Agilent Technologies Power Supply S 6023A And 6028A Users Manual SERVICE

AGILENT S 6023A and 6028A to the manual eef2d6c7-17f4-4bde-a75f-78a69ccc4e66

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SERVICE MANUAL
AUTORANGING
DC POWER SUPPLY
AGILENT MODELS
6023A and 6028A

Agilent Part No. 5964-8283

FOR INSTRUMENTS WITH SERIAL NUMBERS
Agilent Model 6023A; Serials

US36490101 and above

Agilent Model 6028A; Serials

US36520101 and above

For instruments with higher serial numbers, a change page may be included.

Microfiche Part No. 5964-8284

Printed in USA: July 2001

CERTIFICATION
Agilent Technologies certifies that this product met its published specifications at time of shipment from the factory. Agilent
Technologies further certifies that its calibration measurements are traceable to the United States National Institute of
Standards and Technology, to the extent allowed by the Institute’s calibration facility, and to the calibration facilities of
other International Standards Organization members.

WARRANTY
This Agilent Technologies hardware product is warranted against defects in material and workmanship for a period of three
years from date of delivery. Agilent Technologies software and firmware products, which are designated by Agilent
Technologies for use with a hardware product and when properly installed on that hardware product, are warranted not to
fail to execute their programming instructions due to defects in material and workmanship for a period of 90 days from date
of delivery. During the warranty period Agilent Technologies will, at its option, either repair or replace products which
prove to be defective. Agilent Technologies does not warrant that the operation of the software, firmware, or hardware shall
be uninterrupted or error free.
For warranty service, with the exception of warranty options, this product must be returned to a service facility designated
by Agilent. Technologies. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products
returned to Agilent Technologies. for warranty service. Except for products returned to Customer from another country,
Agilent Technologies shall pay for return of products to Customer.
Warranty services outside the country of initial purchase are included in Agilent Technologies’ product price, only if
Customer pays Agilent Technologies international prices (defined as destination local currency price, or U.S. or Geneva
Export price).
If Agilent Technologies is unable, within a reasonable time to repair or replace any product to condition as warranted, the
Customer shall be entitled to a refund of the purchase price upon return of the product to Agilent Technologies.

LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the Customer,
Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental
specifications for the product, or improper site preparation and maintenance. NO OTHER WARRANTY IS EXPRESSED
OR IMPLIED. AGILENT TECHNOLOGIES SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER’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
The above statements apply only to the standard product warranty. Warranty options, extended support contracts, product
maintenance agreements and customer assistance agreements are also available. Contact your nearest Agilent
Technologies Sales and Service office for further information on Agilent Technologies’ full line of Support Programs.

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 specific warnings elsewhere in this manual violates safety
standards of design, manufacture, and intended use of the instrument. Agilent Technologies, Inc. assumes no liability for the
customer's failure to comply with these requirements.
BEFORE APPLYING POWER.
Verify that the product is set to match the available line voltage and the correct fuse is installed.
GROUND THE INSTRUMENT.
This product is a Safety Class 1 instrument (provided with a protective earth terminal). To minimize shock hazard, the instrument chassis
and cabinet must be connected to an electrical ground. The instrument must be connected to the ac power supply mains through a threeconductor power cable, with the third wire firmly connected to an electrical ground (safety ground) at the power outlet. For instruments
designed to be hard wired to the ac power lines (supply mains), connect the protective earth terminal to a protective conductor before any
other connection is made. Any interruption of the protective (grounding) conductor or disconnection of the protective earth terminal will
cause a potential shock hazard that could result in personal injury. If the instrument is to be energized via an external autotransformer for
voltage reduction, be certain that the autotransformer common terminal is connected to the neutral (earth pole) of the ac power lines
(supply mains).
INPUT POWER MUST BE SWITCH CONNECTED.
For instruments without a built-in line switch, the input power lines must contain a switch or another adequate means for disconnecting
the instrument from the ac power lines (supply mains).
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.
Do not operate the instrument in the presence of flammable gases or fumes.
KEEP AWAY FROM LIVE CIRCUITS.
Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made by qualified
service personnel. Do not replace components with power cable connected. Under certain conditions, dangerous voltages may exist even
with the power cable removed. To avoid injuries, always disconnect power, discharge circuits and remove external voltage sources before
touching components.
DO NOT SERVICE OR ADJUST ALONE.
Do not attempt internal service or adjustment unless another person, capable of rendering first aid and resuscitation, is present.
DO NOT EXCEED INPUT RATINGS.
This instrument may be equipped with a line filter to reduce electromagnetic interference and must be connected to a properly grounded
receptacle to minimize electric shock hazard. Operation at the line voltage or frequencies in excess of those stated on the data plate may
cause leakage currents in excess of 5.0mA peak.
SAFETY SYMBOLS.
Instruction manual symbol: the product will be marked with this symbol when it is necessary for the user to refer to the
instruction manual (refer to Table of Contents) .
Indicates hazardous voltages.
Indicate earth (ground) terminal.
The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which, if not correctly
performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the indicated
conditions are fully understood and met.
The CAUTION sign denotes a hazard. It calls attention to an operating procedure, 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. Do not proceed beyond
a CAUTION sign until the indicated conditions are fully understood and met.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.
Because of the danger of introducing additional hazards, do not install substitute parts or perform any unauthorized modification to the
instrument. Return the instrument to a Agilent Technologies, Inc. Sales and Service Office for service and repair to ensure that safety
features are maintained.
Instruments which appear damaged or defective should be made inoperative and secured against unintended operation until they can be
repaired by qualified service personnel.

SAFETY SYMBOL DEFINITIONS
Symbol

Description

Symbol

Description

Direct current

Terminal for Line conductor on permanently
installed equipment

Alternating current

Caution, risk of electric shock

Both direct and alternating current

Caution, hot surface

Three-phase alternating current

Caution (refer to accompanying documents)

Earth (ground) terminal

In position of a bi-stable push control

Protective earth (ground) terminal

Out position of a bi-stable push control

Frame or chassis terminal

On (supply)

Terminal for Neutral conductor on
permanently installed equipment

Off (supply)

Terminal is at earth potential
(Used for measurement and control
circuits designed to be operated with
one terminal at earth potential.)

Standby (supply)
Units with this symbol are not completely
disconnected from ac mains when this switch is
off. To completely disconnect the unit from ac
mains, either disconnect the power cord or have
a qualified electrician install an external switch.

Printing History
The edition and current revision of this manual are indicated below. Reprints of this manual containing minor corrections
and updates may have the same printing date. Revised editions are identified by a new printing date. A revised edition
incorporates all new or corrected material since the previous printing date. Changes to the manual occurring between
revisions are covered by change sheets shipped with the manual. Also, if the serial number prefix of your power supply is
higher than those listed on the title page of this manual, then it may or may not include a change sheet. That is because
even though the higher serial number prefix indicates a design change, the change may not affect the content of the manual.
Edition 1

July, 2001

© Copyright 2001 Agilent Technologies, Inc.
This document contains proprietary information protected by copyright. All rights are reserved. No part of this document
may be photocopied, reproduced, or translated into another language without the prior consent of Agilent Technologies,
Inc. The information contained in this document is subject to change without notice.

TABLE OF CONTENTS
Introduction ............................................................................................................................................................................ 7
Scope .................................................................................................................................................................................... 7
Calibration and Verification ............................................................................................................................................. 7
Troubleshooting................................................................................................................................................................ 7
Principles of Operation ..................................................................................................................................................... 7
Replaceable Parts.............................................................................................................................................................. 7
Circuit Diagrams............................................................................................................................................................... 7
Safety Considerations ........................................................................................................................................................... 7
Manual Revisions ................................................................................................................................................................. 8
Calibration and Verification.................................................................................................................................................. 9
Introduction........................................................................................................................................................................... 9
Test Equipment Required ..................................................................................................................................................... 9
Operation Verification Tests................................................................................................................................................. 9
Calibration Procedure ........................................................................................................................................................... 9
Initial Setup..................................................................................................................................................................... 11
Performance Tests .............................................................................................................................................................. 14
Measurement Techniques ............................................................................................................................................... 14
Constant Voltage (CV) Tests .......................................................................................................................................... 15
Constant Current (CC) Tests........................................................................................................................................... 21
Troubleshooting .................................................................................................................................................................... 23
Introduction......................................................................................................................................................................... 23
Initial Troubleshooting Procedures..................................................................................................................................... 23
Electrostatic Protection ....................................................................................................................................................... 25
Repair and Replacement ..................................................................................................................................................... 25
A2 Control Board Removal ............................................................................................................................................ 26
A4 Power Mesh Board Removal .................................................................................................................................... 27
A3 Front-Panel Board Removal...................................................................................................................................... 27
A1 Main Board Removal................................................................................................................................................ 27
Overall Troubleshooting Procedure.................................................................................................................................... 27
Using the Tables ............................................................................................................................................................. 28
Main Troubleshooting Setup .......................................................................................................................................... 29
Troubleshooting No-Output Failures .............................................................................................................................. 31
Front-Panel Troubleshooting .......................................................................................................................................... 31
Troubleshooting Bias Supplies ....................................................................................................................................... 33
Power Section Blocks ..................................................................................................................................................... 35
Troubleshooting AC-Turn-on Circuits............................................................................................................................ 35
Troubleshooting PWM & Clock..................................................................................................................................... 36
Troubleshooting DC-To-DC Converter .......................................................................................................................... 37
Troubleshooting CV Circuit ........................................................................................................................................... 38
Troubleshooting CC Circuit............................................................................................................................................ 38
Troubleshooting Down Programmer .............................................................................................................................. 39
Troubleshooting OVP Circuit ......................................................................................................................................... 39
Principles of Operation ........................................................................................................................................................ 43
Autoranging Power ............................................................................................................................................................. 43
Block Diagram Overview ................................................................................................................................................... 43
Simplified Schematic...................................................................................................................................................... 45
DC-to-DC Converter....................................................................................................................................................... 47
Down Programmer.......................................................................................................................................................... 47
Constant-Voltage (CV) Circuit ....................................................................................................................................... 48
Constant-Current (CC) Circuit........................................................................................................................................ 49

Overvoltage Protection (OVP) Circuit............................................................................................................................ 49
Power-Limit Comparator ................................................................................................................................................ 49
Control-Voltage Comparator .......................................................................................................................................... 49
Initial-Ramp Circuit........................................................................................................................................................ 50
Pulse-Width Modulator (PWM) ..................................................................................................................................... 50
Bias Voltage Detector..................................................................................................................................................... 50
AC-Surge Dropout Detector ........................................................................................................................................... 50
1-Second-Delay Circuit .................................................................................................................................................. 51
Display Circuits .................................................................................................................................................................. 51
Replaceable Parts.................................................................................................................................................................. 53
Introduction......................................................................................................................................................................... 53
Ordering Information.......................................................................................................................................................... 54
Component Location and Circuit Diagrams ...................................................................................................................... 69
System Option 002 ................................................................................................................................................................ 79
General Information............................................................................................................................................................ 79
Specifications.................................................................................................................................................................. 79
Option 002 Hardware...................................................................................................................................................... 79
Installation .......................................................................................................................................................................... 83
Connector Assembly Procedure...................................................................................................................................... 83
Operation ............................................................................................................................................................................ 84
Local/Remote Programming........................................................................................................................................... 85
Remote Resistance Programming ................................................................................................................................... 87
Remote Monitoring......................................................................................................................................................... 89
Status Indicators.............................................................................................................................................................. 90
Remote Control............................................................................................................................................................... 90
Power-On Preset ................................................................................................................................................................. 92
AC Dropout Buffer Circuit ............................................................................................................................................. 93
Multiple Supply System Shutdown ................................................................................................................................ 93
Bias Supplies .................................................................................................................................................................. 94
Maintenance........................................................................................................................................................................ 94
Troubleshooting.............................................................................................................................................................. 95
Troubleshooting Resistance and Voltage Programming................................................................................................. 95
Troubleshooting Current Programming .......................................................................................................................... 95
Backdating........................................................................................................................................................................... 107

1
Introduction
Scope
This manual contains information for troubleshooting the Agilent 6023A or 6028A 200W Autoranging Power Supply to the
component level. Wherever applicable, the service instructions given in this manual refer to pertinent information provided
in the Operation Manual. Both manuals cover Agilent Models 6023A/28A; differences between models are described as
required.
The following information is contained in this manual.

Calibration and Verification
Contains calibration procedures for Agilent Models 6023A/28A. Also contains verification procedures that check the
operation of the supplies to ensure they meet the specifications of Chapter 1 in the Operating Manual.

Troubleshooting
Contains troubleshooting procedures to isolate a malfunction to a defective component on the main circuit board or to a
defective assembly (front-panel, power transformer, or cable assembly). Board and assembly level removal and
replacement procedures are also given in this section.

Principles of Operation
Provides block diagram level descriptions of the supply's circuits. The regulation & control, protection, input power, dc
power conversion and output circuits are described. These descriptions are intended as an aid in troubleshooting.

Replaceable Parts
Provides a listing of replaceable parts for all electronic components and mechanical assemblies for Agilent Models
6023A/28A.

Circuit Diagrams
Contains functional schematics and component location diagrams for all Agilent 6023A/28A circuits. The names that
appear on the functional schematics also appear on the block diagrams in Chapter 4. Thus, the descriptions in Chapter 4 can
be correlated with both the block diagrams and the schematics.

Safety Considerations
This product is a Safety Class 1 instrument, which means that it is provided with a protective earth terminal. Refer to the
Safety Summary page at the beginning of this manual for a summary of general safety information. Safety information for
specific procedures is located at appropriate places in the manual.

Manual Revisions
Agilent Technologies instruments are identified by a 10-digit serial number. The format is described as follows: first two
letters indicate the country of manufacture. The next four digits are a code that identify either the date of manufacture or of
a significant design change. The last four digits are a sequential number assigned to each instrument.
Item

Description

The first two letters indicates the country of manufacture, where US = USA; MY = Malaysia.

3648

This is a code that identifies either the date of manufacture or the date of a significant design change.

0101

The last four digits are a unique number assigned to each power supply.

If the serial number prefix on your unit differs from that shown on the title page of this manual, a yellow Manual Change
sheet may be supplied with the manual. It defines the differences between your unit and the unit described in this manual.
The yellow change sheet may also contain information for correcting errors in the manual.
Note that because not all changes to the product require changes to the manual, there may be no update information
required for your version of the supply.
Older serial number formats used with these instruments had a two-part serial number, i.e. 2701A-00101. This manual also
applies to instruments with these older serial number formats. Refer to Appendix B for backdating information.

2
Calibration and Verification
Introduction
This section provides test and calibration procedures. The operation-verification tests comprise a short procedure to verify
that the unit is performing properly, without testing all specified parameters. After troubleshooting and repair of a defective
power supply you can usually verify proper operation with the turn-on checkout procedure in the Operating Manual.
Repairs to the A1 main board and the A2 control board can involve circuits which, although functional, may prevent the
unit from performing within specified limits. So, after A1 or A2 board repair, decide if recalibration and operation
verification tests are needed according to the faults you discover. Use the calibration procedure both to check repairs and
for regular maintenance.
When verifying the performance of this instrument as described in this chapter, check only those specifications for which a
performance test procedure is included.

Test Equipment Required
Table 2-1 lists the equipment required to perform the tests of this section. You can separately identify the equipment for
performance tests, calibration and troubleshooting using the USE column of the table.

Operation Verification Tests
To assure that the unit is performing properly, without testing all specified parameters, first perform the turn-on checkout
procedure in the Operating Manual. Then perform the following performance tests, in this section.
CV Load Effect
CC Load Effect

Calibration Procedure
Calibrate the unit twice per year and when required during repair. The following calibration procedures which follow
should be performed in the sequence given. Table 2-2 describes in detail these calibration procedures and lists the expected
results to which each adjustment must be made.

Note:

Some of the calibration procedures for this instrument can be performed independently, and some
procedures must be performed together and/or in a prescribed order. If a procedure contains no references
to other procedures, you may assume that it can be performed independently.
To return a serviced unit to specifications as quickly as possible with minimal calibration, the technician
need only perform calibration procedures that affect the repaired circuit. Table 2-3 lists various power
supply circuits with calibration procedures that should be performed after those circuits are serviced.

Table 2-1. Test Equipment Required
TYPE
Oscilloscope

REQUIRED CHARACTERISTICS
Sensitivity: 1 mV
Bandwidth: 20MHz & 100MHz
Input: differential, 50Ω & 10MΩ

USE
P,T

RECOMMENDED MODEL
Agilent 1740A

RMS Voltmeter

True rms, 10MHz bandwidth
Sensitivity: 1 mV
Accuracy: 5%

Agilent 3400B

Logic Pulser

4.5 to 5.5Vdc @ 35mA

Agilent 546A

Multimeter

Resolution: 100nV
Accuracy: 0.0035%, 6½ digit

P,A,T

Agilent 3458A

CC PARD Test
Current Probe

No saturation at 30Adc
Bandwidth: 20Hz to 20MHz

Electronic Load*

Voltage range: 60Vdc
Current range: 60Adc
Power range: 300 watts
Open and short switches
Value: 0.25 ohms >250W
Accuracy: 1%
Rheostat or Resistor Bank

P,A

Tektronix P6303
Probe/AM503 Amp/
TM500 Power Module
Agilent 6060B

6023A
Value: 30mV @ 30A (1mΩ )
Accuracy: 1%
TC: 30ppm/°C
Value: 30mV @ 30A (1mΩ)
Accuracy: 0.05% **
TC: 30ppm/°C (A,P)
6028A
Value 100MΩ ± 0.04% @ 25W
Accuracy: 1%
PC: 0.0004% 1W

P,A

Calibration and Test
Resistors

Value:

A,T

Terminating
Resistors (4)

Value: 50Ω ±5%, noninductive

Blocking
Capacitors (2)
Common-mode
Toroidal Core

Value: 0.01µF, 100Vdc

CC PARD Test & IP
Cal Resistive Load*
Current-Monitoring
Resistors

100Ω, 5%, 1W
1Ω, 5%, 1/2W
1KΩ, 5% 1/4W
5KΩ, 5% 1/4W (6023A)
2KΩ, 0.01% 1/4W

P,A

Guidline 9230/15

Ferrox-Cube
500T600-3C8,
Agilent 9170-0061

Table 2-1. Test Equipment Required (continued)
TYPE
Switch
DC Power Supply

REQUIRED CHARACTERISTICS
SPST, 30A @ 20V
Voltage range: 0-60Vdc
Current range: 0-3Adc

USE
P
T,P

Variable Voltage
Transformer
(autotransformer)

Range greater than -13% to +6% of
nominal input AC voltage
1KVA

P,A

P = performance testing

A = calibration adjustments

RECOMMENDED MODEL
Agilent 6296A

T = troubleshooting

* Resistors may be substituted for test where an electronic load is not available.
** Less accurate, and less expensive, current-monitor resistors can be used, but the accuracy to which current programming
and current meter reading can be checked must be reduced accordingly.

Initial Setup
Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by service trained
personnel who are aware of the hazards involved (for example, fire and electrical shock).
Turn off ac power when making or removing connections to the power supply. Where
maintenance can be performed without power applied, the power should be
removed.
a.
b.
c.
d.
e.
f.

g.
h.
i.
j.
k.

Unplug the line cable and remove the top cover by removing three screws; the rear handle screw and the two top-rear
corner screws. Do not remove the front handle screw as the retaining nut will fall into the unit.
Slide the cover to the rear.
Plug a control board test connector A2P3 onto the A2J3 card-edge fingers.
Turn OVERVOLTAGE ADJUST control A3R59 fully clockwise.
Disconnect all loads from output terminals.
Connect power supply for local sensing, and ensure that MODE switches are set as shown below.

Reconnect the line cable and turn on ac power.
Allow unit to warm up for 30 minutes.
When attaching the DVM, the minus lead of the DVM should be connected to the first node listed, and the plus lead
should be connected to the second node listed.
At the beginning of each calibration procedure, the power supply should be in its power-off state, with no external
circuitry connected except as instructed.
The POWER LIMIT adjustment (A2R25) must be adjusted at least coarsely before many of the calibration procedures
can be performed. If you have no reason to suspect that the Power Limit circuit is out of adjustment, and you do not
intend to recalibrate it, do not disturb its setting. Otherwise, center A2R25 before you begin to calibrate the power
supply.
To disable the power supply, short INHIBIT line A2J3 pin 8 to COMMON A2J3 pin 4.

Table 2-2. Calibration Procedure
TEST
Meter F/S
Adjust.

