners
The 4338B mechanical components are secured using metric threaded fasteners. Many
fasteners in the 4338B may appear to be Phillips type, but they are in fact, Pozidrive type. To
avoid damaging them, use only pozidrive screwdrivers to remove or tighten pozidrive type
fasteners.
Cover Removal
The following procedure is common for gaining access to any of the assemblies.
Figure 3-1. Cover Removal
1. Remove the two screws which fasten the cover to the chassis rear panel.
2. Slide the cover toward the rear while holding the front panel bezel.
Assembly Replacement 3-9
A1 Main Board Removal
Removal Procedure
1. Remove the A2 CPU Board Assembly referring to \A2 CPU Board Assembly Removal".
2. Disconnect the following cable assemblies and wire assemblies from the A1 assembly.
a. The three cable assemblies marked \A", \B", and \C" which are connected to the
UNKNOWN connectors on the Front Panel
b. The wire assembly which is connected to the transformer
c. The two wire assemblies which are connected to the DC-DC Converter
3. Remove the nut which fasten the Ext Trigger connector to the rear panel.
4. Remove the four studs, that secure the A1 assembly to the chassis, by rotating them with a
at bladed screwdriver.
5. Remove the three screws that secure the A1 assembly to the chassis.
6. Remove the A1 assembly from the chassis by sliding the assembly toward forward before
lifting.
A2 CPU Board Assembly Removal
Removal Procedure
1. Remove the cover referring to \Cover Removal".
2. Disconnect the two
atcable assemblies and the wire assembly from the front side of the A2
assembly.
3. Disconnect the
atcable assembly, which is connected to the GPIB connector on the rear
panel, from the rear right side of the A2 assembly.
4. Remove the four screws that secure the A2 assembly to the stud.
5. Remove the
at cable assembly which is connected to the A1 main board assembly on the
bottom, while sliding the A2 assembly toward front.
6. Remove the A2 assembly from the chassis.
Note The ROM and EEPROM on the A2 assembly may be transferred to the new
assembly to minimize the repair time and parts cost. Refer to \Replacing the
A2 CPU Board Assembly" for more information.
A5 AC Inlet Board Assembly Removal
Removal Procedure
1. Disconnect the cable assembly with the 4 pin connector from the A5 assembly.
2. Disconnect the cable assembly with the 3 pin connector from the A5 assembly.
3. Remove the screw which xes the green and yellow wire connected to the neutral terminal
of the power cable connector to the chassis bottom.
4. Remove the ve screws which secure the A5 assembly to the chassis, from the side.
5. Slide the A5 assembly toward the right to remove the switch on the A5 assembly from the
line switch plate slot.
3-10 Assembly Replacement
6. Remove the A5 assembly from the chassis.
Keyboard Assembly Removal
Removal Procedure
1. Remove the cover referring to \Cover Removal".
2. Disconnect the two
atcable assemblies and the wire assembly from the front side of the A2
assembly.
3. Remove the two
at head screws that secure the front panel from the bottom.
4. Remove the side trim label from both sides of the front bezel.
5. Remove four screws that secure the front panel bezel to the chassis from both sides.
6. Place the front panel assembly, so that the front panel faces down.
7. Remove the screw that secures the keyboard to the front panel bezel.
8. Remove the keyboard assembly from the front panel bezel.
LCD Assembly Removal
Removal Procedure
1. Remove the cover referring to \Cover Removal".
2. Disconnect the two
atcable assemblies and the wire assembly from the front side of the A2
assembly.
3. Remove the two
at head screws that secure the front panel from the bottom.
4. Remove the side trim label from both sides of the front bezel.
5. Remove the four screws that secure the front panel bezel to the chassis from both sides.
6. Place the front panel assembly, so that the front panel faces down.
7. Remove the two screws that secure the LCD to the front panel bezel.
8. Remove the LCD assembly from the front panel bezel.
BNC Connector Removal
Removal Procedure
1. Remove the cover referring to \Cover Removal".
2. Disconnect the two
atcable assemblies and the wire assembly from the front side of the
A2 assembly.
3. Remove the two
at head screws that secure the front panel from the bottom.
4. Remove the side trim label from both sides of the front bezel.
5. Remove four screws that secure the front panel bezel to the chassis from both sides.
6. Place the front panel assembly, so that the panel faces down.
7. Disconnect the cable assembly which is connected to the BNC being replaced connector
from the A1 main board assembly.
Assembly Replacement 3-11
8. Remove the core holder which holds the cable assembly which is connected to the BNC
connector being replaced, by unscrewing the screw secures the holder from the front side.
9. Disconnect the cable from the BNC connector housing being replaced, by unscrewing the
nut which fastens, from the back of the front panel, the cable to the BNC connector.
10. Unscrew the nut which connects the BNC connector housing to the sub panel.
11. Remove the BNC connector.
3-12 Assembly Replacement
4
Troubleshooting
Introduction
This chapter provides assembly level troubleshooting information for the 4338B. The
information includes theory of operation, and troubleshooting.
Safety Considerations
This chapter contains WARNINGs and CAUTIONs that must be followed for your protection and
to avoid damaging the equipment.
Warning The servicing procedures described herein are performed when power is
supplied to the instrument and its protective covers are removed. This
type of servicing must be performed only by service trained personnel
who are aware of the hazards involved (for example, re, and electrical
shock). When serving can be performed without power applied to the
instrument, remove power from the instrument. Before any repair is
completed, ensure that all safety features are intact and functioning,
and that all necessary parts are properly connected to the protective
grounding system.
Required Equipment
Table 1-1 lists the equipment required for troubleshooting.
Troubleshooting 4-1
After Service Product Safety Checks
Warning Whenever it appears likely that protective safety provisions have been
impaired, the apparatus shall be marked as inoperative and should be
secured against any unintended operation. The protection provisions will
have likely been compromised if, for example:
The instrument shows visible signs of damage.
The instrument fails to perform the intended measurement.
The unit has undergone prolonged storage under unfavorable conditions.
The instrument was severely stressed in transport.
Perform the following ve safety checks to verify the safety condition of the 4338B (these
checks may also be used for safety checks after troubleshooting and repair).
1. Visually inspect the interior of the instrument for any signs of abnormal internally generated
heat, such as discolored printed circuit boards and components, damaged insulation, or
evidence of arcing. Determine the cause, and repair.
2. Use an ohmmeter which can accurately measure 0.1
to check the resistance from the
instrument enclosure to the power cord's ground pin. The resistance must be less than
0.1
. Flex the power cord while making this measurement to determine if any intermittent
discontinuities exist.
3. Unplug the 4338B's power plug from the power source. Set the line switch to ON. Tie the
line and neutral pins of the power connector together and check the resistance between
them and enclosure. The minimum acceptable resistance is 5 M
. Find and replace any
component which causes the instrument to fail this test.
4. Verify that the correct fuse is installed.
5. Verify that the grounding wire (green and yellow) is secured to the chassis by a screw and
washer.
4-2 Troubleshooting
Theory of Operation
This section describes the general overall operation of the 4338B and the operation of each
assembly.
Overall Measurement Theory
The 4338B measures the resistance of the Device Under Test (DUT) by measuring vector
voltage to current ratio. A vector is a value which consists of a magnitude and a phase. The
DUT resistance is the real part of vector impedance which is determined by the vector ratio
between the voltage across the DUT and the current
owing through the DUT.
Figure 4-1. Voltage Current Ratio Measurement Principle
In Figure 4-1, a DUT is connected in series with a signal source, voltmeter V, and ammeter A. If
the ammeter measures i amperes when the source voltage is v volts, the DUT's impedance Zx
is expressed by:
v
Zx =
i
The DUT resistance, R, is the real part of Zx expressed in the complex real-imaginary number
format:
Zx = R + jX
where, j is the imaginary unit and X is the reactance.