TESTED
VARIABLE
Meter Ref.
Voltage

TEST POINTS
A2J3 pin 6 ( + )
M(-)

TEST SEQUENCE AND ADJUSTMENTS
a.
b.

Resistance
Programming
F/S
Adjust.

Prog. Voltage

VP ( + )
P(-)

a.
b.
c.

V-MON
Zero
Adjust.

V-MON

VM ( + )
M(-)

a.
b.
c.
d.

Common
Mode
Adjust.

Residual
Output
Voltage
VM( + )

VM ( + )
M(-)

a.
b.
c.
d.

I-MON
Zero
Adjust.

I-MON

IM ( + )
M (-)

I-MON
F/S
Adjust.

I-MON

IM ( + )
M(-)

e.
f.
a.
b.
c.
a.
b.
c.
d.

Rm ( + )
Rm ( - )

*IR = Initial Reading

Connect DVM across test points and turn on
ac power.
Adjust A2R24 to obtain the voltage range
specified in the results.
Connect a 2KΩ 0.01%, ¼W programming
resistor and DVM between test points.
Set MODE switch as in Figure 2-1 and turn on
ac power.
Adjust A2R23 to obtain the voltage range
specified in the results.
Set voltage and current controls to minimum
settings.
Disable power supply as in Initial Setup step i.
Short circuit output terminals and connect the
DVM between test points. Turn on power
supply.
Adjust V-MON Zero trim pot A2R22 to
voltage range specified in the results.
Set voltage and current controls to minimum.
Disable power supply as Initial Setup step i.
Turn on ac power and record the initial
voltage (IR) with DVM across test points.
Remove the - S( + ) and – OUT( - ) and
connect a 1Vdc power supply between - S( + )
and – OUT( - ). See Figure 2-1.
Adjust A2R21 to the voltage range specified.
Remove the 1V supply and replace jumpers.
Set voltage and current controls to minimum.
Turn on ac power.
Connect DVM across test points and adjust
I-MON Zero trim pot A2R8 as shown in
results.
Perform I-MON Zero Adjust before
proceeding .
Connect a 0.001Ω 0.05% (6023A), 0.100Ω
0.05% (6028A) current monitoring resistor
Rm across the output terminals.
Turn on ac power and using the “Display
Setting”, set current control to 30A (6023A),
10A (6028A), and voltage control to 5V.
Connect DVM across test points and take an
initial reading (IR).
Connect DVM across Rm monitoring
terminals and adjust A2R9 as shown in the
results.

EXPECTED
RESULTS
0.5V ± 50µV

2.5V ±4mV

0 ± 20µV

IR ± 20µV

0 ± 100µV
(6023A)
0 ± 25µV
(6028A)
IR*

0.006 IR*
+40µV (6023A),
0.200 ± 1µV
(6028A)

Table 2-2. Calibration Procedure (continued)
TEST
Power
Limit
Adjust.

TESTED
VARIABLE
V(OUT)
I(OUT)

TEST POINTS

TEST SEQUENCE AND ADJUSTMENTS
a.

Perform I-MON F/S Adjust before
proceeding.
b. Connect the unit to the ac power line via the
external variable auto-transformer which is set
to nominal line voltage.
c. Connect a 0.25Ω, 250W (6023A), 2.3Ω,
250W (6028A) resistor across the unit's output
and turn on ac power.
d. Set voltage control to 9V (6023A) 9V≥ 3V
(6028A) and current control to 30.2A
(6023A), 10.2A (6028A)
e. Set auto-transformer to minimum line
voltage.
f. Turn A2R25 fully counterclockwise.
g. Slowly adjust A2R25 clockwise until CC
LED just lights.

EXPECTED
RESULTS
30.2A 7.55V for
CC operation
(6023A)
10.2A, 23V for
CC operation
(6028A)

Figure 2-1. Common Mode Setup

Table 2-3. Guide to Recalibration After Repair
Printed Circuit
Board
A1 Main Board
A1 Main Board
A4 Power Mesh
A4 Power Mesh
A2 Control Board
A2 Control Board
A2 Control Board
A2 Control Board
A2 Control Board
A2 Control Board
1.
2.
3.

Block Name

Constant Voltage
(CV) Circuit
Constant Voltage
(CV) Circuit
Constant Current
(CC) Circuit
Power Limit
Comparator
Bias Power Supplies

Circuit Within
Block

All Except Current
Source
Current Source

Ref.
Designator
R3
T1
T3
CR7
All

Perform These
Procedures*
4
4 then 5
4 then 5 Board
4 then 5 Board
1 then 2

All

3 then 4

All

4 then 5

All
All
U9, R79, R80, R24 7
* Code To Calibration Procedure To Be Performed
V-MON Zero Calibration
4. I-MON Full Scale (F/S) Calibration
Common-Mode Calibration
5. Power Limit Calibration
I-MON Full Scale (F/S) Zero Calibration
6. Resistance Programming Full Scale (F/S) Calibration
7. Meter Full Scale (F/S) Calibration
± 15V Supplies

Performance Tests
The following paragraphs provide test procedures for verifying the unit's compliance with the specifications of Table 1-1 in
the Operating Manual. Please refer to CALIBRATION PROCEDURE or TROUBLESHOOTING if you observe
out-of-specification performance.

Measurement Techniques
Setup For All Tests. Measure the output voltage directly at the + S and - S terminals. Connect unit for local sensing, and
ensure that MODE switches are set as shown below. Select an adequate wire gauge for load leads using the procedures
given in the Operating Manual for connecting the load.

Electronic Load. The test and calibration procedures use an electronic load to test the unit quickly and accurately. If an
electronic load is not available, you may substitute a 2Ω 250W load resistor for the electronic load in these tests:
CV Source Effect (Line Regulation)
CC Load Effect (Load Regulation)
You may substitute a 0.25Ω 250W load resistor in these tests:
CV Load Effect (Load Regulation)
CV PARD (Ripple and Noise)
CC Source Effect (Line Regulation)
CC PARD (Ripple and Noise)

The substitution of the load resistor requires adding a load switch to open and short the load in the CC or CV load
regulation tests. The load transient recovery time test procedure cannot be performed using load resistors.
An electronic load is considerably easier to use than a load resistor. It eliminates the need for connecting resistors or
rheostats in parallel to handle the power, it is much more stable than a carbon-pile load, and it makes easy work of
switching between load conditions as is required for the load regulation and load transient-response tests.
Current-Monitoring Resistor Rm. To eliminate output current measurement error caused by voltage drops in the leads
and connections, connect the current-monitoring resistor between -OUT and the load as a four-terminal device. Figure 2-2
shows correct connections. Select a resistor with stable characteristics: 0.001, 1% accuracy, 30 ppm/°C or lower
temperature coefficient and 20W power rating (20 times actual power if other than 0.001Ω is used).

Figure 2-2. Current-Monitoring Resistor Setup

Constant Voltage (CV) Tests
CV Setup. If more than one meter or a meter and an oscilloscope are used, connect each to the + S and - S terminals by a
separate pair of leads to avoid mutual coupling effects. Connect only to + S and -S (except for peak-to-peak PARD)
because the unit regulates the output voltage between + S and - S, not between + OUT and - OUT. Use coaxial cable or
shielded 2-wire cable to avoid pickup on test leads. For all CV tests set the output current at full output to assure CV
operation.
Load Effect (Load Regulation). Constant-voltage load effect is the change in dc output voltage (Eo) resulting from a
load-resistance change from open-circuit to full-load. Full-load is the resistance which draws the maximum rated output
current at voltage Eo. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:
7.0Vdc (6023A)
20.0Vdc (6028A)
as read on the digital voltmeter.

Figure 2-3. Basic Test Setup
d.

e.
f.
g.

Reduce the resistance of the load to draw an output current of:
29Adc (6023A)
10Adc (6028A)
Check that the unit's CV LED remains lighted.
Record the output voltage at the digital voltmeter.
Open-circuit the load.
When the reading settles, record the output voltage again. Check that the two recorded readings differ no more than:
± 0.0027Vdc (6023A)
± 0.0090Vdc (6028A)

Source Effect (Line Regulation). Source effect is the change in dc output voltage resulting from a change in ac input
voltage from the minimum to the maximum value as specified in Input Power Requirements in the Specifications Table, in
the Operating Manual. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Connect the unit to the ac power line through a variable autotransformer which is set for low line voltage (104Vac for
120Vac).
c. Turn the unit's power on, and turn up current setting to full output.
d. Turn up output voltage to:
20.0Vdc (6023A)
60Vdc (6028A)
as read on the digital voltmeter.
e. Reduce the resistance of the load to draw an output current of:
10Adc (0.010Vdc across Rm) (6023A)
3.3Adc(0.33Vdc across Rm) (6028A)
Check that the unit's CV LED remains lighted.

f.
g.
h.

Record the output voltage at the digital voltmeter.
Adjust autotransformer to the maximum for your line voltage.
When the reading settles record the output voltage again. Check that the two recorded readings differ no more than:
± 0.0030Vdc (6023A)
± 0.0080Vdc (6028A)

PARD (Ripple And Noise). Periodic and random deviations (PARD) in the unit's output-ripple and noise-combine to
produce a residual ac voltage superimposed on the dc output voltage. Constant-voltage PARD is specified as the
root-mean-square (rms) or peak-to-peak (pp) output voltage in a frequency range of 20Hz to 20MHz.
RMS Measurement Procedure. Figure 2-4 shows the interconnections of equipment to measure PARD in Vrms. To
ensure that there is no voltage difference between the voltmeter's case and the unit's case, connect both to the same ac
power outlet or check that the two ac power outlets used have the same earth-ground connection.
Use the common-mode choke as shown to reduce ground-loop currents from interfering with measurement. Reduce noise
pickup on the test leads by using 50Ω coaxial cable, and wind it five turns through the magnetic core to form the
common-mode choke. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-4. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:
7Vdc (6023A)
20Vdc (6028A)
d. Reduce the resistance of the load to draw an output current of:
29Adc (6023A)
10Adc (6028A)
Check that the unit's CV LED remains lighted.
e. Check that the rms noise voltage at the true rms voltmeter is no more than:
3.0mV rms (6023A)
3.0mV rms (6028A)

Figure 2-4. RMS Measurement Test Setup, CV PARD Test
Peak Measurement Procedure. Figure 2-5 shows the interconnections of equipment to measure PARD in Vpp. The
equipment grounding and power connection instructions of PARD rms test apply to this setup also. Connect the
oscilloscope to the + OUT and - OUT terminals through 0.01µF blocking capacitors to protect the oscilloscope's input from

the unit's output voltage. To reduce common-mode noise pickup, set up the oscilloscope for a differential, two-channel
voltage measurement. To reduce normal-mode noise pickup, use twisted, 1 meter or shorter, 50Ω coaxial cables with
shields connected to the oscilloscope case and to each other at the other ends. Proceed as follows:
a.
b.
c.
d.

e.
f.

Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
Turn the unit's power on, and turn up current setting to full output.
Turn up output voltage to:
7.0Vdc (6023A)
20Vdc (6028A)
Reduce the resistance of the load to draw an output current of:
29.0Adc (6023A)
10Adc (6028A)
Check that the unit's CV LED remains lighted.
Set the oscilloscope's input impedance to 50Ω and bandwidth to 20MHz. Adjust the controls to show the 20KHz and
higher frequency output-noise waveform of Figure 2-6.
Check that the peak-to-peak is no more than 30mV.

Figure 2-5. Peak-To-Peak Measurement Test Setup, CV PARD Test

6023A

6028A

Figure 2-6. 20KHz Noise, CV Peak-to-Peak PARD
Load Transient Recovery Time. Specified for CV operation only; load transient recovery time is the time for the output
voltage to return to within a specified band around its set voltage following a step change in load.
Proceed as follows:
a.
b.
c.

e.
f.
g.

Connect the test equipment as shown in Figure 2-3. Operate the load in constant-current mode and set for minimum
current.
Turn the unit's power on, and turn up current setting to full output.
Turn up output voltage to:
6.70Vdc (6023A)
20.0Vdc (6028A)
as read on the digital voltmeter.
Set the load to vary the load current between:
27 and 30Adc (6023A)
9 and 10Adc (6028A)
at a 30Hz rate.
Set the oscilloscope for ac coupling, internal sync and lock on either the positive or negative load transient.
Adjust the oscilloscope to display transients as in Figure 2-7.
Check that the pulse width of the transient pulse is no more than:
50mV (6023A)
75mV (6028A)

6023A

6028A

Figure 2-7. Load Transient Recovery Waveform
Temperature Coefficient. (6023A) Temperature coefficient (TC) is the change in output voltage for each °C change in
ambient temperature with constant ac line voltage, constant output voltage setting and constant load resistance. Measure
temperature coefficient by placing the unit in an oven, varying the temperature over a range within the unit's operating
temperature range, and measuring the change in output voltage. Use a large, forced air oven for even temperature distribution.
Leave the unit at each temperature measurement for half hour to ensure stability in the measured variable. Measure the output
voltage with a stable DVM located outside the oven so voltmeter drift does not affect the measurement accuracy. To measure
offset TC, repeat the procedure with output voltage set to 0.10Vdc.
Proceed as follows:
a.
b.
c.
d.
e.
f.
g.
h.

Connect DVM between +S and -S.
Place power supply in oven, and set temperature to 30°C.
Turn the unit's power on and turn up current setting to full output.
Turn up output voltage to 20Vdc as read on the DVM.
After 30 minutes stabilization record the temperature to the nearest 0.1°C. Record the output voltage at the DVM.
Set oven temperature to 50°C.
After 30 minutes stabilization, record the temperature to the nearest 0.1°C. Record output voltage.
Check that the magnitude of the output voltage change is no greater than 32mV.

Drift (Stability) (6023A). Drift is the change in output voltage beginning after a 30-minute warm-up during 8 hours operation
with constant ac input line voltage, constant load resistance and constant ambient temperature. Use a DVM and record the
output at intervals, or use a strip-chart recorder to provide a continuous record. Check that the DVM's or recorder's specified
drift during the 8 hours will be no more than 0.001%. Place the unit in a location with constant air temperature preferably a
large forced-air oven set to 30°C and verify that the ambient temperature does not change by monitoring with a thermometer
near the unit. Typically the drift during 30 minute warm-up exceeds the drift during the 8-hour test. To measure offset drift,
repeat the procedure with output voltage set to 0.10Vdc.
a.
b.
c.
d.
e.

Connect DVM between + S and - S.
Turn the unit's power on and turn up current setting to full output.
Turn up output voltage to 20Vdc as read on the digital voltmeter.
After a 30 minute warmup, note reading on DVM.
The output voltage should not deviate more than 5mV from the reading obtained in step d over a period of 8 hours.

Constant Current (CC) Tests
CC Setup. Constant-current tests are analogous to constant-voltage tests, with the unit's output short circuited and the
voltage set to full output to assure CC operation. Follow the general setup instructions.
Load Effect (Load Regulation). Constant current load effect is the change in dc output current (Io) resulting from a
load-resistance change from short-circuit to full-load, or full-load to short-circuit. Full-load is the resistance which develops
the maximum rated output voltage at current Io. Proceed as follows:
a.
b.
c.
d.

e.
f.
g.

Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
Turn the unit's power on, and turn up voltage setting to full output.
Turn up output current to:
10.0Adc (0.010Vdc across Rm) (6023A). Check that the AMPS display reads about 10 amps.
3.3Adc (0.335Vdc across Rm) (6028A) Check that the AMPS display reads about 3.3 amps.
Increase the load resistance until the output voltage at +S and -S increases to:
20Vdc (6023A).
60Vdc (6028A).
Check that the CC LED is lighted and AMPS display still reads ≈ current setting.
Record voltage across Rm.
Short circuit the load.
When the reading settles (≈ 10s), record the voltage across Rm again. Check that the two recorded readings differ no
more than:
± 0.010mVdc (6023A)
± 0.0053mVdc (6028A)
Disconnect the short across the load.

Source Effect (Line Regulation). Constant current source effect is the change in dc output current resulting from a
change in ac input voltage from the minimum to the maximum values listed in the Specifications Table in the Operating
Manual. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Connect the unit to the ac power line through a variable autotransformer set for low line voltage (e.g. 104Vac for
120Vac).
c. Switch the unit's power on and turn up output voltage setting to full output.
d. Turn up output current to:
29.0Adc (0.029Vdc across Rm) (6023A)
10.0Adc (1.0Vdc across Rm) (6028A)
Check that the AMPS display reads ≈ current setting.
e. Increase the load resistance until the output voltage between + S and - S increases to:
7.0Vdc (603A)
20.0Vdc (6028A)
Check that the CC LED is still on and the AMPS display still reads ≈ current setting.
f. Record the voltage across Rm.
g. Adjust autotransformer to the maximum for your line voltage.
h. When the reading settles record the voltage across Rm again. Check that the two recorded readings differ no more than:
± 0.0090mVdc (6023A)
± 0.030mVdc (6028A)
PARD Ripple And Noise. Periodic and random deviations (PARD) in the unit's output (ripple and noise) combine to
produce a residual ac current as well as an ac voltage super-imposed on the dc output. The ac voltage is measured as
constant-voltage PARD. Constant-current PARD is specified as the root-mean-square (rms) output current in a frequency
range 20Hz to 20MHz with the unit in CC operation. To avoid incorrect measurements, with the unit in CC operation,
caused by the impedance of the electronic load at noise frequencies, use a:

0.25Ω (6023A)
2.0Ω (6028A)
load resistor that is capable of safely dissipating 250 watts. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-8.
b. Switch the unit's power on and turn the output voltage all the way up.
c. Turn up output current to:
29.0Vdc (6023A)
10Vdc (6028A)
Check that the unit's CC LED remains lighted.
d. Check that the rms noise current measured by the current probe and rms voltmeter is no more than:
15mA rms (6023A).
5mA rms (6028A)

Figure 2-8. CC PARD Test Setup

3
Troubleshooting
Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by service-trained personnel who are aware of the
hazards involved (for example, fire and electrical shock). Where maintenance can be performed without
power applied, the power should be removed.

Introduction
Before attempting to troubleshoot this instrument, ensure that the fault is with the instrument itself and not with an
associated circuit. The performance test enables this to be determined without having to remove the covers from the supply.
The most important aspect of troubleshooting is the formulation of a logical approach to locating the source of trouble. A
good understanding of the principles of operation is particularly helpful, and it is recommended that Chapter 4 of this
manual be reviewed before attempting to troubleshoot the unit. Often the user will then be able to isolate a problem simply
by using the operating controls and indicators. Once the principles of operation are understood, refer to the following
paragraphs.
Table 2-1 lists the test equipment for troubleshooting. Chapter 6 contains schematic diagrams and information concerning
the voltage levels and waveforms at many of the important test points. Most of the test points used for troubleshooting the
supply are located on the control board test "fingers", which are accessible close to the top of the board. See Table 3-1.
If a component is found to be defective, replace it and re-conduct the performance test. When a component is replaced,
refer to Calibration Procedure (Chapter 2). It may be necessary to perform one or more of the adjustment procedures after a
component is replaced.

Initial Troubleshooting Procedures
If a problem occurs, follow the steps below in sequence:
a.
b.
c.
d.

Check that input power is available, and check the power cord and rear-panel circuit breaker.
Check that the settings of mode switch A2S1 are correct for the desired mode of operation. (See Operating Manual).
Check that all connections to the power supply are secure and that circuits between the supply and external devices are
not interrupted.
If the power supply fails turn-on self-test or gives any other indication of malfunction, remove the unit from the
operating system before proceeding with further testing.
Some circuits on the power mesh are connected directly to the ac power line. Exercise extreme caution
when working on energized circuits. Energize the supply through an isolation transformer to avoid
shorting ac energized circuits through the test instrument's input leads. The isolation transformer must
have a power rating of at least 1KVA. During work on energized circuits, the safest practice is to
disconnect power, make or change the test connections, and then re-apply power.
Make certain that the supply's ground terminal (┴) is securely connected to an earth ground before applying
power. Failure to do so will cause a potential shock hazard that could result in personal injury.

Table 3-1. Control Board Test Connector, A2J7
PIN NO.

SIGNAL NAME

Vdc

Digital-Circuits Bias & Reference Voltages
1
+5V
22
+ 20V(5V UNREG)
14
2.5V ref
6
0.5V ref

5.0
20.0
2.50
0.50

Analog-Circuits Bias Voltages
2
+ 15V
21
- 15V

15.0
-15.0

WAVEFORM/CONDITIONS

with 120Hz & 45KHz ripple

SOURCE
A2Q3 (emitter)
A1CR6, A1CR7
A2U9 (OUT)
A2R79,A2R80
A2U12 (OUT)
A2U4 (OUT )

Status Signals
17
CV
16
CC
13
OV
11
DROPOUT

TTL Lo
TTL Lo
TTL Hi
TTL Hi

if in CV operation
if in CC operation
if not OVP shutdown
if ac mains okay

A2Q6C-7 (collector)
A2Q6F-14 (collector)
A2U11D-11
A2U17D-11

TTL Hi

if not overtemp shutdown

A2U11B-6

Control Signals
25
PWM OFF
26
PWM ON
18
Ip MONITOR
8
INHIBIT
15
DOWN PROGRAM

<0.5
<1.0
<0.5
TTL hi

1.7µs TTL pulses, 20KHz
1.7µs TTL pulses, 20KHz
1V pk, ½ sawtooth, 20KHz
if not remotely inhibited

U1A-5
U2B-6
A2CR26 (cathode)
A2R185C, U19A-2

OVP PROGRAM

OV CLR

1.2-3.0
1/10 OVP (6023A)
1/30 OVP (6028A)
+5V

A2CR21, A2CR27
e.g.: 2Vdc if OVP set to 20

A3R6 (wiper)

inverted OV reset line

A7U29-5

PCLR 2
Commons & Current-Monitor
4
L COMMON

+5V

if +5V bias OK

A2Q60-9

0.0

A2C20 (-), A2R50,
A2U6-4

M COMMON

0.0

10
3

I-TEST
NOT USED

common return for all bias
voltages, and status and control
signals
common return for 2.5V ref.
and 0.5V ref.
inboard-side monitoring res.

≈0.005 ( Iout)

A2R83, A21-20
A1R3,A1T2

Electrostatic Protection
The following caution outlines important precautions which should be observed when working with static sensitive
components in the power supply.
This instrument uses components which can be damaged by static charge. Most semiconductors can
suffer serious performance degradation as a result of static charges, even though complete failure may
not occur. The following precautions should be observed when handling static-sensitive devices.
a.
b.
c.

d.
e.
f.

Always turn power off before removing or installing printed-circuit boards.
Always stored or transport static-sensitive devices (all semiconductors and thin-film devices) in conductive material.
Attach warning labels to the container or bag enclosing the device.
Handle static-sensitive devices only at static-free work stations. These work stations should include special conductive
work surfaces (such as Agilent Part No. 9300-0797) grounded through a one-megohm resistor. Note that metal table
tops and highly conductive carbon-impregnated plastic surfaces are too conductive; they can act as large capacitors and
shunt charges too quickly. The work surfaces should have distributed resistance of between 106and 10l2 Ω per square.
Ground all conductive equipment or devices that may come in contact with static-sensitive devices or subassemblies
containing same.
Where direct grounding of objects in the work area is impractical, a static neutralizer should be used (ionized air
blower directed at work). Note that this method is considerably less effective than direct grounding and provides less
protection for static-sensitive devices.
While working with equipment on which no point exceeds 500 volts, use a conductive wrist strap in contact with skin.
The wrist strap should be connected to ground through a one-megohm resistor. A wrist strap with insulated cord and
built-in resistor is recommended, such as 3M Co. No. 1066 (Agilent Part No. 9300-0969 (small) and 9300-0970
[large]).
Do not wear a conductive wrist strap when working with potentials in excess of 500 volts; the one-megohm
resistor will provide insufficient current limiting for personal safety.

All grounding (device being repaired, test equipment, soldering iron, work surface, wrist strap, etc.) should be done to
the same point.
h. Do not wear nylon clothing. Keep clothing of any kind from coming within 12 inches of static-sensitive devices.
i. Low-impedance test equipment (signal generators, logic pulsers, etc.) should be connected to static-sensitive inputs
only while the components are powered.
j. Use a mildly activated rosin core solder (such as Alpha Metal Reliacor No. 1, Agilent Part No. 8090-0098) for repair.
The flux residue of this type of solder can be left on the printed circuit board. Generally, it is safer not to clean the
printed-circuit board after repair. Do not use Freon or other types of spray cleaners. If necessary, the printed-circuit
board can be brushed using a natural-bristle brush only. Do not use nylon-bristle or other synthetic-bristle brushes. Do
not use high-velocity air blowers (unless ionized).
k. Keep the work area free of non-conductive objects such as Styrofoam-type cups, polystyrene foam, polyethylene bags,
and plastic wrappers. Non-conductive devices that are necessary in the area can be kept from building up a static
charge by spraying them with an anti-static chemical (Agilent Part No. 8500-3397).
l. Do not allow long hair to come in contact with static-sensitive assemblies.
m. Do not exceed the maximum rated voltages specified for the device.

Repair and Replacement
Repair and replacement of most components in the power supply require only standard techniques that should be apparent
to the technician. The following paragraphs provide instructions for removing certain assemblies and components for which
the procedure may not be obvious upon inspection.

To avoid the possibility of personal injury, remove the power supply from operation before opening the
cabinet. Turn off ac power and disconnect the line cord, load, and remote sense leads before attempting
any repair or replacement.

When replacing any heatsink-mounted components except thermostat, smear a thin coating of heatsink
compound between the component and heatsink. If a mica insulator is used, smear a thin coating of
heatsink compound on both sides of the mica insulator.
Do not use any heatsink compound containing silicone, which can migrate and foul electrical contacts
elsewhere in the system. An organic zinc oxide cream, such as American Oil and Supply Company
Heatsink Compound #100, is recommended.

Most of thc attaching hardware in this unit is metric. The only non-metric (sometimes called English or
inch) fittings are listed below. Be careful when both types of screws are removed not to get them
mixed up.
a.
b.
c.
d.
e.
f.

Lock-link/shelf-mounting blocks (4 on rear panel, one at each corner).
Rear-panel fuse holder.
Rear-panel ground binding post.
Strap-handle screws (2).
Screws that secure side chassis to front-frame casting (8, 4 on each side).
Screws that secure front-panel to front-frame casting (4, 2 on top and 2 on bottom).

Top Outside Cover Removal. Remove three screws, the rear handle screw (Phillips, 10x32) and two top-rear corner
screws (Pozidriv, M4x.7) using a Size 1, Pozidriv screwdriver. A Phillips head screwdriver does not fully seat into
Pozidriv screws and risks stripping the heads. Do not remove the front handle screw, as the retaining nut will fall into the
unit. Remove the top cover by sliding it to the rear and lifting at the front.
Bottom Cover Removal. Remove only for repair of main board. Remove two bottom-rear corner screws. (Pozidriv,
M4x.7) and remove the bottom cover by sliding it to the rear. You do not need to remove the unit's feet.
Inside Top Cover Removal. The unit includes an inside cover which secures the vertical board assemblies. Remove the
inside cover for repair but not for calibration. Remove the six mounting screws (Pozidriv, M4x.7) – three on each side and
five board fastening screws (Pozidriv, M4x.7) all on top. Remove the inside cover by lifting at the front edge.

When installing the inside cover, insert it first at the right side. While holding it tilted up at the left, reach through the
cutouts in the cover and fit the top tabs of the A2 control board into the mating slots in the cover. With the top cover in
place reach through the cutout above the A4 power mesh board, align the board-fastening screw holes, and replace the rearmost screw to secure the A4 board. Press the inside cover down firmly while tightening screws that secure cover to chassis.
Complete the installation by replacing the remaining ten screws. Be careful when replacing printed-circuit assemblies and
covers not to bend any boards or components.

A2 Control Board Removal
After removing the inside cover, remove the A2 board by lifting first at the front edge and than pulling it up and out of the
unit. Two connectors hold the A2 board at its bottom edge.
When installing the A2 board, insert it first at the rear of the unit. While holding it tilted up at the front, fit the A2TB1
terminal strip into the mating cutout in the rear panel. Then lower the A2 board's bottom connectors into the mating
connectors on the main board. Press the A2 board into the connectors.

A4 Power Mesh Board Removal
After removing the inside cover, remove the A4 power mesh board by lifting, using the large aluminum heatsink as a
handle. Two connectors hold the A4 board at its bottom edge.
When installing the A4 power mesh board, lower it vertically into its connectors and press in place.

A3 Front-Panel Board Removal
Remove the A3 front-panel board by first removing the entire front-panel assembly. You do not need to remove the top
cover. Follow this procedure:
a. Remove the top plastic insert by prying up with a flat-blade screwdriver, and remove the front feet by lifting the tabs
and sliding toward the front of the unit.
b. Remove the four front-panel assembly mounting screws (Phillips 8-32) on the top and bottom at the corners using a
Pozidriv or Phillips head screwdriver (Phillips head screwdriver may be used only with these four screws).
c. Gently pull the front-panel assembly away from the unit as far as permitted by the connecting cables.
d. Remove the ground-wire screw (Pozidriv, M4x.7) holding the green-yellow ground wire.
e. Note the locations of the four power-wire connections to the power switch and then unplug the quick-connect plugs.
f. Unplug the W3 3-wire cable from connector A1J3 on the A1 main board.
g. Remove the A3 board from the front-panel assembly by removing the five mounting screws (Pozidriv, M4x.7)
Install the A3 Board by reversing the steps above. The power wires are correctly connected to the power switch wires if
they do not cross each other.

A1 Main Board Removal
Removing the A1 main board requires removing the rear panel, all boards except the A3 front-panel board, and 17 A1
board mounting screws. Component-access cutouts in the bottom inside cover allow unsoldering most A1-board
components for repair without removing the A1 board.
To remove the A1 board, proceed as follows:
a. Remove the A2 and A4 boards according to the above instructions.
b. Detach the rear panel by removing the four mounting screws (Pozidriv, M4x.7) two on each side. Gently pull the rear
panel away from the unit as far as permitted by the four wires connected to the A1 board.
c. Unplug the W1 ribbon cable from connector A1J1.
d. Remove the A1 board by removing the 17 mounting screws (Pozdriv, M4x.7).
e. Note locations and the unplug the two ac power wires and the two fan wires to the A1 board.

Overall Troubleshooting Procedure
Perform the troubleshooting and repair procedures which follow only if you are trained in equipment
service and are aware of the danger from fire and electrical-shock hazards. Some of the procedures include
removing the unit's protective covers which may expose you to potentially lethal electrical shock.
Whenever possible, make test connections and perform service with the power removed.
After performing the Initial Troubleshooting Procedures, focus on developing a logical approach to locating the source of
the trouble. The underlying strategy for the troubleshooting procedures here is to guide you to the faulty circuit nodes
which have improper signals or voltages. It relies on you to identify the particular functional circuit to troubleshoot from
symptom tables and by understanding how the unit works. It then relies on you to discover the defective component or
components which cause the faulty circuit nodes. So, read the BLOCK DIAGRAM overview in Chapter 4 and read the
functional circuit descriptions for the circuits that you suspect may be defective. Then return to this section for help finding
the faulty circuit nodes.

Table 3-1 gives the signals for each of the test points on the control board test connector. This connector is provided in
service kit P/N 06033-60005. The measurements given here include bias and reference voltages as well as power supply
status signals and waveform information.
Table 3-2 provides troubleshooting information based on the status of the PWM-ON and PWM-OFF signals which drive
the PFETs. This table is used for no-output failures.
Tables 3-3 and 3-4 give measurements for the test points on the A3 front-panel board and possible failure symptoms
respectively.
Table 3-5 describes possible symptoms for overall performance failures of the power supply. It is necessary to have a
properly working front-panel before using this table.
Chapter 6 contains schematic diagrams and voltage levels, and component location diagrams to help you locate components
and test points.
Make most voltage measurements (except DC-to-DC Converter and ac mains-connected circuits) referenced to the unit's
output common which is accessible at rear-panel terminal VM. All voltages are ± 5% unless a range is given.

Using the Tables
Typically there will be two types of power supply failures; no-output and performance failures.
1.

No-OUTPUT FAILURE:
Tables 3-1 and 3-3.

PERFORMANCE FAILURE: If the power supply produces an output but does not perform to specifications, begin by
verifying the measurements at the A2J7 test connector using Table 3-1. Next, verify the front-panel by doing the
procedure outlined in the FRONT-PANEL TROUBLESHOOTING section. After the front-panel has been verified
consult Table 3-5 for the performance failure symptom which seems closest to the one observed and proceed to the
functional circuit given for that failure.

Start with the TROUBLESHOOTING NO-OUTPUT FAILURES section which references

The circuits referenced in Tables 3-2 and 3-5 are derived from functional blocks of circuits in the power supply. These
blocks are given in the Power Supply Blocks section starting on page 35. Troubleshooting information for each block will
include a brief description of the circuit involved. The columns provided in each block are as follows:
NODE:

This column lists the nodes where the measurements should be taken. In some cases this will be
stated as NODE ( + ) and NODE (- ) where the first is the test node and the second is the
reference.

SETUP:

If a certain setup is required for the measurement, it will be given in this column.

MEASUREMENT:

This column indicates what the expected measurement is for the given node.

SOURCE:

If applicable, the components which generate the signal will be provided in this column .

Some blocks will have Input and Output sections. The input section will have a source column to indicate which
components generated the measured signal. The output section will list all the important output signals from that block.
However, because the outputs of one block are the inputs to another, the schematic should be consulted if an output
measurement is incorrect. This will indicate the next circuit block to be trouble shot.

Main Troubleshooting Setup
Figure 3-1 shows the troubleshooting setup for troubleshooting all of the unit except the front-panel and initial no output
failures (See page 31). The external power supply provides the unit's internal bus voltage. The ac mains cord connects to
the unit's A1T3 bias transformer via an isolation transformer, thereby energizing the bias supplies, but it does not connect to
the input rectifier and filter because that would create the bus voltage. With the external supply the unit operates as a
dc-to-dc converter. The supply biases the A4Q3 and A4Q4 PFETs with a low voltage rather than the 320Vdc bus voltage.
This protects the PFETs from failure from excess power dissipation if the power-limit comparator or the off-pulse circuitry
are defective. It also reduces the possibility of electrical shock to the troubleshooter.

Figure 3-1. Main Troubleshooting Setup

The troubleshooting setup of Figure 3-1 connects high ac mains voltage to the A1F2 fuse, the A1S2 MainsVoltage Select Switch, the fan and printed-circuit traces at the left edge of the A1 main board. Be
extremely careful when working on the unit with the protective inside cover removed to avoid touching the
ac mains voltage.

As a convenience in implementing the troubleshooting setup, prepare cord sets as shown in Figure 3-2. This facilitates
connecting the unit's input power receptacle to the external supply and connecting the bias transformer to the ac mains.

Figure 3-2. Modified Mains Cord Set For Troubleshooting

With the mains cord unplugged proceed as follows:
a.

Remove the top cover and the inside cover as described on page 26. Set switch S4 (front-left corner of the A1 main
board) in TEST position.
If switch is not in the TEST position and remains in the NORM position, completion of step e below will
allow the unit to develop its 320Vdc bus voltage across PFETs A3Q3 and A3Q4 and will connect the ac
mains voltage to the output of the external power supply. This will probably damage the external supply
and is a shock hazard to you.

b.
c.

Install control board test connector onto the A2J3 card edge fingers.
Connect a 50Ω, 10W, load resistor to the unit's output terminals.

d.
e.

With the LINE switch off, connect an external dc supply to the outside prongs of the unit’s power receptacle. Ignore
polarity as the unit’s input rectifying diodes steer the dc power to the correct nodes.
Complete the setup of Figure 3-1 by attaching an ac mains cord to test points TP1 (L, black wire) and TP2 (N, white
wire) and connect the green ground wire to the unit's case ground terminal or a suitably grounded cabinet screw. TP1
and TP2 are accessible through the cutout on the left side of the unit and are at the left edge of the A1 main board.

Troubleshooting No-Output Failures
No-output failures often include failure of the A4Q3 and A4Q4 PFETs and their fuses, A4F1 and A4F2. When either the
off-pulses or the power-limit comparator fails, the PFETs can fail from excessive power dissipation. The strategy for
localizing no-output failures is to check the voltages and waveforms at the control board test connector to predict if that
circuit failure would cause the PFETs to fail. This makes it possible to develop your troubleshooting approach without an
extensive equipment setup. Proceed as follows:
a.
b.
c.
d.

With the mains cord unplugged remove the A4 power mesh board as described on page 27. Plug in the mains cord
and switch on power.
Using Table 3-1 check the bias voltages, the PWM-OFF, PWM-ON and other signals of interest at the A2 control
board test fingers, A2J3.
Check for the presence of program voltages, VP and IP, at the rear panel.
Check for presence of the 320Vdc rail voltage between the cathodes of diodes A1CR3 and A1CR4. If there is no rail
voltage, check diodes A1CR1 through A1CR4.
Diodes A1CR1 through A1CR4 connect to the ac mains voltage. Use a voltmeter with both input terminals
floating to measure the rail voltage.

Select the functional circuit for troubleshooting based on your measurements and Table 3-2, which provides direction
based on the status of the PWM OFF and PWM ON signals .

Front-Panel Troubleshooting
The A3 front-panel board can be troubleshot by first doing the following setup.
a. Remove the top cover of the unit.
b. Remove the 4 side screws holding the front-panel assembly to the power supply chassis and pull the entire assembly
forward.
c. Disconnect the W1 ribbon cable from connector A1J1 on the A1 main board and remove the ground wire screw
holding the green/yellow ground wire. Unplug the four wires to the LINE switch noting the configuration.
d. Detach the A3 board from the front-panel assembly by removing the five mounting screws.
e. Reconnect the W1 jumper to connector A1J1 and place the A3 board vertically against the supply with a piece of
insulating material between. The test connector can then be attached to the A3 board. The rest of the front-panel
assembly can stand vertically so that the pots and the switches can be accessed while troubleshooting.
f. Attach the external line cord and place switch A1S4 in the TEST position.
The ac mains voltage connects directly to the LINE switch and to components and traces at the front of
the A1 main board. Be extremely careful to avoid touching the ac mains voltage.
Start troubleshooting by performing the tests given in Table 3-3. This table provides the measurements for the test points on
the test connector as well as the source components for that measurement. Switch A1S4 should be in the TEST position for
all measurements except where noted. Table 3-4 gives front-panel symptoms as well as the circuits or components that
may cause the supply to exhibit those symptoms. Both Tables 3-3 and 3-4 should be used to check out and troubleshoot the
front-panel.

Table 3-2. No-Output Failures
(Bias supplies and AC turn-on circuit functioning)
Status of PFET on/off-Pulses
PWM-ON
PWM-OFF
DEFECTIVE
A2J7-26
A2J7-25
BOARD
lo
lo
A2

CHECK FUNCTIONAL CIRCUITS

Control ckts: CV & CC thru on- & off-Pulse Oneshots *

A2 & A4

PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

A2 & A4

PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

A2 & A4

Off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

A2 & A4

A2U17A, on-Pulse Oneshot & DC-to-DC: A4Q3, and A4Q4 probably
failed
off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

A2 & A4

lo= TTL low

hi= TTL high

PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed
A2U17B,on-Pulse Oneshot and A2Q6A

Power-Limit Comparator and DC-to-DC: A4Q3 and A4Q4 probably
failed
N = normal 20KHz pulse train, TTL levels

* Decide which to troubleshoot -- the CV Circuit, the CC Circuit, or the PWM and Off-Pulse & On-Pulse Oneshots -- by
measuring the CV CONTROL (A2CR24, cathode) and the CC CONTROL (A2CR19 cathode) voltages. Troubleshoot
whichever is negative, and if neither is negative, troubleshoot the PWM. Make these voltage measurements after you have
implemented the Main Troubleshooting Setup.
Table 3-3. Front-Panel Board Tests

.
Pin
No
1
2
*3
*4
5

6
*7
8

Signal Name

+7.5V
-1V
CV VOLTAGE
CC VOLTAGE
VOLTS test
AMPS test

Description

Source

Derived from + 15V bias.
Derived from –15V bias.
For 0 to full scale output voltage.
For 0 to full scale output current.
Jumper to + 5V on A3 board.

A3VR2, A3R3
A3R86, A3R85, A3C17
A3U2-2, A3R1, A3R87.
A3U3A-1, A3R67
A3U4-37

Jumper to + 5V on A3 board.

A3U5-37

For 0 to full scale output voltage.
If VOLTS display is below 20 volts
(press DISPLAY SETTINGS).
9
DISPLAY
TTL high
If DISPLAY SETTINGS switch on
SETTINGS
front-panel is depressed.
10
DISPLAY OVP
TTL high
If DISPLAY OVP switch on frontpanel is depressed.
*11
AMPS input
0-150mV
For 0 to full scale output current.
12
-5 V
-5.0V
Derived from -15 V bias.
13
buffered OVP
0-2.2V
1/10 of OVP voltage setting when
DISPLAY OVP switch is
depressed. Varies with OVP
ADJUST pot.
* Switch A1S4 should be in the NORM position for these tests.