Note For accurate and stable low-resistance-measurement, the 4338B employs an ac
voltage source, rather than a dc voltage source.
The 4338B essentially consists of a signal source, a vector voltmeter, and a vector current
meter.
Troubleshooting 4-3
Overall Block Diagram
Figure 4-2 shows the overall block diagram of the 4338B.
Figure 4-2. 4338B Overall Block Diagram
The signal source section applies measurement signal to the range resistor and DUT in
series. The current sense ampli er measures the voltage across the range resistor, which is
proportional to the current
owing through the DUT. The voltage sense ampli er measures the
voltage across the DUT. The process ampli er switches these two voltages to be converted into
digital data. The CPU calculates DUT resistance, derived from impedance, from the vector ratio
of these two voltages, and displays the result on the LCD.
4-4 Troubleshooting
Analog Section
Figure 4-3 shows the analog section block diagram. The 4338B analog section can be divided
in six sections, the signal source, range resistor, current sense ampli er, voltage sense ampli er,
process ampli er, and dry circuit loop.
The signal source generates a 1 kHz signal of which level is set from the keyboard or by GPIB
commands. The signal is applied to the range resistor and to the DUT via the High-Current
(HCUR ) connector. The current
owing through the DUT
ows into the ground via the
Low-Current (LCUR ) connector and outer shield of the HCUR connector.
The vector current
owing through the DUT is measured by the current sense ampli er in
terms of the vector voltage across the range resistor. The vector voltage across the DUT is
measured by the voltage sense ampli er.
The process ampli er selects one of the above two vector voltages. The selected voltage is
processed according to measurement conditions, such as signal source level and measurement
range, and is converted into digital data by the Analog-to-Digital Converter (ADC).
The dry circuit loop attains the dry circuit mode by limiting the signal source output, so that
the voltage across the DUT is not more than 20 mV.
Figure 4-3. Analog Section Block Diagram
Troubleshooting 4-5
Signal Source Section
The signal source generates a 1 kHz signal of which output current is selected from among
1 A, 10 A, 100 A, 1 mA, and 10 mA (in rms).
The output current is determined by the attenuator and the following ampli er. The dry circuit
loop controls the attenuation, so that the voltage across the DUT is not more than 20 mV.
Figure 4-4. Signal Source Section Block Diagram
4-6 Troubleshooting
Range Resistor and Current Sense Ampli er Sections
These sections measure current
owing through the DUT. Figure 4-5 shows this section's block
diagram.
Figure 4-5. Range Resistor and Current Sense Amp. Block Diagram
The range resistor converts the current to a proportional voltage which is measured. The range
resistor consists of four resistors, which are switched according to the signal source output
level.
The current sense ampli er, which is a dierential ampli er, ampli es the voltage across the
range resistor.
Troubleshooting 4-7
Voltage Sense Ampli er and Process Ampli er Sections
These sections measure the voltage across the DUT and processes the outputs from the voltage
sense ampli er and the current sense ampli er. Figure 4-6 shows this section's block diagram.
Figure 4-6. Voltage Sense Amp. and Process Amp. Block Diagram
The voltage sense ampli er, which is a dierential ampli er, measures the vector voltage across
the DUT via the High-Potential (HPOT ) and Low-Potential (LPOT ) connectors.
The output of the voltage sense ampli er is fed back to the signal source section for dry circuit
measurement.
SW1 in the process ampli er selects the inputs from the voltage sense ampli er and current
sense ampli er to be processed. The selected signal is attenuated according to the range
resistor setting. The lter passes the fundamental signal (1 kHz) in order to purify the signal
for accurate and stable measurement. The ltered signal is converted into digital data to be
processed by the digital section.
4-8 Troubleshooting
Digital Section
Figure 4-7 shows the Digital Section block diagram.