VOLTS input
VOLTS low range

Measureme
nt
7.5V
-1.0V
0-5V
0-5V
-1888 on
volts display
-1888 on
amps display
0-1V
TTL high

A3R8,A3U7-2,3,10
A3U9C-13, A3U6B
A3S1,A3R80
A3S2,A3R82, A3U6C-8
A3R65,A3R66,A3R67
A3VR1, A3R2
A3U3B-6,A3CR5,A3R72

Troubleshooting Bias Supplies
+5V on A2 Control Board. The PWM A2U6 includes a clock generator (45KHz set by A2R53 and A2C26), and a current
limit (2Adc set by 0.15Vdc across A2R50). It turns off each output pulse using the difference between the voltage at
voltage divider A2R46-A2R47 and the 2.5Vdc set by voltage regulator A2U5.
Circuit Included. + 5Vdc bias supply circuitry from connector pin A2P1-15 through jumper A2W3 on A2 control board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.
Input:
NODE +
A2J3-22

MEASUREMENT
≈ 20Vdc

SOURCE
A1CR6,A1CR7

Outputs
NODE
A2U6-6
A2U6-12,13
A2Q3 (emit)
A2U5 (OUT)
A2R50, A2CR11 (anode)
A2R161, A2R163

MEASUREMENT
≈ 2 to 4Vdc sawtooth, 45KHz
≈ 19Vpk, 15µs pulses, 45KHz
≈ 20Vpk, 5µs pulses, 45KHz
2.5 Vdc
≈ 0 > V > -0.07Vdc
2.5 Vdc

To check if load on + 5 V is shorted, remove jumper A2W3
Table 3-4. A3 Front-Panel Board Failure Symptoms
SYMPTOMS
DEFECTIVE CIRCUIT
CHECK COMPONENTS
Error when pressing DISPLAY SETTINGS
Limits display.
A3U1, A3U9
Error in VOLTS or AMPS
Input ranging or DVMS. A3U1,A3U2,A3U4,A3U5,A3U7
* one or more display digits out
Display LEDs.
A3DS1 through A3DS7
Unable to adjust VOLTAGE or CURRENT
Potentiometers.
A3R4, A3R5
or always max
VOLTS decimal point error
Decimal drivers.
A3U6
* Note that the Volts and Amps tests (Table 3-3 pins 5 and 6) verify that all the current and voltage display segments light
except for the decimal points.
Table 3 5. Performance Failure Symptoms
SYMPTOMS

Unexplained OVP shutdowns

DEFECTIVE
BOARD
A2

CHECK FUNCTIONAL CIRCUITS

OVP Circuit, CV Circuit

No current limit

CC Circuit

Max current < 30Adc

CC Clamp, CC Circuit

Max power < specified

A2, A1

Power Limit, 20KHz clock, transformer A1T1

Max voltage < 20Vdc

A2, A1

CV Circuit, diodes A1CR1-CR4

Cycles on & off randomly

A2, A1

AC-Surge-&-Dropout Detector, Mains Voltage
Select switch A1S2

Table 3 5. Performance Failure Symptoms (continued)
SYMPTOMS

DEFECTIVE
BOARD
A2

CV overshoots

CHECK FUNCTIONAL CIRCUITS

A2U10A, A2CR20, A2R94

Output noise ( < 1KHz)

A2, A1

CV Circuit

Output noise ( > 1KHz)

A1, A4

CV regulation, transient response,
programming time
CC regulation

A2, A1

Transformer A1T1, Output Filter, snubbers A4R7
/R8 /C5 / CR5, A4R13/ 14 / C6 /CR6, A4R33 /C13
Wrong sensing (paragraph 3-40), low ac mains
voltage, CV Circuit
Low ac mains voltage, CC circuit

CV oscillates with capacitive loads

CC oscillates with inductive loads

A2U10, A2C51, A2R95, A2R96, A2R86, A2C47,
A2R71, A2C36
A2U10, A2R86, A2C47, A2C43, A2R77, A2U3D,
A2R30, A2C44, A2R76, A2R75, A2C42, A2C41,
A2R16

+15V on A2 Control Board. Voltage regulator A2U12 regulates the voltage across resistor A2R29 to be 1.25Vdc. That
sets the current through zener diode A2VR1 at 7.5mAdc. The output voltage is 1.25Vdc plus 11.7Vdc across A2VR1 plus
the voltage across A2R34.
Circuit Included. + 15Vdc bias supply circuitry from connector pin A2P1-27 through test point A2J3-2 on A2 control
board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.
Input:
NODE (+ )
A2U12(IN), A2C17(+)

MEASUREMENT
≈ 24Vdc

SOURCE
A1U1, AlC1 (+)

Outputs:
NODE ( + )
A2U12 (OUT)
A2U12 (cath.)
A2U12 (anode.)
A2VR1 (anode.)
A2R34, A2R33
A2LR3 (cath.)
A2VR3 (anode.)

N0DE ( - )
A2U12 (ADJ)

MEASUREMENT
1.25Vdc

11.7Vdc
2.05Vdc
6.2Vdc

To check if load on + 15V is shorted, remove jumper A2W1 .
-15V on A2 Control Board. Voltage regulator A2U4 regulates the voltage across resistor A2R32 to be 1.25Vdc.
Circuit Included. -15Vdc bias supply circuitry from connector pin A2P1-30 through test point A2J3-21 on A2 control
board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.

Input:
NODE ( + )
A2U4 (IN), A2C16 (-)

MEASUREMENT
≈ -24Vdc

SOURCE
A1U1, AlC1 ( + )

N0DE ( - )
A2U4 (OUT)
A2VR2 (anode)
A2VR2 (cath.)

MEASUREMENT
1.25Vdc
11.7Vdc
2.05Vdc

Outputs:
NODE ( + )
A2U4 (ADJ)
A2VR2 (cath.)
A2R33, A2R34

To check if load on -15V is shorted, remove jumper A2W3.
Refer to Down Programmer, page 39, for the + 8.9V bias supply, and refer to OVP Circuit, page 39, for the +2.5V bias
supply.

Power Section Blocks
This section contains the blocks referenced in Tables 3-2 and 3-5.

Troubleshooting AC-Turn-on Circuits
Relay A1K1 closes at 1.0 seconds and DROPOUT goes high at 1.1 seconds after 20V (5V UNREG) reaches about 11Vdc.
DROPOUT high enables the PWM if OVERVOLTAGE, and OVERTEMPERATURE are also high.
Circuits Included. AC-Surge-&-Dropout Detector, Bias Voltage Detector, U11A, 1-Second Delay and Relay Driver--all
on A2 control board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.
Inputs:
NODE ( + ) *
A2J3-1
A2J3-22
A2U20-8,10
A2U22-13

SETUP
wait 2s

MEASUREMENT
5.0Vdc
20Vdc
f.w.rect.,1-2Vpk
TTL sq wave, 20KHz

SETUP
cycle power
cycle power
cycle power
cycle power
wait 2s
wait 2s
cycle power
cycle power

MEASUREMENT
transition 0 to 13.5Vdc
transition 0 to 1.4Vdc
transition 0 to 5.0 to 0.3Vdc
transition 0 to 0.3 to 5.0Vdc
< 0.25Vdc
hi (5Vdc)
transition lo to hi to lo
burst 1.25 KHz sq. wave 1.1s

SOURCE
A2Q3 (emit.)
A1CR6, AlCR7
A1CR8,AlCR9
A2U22-6

Outputs:
NODE ( + ) *
A2U20-5
A2U20-2
A2Q6-1
A2Q6-9
A2U20-6
A2U20-1,14
A2U11-3
A2U18-10

A2U18-13
A2U18-12
A2U18-15
A2U17-8
A2U17-11
DROPOUT A2Q5 (col)
(RELAY ENABLE)

cycle power
cycle power
cycle power
cycle power
cycle power
cycle power

five 100ms pulses then hi
two 200ms pulses then hi
transition lo to hi at 800 msec
transition lo to hi at 1.0 sec
transition lo to hi at 1.1 sec
transistion 5.0 to 0.3Vdc at 1.0s

Troubleshooting PWM & Clock
The inputs to inhibit Gate A2U19A and PWM gate A2U19B are the keys to PWM troubleshooting. The 20KHz clock starts
each PWM output pulse, and the pulse stops when any of the inputs to A2U19A or A2U19B goes low. The PWM is
inhibited and prevented from initiating output pulses as long as any of the eight inputs is low.
Circuit Included. Pulse Width Modulator (PWM), Inhibit Gate A2U19A, Off-Pulse Oneshot, On-Pulse Oneshot, A2U17B,
20KHz Clock.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer and switch on the
LINE switch. Adjust the units current setting above 1.0Adc. Set the external supply (EXTERNAL) and adjust the unit's
voltage setting (INTERNAL) as instructed below.
Inputs:

NODE ( - ) = A2J7-4
NODE ( + )
A2J3-1
A2U19-1
A2U19-2
A2U19-4
A2U19-5
A2U19-10
A2U19-12
A2U19-12

SETUP

POWER LIMIT fully CCW
POWER LIMIT fully CW

MEASUREMENT
5.0Vdc
Hi
Hi
Hi
Hi
Hi
Lo
Hi

SOURCE
A2Q3 (emitter)
A2U17D-11
remote inhibit
A2U14-1,8
A2U11B-6
A2U16-7
A2U14-2
A2U14-2

Outputs:
NODE ( + )
A2U21-7
A2U22-3
A2U22-6
A2U13-5
A2U13-9
A2U14-2

EXTERNAL
0
0
0
0
0
40

A2U19-5
A2U13-9
A2U17-6
A2U15-13
A2U15-5
A2U17-6

40
40
40
40
40
40

A2U17-5

SET VOLTAGE (Vdc)
INTERNAL
SETUP
0
0
0
0
0
0
POWER LIMIT
fully CCW
0
0
0
0
0
0
POWER LIMIT
fully CW
0

MEASUREMENT
TTL sq wave, 320KHz
TTL sq wave, 160KHz
TTL sq wave, 20KHz
23.5µs TTL pulses, 20KHz
23.5µs TTL pulses, 20KHz
lo

lo
lo
lo
lo
lo
groups of 4 pulses 1.7µs, TTL, 20KHz
1.7µs, TTL, 20KHz

+ OUT
+ OUT
+ OUT

40
40
40

10
2
2

short A2J3-4 to
A2J3-8

3.8Vdc (OVERRANGE)
2.0Vdc (CV)
0.0Vdc

Troubleshooting DC-To-DC Converter
Parallel NOR gates A4U2A, A4U2B and A4U1A act as drivers and switch on FETs A4Q3 and A4Q4 through pulse
transformer A4T1. NOR gate A4U1B turns off the PFETs through pulse transformer A4T2 and transistors A4Q1 and
A4Q2.
Circuits Included. On-Pulse Driver, Off-Pulse Driver, PFET Switches and Drivers on A4 power mesh board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, set the external
supply to 40Vdc and switch on the LINE switch. Set the unit's output voltage to 20Vdc and current to above 1Adc. Verify
the UNREGULATED LED lights.
Inputs:
NODE ( + )
A2J3-26
(PWM-ON)
A2J3-25
(PWM-OFF)
A4Q2-D

NODE ( - )
VM

MEASUREMENT
waveform 1

SOURCE
A2U17-6, A2P1-7, A4P1-24,C

waveform 2

A2U15-5, A2P1-13, A4P1-26,A

A4Q4-S

39Vdc

A1C4 (+), A4P1-10, A,C
A1C4 (-), A4P1-4,A,C

NODE ( - )
A4Q3-S
A4Q4-S
A4Q3-S
A4Q4-S
A2J3-4

MEASUREMENT
Waveform 3
Waveform 3
Waveform 4
Waveform 4
Waveform 5

Outputs:
NODE ( + )
A4Q3-G
A4Q4-G
A4Q3-D
A4Q4-D
A2J3-18

Note

The Gate (G) and Source (S) leads of PFETs A4Q3 and A4Q4 can be accessed from the circuit side of the
board and used as test points. The Drain (D) of A4Q3 can be picked up at its case or from the cathode of
A4CR13. The Drain of A4Q4 can be picked up at its case or from the anode of A4CR14.

If all the INPUT measurements are correct but the OUTPUT Vgs waveform (3) is incorrect, the problem may be caused by
weak PFETs. Two 6800pF capacitors (Agilent P/N 0160-0159) can be substituted for the PFETs (G to S) to check
waveform 3. If the waveform is still incorrect, the problem may be located in the drive components.
The PFETs are static sensitive and can be destroyed by relatively low levels of electrostatic voltage.
Handle the A4 power mesh board and the PFETs only after you, your work surface and your equipment
are properly grounded with appropriate resistive grounding straps. Avoid touching the PFET's gate and
source pins.

Troubleshooting CV Circuit
V-MON, the output of CV Monitor Amp A2U7, is 1/4 the voltage between + S and - S. CV Error Amp A2U8 compares
V-MON to CV PROGRAM. Innerloop Amp A2U10A stabilizes the CV loop with IVS input from A2U10C. The
measurements below verify that the operational amplifier circuits provide expected positive and negative dc voltage
excursion when the CV loop is open and the power mesh shut down.
Circuits Included. Constant Voltage (CV) Circuit and buffer amplifier A2U10C.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and disconnect the
external supply Remove the + S jumper and connect A2J3-2 ( + 15V) to + S. Set MODE switch settings B4, B5 and B6 all
to 0. Set VP to 0Vdc by connecting to P or set VP to + 5Vdc by connecting to A2J3-1 according to SETUP below.
Outputs:
NODE ( + )
VM
A2U10C-8
A2U8-6
A2U10A-1
A2U8-6
A2U10A-1

SETUP

VP = 0
VP = 0
VP = 5
VP = 5

MEASUREMENT
3.75Vdc
4.7Vdc
-14Vdc
-14Vdc
4.7Vdc
5.1Vdc

If the failure symptoms include output voltage oscillation, check if the CV Error Amp circuit is at fault by shorting A2U8-6
to A2U8-2. If oscillations stop, the CV Error Amp circuit is probably at fault.

Troubleshooting CC Circuit
I-MON, the output of CC Monitor Amp A2U1, in volts is 1/6 the output current in amperes. CC Error Amp A2U2B
compares I-MON to CC PROGRAM. Differentiator circuit A2U3D and A2U3C stabilizes the CC loop. It differentiates
IVS and has a voltage gain of 16. Its output is summed with CC PROGRAM at CC Error Amp A2U2B.
The measurements below verify that the operational amplifier circuits provide expected positive and negative do voltage
gain when the CC loop is open and the power mesh shut down.
Circuits Included. Constant Current (CC) Circuit on A2 control board.
Setup. The Main Troubleshooting Setup, page 29, except connect the external supply with polarity reversed to the unit's +
OUT ( - ) and - OUT ( + ) terminals. Apply the ac mains voltage to the bias transformer. Set the external supply to 3.0Adc
constant current with a voltage limit in the range 5 to 20Vdc.Set IP to 0Vdc by connecting to P or set IP to + 5Vdc by
connecting to A2J3-1 according to SETUP below.
Outputs:
NODE ( + )

SETUP

IM
A2U2B-7
A2U2B-7
A2U3D-13
A2U3C-9
A2U3C-8

IP = 0
IP = 5
+0.015Vdc
+0.015Vdc
+0.25Vdc

MEASUREMENT

0.50Vdc
-14Vdc
+14Vdc

If the failure symptoms include output current oscillation, check if the differentiator circuit is at fault by removing resistor
A2R16 (3.3M ohm ). If oscillations stop, the differentiator is probably at fault.

Troubleshooting Down Programmer
The down programmer decreases the output when either MASTER ENABLE is low or CV ERROR is more negative than
about - 6Vdc. Comparator A4U3B triggers down programming when the voltage at A4U3B-5 is less than about 3Vdc. The
collector-emitter current through transistor A4Q6 increases as the output voltage decreases because of feedback from
voltage divider A4R24-A4R27 at A4U3A-2
Circuit Included. Down programmer and 8.9V bias supply on A4 power mesh board.
Setup. The Main Troubleshooting Setup, Paragraph 5-73, except connect the external supply to the unit's + OUT ( + ) and OUT ( - ) terminals. Apply the ac mains voltage to the bias transformer. Set the external supply (EXTERNAL) and adjust
unit’s voltage setting (INTERNAL) as instructed below.
Outputs:
NODE ( + )
A4U4(OUT)
A4U3B-7
A4U3B-7
A4U3B-7
A4U3A-2
A4F1
A4Q6(base)
A4U3A-1
A4F1

EXT
0
10
0
0
0
0
20
20

SET VOLTAGE (Vdc)
INT
SETUP
2
unplug TS1
0
reconnect TS1
2
2
unplug TS1
2
2
2
2

MEASUREMENT
8.9Vdc
0Vdc
0Vdc
0Vdc
0.43Vdc
0.2Vdc
1.0Vdc
4.0Vdc
0.11Vdc

Troubleshooting OVP Circuit
Comparator A2U14D sets and gate A2U17A resets, flipflop A2U14B-A2U14C. TTL low at A2U14-1,8,13 inhibits the
PWM.
Circuit included. OVP Circuit and 2.5V bias supply on A2 control board.
Setup. The Main Troubleshooting Setup, page 29, except connect the external supply to the unit's + OUT ( + ) and - OUT
( - ) terminals. Apply the ac mains voltage to the bias transformer. Adjust the unit's OVP limit to 15Vdc. Set the external
supply (EXTERNAL) as instructed below.

Figure 3-3. Waveforms

Outputs:

NODE ( - ) = A2J7-4
NODE ( + )
A2U9 (OUT)
A2U14-10
A2U14-11
A2J3-13
A2J3-13
A2J3-13
A2J3-13

Note

SET VOLTAGE (Vdc)
EXTERNAL
INTERNAL
10
10
20
10
10

SETUP

cycle power

MEASUREMENT
2.5Vdc
1.0Vdc
1.5Vdc
hi
lo
lo
hi

Connecting a test probe to either input of either comparator in the OV Flip flop (pins A2U14-1, 6, 7, 8, 9,
14 or A2U11-13) may cause the flip flop to change states and cause the probed input to be low.

4
Principles of Operation
Autoranging Power
Autoranging allows the unit to be compact and light weight and yet to deliver a range of output voltage current
combinations which otherwise would require the use of more than one supply or a higher rated-power supply. Autoranging
is a name for circuitry which automatically makes full power available at all but low rated output voltages and currents. By
comparison, a conventional constant-voltage/constant-current (CV/CC) power supply can provide full output power only at
maximum rated output voltage and current. For example the power available from a 200 watt, 20V, 10A CV/CC supply
adjusted to deliver 10V is only 100 watts.
The power available from the unit when adjusted to 10V is more than 200 watts. The permitted maximum voltage and
current of the unit change as current and voltage are adjusted by the user. Thus the unit can be a 20V, 10A supply; a 10V,
20A supply; a 6.7V 30A supply, or any other supply in the range shown graphically in Figure 4-1.

Figure 4-1. Output Characteristics: Typical CV/CC and Autoranging Power Supplies

Block Diagram Overview
This section is an overview. Using the block diagram, Figure 4-2, it explains how the unit works, how major circuits are
interconnected and what signals are called. The next section, explains more thoroughly how major circuits operate and uses
the simplified schematic, Figure 4-3. Power flows from the ac mains at the left of the block diagram through circuit blocks
connected by heavy lines to the load on the output terminals at the right. The Down Programmer lowers the output voltage
when required by the CV Circuit. Overvoltage Protection senses the output and shuts down the unit by inhibiting the Pulse
Width Modulator (PWM) through the MASTER ENABLE input when an overvoltage is detected. Other protection circuits
(not shown) can also inhibit the PWM through the Inhibit Gate.

Figure 4-2. Block Diagram

Control signals flow from right to left with separate circuits for constant-voltage, constant-current and power-limit control.
These three control circuits jointly provide the Autoranging characteristic of Figure 4-lB. AC Turn-on Circuits limit inrush
current to the input filter and assure transient free turn-on. Internal Bias Supplies provide five bias and two reference
voltages to the unit's circuits and provide input signals to the AC Turn-on Circuits.
The unit is a flyback switching power supply. The power transformer stores energy in its magnetic field while current flows
in its primary, and energy transfers to the secondary when current flow in the primary turns off. A pair of PFET switches in
series with the primary turns on and off at a 20KHz rate controlling the current flow; and the PWM varies the on-time of
the PFET switches to regulate the output voltage or current.
In CV or CC operation the PWM turns the PFET switches on at each clock pulse and turns them off when the IpRAMP
VOLTAGE exceeds the CP control-port voltage. The IpRAMP VOLTAGE is derived from a sensing transformer in series
with the power transformer primary and is proportional to the primary current. The CP control-port voltage is determined
by the CV Control Circuit when the unit is in constant-voltage operation and is determined by the CC Control Circuit when
in constant-current operation. Follow the block diagram from right to left to see how the output voltage is regulated during
CV mode of operation. The output voltage is monitored both at the output sense terminals + S and--S (OVS outerloop
voltage) and also before the two stages of output filter (IVS innerloop voltage). Sensing with output sense terminals
provides accurate load-voltage control, and sensing before the output filter stabilizes the supply and permits it to power
highly reactive loads.
The CV Monitor Amplifier buffers the OVS outerloop voltage to produce the VMON output monitoring voltage. A buffer
amplifier (not shown) monitors the voltage before the output filter to produce the IVS innerloop voltage. CV Error and
Innerloop Amplifiers compare V-MON and IVS with the CV PROGRAM Voltage which is set by the front-panel
VOLTAGE control or by remote programming to develop the CV CONTROL Voltage. When the CV CONTROL Voltage
is lower than the CC CONTROL Voltage, CV determines CP and regulates the output voltage by controlling the turn-off of
the PWM.
While the PWM turns off when any of the four inputs shown go low, in CV and CC operation it is controlled by the
CONTROL V LIMIT input from the Control Voltage Comparator. When the Ip-RAMP VOLTAGE exceeds CP,
CONTROL V LIMIT goes low and the PWM turns off the PFET switches. The next clock pulse causes the PWM to turn
on the PFET switches, and thus the cycle repeats at a 20KHz rate. Power is transferred through the transformer as required
to produce the output voltage determined by the CV PROGRAM Voltage.
When in CC operation, the output current is regulated in a similar manner. Output current is sensed as the OCS outerloop
voltage across a Current Monitoring resistor. OCS is buffered to produce I-MON. IVS is differentiated to produce an
innerloop current-sensing voltage; and CC Error amplifier compares these to the CC PROGRAM Voltage from the frontpanel CURRENT control or remote programming to develop the CC CONTROL Voltage.

Simplified Schematic
The simplified schematic, Figure 4-3, shows the basic operating circuits of the unit. Detailed descriptions follow for major
circuits and components in clockwise order. The circuit names and layout of the simplified schematic are the same as used
on the complete schematic in Section 7. The heavy lines are the path of power flow through the unit. Please see Figure 4-5
for the display circuits.
Primary power comes to the Input Rectifier through a resistor which limits turn-on inrush current to the input filter. Jumper
A1W1 connects the Input Rectifier and Filter as a voltage doubler for 120Vac mains. This jumper is not used for
220/240Vac; thus the Input Filter develops a dc bus voltage of about 300Vdc for either 120 or 220/240Vac ac mains
voltages. Primary power also comes through Mains-Voltage Select switches to the Bias Power Supplies which provide the
internal operating voltages for the unit. The Mains-Voltage Select switches connect the primary windings of the bias
supplies transformer for operation at 120, 220, or 240Vac.

Figure 4-3. Simplified Schematic

The unit checks that the + 5Vdc bias voltage and the ac mains voltage are within acceptable limits as part of its turn on
sequence. When + 5Vdc comes up, the Bias Voltage Detector resets the Overvoltage-Protection circuit, enables the On
Pulse Driver for the PFET switches, and with the AC Surge-Dropout Detector starts the 1-Second-Delay circuit. After one
second, relay A1K1 bypasses the Inrush-Current Limiting resistor. After 0.1 seconds more, the 1-Second-Delay circuit
enables the PWM through the DROPOUT signal. The unit is then ready to deliver power.
When the AC-Surge and Dropout Detector detects high or low mains voltage, the unit shuts down until an acceptable ac
mains voltage returns. Then it repeats the above turn-on sequence. This protects the unit from damage from ac mains surges
and brownouts.

DC-to-DC Converter
PFET switches A4Q3 and A4Q4 control current flow from the Input Filter through power transformer T1. The PWM
triggers on-pulses and off-pulses for the PFETs. A train of on-pulses comes through diodes A4CR4 and A4CR3 to the
PFETs' gates to turn on the PFETs. The PFETs' input capacitances hold the PFETs on between on-pulses. Off-pulses turn
on transistors A4Q1 and A4Q2 which then short the PFETs input capacitances and turn off the PFETS .
The on-Pulse one-shot A2U15B and off-Pulse one-shot A2U15A generate the on- and off-pulses. A2U15B produces a train
of up-to four 160KHz on-pulses during the PWM output pulse. A2U15A triggers an off-pulse at each trailing edge of the
PWM pulses. Figure 4-4 shows the timing.
When the PFETs turn on, current flows through the primary of power transformer A1T1 and primary-current monitor
transformer, A4T3. The Output Rectifier, A4CR7, is reverse biased and blocks current flow in the A1T1 secondary.
consequently, the A1T1 transformer stores energy. When the PFETs apply the dc bus voltage to the primary, the primary
current ramps up storing more and more energy. The A4T3 transformer senses the A1T1 primary current, and the
secondary of A4T3 develops the Ip-Ramp Voltage across resistor A2R108. This linearly increasing voltage predicts the
correction in the supply's output voltage or current which will occur when the PFETs are turned off. Comparators
monitoring the Ip-Ramp Voltage signal the PWM to turn off the PFETs when it exceeds either the CP control-port voltage
or the Power-Limit reference voltage.
When the PFETs turn off, the collapsing magnetic field reverses the polarity of the voltages across the AlT1 primary and
secondary, and current flows from the AlT1 secondary through output Rectifier A4CR7 to charge output capacitors A1C8,
A1C9 and A1C10. When the PFETs turn off, the leakage inductance of Tl forces current to continue to flow in the primary.
Flyback Diodes A4CR13 and A4CR14 protect the PFETs from excess reverse voltage by conducting this current around
the PFETs and back to the input filter.

Down Programmer
The Down Programmer lowers the output voltage by rapidly discharging the output-filter capacitors. The Down
Programmer causes the output voltage to drop more quickly than it would if only the load discharged the capacitors. Its
negative resistance load characteristic discharges the output-filter capacitors at about a 1 ampere rate when the output
voltage is high 60Vdc and increases to about a 4 ampere rate when the output voltage is low (1Vdc). Five conditions can
trigger down programming: Programming of a lower output voltage, an overvoltage, an overtemperature, a remote disable,
or a primary power failure.
The Down-Programmer's input circuit is the diode-OR connection of the Master enable output from Inhibit Gate A2U19B
and the CV Error Voltage from CV Error Amplifier A2U8. The Down Programmer turns on when either the Master Enable
is low or when the CV Error Voltage is more negative than about -6Vdc. The + 8.9Vdc bias supply for the Down
Programmer stores enough energy in its input capacitor to operate the Down Programmer after loss of primary power. This
ensures that the Down Programmer will be able to discharge the output circuit when primary power is turned off.

Figure 4-4. PFET Control Signals Timing Diagram

Constant-Voltage (CV) Circuit
The Constant-Voltage Circuit compares the output voltage to the user-set CV PROGRAM Voltage to produce the CV
CONTROL Voltage. Two comparison amplifier loops accomplish the comparison. In the outerloop, CV Error Amplifier
A2U8 compares V-MON, a buffered fraction of the sensed output voltage OVS, to the program voltage from the CV
Programming Switches to create the CV ERROR Voltage. Then in the innerloop, Innerloop Amplifier A2U10A compares
this error voltage to IVS, a buffered fraction of the innerloop output voltage, to produce the CV CONTROL Voltage. The
CV ERROR Voltage is also diode-OR connected through diode A2CR21 as an input to the Down Programmer.
V-MON also connects through protective circuitry to rear-panel terminal VM for remote monitoring of the output voltage.
It is equal to 1/4 of the sensed output voltage OVS, and is 5Vdc for 60Vdc full output.
Settings of the CV Programming Switches, the B6, B5, and B4 MODE switch settings allow the CV PROGRAM Voltage
to come from the front-panel VOLTAGE Control; from an external voltage applied between rear-panel terminals VP and
sP; or from an external resistor between VP and sP. When using either the VOLTAGE Control or external resistor,
current from the CV Constant-Current Source flows through the applicable resistance to develop the CV PROGRAM
Voltage.
In CV mode, the CV CONTROL Voltage varies between about -0.5Vdc and about + 1.0Vdc. It is most negative when the
load is drawing no power. As the load draws more power, the voltage becomes more positive. The CV CONTROL Voltage
is at the cathode of diode A2CR24, part of the diode-OR input to the Control-Voltage Comparator. Diode A2CR20 prevents
voltage overshoots during transient load changes and program changes.

Constant-Current (CC) Circuit
The Constant-Current Circuit compares the output current to the user-set CC PROGRAM Voltage to produce the CC
CONTROL Voltage. As with the CV Circuit, two comparison amplifier loops accomplish the comparison. OCS is the
voltage across Current-Monitoring resistor A1R3, and it senses the output current for the outer loop which is the unit's
output current.
To compensate for the fraction of the output current which flows through the unit's output-voltage sensing resistors and not
through the load, CC Monitor Amplifier A2U1 adds a fraction of V-MON to OCS. It amplifies that sum to produce the
outerloop current-sense voltage, I-MON. I-MON also connects through protective circuitry to rear-panel terminal IM for
remote monitoring of the output current. In volts it is equal to 1/6 of the output current in amperes, and is 5Vdc for 10Adc
full output.
Differentiation of IVS develops a current-proportional voltage which senses the innerloop current flowing into the
capacitive output filter. CC Error Amplifier A2U2B sums this differentiated innerloop voltage with I-MON and subtracts
the sum from the CC PROGRAM Voltage to produce the CC CONTROL Voltage. In CC mode the CC CONTROL
Voltage varies from about--0.5Vdc to +1.0Vdc at the cathode of diode A2CR19. CC Clamp A2U2A limits the CC
PROGRAM Voltage to about 5.6 peak volts.
Settings of the rear-panel CC Programming Switches the B3, B2 and B1 MODE switch settings allow the CC PROGRAM
Voltage to come from the front-panel CURRENT Control, from an external voltage applied between terminals IP and /P, or
from an external resistor between IP and /P. When using either the CURRENT Control or external resistor, current from the
CC Constant-Current Source flows through the applicable resistance to develop the CC PROGRAM Voltage.

Overvoltage Protection (OVP) Circuit
The Overvoltage Protection Circuit (OVP) shuts down the unit when a monitored 1/30 fraction of the output voltage
exceeds the limit voltage set by the front-panel op ADJUST Control. If the output voltage exceeds the preset limit, the OVP
inhibits the PWM, triggers the Down Programmer, lights the OV LED and latches itself on until the unit is turned off. The
Bias Voltage Detector resets the OVP at turn-on of the unit. option 002 allows remote reset of OVP.

Power-Limit Comparator
Two comparisons with the Ip-RAMP VOLTAGE provide POWER LIMIT and CONTROL V LIMIT, two of the four
inputs for the PWM. POWER LIMIT is the output of the Power Limit Comparator A2U14A. The comparator compares the
IpRAMP VOLTAGE with the power-limit reference voltage of about 1.0Vdc. The reference is adjustable with the POWER
LIMIT calibration trim pot A2R25. The POWER LIMIT sets the maximum primary current in power transformer A1T1 by
going low and turning off the PWM when the Ip-RAMP VOLTAGE exceeds the reference.
Primary current is proportional to output power, and POWER LIMIT turns off the PWM when the CONTROL V LIMIT
would otherwise allow the unit to deliver more than about 200 watts. This occurs during transient load increases, step
increases in CV Program Voltage and when the combination of the CV PROGRAM Voltage and the CC PROGRAM
Voltage calls for more than 200 watts. The Power-Limit Comparator produces the power-limited portion of the unit's output
characteristic curve in Figure 4-1 and is the essence of the unit's Autoranging power.

Control-Voltage Comparator
The Control-Voltage Comparator A2U16 produces the CONTROL V LIMIT input to the PWM by comparing the IpRAMP
VOLTAGE to the CP control-port voltage. In CV or CC operation CP is one diode-drop more than the lower of the CV and
CC CONTROL Voltages. CONTROL V LIMIT goes low and turns off the PWM when the Ip-RAMP VOLTAGE exceeds
CP. The A2R113-A2R114 voltage divider steers control of CP by its connection at the anodes of series diodes A2CR19 and

A2CR24. The A2R113-A2R114 voltage divider sets the maximum CP voltage to + 1.5Vdc and assures that the diode with
the lower control voltage will be forward biased when its control voltage is less than + 1.5Vdc. As an illustration of CV-CC
selection, suppose the unit is in CV operation and diode A2CR24 is forward biased by a low CV CONTRL Voltage: Then
CV sets CP to less than + 1.5Vdc.
CV keeps diode A2CR19 reverse biased and prevents CC control until the CC CONTROL Voltage is even lower.
The lower of the control voltages varies between about--0.5Vdc and + 1.0Vdc regulating the unit's output. The higher
control voltage has no effect on the output and increases in response to the error voltage in its circuit. When higher, the CC
CONTROL Voltage limits at about 6Vdc. When higher, the CV CONTROL Voltage increases only slightly. In CV or CC
mode CP remains one diode-drop more than the lower control voltage and varies from about 0.0 to + 1.5Vdc. In
UNREGULATED mode CP is +1.5Vdc and both control voltages are more than about + 1.0Vdc.

Initial-Ramp Circuit
The Control Voltage and Ramp Voltage waveforms in Figure 4-4 show that there is a time delay between when the control
voltage is exceeded and when the PFETs turn off. This cumulative circuit delay would cause the PFETs to deliver power
even when no power is requested by the control circuits. To eliminate the delay, the Initial-Ramp Circuit adds a ramp
voltage to the Ip-RAMP VOLTAGE at the input to the Control Voltage Comparator. The added ramp voltage starts with
the 20KHz clock pulse and causes the combined-ramp voltage to exceed the control voltage earlier thereby essentially
eliminating the PFET turn-off delay. A two-stage RC integrating network consisting of resistors A2R116 and A2R117 and
capacitors A2C59 and A2C61 creates the Initial-Ramp by shaping the 20KHz clock pulses.

Pulse-Width Modulator (PWM)
The PWM generates 20KHz repetition-rate pulses which vary in length according to the unit's output requirements. The
pulses start 1.5µ after each 20KHz clock pulse and turn off when any of these four inputs go low. The output of the
Control-Voltage Comparator (CONTROL V LIMIT), the output of the Power-Limit Comparator (POWER LIMIT), the
20KHz clock pulse (50%-DUTY-CYCLE LIMIT), or the output of the Inhibit Gate A2U19A (MASTER ENABLE). As
discussed earlier, the PFETs turn on during, and turn off at the trailing edges of PWM output pulses.
The PWM generates pulses as follows: A 20KHz clock pulse holds the 1.5µ Delay Flip-flop A2U13B reset; 1.5µ after the
trailing edge of the 20KHz pulse, the next pulse from the 320KHz Clock oscillator clocks the output of A2U13B high, and
this initiates the PWM pulse from PWM Flip-flop A2U13A. When one of the above four inputs to AND-gate A2U19B goes
low. A2U19B resets A2U13A, and the PWM pulse turns off.

Bias Voltage Detector
The Bias Voltage Detector prevents spurious operation which might occur at power-on of the unit if circuits tried to operate
before the + 5Vdc bias voltage is at the clock, PWM, and logic circuits. After power-on, as the output of the + 5Vdc bias
supply rises from 0Vdc through about 1Vdc, three transistor switches in the Bias Voltage Detector turn on. They inhibit the
Relay Driver and the on-Pulse Driver, and they create the power-clear signal, PCLR2. The transistors inhibit the circuits
and hold PCLR2 low until the unregulated input to the +5Vdc bias supply is greater than about 11Vdc, an input voltage
sufficient to assure + 5Vdc bias output. PCLR2 resets the OVP at turn-on, and Option 002 uses PCLR2 in creating its
DROPOUT, OVERVOLTAGE, and POWER-ON RESET outputs.

AC-Surge Dropout Detector
Dropout Detector protects the unit from damage from ac mains voltage surges and dropouts by shutting down the unit when
there is either a 40% overvoltage or a 20 ms voltage interruption in the ac mains voltage. The detector shuts down the unit

by inhibiting the PWM through the DROPOUT signal from the l-Second-Delay Circuit. Mains Detect signal, which is
fullwave-rectified ac from the + 5Vdc secondary of the bias-supplies transformer, senses the ac mains voltage. The Dropout
Detector, including comparators A2U20A and A2U20C, operates by enabling a capacitor-timing ramp when Mains-Detect
ceases. Comparator A2U20D monitors the amplitude of Mains-Detect to provide ac surge voltage detection.

1-Second-Delay Circuit
The l-Second-Delay Circuit is the heart of the unit's controlled turn-on. It causes relay A1K1 to bypass inrush
current-limiting resistor A1R1 one second after turn-on, and it enables the PWM 0.1 seconds later. When either the output
of the AC-Surge and Dropout Detector or PCLR2 is low, NAND gate A2U11A holds the circuit reset. The circuit starts
counting at 1/16 the clock frequency (1.25 kHz) when both inputs to A2U11A are high and causes Relay Enable to go high
in 1.0 seconds and DROPOUT to go high in 1.1 seconds. When DROPOUT goes high, it stops the count, and it enables the
PWM. option 002 uses DROPOUT in creating its DROPOUT output.

Display Circuits
Figure 4-5 is a simplified schematic for the display circuits. The named signals from the CV and CC Circuits are connected
through semiconductor bilateral switches to the VOLTS digital voltage display and to the AMPS digital current display.
Either a blank display or a depressing of the DISPLAY OVP switch changes the VOLTS display from low range to high
range. A blank display occurs when the Voltage DVM A3U4 receives an over-range voltage, a voltage greater than
0.999Vdc. The blank display is detected by the Voltage-Range Switching Circuit. The diode-AND connection at inverting
amplifier A3U9A senses when two selected segments of the 7-segment LED for the second digit are both not lighted. The
detection scheme works because at least one of the selected segments is lighted for all digits 0 though 9.
The normal display is the actual output voltage and current and has bilateral switches A3U1A and A3U1D closed. Switch
A3UlA connects V-MON through buffer amplifier A3U2 and range-switching bilateral switches to the VOLTS DVM.
Switch A3Ul D connects I-MON through buffer amplifier A3U3A to the AMPS DVM. Depress the DISPLAY LIMITS
Switch, and CV and CC PROGRAM Voltages connect through bilateral switches A3U1B and A3U1C to display the
programmed output voltage and current. Depress the DISPLAY OVP Switch, and OV PROGRAM Voltage from the OVP
ADJUST Control connects through buffer amplifier A3U3B and bilateral switch A3U7B to display the programmed OVP
voltage limit. The CV and CC CONTROL Voltages also control the front-panel mode LEDs. When CV CONTROL
Voltage is more negative than CP, transistor A2Q6C lights CV LED A3DS9 showing that the unit is operating in
constant-voltage mode. When CC CONTROL is more negative than CP, transistor A2Q6F lights CC LED A3DS10
showing that the unit is operating in constant-current mode. And when both CV and CC are more positive than CP,
NAND-gate A2U11C lights UNREGULATED LED A3DS11 showing the unit is operating in power-limited, unregulated
mode.

5
Replaceable Parts
Introduction
This chapter contains information for ordering replacement parts. Table 5-3 lists parts in alpha-numeric order by reference
designators and provides the following information:
a.
b.
c.
d.

Reference Designators. Refer to Table 5-1.
Agilent Model in which the particular part is used.
Agilent Part Number.
Description. Refer to Table 5-2 for abbreviations.

Parts not identified by reference designator are listed at the end of Table 5-3 under Mechanical and/or Miscellaneous.
Table 5-1. Reference Designators

A
B
C
CR
DS
F
FL
G
J
K
L
Q
R
RT
S
T
TB
TS
U
VR
W
X
Y

Assembly
Blower
Capacitor
Diode
Signaling Device (light)
Fuse
Filter
Pulse Generator
Jack
Relay
Inductor
Transistor
Resistor
Thermistor Disc
Switch
Transformer
Terminal Block
Thermal Switch
Integrated Circuit
Voltage Regulator (Zener diode)
Wire (Jumper)
Socket*
Oscillator

* Reference designator following "X" (e.g. XA2) indicates assembly or device mounted in socket.