Figure 4-7. Digital Section Block Diagram
The digital section consists of the A2 CPU Board Assembly and other peripheral assemblies
such as the keyboard and LCD. The section communicates with the A1 Main Board Assembly in
order to control the latches, switches, and other components on the A1 assembly and receive
the measurement data. The GPIB interface on the A2 Assembly allows the 4338B communicate
with a controller. A handler interface on the A1 Assembly allows the 4338B communicate with
an external handler.
The A2 CPU Board Assembly includes a processor, ROM, EEPROM, jumpers, switches, and
LEDs.
ROM (A2U11) stores the rmware which controls all the 4338B's operation and functions. The
ROM is mounted in a socket for easy replacement.
The EEPROM (A2U1) stores the unit unique data, such as the adjustment data and the operator
unique data, such as the operator saved measurement setup condition. The EEPROM will
not lose its data when power is turned o. The EEPROM is mounted in a socket for easy
replacement.
Jumpers and switches set the 4338B's conditions. Refer to Appendix B for more information.
Troubleshooting 4-9
Power Supply Section
Figure 4-8 shows the power supply section block diagram.
Figure 4-8. Power Supply Section Block Diagram
The ac line power is connected to the A5 AC Inlet Board Assembly, which consists of the fuse,
line switch, and varistors. The voltage selection switch on the rear panel selects the ac line
voltage from 230V or 115V. According to the selection, the ac line power is connected to the
corresponding primary tap of the transformer. Varistor, VR1 protects the circuit from surge
voltage on the line power. VR2 blows fuse F1 if the 4338B is turned on with the wrong line
voltage setting selection, for example, 115V selection when using a 230V line.
The transformer secondary voltage is approximately 14 V. The ac voltage is recti ed and
ltered by circuitry on the A1 Main Board Assembly, and produces approximately 14V dc. The
dc voltage is applied to the DC-DC Converter to produce regulated +12V, +5V, and 012V dc.
The dc voltages are supplied to all assemblies, either directly or indirectly via the A1 assembly.
4-10 Troubleshooting
Troubleshooting
Figure 4-9 shows the overall troubleshooting
owchart to nd the defect assembly. Follow the
owchart when troubleshooting. Refer to the \Check Procedure References" for the detailed
procedure to check each item.
Refer to Chapter 3 for assembly replacement.
Note Because of each assembly's high SMD (surface mount device) ratio, the repair
should be done by assembly replacement. The troubleshooting procedure,
therefore, only isolates the defective assembly.
Troubleshooting 4-11
Figure 4-9. Troubleshooting Flow
4-12 Troubleshooting
Check Procedure References
Refer to the corresponding check procedure. Each check procedure is numbered the same as in
Figure 4-9 for quick reference.
Check 1, DC-DC Converter Output Voltage
1. Remove the cover referring to \Cover Removal" in Chapter 3.
2. Turn on the 4338B.
3. Using a multimeter, check to see if the voltages between the test pads and the ground
(TP500), shown in Table 4-1, on A1 Main Board Assembly are in the ranges shown.
4. If passed, proceed to \Check 2, LCD Displays Anything?", otherwise proceed to \Check 9,
Fuse and Line Switch".
Figure 4-10. DC-DC Converter Output Voltage Check
Table 4-1. DC-DC Converter Output Voltage (Connected)
Test Pad (+) Test Pin (0) Range
\+5 V" 500 5.160.2 V
\+12 V" 500 1260.6 V
\012 V" 500 01260.6 V
Troubleshooting 4-13
Check 2, LCD Displays Anything?
1. Turn o the 4338B.
2. Turn on the 4338B while watching the LCD.
3. Check for a beep sound for a moment and if you see anything is displayed on the LCD.
4. If beep sounds and LCD displays something, proceed to \Check 3, LCD Operates Correctly?",
otherwise proceed to \Check 6, CPU Power LED Lights?".
Check 3, LCD Operates Correctly?
1. Turn on the 4338B.
2. Reset the 4338B.
3. Check if the LCD's back light is lit.
4. Press some front panel keys such as 4Meas Prmtr5