Ordering Information
To order a replacement part, address order or inquiry to your local Agilent Technolgies sales office. Specify the following
information for each part: Model, complete serial number, and any option or special modification (J) numbers of the
instrument; Agilent part number; circuit reference designator; and description. To order a part not listed in Table 5-3, give a
complete description of the part, its function, and its location.
Table 5-2. Description Abbreviations

ADDR
ASSY
AWG
BUFF
CER
COMP
CONV
DECODER/DEMULTI
ELECT
EPROM
FET
FF
FXD
IC
INP
LED
MET
MOS
OP AMP
OPTO
OVP
PCB
PORC
POS
PRIOR
ROM
RAM
RECT
REGIS
RES
TBAX
TRIG
UNI
VAR
VLTG REG
WW

Addressable
Assembly
American Wire Gauge
Buffer
Ceramic
Carbon Film Composition
Converter
Decoder/Demultiplexer
Electrolytic
Erasable Programmable Read-Only Memory
Field Effect Transistor
Flip-Flop
Fixed
Integrated Circuit
Input
Light Emitting Diode
Metalized
Metal-Oxide Silicon
Operational Amplifier
Optical
Over Voltage Protection
Printed Circuit Board
Porcelain
Positive
Priority
Read-Only Memory
Random Access Memory
Rectifier
Register
Resistor
Tube Axial
Triggered
Universal
Variable
Voltage Regulator
Wire Wound

Table 5-3. A1 Main Board Parts List
Ref. Desig.
Al
Al
C1
C2,3
C4
C5
C6,7
C8-10
C8-10
C11-12
C11-12
C13,14
C13,14
C15,16
C17
C17
C20,21
C22,23
C24,25
C26
CR1-4
CR1
CR2
CR3
CR4
CR6, 7
CR8, 9
CR13, 15
F2
F3
J1
J2
J3
K1
L1
L3
L3
Q1
Q2
R1
R2
R3
R4
R5
R5
R6
R7
R8-10

Agilent Model

Agilent Part Number

6023A
6028A
All
All
All
All
All
6023A
6028A
6023A
6028A
6023A
6028A
All
6023A
6028A
All
All
6028A
6028A
6023A
6028A
6028A
6028A
6028A
All
All
All
All
6028A
All
All
All
All
All
6023A
6028A
6028A
6028A
All
All
6023A
All
6023A
6028A
All
6028A
6023A

ELECTRICAL PARTS
06038-60021
06038-61021
0160-4962
0180-3426
0180-3427
0160-4962
0160-5933
0180-3425
0160-3548
0160-5377
0160-6167
0160-7731
0160-5933
0160-4355
0160-5422
0160-4834
0180-3428
0160-4439
0160-4281
0160-4323
1901-1199
1901-1087
1901-0759
1901-1087
1901-0759
1901-0731
1901-0050
1901-0731
2110-0007
2110-0763
1251-5927
1251-5384
1251-8676
0490-1417
06024-80094
5080-1981
9140-0987
1854-0087
1854-0799
0811-3667
0811-1865
5080-2007
0683-1025
8151-0013
7175-0057
0683-1025
0699-1210
8151-0013

Description
Main Board Assembly
Main Board Assembly
Capacitor, 1µF + 10% 50Vac
Capacitor, 590µF + 50-10% 400V
Capacitor, 300µF + 50-10% 200V
Capacitor, lµF + 10% 50V
Capacitor, 0.022µF + 10% 1500V
Capacitor, 5500µF +50-10% 40V
Capacitor, 1700µF 75V
Capacitor, 2.2µF +10% 6.3V
Capacitor, 2.2µF 63V
Capacitor, 0.22µF + 10% 1500V
Capacitor, 0.022µF + 10% 1500V
Capacitor, 0.01µF + 10% 250V
Capacitor, 0.047µF + 20% 50V
Capacitor, 0.047µF + 20% 50V
Capacitor, 1000µF 50V
Capacitor, 4700µF 20% 250V
Capacitor, 2200µF 20% 250V
Capacitor, 0.047µF 20% 250V
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Diode power rectifier 600V 3A
Fuse 1A 250V
Fuse 1/4A 125V
Connector, 26-contact
Connector, 3-contact
Connector, 5-contact
Relay, DPST
Choke RFI 3A (magnetic core 9170-0721)
Choke, output 0.5µH
Choke 3µH
Transistor NPN SI
Transistor NPN SI TIP41C
Resistor 20Ω 5% 7W
Resistor 2kΩ 10% 5W
Sensing resistor 0.005
Resistor 1KΩ 5% 1/4W
Wire, 22 AWG
Wire, tinned copper, AWG 22
Resistor 1KΩ 5% 1/4W
Resistor 80KΩ 0.1% 0.1W
Wire, 22 AWG

Table 5-3. A1 Main Board Parts List (continued)
Ref. Desig.
R8
R9
R10
R11
R12
R14
R15
R15
R17,18
R19
R20,21
R22.23
R24,25
R26
R27A,28B
R29
R30
R31
R32
R33
R34
S1

Agilent Model
6028A
6028A
6028A
All
All
6023A
6023A
6028A
All
All
All
All
All
All
6028A
6028A
6028A
6028A
6028A
6028A
6028A
6023A

Agilent Part Number
0699-0118
7175-0057
0698-6359
0698-6322
0698-8695
0698-3572
8151-0013
0757-0270
0683-1005
0683-1055
0811-1867
0686-1065
0686-1035
0683-3315
0811-3823
0686-3335
0811-1865
0812-0098
0683-1035
0683-4745
0683-2035
3101-0402

S2
S4
T1
T1
T2

All
All
6023A
6028A
All

3101-1914
3101-2046
5080-1978
06038-80090
9170-1264

T3
T4
TP1, 2
U1
VR1, 2
W1, 2
XA2P1
XA2P2
XA4P1, 2

All
All
All
All
6028A
All
All
All
All

9100-4864
5080-1984
1251-5613
1906-0006
1902-1377
06023-80003
1251-8665
1251-8667
1251-8806

6028A
6028A
6028A
6028A
6028A
6023A
6023A
6023A

MECHANICAL PARTS
1480-0552
0380-1489
2110-0269
0360-2190
0360-1833
0515-0964
2190-0586
3050-0893

Description
Resistor 20Ω 0.1% 0.1W
Wire tinned copper AWG 22
Resistor 80KΩ 0.1% 1/8W
Resistor 4KΩ 0.1% 1/8W
Resistor 36KΩ 0.1% 1/8W
Resistor 60.4Ω 1% 1/8W
Wire 22 AWG
Resistor 249KΩ 1% 1/4W
Resistor 10Ω 5% 1/4W
Resistor 1MΩ 5% 1/4W
Resistor 15KΩ 5% 5W
Resistor 10MΩ 5% 1/2W
Resistor 10KΩ 5% 1/2W
Resistor 330Ω 5% 1/4W
Resistor 0.1Ω 5% 20W
Resistor 33KΩ 5% 1/2W
Resistor 2KΩ 1% 5W
Resistor 135Ω 5% 5W
Resistor 10KΩ 5% 1/4W
Resistor 470Ω 5% 1/4W
Resistor 20KΩ 5% 1/4W
Switch DPST rocker (mounted on frontpanel)
Switch 2-DPDT slide
Switch DPDT slide
Transformer, power
Transformer, power
Core magnetic (used with primary wire
06023-80004)
Transformer bias
Choke line 2mH
Connector single contact
Rectifier bridge 400V 1A
Diode zener 6.19V 2%
Jumper output 10 AWG
Connector, 30-contact
Connector, 20 contact
Connector, DIN 32-contact

Pin, escutcheon (L1)
Snap-in-spacer
Fuseholder, clip type F2
Jumper, locai sensing (2)
Barrier block, 6-position
screw
washer, lock
washer, flat

Table 5-4. A2 Control Board Parts List
Ref. Desig.
A2
A2
C1
C2
C3
C3
C7
C8
C9
C10,11
C12,13
C14
C15
C16,17
C18,19
C18,19
C20
C21
C22
C23
C24
C25
C26
C27,28
C29
C29
C30
C31
C31
C32
C33-37
C33-35
C36
C37
C38
C38
C39,40
C41
C42
C43
C44
C45
C45
C46
C47
C48
C49
C49

Agilent Model

Agilent Part Number

All
All
6023A
6028A
All
All
All
All
All
All
All
All
6023A
6028A
All
All
All
All
All
All
All
All
6023A
6028A
All
6023A
6028A
All
6023A
6028A
6028A
6028A
6023A
6028A
All
All
All
All
All
6023A
6028A
All
All
All
6023A
6028A

ELECTRICAL PARTS
06038-61023
06023-60023
0160-5469
0160-5422
0160-4801
0160-4812
0160-5422
0160-4812
0160-5377
0160-5469
0160-5422
0180-0291
0180-1731
0180-0230
0180-0291
0180-0230
0180-2624
0180-5098
0180-4832
0180-3407
0180-5098
0160-4833
0160-0154
0160-5422
0160-4808
0160-4812
0160-4830
0160-4808
0160-4801
0160-4801
0160-5422
0160-5422
0160-4833
0160-5422
0160-4801
0I60-4803
0160-5422
0160-4835
0160-4805
0160-5422
0160-4805
0160-4808
0160-4810
0160-4807
0160-4822
0160-5422
0160-5644
0160-4833

Description
Control Board Assembly
Control Board Assembly
Capacitor, lµF + 10% 50V
Capacitor, 0.047µF 20% 50V
Capacitor, 100pF 5% 100V
Capacitor, 220pF 5%
Capacitor, 0.047µF 20% 50V
Capacitor, 220pF 5% 100V
Capacitor, 2.2µF 10% 63V
Capacitor, 1µF 10% 50V
Capacitor, 0.047µF 20% 50V
Capacitor, 1µF 10% 35V
Capacitor, 4.7µF 10% 50V
Capacitor, lµF + 20% 50V
Capacitor, lµF 10% 35V
Capacitor, lµF 20% 50V
Capacitor, 2000µF 75-25% 10V
Capacitor, 0.22µF 10% 50V
Capacitor, 0.01µF 10% 100V
Capacitor, 2200pF +50-10% 35V
Capacitor, 0.22µF 10% 50V
Capacitor, 0.022µF 10% 100V
Capacitor, 2200pF 10% 200V
Capacitor, 0.047µF 20% 50V
Capacitor, 470pF 5% 100V
Capacitor, 220pF 5% 100V
Capacitor, 2200pF 10% 100V
Capacitor, 470pF 5% 100V
Capacitor, 100pF 5% 100V
Capacitor, 100pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 0.047µF 20% 50V
Capacitor, 0.022µF 10% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 100pF 5% 100V
Capacitor, 68pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 0.lµF 10% 50V
Capacitor, 47pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 47pF 5% 100V
Capacitor, 470pF 5% 100V
Capacitor, 330pF 5% 100V
Capacitor, 33pF 5% 100V
Capacitor, 1000pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 0.033µF 10% 50V
Capacitor, 0.022µF 10% 100V

Table 5-4. A2 Control Board Parts List (continued)
Ref. Desig.
C50
C50
C51
C52,53
C54
C55,56
C57,58
C59
C60
C61
C62
C63
C64,65
C66
C67,68
C69
C70
C71
C72
CRl,2
CR3
CR5-7
CR8-10
CR11
CR12-16
CR18
CR19
CR20
CR21-30
J1,2
L1
P1
P2
Q1,2
Q3
Q4
Q5
Q6
Q7
R1
R2
R2
R3
R3
R4
R5
R5

Agilent Model
6023A
6028A
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
6028A
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
6028A
All
6023A
6028A
6023A
6028A
All
6023A
6028A

Agilent Part Number
0160-0167
0160-0168
0160-4801
0160-4831
0160-5422
0160-4801
0160-5422
0160-4812
0160-5422
0160-4812
0160-5422
0180-0116
0160-5422
0180-0376
0160-4812
0180-4832
0180-1980
0160-5422
0160-5422
1901-0033
1901-0050
1901-0033
1901-0050
1901-0992
1901-0033
1901-0033
1901-0050
1901-0033
1901-0050
1251-8417
06023-80090
1251-8664
1251-8666
1855-0413
1854-0635
1853-0012
1854-0823
1858-0023
1854-0087
0683-5125
0683-3925
0757-0419
0698-6329
0698-6393
0683-1035
0698-7880
0699-0774

Description
Capacitor, 0.082µF 10% 200V
Capacitor, 0.lµF 10% 200V
Capacitor, 100pF 5% 100V
Capacitor, 4700pF 10% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 100pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 220pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 220pF 5% 100V
Capacitor, 0.047µF 20% 50V
Capacitor, 6.8µF 10% 35V
Capacitor, 0.047µF 20% 50V
Capacitor, 0.47µF 10% 35V
Capacitor, 220pF 5% 100V
Capacitor, 0.01µF 10% 100V
Capacitor, 1µF 5% 35V
Capacitor, 0.047µF 20% 50V
Capacitor, 0.047µF 20% 50V
Diode general purpose 180V 200mA
Diode switching 80V 200A
Diode general purpose 180V 200mA
Diode switching 80V 200A
Diode power rectifier 40V 3A
Diode general purpose 180V 200mA
Diode general purpose 180V 200mA
Diode switching 80V 200A
Diode general purpose 180V 200mA
Diode switching 80V 200A
Connector, 16-contact
Choke bias 820 µH
Connector 30-contact
Connector 20-contact
Transistor J-FET P-chan 2N5116
Transistor NPN SI D44H5
Transistor PNP SI 2N2904A
Transistor NPN SI
Transistor array CA3081E
Transistor NPN SI
Resistor 51kΩ 1/2W
Resistor 39KΩ 5% 1/4W
Resistor 681Ω 1% 1/8W
Resistor 845Ω 1% 1/8W
Resistor 585Ω 1% 1/8W
Resistor 10KΩ 5% 1/4W
Resistor 28.7KΩ 1% 1/8W
Resistor 6.65KΩ 1% 1/8W

Table 5-4. A2 Control Board Parts List (continued)
Ref. Desig.
R6
R7
R8
R9
R9
R10
R10
R11
R11
R12
R13
R14
R15
R16
R16
R17
R17
R18
R18
R19
R19
R20
R21
R21
R22
R23
R24
R25
R26
R27
R28
R29
R30
R31
R32
R33
R34
R35
R36
R37,38
R39
R40
R41,42
R43
R44
R45
R46,47

Agilent Model
All
All
All
6023A
6028A
6023A
6028A
6023A
6028A
All
All
All
All
6023A
6028A
6023A
6028A
6023A
6028A
6023A
6028A
All
6023A
6028A
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All

Agilent Part Number
0683-5125
0683-4745
2100-3353
2100-3350
2100-3993
0683-5625
0757-0427
0698-3136
0683-1025
0683-1025
0683-2735
0686-5125
0683-2015
0683-3355
0683-2255
0683-6835
0757-0289
0683-3035
0757-0449
0683-4735
0757-0449
0683-1035
2100-3350
2100-3273
2100-3353
2100-3273
2100-3350
2100-3207
0683-1045
0698-6322
0683-1045
0698-4416
0683-7545
0698-6322
0698-4416
0698-4447
0757-0404
0698-4608
0757-0438
0683-1035
0686-2005
0683-1005
0683-6215
0683-1515
0757-0434
0757-0442
0757-0283

Description
Resistor 5.1KΩ 5% 1/4W
Resistor 470K 5% 1/4W
Trimmer 20KΩ side adjust
Trimmer 200 side adjust
Trimmer 200 side adjust
Resistor 5.6KΩ 5% 1/4W
Resistor 1.5KΩ 1% 1/8W
Resistor 17.8KΩ 1% 1/8W
Resistor 12KΩ 5% 1/4W
Resistor 1KΩ 5% 1/4W
Resistor 27KΩ 5% 1/4W
Resistor 5.1KΩ 5% 1/4W
Resistor 200Ω 5% 1/4W
Resistor 3.3MΩ 5% 1/4W
Resistor 2.2MΩ 5% 1/4W
Resistor 68KΩ 5% 1/4W
Resistor 13.3KΩ 1% 1/8W
Resistor 50KΩ 5% 1/4W
Resistor 20KΩ l% 1/8W
Resistor 47KΩ 5% 1/4W
Resistor 20KΩ 1% 1/8W
Trimmer 200Ω side adjust
Resistor 3.3MΩ 5% 1/4W
Trimmer 2KΩ side adjust
Trimmer 20KΩ side adjust
Trimmer 2KΩ side adjust
Trimmer 200Ω side adjust
Trimmer 5KΩ side adjust
Resistor 100KΩ 5% 1/4W
Resistor 4KΩ 0.1% 1/8W
Resistor 100KΩ 5% 1/4W
Resistor 169Ω 1% 1/8W
Resistor 750KΩ 5% 1/4W
Resistor 4KΩ 0.1% 1/8W
Resistor 169Ω 1% 1/8W
Resistor 280Ω 1% 1/8W
Resistor 130Ω 1% 1/8W
Resistor 806Ω 1% 1/8W
Resistor 5.11kΩ 1% 1/8W
Resistor 10KΩ 5% 1/4W
Resistor 20Ω 5% 1/2W
Resistor 10Ω 5% 1/4W
Resistor 620Ω 5% 1/2W
Resistor 150Ω 5% 1/4W
Resistor 3.65KΩ 1% 1/8W
Resistor 10KΩ 1% 1/8W
Resistor 2KΩ 1% 1/8W

Table 5-4. A2 Control Board Parts List (continued)
Ref. Desig.
R48,49
R50
R51
R52
R53
R54
R55
R55
R56
R56
R57
R57
R58
R59
R60
R61
R61
R62
R62
R63
R63
R64
R65,66
R65
R66
R67,68
R69
R70
R71
R71
R72
R72
R73,74
R73,74
R75
R76
R76
R77
R77
R78
R78
R79
R80
R81
R82
R83
R84
R84

Agilent Model
All
All
All
All
All
All
6023A
6028A
6023A
6028A
6023A
6028A
All
All
All
6023A
6028A
6023A
6028A
6023A
6028A
All
6023A
6028A
6028A
All
All
All
6023A
6028A
6023A
6028A
6023A
6028A
All
6023A
6028A
6023A
6028A
6023A
6028A
All
All
All
All
All
6023A
6023A

Agilent Part Number
0686-1315
0811-3174
0698-6076
0757-0280
0698-4121
0683-2015
0683-5655
0683-1055
0757-0408
0757-0269
0683-1325
0683-2015
0683-1045
0698-8816
0757-0199
0699-0059
0698-6360
0698-3432
8159-0005
0699-0059
0698-6360
0683-5125
0699-0118
0699-1210
0699-1211
0686-5125
0683-2225
0683-2015
0683-2735
0698-5089
0757-0465
0757-0470
0683-2035
0757-0452
0683-7545
0683-4735
0757-0446
0683-7545
0757-0469
0757-0415
0698-4014
0698-6983
0698-6320
0757-0459
0683-3325
0757-0270
0683-5125
0757-0442

Description
Resistor 130Ω 5% 1/2W
Resistor 0.07Ω 5% 5W
Resistor 39KΩ 1% 1/8W
Resistor 1KΩ 1% 1/8W
Resistor 11.3KΩ 1% 1/8W
Resistor 200Ω 5% 1/4W
Resistor 5.6MΩ 5% 1/4W
Resistor 1MΩ 5% 1/4W
Resistor 243Ω 1% 1/4W
Resistor 270Ω 1/4W
Resistor 1.3KΩ 5% 1/4W
Resistor 200Ω 5% 1/4W
Resistor 100KΩ 5% 1/4W
Resistor 2.15Ω 1% 1/8W
Resistor 21.5KΩ 1% 1/8W
Resistor 5KΩ 0.1% 0.1W
Resistor 10KΩ 0.1% 1/8W
Resistor 26.1Ω 1% 1/8W
Wire tinned copper AWG 22
Resistor 5KΩ 0.1% 0.1W
Resistor 10KΩ 1/8W
Resistor 5.1KΩ 5% 1/4W
Resistor 20KΩ 0.1% 0.1W
Resistor 80KΩ 0.1% 0.1W
Resistor 95KΩ 0.1% 0.1W
Resistor 5.1KΩ 5% 1/2W
Resistor 2.2KΩ 5% 1/4W
Resistor 200Ω 5% 1/4W
Resistor 27KΩ 5% 1/4W
Resistor 33KΩ 1% 1/8W
Resistor 100KΩ 1% 1/8W
Resistor 162KΩ 1% 1/8W
Resistor 20KΩ 5% 1/4W
Resistor 27.4KΩ 1% 1/8W
Resistor 750KΩ 5% 1/4W
Resistor 47KΩ 5% 1/4W
Resistor 15KΩ 1% 1/8W
Resistor 750KΩ 5% 1/4W
Resistor 150KΩ 1% 1/8W
Resistor 475Ω 1% 1/8W
Resistor 787Ω 1% 1/8W
Resistor 20.4KΩ 0.1% 1/8W
Resistor 5KΩ 0.1% 1/8W
Resistor 56.2KΩ 0.1% 1/8W
Resistor 3.3KΩ 5% 1/8W
Resistor 249KΩ 1% 1/8W
Resistor 5.1KΩ 5% 1/4W
Resistor 10KΩ 1% 1/8W

Table 5-4. A2 Control Board Parts List (continued)
Ref. Desig.
R85
R86
R87
R88,89
R90
R91
R92
R93
R94
R95
R96
R96
R97
R98
R99
R100,101
R102,103
R104
R105
R106
R107
R108
R109
R110
R111
R112
R113
R114
R115
R116
R117
R118
R119
R120
R121
R122
R123-126
R127
R128
R129
R130
R131
R132
R133
R134
R135,136
R137
R138

Agilent Model
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All
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6023A
6028A
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All
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Agilent Part Number
0698-3450
0757-0452
0683-2715
0683-2225
0683-2715
0683-2225
0683-2015
0686-5125
0686-1035
0757-0472
0698-3572
0757-0455
0686-5125
0686-2735
0686-1035
1810-0365
0757-0449
0757-0280
0698-3430
0698-3449
0698-3153
0683-2035
0683-2225
0683-4725
0683-2025
0683-1125
0757-0442
0757-0424
0683-1015
0683-3498
0757-0438
1810-0365
0757-0288
0683-1005
0757-0442
0683-5135
0683-4725
0683-1855
0683-6835
0757-0439
0683-1055
0683-3335
0683-2225
0683-2735
0757-0466
0757-0442
0698-3455
0683-2045

Description
Resistor 42.2KΩ 1% 1/8W
Resistor 27.4KΩ 1% 1/8W
Resistor 270Ω 5% 1/8W
Resistor 2.2KΩ 5% 1/4W
Resistor 270Ω 5% 1/8W
Resistor 2.2KΩ 5% 1/4W
Resistor 200Ω 5% 1/4W
Resistor 5.1KΩ 5% 1/4W
Resistor 10KΩ 5% 1/4W
Resistor 200KΩ 1% 1/8W
Resistor 60.4KΩ 1% 1/8W
Resistor 36.5KΩ 1% 1/8W
Resistor 5.1KΩ 5% 1/4W
Resistor 27KΩ 5% 1/4W
Resistor 10KΩ 5% 1/4W
Network sip 2.2KΩ X5
Resistor 20KΩ 1% 1/8W
Resistor 1KΩ l% 1/8W
Resistor 21.5KΩ 1% 1/8W
Resistor 28.7KΩ 1% 1/8W
Resistor 3.38KΩ 1% 1/8W
Resistor 20KΩ 5% 1/4W
Resistor 2.2KΩ 5% 1/4W
Resistor 4.7KΩ 5% 1/4W
Resistor 2KΩ 5% 1/4W
Resistor 1.1KΩ 5% 1/4W
Resistor 10KΩ 1% 1/8W
Resistor 1.1KΩ 1% 1/8W
Resistor 100Ω 5% 1/4W
Resistor 8.66KΩ 1% 1/8W
Resistor 5.11KΩ 1% 1/8W
Network sip 2.2KΩ X5
Resistor 9.09Ω 1% 1/8W
Resistor 10Ω 5% 1/4W
Resistor 10KΩ 1% 1/8W
Resistor 51KΩ 5% 1/4W
Resistor 4.7KΩ 5% 1/4W
Resistor 1.8MO 5% 1/4W
Resistor 68KΩ 5% 1/4W
Resistor 6.8KΩ l% 1/8W
Resistor 1MΩ 5% 1/4W
Resistor 33KΩ 5% 1/4W
Resistor 2.2KΩ 5% 1/4W
Resistor 27KΩ 5% 1/4W
Resistor 110KΩ 1% 1/8W
Resistor 10KΩ 1% 1/8W
Resistor 261KΩ 1% 1/8W
Resistor 200KΩ 5% 1/4W

Table 5-4. A2 Control Board Parts List (continued)
Ref. Desig.
R139
R140
R141
R142
R143
R144
R145
R146,147
R148
R149
R150,151
R152
R153
R155,158
R155
R156-158
S1
U1
U2
U3
U4
U5
U6
U7,8
U9
U10
U11
U12
U13
U14
U15
U16
U17
U18
U19
U20
U21
U22
VR1,2
VR3
VR4
VR5
W1-3
Y1

Agilent Model
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6028A
6023A
6028A
6028A
All
All
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All
All
All
All
All
All
All
All
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All
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All
All
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Agilent Part Number
0757-0442
0698-3160
0683-1025
0683-2225
0683-1045
0683-4725
0683-4715
0683-1125
0683-3925
1810-0365
0683-1815
0683-1025
0683-1035
8159-0005
0683-1005
0683-1005
3101-2097
1826-0493
1826-0346
1826-0161
1826-0527
1826-0544
1826-0428
1826-0493
1826-0544
1826-0161
1820-1209
1826-0393
1820-1112
1820-0138
1820-1437
1820-0065
1820-1246
1820-0935
1820-1205
1826-0138
1826-0065
1820-2096
1902-0018
1902-0777
1902-3110
1902-0575
7175-0057
0960-0586

Description
Resistor 10KΩ 1% 1/8W
Resistor 31.6KΩ 1% 1/8W
Resistor 1KΩ 5% 1/4W
Resistor 2.2KΩ 5% 1/4W
Resistor 100KΩ 5% 1/4W
Resistor 4.7KΩ 5% 1/4W
Resistor 470Ω 5% 1/4W
Resistor l.1KΩ 5% 1/4W
Resistor 3.9KΩ 5% 1/4W
Network sip 2.2KΩ X5
Resistor 180Ω 5% 1/4W
Resistor 1KΩ 5% 1/4W
Resistor 10KΩ 5% 1/4W
Resistor 0Ω
Resistor 10Ω 5% 1/4W
Resistor 10Ω 5% 1/4W
Switch 6-lA slide
IC op amp lo-bias hi-impedance
IC op amp dual general purpose
IC op amp quad general purpose
IC voltage regulator 1.2/37V
IC voltage reference 2.5V
IC voltage regulator 1/40V
IC op amp lo-bias hi-impedance
IC voltage reference 2.5V
IC op amp quad general purpose
IC flip flop D-type
IC voltage regulator 1.2/37V
IC flip flop D-type
IC comparator quad
IC multivibrator monostable dual
IC comparator precision
IC gate quad AND
IC counter binary CMOS
IC gate dual AND
IC comparator quad
IC comparator precision
IC counter binary dual
Diode zener 11.7V 5%
Diode zener 6.2V 5%
Diode zener 5.9V 2%
Diode zener 6.5V 2%
Jumper wire 22 AWG
Resonator 320kHz

6028A
6028A
6028A
6028A
6028A

MECHANICAL PARTS
5060-2942
1200-0181
1200-0485
0360-2195
1531-0309

Heatsink (Q2, U15, 16)
Insulator
Socket (S1)
Terminal block, 6-position
Clevis, tapped

Table 5-5. A3 Front-Panel Board Parts List
Ref. Desig.
A3
A3
C1
C2-4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14-15
C16
C17
C80
CR1,2
CR3,4
CR5
DS1-8
DS1
DS2-4
DS5
DS6-8
DS9,10
J1
R1
R2
R3
R4,5
R6
R7
R7
R8
R10-57
R58
R59
R60
R61,62
R63
R64
R65
R66
R67
R67

Agilent Model
6023A
6028A
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All
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All
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All
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All
All
All
All
All
All
All
All
6023A
6028A
6028A
6028A
6028A
All
All
All
All
All
6023A
All
6023A
6028A
All
All
All
All
All
All
All
All
All
All
6023A
6028A

Agilent Part Number

ELECTRICAL PARTS
06023-60020
06028-61020
0160-4807
0160-5422
0160-4805
0160-4835
0160-0168
0160-5893
0160-5422
0160-4805
0160-4835
0160-0168
0160-5893
0160-5422
0160-4831
0160-5422
0160-4835
1901-0033
1901-0050
1901-0033
1990-0985
1990-0681
1990-0540
1990-0681
1990-0540
1990-0951
1251-5055
0683-3925
0683-6815
0683-2025
2100-1775
0757-0415
0698-4457
0683-1045
0683-2015
0683-6215
0757-0458
0757-0270
0683-5615
0757-0458
0757-0270
0683-1045
0698-8498
0699-0721
0757-7929

Description
Front-Panel Board Assembly
Front-Panel Board Assembly
Capacitor, fixed ceramic 33pF ±5% 100V
Capacitor, fixed ceramic 0.047µF ±20% 5OV
Capacitor, fixed ceramic 47pF ±5% 100V
Capacitor, fixed ceramic 0.1µF ±10% 50V
Capacitor, fixed ceramic 0.1/1F ±10% 200V
Capacitor, fixed met 0.047µF ±10% 100V
Capacitor, fixed ceramic 0.047µF ±20% 50V
Capacitor, fixed ceramic 47pF ±5% 100V
Capacitor, fixed ceramic 0.1µF ±10% 50V
Capacitor, fixed ceramic 0.1µF ±10% 200V
Capacitor, fixed ceramic 0.047µF ±10% 100V
Capacitor, fixed ceramic 0.047µF ±20% 50V
Capacitor, fixed ceramic 4700pF 10% 100V
Capacitor, fixed ceramic 0.047µF ±20% 50V
Capacitor, fixed ceramic 0.1µF ±10% 50V
Diode general purpose 180V 200mA
Diode switching 80V 200mA
Diode general purpose 180V 200mA
Display kit
Display, analog
Display, numeric
Display, analog
Display, numeric
LED, green
Connector, post type 26-contacts
Resistor, composition 3.9KΩ 5% 1/4W
Resistor, composition 680Ω 5% 1/2W
Resistor, composition 2KΩ 5% 1/4W
See Chassis Electrical
Termistor 5KΩ 5% 1-turn side adjust
Resistor, fixed film 475Ω 1% 1/8W
Resistor, fixed film 576Ω 1% 1/8W
Resistor, fixed composition 100KΩ 5% 1/4W
Resistor, fixed composition 200Ω 5% 1/4W
Resistor, fixed composition 620Ω 5% 1/2W
Resistor, fixed film 51.1KΩ 1% 1/8W
Resistor, fixed film 249KΩ 1% 1/8W
Resistor, fixed composition 560Ω 5% 1/4W
Resistor, fixed film 51.1KΩ 1% 1/8W
Resistor, fixed film 249KΩ 1% 1/8W
Resistor, fixed composition 100KΩ 5% 1/4W
Resistor, fixed film 1.02KΩ 0.1% 1/8W
Resistor, fixed film 33KΩ 0.1% 1/8W
Resistor, fixed film 9.09KΩ 1% 1/8W

Table 5-5. A3 Front-Panel Board Parts List
Ref. Desig.
R68
R69
R71
R71
R72
R72
R73
R73
R74
R75
R77
R78
R79
R80
R81
R82
R83
R84
R85
R86
R87
R87
R88
R88
R89
R90
R91
R92,93
S1,2
U1
U2
U3
U4,5
U6
U7
U9
VR1
VR2
W4
W7
W8
W11

Agilent Model
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6023A
6028A
6023A
6028A
6023A
6028A
All
All
All
All
All
All
All
All
All
All
All
All
6023A
6028A
6023A
6028A
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
6028A
6023A
All

Agilent Part Number
0698-6362
0698-6343
0698-6363
0698-8861
0698-7353
0698-4493
0757-0280
0698-3476
0683-1025
0683-3025
0757-0458
0698-3159
0757-0441
0757-0438
0683-5135
0683-1025
0683-5125
0683-1025
0757-0280
0698-5808
0698-3201
0757-0449
0757-0449
0757-0453
0683-5135
0757-0199
0683-5235
0757-0452
5060-9436
1826-0502
1826-0493
1826-0346
1826-0876
1820-1144
1826-0502
1826-0138
1902-3092
1902-0064
7175-0057
7175-0057
7175-0057
7175-0057

Description
Resistor, fixed film 1KΩ 0.1% 1/8W
Resistor, fixed film 9KΩ 0.1% 1/8W
Resistor, fixed film 40KΩ 0.1% 1/8W
Resistor, fixed film 6.66KΩ 0.1% 1/8W
Resistor, fixed film 19KΩ 1% 1/8W
Resistor, fixed film 34KΩ 1% 1/8W
Resistor, fixed film 1KΩ 1% 1/8W
Resistor, fixed film 6.00KΩ 1% 1/8W
Resistor, fixed film 1KΩ 5% 1/4W
Resistor, fixed composition 3KΩ 5% 1/4W
Resistor, fixed film 51.1KΩ 1% 1/8W
Resistor, fixed film 26.1KΩ 1% 1/8W
Resistor, fixed film 8.25KΩ 1% 1/8W
Resistor, fixed film 5.11KΩ +1% 1/8W
Resistor, fixed composition 51KΩ ± % 1/4W
Resistor, fixed composition 1KΩ 5% 1/4W
Resistor, fixed composition 5.1KΩ ~5% 1/4W
Resistor, fixed composition 1KΩ 5% 1/4W
Resistor, fixed film 1KΩ 1% 1/8W
Resistor, fixed film 4KΩ 1% 1/8W
Resistor, fixed film 80KΩ 1% 1/8W
Resistor, fixed film 20KΩ 1% 1/8W
Resistor, fixed film 20KΩ 1% 1/8W
Resistor, fixed film 30.1KΩ 1% 1/8W
Resistor, fixed composition 51KΩ 5% 1/4W
Resistor, fixed film 21.5KΩ + 1% 1/4W
Resistor, fixed composition 51KΩ 5% 1/4W
Resistor, fixed film 27.4KΩ 1% 1/8W
Switch lighted pusbutton
IC switch analog quad
IC op amp lo-bias hi-impedance
IC op amp dual general purpose
IC A/D CMOS 3-1/2 DGT
IC gate TTL LS NOR quad
IC switch analog quad
IC comparator GP quad
Diode zener 4.99V 2%
Diode zener 7.5V 5%
Wire 22 AWG
Wire 22 AWG
Wire 22 AWG
Wire 22 AWG

Table 5-6. A4 Power Mesh Parts List
Ref. Desig.
A4
C1
C2
C5,6
C7
C8
C9
C10
C11,12
C13
CR1-4
CR5,6
CR7
CR10,11
CR13,14
F1,2
F3
F3
L3
L4
P1,2
Q1,2
Q3,4
Q3,4
Q6
Q7
R1,2
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16
R17
R18
R19
R20
R21,22
R23

Agilent Model

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All
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All
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All
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6023A
6028A
All
All
All
All
6023A
6028A
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All

Agilent Part Number
06038-61022
0160-5891
0160-5422
0160-4960
0180-0155
0160-0127
0180-2780
0160-4834
0160-4835
0160-0161
1901-0050
1901-1065
1901-1127
1901-0050
1901-1087
2110-0671
2110-0699
2110-0688
06024-80096
9170-1265
1251-8807
1854-0477
1855-0916
1855-0547
1854-0264
1855-0549
0686-0275
0683-3915
0683-1015
0683-4705
0683-1045
0811-1857
0698-3601
0683-3915
0683-1015
0683-4705
0683-1045
0811-1857
0698-3601
0757-0403
0683-3305
0683-1025
0683-0475
0683-2025
0683-0275
0683-0475
0683-2725

Description
Power Mesh Assembly
Fixed met 0.47µF +l0% 630V
Fixed cer 0.047µF +20% 50V
Fixed film 2200pF +10% 1.6kV
Fixed elect 2.2µF +20% 20V
Fixed ceramic lµF +20% 25V
Fixed elect 470µF +75-10% 16V
Fixed cer 0.047µF +10% 100V
Fixed cer 0.1µF +10% 50V
Fixed poly 0.01µF +10% 200V
Switching 80V 200mA
Pwr rect 400V lA
Pwr rect 150V 70A
Switching 80V 200mA
Pwr rect 600V 3A
Axial lead, 1/8A
Fuse, 5A 125V
Fuse, 5A 125V
Inductor, 3A
Core, ferrite, 5uH
Connector, DIN type 32-contact F
NPN SI
MOSFET N-channel
PFET
NPN SI
PFET
Fixed comp. 2.7 5% 1/2W
Fixed comp. 390 5% 1/4W
Fixed comp. 100 5% 1/4W
Fixed comp. 47 5% 1/4W
Fixed comp. l00K 5% 1/4W
Fixed ww 400 5% 5W
Fixed met ox 10 5% 2W
Fixed comp. 390 5% 1/4W
Fixed comp. 100 5% 1/4W
Fixed comp. 47 5% 1/4W
Fixed comp. 100K 5% 1/4W
Fixed ww 400 5% 5W
Fixed met ox 10 5% 2W
Fixed film 121 1% 1/8W
Fixed comp. 33 5% 1/4W
Fixed comp. 1K 5% 1/4W
Fixed comp. 4.7 5% 1/4W
Fixed comp. 2K 5% 1/4W
Fixed comp. 2.7 5% 1/4W
Fixed comp. 4.7 5%. 1/4W
Fixed comp. 2.7K 5% 1/4W

Table 5-6. A4 Power Mesh Parts List (continued)
Ref. Desig.
R24
R25
R26
R27
R28
R29
R30
R31
R32
R33
R34
R35,36
R37
R39
T1,2
T3
TS1
TP1-4
U1,2
U3
U4
VR2
VR3
VR4

R4,R5

Agilent Model
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All
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All
All

Agilent Part Number
0757-0464
0686-1005
0811-2490
0698-3225
0757-0279
0698-3159
0698-3202
0698-4046
0757-0442
0698-3601
0698-4484
0683-3305
0683-3325
0683-1055
5080-1983
9100-4350
3103-0116
1251-0646
1820-1050
1826-0346
1826-0393
1902-3002
1902-0057
1902-0575
CHASSIS ELECTRICAL

6023A
All
All
All
All
All

2100-4060
3160-0343
9135-0223
8120-1348
8120-4353
8120-4383

Description
Fixed film 90.9K 1% A 1/8W
Fixed comp. 10 5% 1/2W
Fixed ww 0.1 3% 5W
Fixed film 1.43k 1% 1/8W
Fixed film 3.16K 1%1/8W
Fixed film 26.1K 1%1/8W
Fixed film 1.74K 1% 1/8W
Fixed film 732 1% 1/8W
Fixed film 10K 1% 1/8W
Fixed met ox 10 5% 2W
Fixed film l9.1K 1% 1/8W
Fixed comp. 33 5% 1/4W
Fixed comp. 3.3k 5% 1/4W
Fixed comp. 1M 5% 1/4W
transformer, FET driver
transformer, current
Switch, thermal 100 C
Contact connector, post type
IC DRVR TTL NOR dual
IC op amp GP dual
IC voltage regulator 1.2/37V
Zener 2.37V 5V
Zener 6.49V 5V
Zener 6.5V 2V

Resistor, variable, 5K (ref. front-panel)
Fan, axial tube
Line filter, IEC
Cable assembly (power cord) 18 AWG
Cable assembly (A1 board to A3 board)
Cable assembly (Line Cord)

Table 5-7. Other Replacement Assemblies
Ref. Desig.

A1J1
A1J2
A1J3
XA2P1
XA2P2
XA4P1,P2

A1TB1
A2P1
A2P2
A2J1, J2

A1J1
A4P1,P2

TP1-4

Agilent Model

6023A
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
6023A
6028A
All
All
All
All
6028A
All
All
All
All
All
6023A
6023A
6023A
6028A
All

Agilent Part Number
Description
A1 Board Mechanical Parts
1251-0600
Contact-conn M (Ref Fan)
1251-5927
Connector post type header
1251-5384
Connector post type header
1251-8676
Connector post type
1251-8665
Connector post type
1251-8667
Connector post type
1251-8806
Din Connector
1251-5613
Single contact connector (ref. AC line
voltage select)
1480-0552
Pin, escutcheon (ref. L1)
2110-0269
Fuseholder, clip type (ref. F2)
0360-2192
Barrier block
0360-2190
Jumper, barrier block
A2 Board Mechanical Parts
1251-8664
Connector post type
1251-8666
Connector post type
1251-8417
Din Connector
1200-0485
Socket, IC 14-contact (ref.
1205-0282
Heatsink (ref. Q2, U15, U16)
1531-0309
Clevis (ref. A2 Board)
0360-2195
Barrier block
A3 Board Mechanical Parts
4040-2121
Plastic (ref. DS9-12)
1251-5055
Connector post type header
A4 Board Mechanical Parts
1251-8807
Din Connector
0362-0335
Single contact Connector (AC)
1205-0919
Heatsink (ref. Q3, Q4)
1205-0256
Heatsink (ref. Q3, Q4)
1205-0282
Heatsink (ref. Q7)
1531-0309
Clevis (ref. A4 Board)
06023-20001
Heatsink (ref. CR7)
06023-80002
Jumper, 10 AWG
0380-1679
Hex head stand off (ref.Q3, Q4)
1251-0646
Connector single contact (pin)
CHASSIS MECHANICAL PARTS

0380-1489
0370-1091
0403-0282
1510-0044
2110-0564
2110-0565
2110-0569
2110-0926
3160-0309

Spacer, snap in
Knob, base round
Bumper feet
Binding post, single
Fuseholder body (chassis fuse)
Fuseholder cap (chassis fuse)
Fuseholder nut (chassis fuse)
Fuseholder assembly, (chassis fuse)
Finger guard (ref. fan)

Table 5-7. Other Replacement Assemblies (continued)
Ref. Desig.

Agilent Model
All
6023A
All
All
All
All
All
All
All
All
All
All

All
All
6023A
6028A
All
All
6023A
6023A
6023A
6023A
6023A
All
6023A
6028A
6023A
6028A
All
All
6023A
6028A
6023A
All
All
All
All
All
All
All
All

Agilent Part Number
4040-1954
5020-8847
5041-8803
5001-0540
5021-8417
5041-8801
5041-8819
5041-8820
5041-0309
5062-3703
7120-1254
7120-8572

Description
Window, display
Trim strip
Trim strip, top
Trim, side 7in
Frame front
Foot
Retainer, strap handle
Retainer, strap handle
Key cap, quarter
Assembly, handle strap
Nameplate
Canadian Standards Association Label (ref.
rear panel)
7121-2527
Metric and Inch Label (ref. rear panel)
7121-2794
Serial Identification Label (ref. rear panel)
06023-00016
Chassis
06023-00001
Chassis
06023-00020
Cover, top
06023-00022
Cover, bottom
06023-00004
Bracket, upper
06023-00014
Panel, sub
06023-00018
Sub panel, front
06023-00007
Bus bar, negative
06023-00008
Bus bar, positive
06023-00009
Cover, bar block
06023-00010
Cover,(top plate screened)
06023-00026
Cover,(top plate screened)
06023-00019
Rear panel, screened
06023-00011
Rear panel, screened
06028-00021
Front-panel, screened
06023-81003
Line Voltage Label (ref. rear panel) 28480
06023-90001
Operating and Service manual
06028-90001
Operating and Service manual
1990-0521
Cover, terminal block
Option 220 (220V Operation)

2110-0055
Fuse 4A 250V (rear chassis)
2110-0383
Fuse 8A 250V (rear chassis)
7120-8572
Label, info
06023-81001
Label, info
Option 240 (240V Operation)
2110-0055
2110-0383
7120-8572
06023-81002

Fuse 4A 250V (rear chassis)
Fuse 8A 250V (rear chassis)
Label, info
Label, info

6
Component Location and Circuit Diagrams
This chapter contains component location diagrams, schematics, and other drawings useful for maintenance of the power
supply. Included in this section are:
a.
b.
c.

Component location illustrations (Figures 6-1 through 6-5), showing the physical location and reference designators of
almost all electrical parts. (Components located on the rear panel are easily identified.)
Notes (Table 6-1) that apply to all schematic diagrams.
Figures 6-6 and 6-7 illustrate the detailed schematic of the unit. Test points are called out and short explanatory notes
are positioned close to the related circuit to enhance schematic readibility.
AC line voltage is present on the A1 Main Board Assembly whenever the power cord is connected to an ac
power source.

Table 6-1. Schematic Diagram Notes

denotes front-panel marking.

denotes rear-panel marking.

Complete reference designator consists of component reference designator prefixed with assembly number
(e.g.: A2R14).

Resistor values are in ohms. Unless otherwise noted, resistors are either 1/4W, 5% or 1/8W, 1%. Parts list provides
power rating and tolerance for all resistors.

Unless otherwise noted, capacitor values are in microfarads.

Square p.c. pads indicate one of the following:
a. pin 1 of an integrated circuit.
b. the cathode of a diode or emitter of a transistor.
c. the positive end of a polarized capacitor.

In schematic symbols drawn to show right-to-left signal flow, blocks of information are still read left to right. For
example:

9.
10.

indicates shift away from control block (normally down and to right). indicates shift toward control block
(normally up and to left).
indicates multiple paths represented by only one line. Reference designators with pin
numbers indicate destination, or signal names identify individual paths. Numbers
indicate number of paths represented by the line.

Inter-board commons have letter identifications (e.g. : ); commons existing on a single assembly have number
identifications (e.g.: ).
For single in-line resistor packages, pin 1 is marked with a dot. For dual in-line integrated circuit packages, pin 1 is
either marked with a dot, or pin 1 is to the left (as viewed from top) of indication at end of integrated circuit
package. e.g.:

Table 6-1. Schematic Diagram Notes (continued)

Pin locations for other semi-conductors are shown below:

Figure 6-1. Top View, Top Covers Removed

Figure 6-2. Main Board (A1) Component Location

Figure 6-3. Control Board (A2) Component Location

Figure 6-4. Front-Panel Board (A3) Component Location

Figure 6-5. Power Mesh Board (A4) Component Location

A
System Option 002
General Information
This option facilitates the operation of the power supply in an automated system. Four major circuit blocks provide:
1 ) remote analog programming of the supply's output by three different control methods; 2) signals indicating the power
supply modes and conditions; 3) two different digital methods of remote control; and 4) the outputs of three bias supplies
for use with external circuitry.
The power supply equipped with this option can be operated from either a 6940B Multiprogrammer equipped with a
69520A power supply programming card or a 6942A Multiprogrammer equipped with a 69709A power supply
programming card.
Remote Programming. Through this interface both the output voltage and current can be remote programmed by either an
external voltage source, resistance, or a current sink.
Status Indicators. Six optically isolated lines provide open-collector digital outputs which indicate the following states:
constant voltage mode, constant current mode, output unregulated, ac dropout, overvoltage, and overtemperature.
Remote Control. Two optically isolated methods of remote control are available. 0ne method requires a negative going
edge, which sets a latch on the 002 card to inhibit the power supply. The latch and OVP are reset by a negative-going pulse
on another input line. The second method of remote control requires a low logic level to inhibit the power supply for the
duration of the low level.
Bias Supplies. The outputs of three bias supplies are also available at the option connector. These outputs are + 15V, -15V,
and +5V.
Monitoring. The 002 Option Board provides two monitoring outputs (I.MON. and V.MON) available at the option
connector. They both vary from 0 to 5V corresponding to a 0 to full scale output.

Other modes of operation, such as multiple supply system control, are described in detail in later paragraphs. Modes such as
Auto Series, Auto Parallel, and Auto Tracking Operation are described in the Operating Manual.

Specifications
Table A-1 provides specifications for the Option 002. This table is referred to periodically throughout the text of this
Appendix.

Option 002 Hardware
The Option 002 hardware consists of a single printed circuit board installed at the right side (facing the front-panel) of the
chassis. Two cables connect the option board to the A2 control board at A2J1 and A2J2. Connections between the option
board and external circuits are made via the 37-pin connector mounted on the option board and available at the rear of the
power supply. A mating connector is also included for the user's convenience.

Table A-1. Specifications, Option 002
Remote Programming
Resistance Programming: 0 to 4K ohm provides 0 to maximum rated voltage or current output.
Accuracy:

@25°C
CV: 0.5% + 12mV (6023A)
CC: 1.0% + 110mA (6023A)

0.5% + 70mV (6028A)
1.0% + 500mA (6028A)

Voltage Programming: 0 to 5V provides 0 to maximum rated voltage or current output.
Accuracy:

@25°C
CV: 0.25% + 12mV (6023A)
CC: 0.30% + 110mA (6023A)

0.33% + 70mV (6028A)
0.36% ± 500mA (6028A)

Current Programming: 0 to 2mA current sink provides 0 to maximum rated voltage or current output.
Accuracy:

@25°C
CV: 0.38% + 16mV (6023A)
CC: 0.43% + 115mA (6023A)

0.43% ± 71mV (6028A)
0.50% + 500mV (6028A)

Input Compliance Voltage: ± 1V
Current Programming Enable:

Relays K2 (CV) and K1 (CC) are biased from the Control Isolator Bias input (See Remote Shutdown and OVP Clear).
Relay Bias Voltage: +4V minimum + 7V maximum
Relay Resistance: 500Ω ± 10%
Note

For Control Isolator Bias voltages greater than 7V, a series resistor must be used to maintain the relay bias voltage within
specified limits.
Enabling either relay is accomplished by bringing CV or CC enable line to Control Isolator Bias common via a suitable
driver; maximum driver off-state leakage =5mA.
Output Voltage and Current Monitor: 0 to 5V output indicates 0 to maximum rated output voltage or current.
Accuracy:

@25°C
CV: 0.25% + 2mV (6023A)
CC: 0.30% + 15mA (6023A)

0.39% + 15mV (6028A) TC: 10ppm +0.2mV/°C
0.36% + 20mA (6028A) TC: 70ppm +1.5mA/°C

Output Impedance: 10.2 k ohm ± 5%
Temperature Coefficient:
CV: 70 ppm/°C +600µV/°C (6023A)
CC: 100 ppm/°C + 2.0mA/°C (6023A)

12.5 ppm/°C +810µV/°C (6028A)
47 ppm/°C + 1.6mA/°C (6028A)

Status Indicators:
Status Isolator Bias input (referred to Status Isolator Common).

Table A-1. Specifications, Option 002 (continued)
Voltage Range: +4.75V to 16V
Current Drain: 20mA maximum

Status Indicator output:
Open collector output:
Maximum Output Voltage (logic high): + 16V
Logic Low output: + 0.4V maximum at 8mA
Remote Control (Trip, Reset, Inhibit) Control Isolator Bias Input
Voltage Range: +4.75V to 16V

Remote Control Inputs ( Remote Trip , Remote Reset ) Remote Inhibit .
On State (logic low):
Minimum forward current required (If): 1.6mA Isolator forward voltage (Vf) at 1.6mA (If): 1.4V typical, 1.75
maximum

For Control Isolator Bias voltage greater than ± 5V, an optional resistor (Ropt) may be added to reduce drive current .
Off state ( logic high) maximum leakage current: 100µA.
REMOTE TRIP and REMOTE RESET Timing

Pulse duration (TL): 15µS minimum
Reset time (TH): 125µs minimum
Set-up time (Ts): 25µs minimum
OVP clear delay: 1 sec ± 30%
Power-on Preset
Output Ratings: open collector output (referred to power supply common)
Maximum output voltage (logic high): + 16V
Logic low output: +0.4V maximum at 8mA

Table A-1. Specifications, Option 002 (continued)
Pulse Timing

Low Bias or AC DROPOUT will go false after 5V supply stabilizes.
Bias Supplies
DC Output Ratings: (25°C ± 5)
No Load to Full Load 104V to 127V line.

+ 5V ± 3% at 100mA
+15V ± 3% at 75mA
-15V ± 4% at 75mA
Short Circuit Output Current:

+5V
+ 15V
-15V

125mA ± 6%
103mA ± 6%
103mA ± 6%

PARD (Typical):

+ 5V
+ 15V
-15V

25mV pk-pk
Same
Same

1.5mV Rms
Same
Same

Isolation:

Status Indicator lines and Remote Control lines may be floated a maximum of 240Vdc (6010A, 250Vdc, 6011A, 6012B)
from ground from the power supply or from each other. These lines may not be connected to any primary circuits.
Jumpers Designation
W1--jumpered:

OV indication @ A7J3-17 is active (lo) if OVP; Remote Trip or Remote Inhibit is
active.

W1--open:

OV indication is active (lo) if OVP or Remote Trip is active.

Normal operation as shipped:

W3 and W4 jumpered W2 and W5 open.

OVP Programmable

CV: W2 jumpered; W3 open or
CC: W5 jumpered; W4 open
S1A,B in open position

Installation
When installing the board, perform the following steps:
a. Remove the top and inner cover of the power supply as discussed in Section 3 under Repair and Replacement.
b. Remove the plate next to the barrier strip on the rear panel of the supply by unscrewing the 2 M3 screws.
c. Insert the already prepared 002 board in the slot closest to the right side (looking from the front-panel) of the supply.
d. Use the two M3 screws to connect the rear end of the 002 board to the rear panel of the supply.
e. Attach ribbon cables from the A2 Control Board A2J1 to A7J1 and A2J2 to A7J2.
f. Replace the inner and outer cover of the supply.

Connector Assembly Procedure
The following instructions describe assembly of the mating connector provided to interface the user's system with the
option connector, J3. Figure A-1 identifies the parts of the mating connector.
Proceed as follows:

Note:

It may be desirable to set up a test interface before final assembly of the mating connector to allow
checkout of the system. A mating connector with pins accessible for temporary wiring is available from
Agilent Technologies, Agilent part number 1251-4464.
If the cable assembly presents RFI or ESD problems, a shielded cable assembly accessory Agilent Part
Number 5060-2890 can be ordered.

If a multi-wire cable is being used (as opposed to individual wires), remove approximately 1 1/2 inches of cable
insulation from the end. Be careful not to cut the insulation on the individual wires.

Strip 3/16 inch of insulation from the end of each wire to be used.

Insert each wire into a contact pin (1) and crimp firmly.

Insert each pin into a proper hole in connector-pin house (2) from rear. Pins will lock into housing when fully inserted.

Note

Once the pins are locked into the connector-pin housing, they are extremely difficult to remove.
Therefore, be certain pin is in proper hole before inserting fully.

Screw a slotted setscrew (3) partially into a square nut (4) and place in position in connector shield assembly (6).

Place strain relief (5) in position in connector shield assembly (6), just under set screw (3). Be certain that strain relief
is oriented as shown in Figure A-1.

Place connector pin housing (2) in shield assembly (6) and route cable through cable entrance.

Fold connector assembly (6) and secure with three screws.

Strain relief set screw (3) can now be adjusted from top of connector to clamp firmly on cable.

Clip fasteners (7) onto ends of connector pin housing (2).

Connector can now be plugged onto option connector J3 and secured with two screws (8) into the threaded stand-offs
on either side of J3.

Figure A-1. Mating Connector Assembly

Operation
The following paragraphs provide the operating instructions necessary to interface a 002-equipped power supply into an
automated system. A brief description of some circuits is also provided. The unit is shipped for front-panel operation with
mode switch settings as follows:
B1

Before beginning, switch the power supply's rear panel MODE switches B1 through B6 to their correct positions for the
programming source being used, (See Table A-2).
Next switch A1 and A2 also on the rear panel, to the correct program source function, See Figure A-2. All connections are
made at the 37-pin rear panel connector J3, and can be wired directly into the mating connector supplied for this purpose.

Figure A-2. 002 Option Rear Panel Connector J3 and Switches A1 and A2.

Local/Remote Programming
When switching to local/ control, remember to set Front-Panel Voltage and Current Control to safe levels.

Local Programming (Figure A-3). The supply can be switched back and forth between remote and local programming
while initially checking out a remote programming circuit. For proper operation of local programming, the user must
supply the bias voltage (CONTROL ISOLATOR BIAS). The Control Isolator Bias voltage can range from +4.75V to
+ 16V depending upon the user's interface circuits. Refer to Specifications Table A-1. For local programming, take the
Control Isolator Bias common and connect it to both of the LOC/REM terminals, and position mode switch as indicated in
Operation.

Although CONTROL ISOLATOR BIAS can be + 4. 75V to + 16V, a supply voltage of more than 7V
may damage the relays. Therefore, if CONTROL ISOLATOR BIAS exceeds 7V it is necessary to use a
resistor in series with each of the LOC/REM terminals. Figure A-4 provides a graph from which the
proper series resistance value can be determined. Note that the tolerances of both the Control Isolator
Bias and the resistor must be taken into account. The actual Control Bias used in Figure A-4 is obtained
after subtracting any driver gate voltage drop.

Figure A-3. Accessing Local Programming While In Remote Programming Mode

If solid state circuitry is used, connect the Control Isolator Bias to a driver capable of sinking 10mA of current, then
connect the driver's output to both of the LOC/REM terminals. Refer to Figure A-3. Either method will enable relays K1
(CV) and K2 (CC) to switch regulation to the front-panel VOLTAGE and CURRENT controls. For Control Isolator Bias
voltages greater than 7V, a resistor (Ropt) must be used in series with the Control Isolator Bias common or the Driver's
output. Figure A-4 provides a graph for determining the proper series resistance value depending on the Control Isolator
Bias voltage being used.
The supply can be returned to the remote programming mode by switching off the Control Isolator Bias common or by
increasing the Driver's output signal to within 1V of the Control Isolator Bias voltage. If remote programming is solely
desired, leave the LOC/REM terminals open and make the proper connections to the RESISTOR/VOLTAGE PROG. or
CURRENT PROG. terminals (See Figures A-5, A-6, A-7).
Table A-2. Mode Switch Settings For Enabling Different Programming Sources
Program Source
Resistance
Voltage or
Current

B1
0
0

Switch Pole Settings
Mode
B2
B3
B4
B5
0
1
0
0
1
0
0
1

B6
1
0

Figure A-4. Calculating Value of Series Dropping Resistor

Remote Resistance Programming
Check switches A1 and A2 on the rear panel, they must be in their correct positions for CV and CC resistance/voltage
programming (See Figure A-2). A resistance variable from 0 to 4K ohms can be used to program the output voltage or
current from 0 to full scale. To program the output voltage, connect the variable resistance between J3-25 (CV RES/VOLT
PROG.) and J3-22 (E COM.). To program the output current, connect the variable resistance from J3-24 (CC RES/VOLT
PROG.) to J3-22 (E COM.).
If the programming lines become open circuited during resistance programming (user’s system becomes
disconnected from J3), the power supply's output will tend to rise above rating. The supply will not be
damaged if this occurs, but the user's load may be damaged. To protect the load, be sure that the
overvoltage trip point is properly adjusted. The unit includes clamp circuits to prevent it from supplying
more than about 120% of rated output voltage or current when the remote programming voltage is
greater than 5Vdc or remote programming resistance is greater than 4K ohm. Do not intentionally
operate the unit above 100% rated output. Limit your programming voltage to 5Vdc and programming
resistance to 4K ohm to assure reliable operation.
Remote Voltage Programming (Figure A-6). Check switches Al and A2 on the rear panel, they must be in the correct
positions for CV and CC resistance/ voltage programming (See Figure A-2). A voltage source variable from 0 to 5 volts,
can be used to program the output voltage or current from 0 to full scale. The load on the programming source is less than
1mA. To program voltage, the voltage source should be connected from J3-25 (CV RES & VOLT PROG) to J3-22 (E
COM). To program current, the voltage source should be connected from J3-24 (CC RES & VOLT PROG) to J3-22 (E.
COMMON). If the programming lines become open circuited (user's system becomes disconnected from J3) during voltage
programming, the Programming Protection circuit will reduce the power supply output to zero.

Figure A-5. Remote Resistance Programming

Figure A-6. Voltage Programming of Output Voltage and Current

Current Programming (Figure A-7). Check switches A1 and A2 on the rear panel, they must be in the correct positions
for CV and CC current programming (See Figure A-2). A current sink variable from 0 to 2mA, can be used to program the
output voltage or current from 0 to full scale (See Figure A-7). The following paragraph provides a brief circuit description,
refer to schematic diagram.

Figure A-7. Current Programming of Output Voltage and Current

To program voltage, the current sink can be connected from J3-21 (CV CURRENT PROG) to J3-20 ( -15V). To program
current, the current sink can be connected from J3-2 (CC CURRENT PROG) to J3-20 ( -15V). Current sinks can either be
connected to the power supply ( -15V) or to an external negative supply that is referenced to the L. COMMON of the power
supply.
The 0 to 2mA current sink will cause the output signal of op-amps U17 and U18 to vary proportionally from 0 to 5 volts.
These signals are then coupled through relays K1 and K2 and then on to the A2 Board's CV and CC circuits which, in-turn,
will program the supply's output from 0 to full scale. If the programming lines become open circuited (user's system
becomes disconnected from J3) during current programming, the Programming Protection circuit will bring the power
supply output to zero.

Remote Monitoring
The 002 Option board provides a protected 0 to 5V output corresponding to a full scale voltage output. The voltage monitor
output is available between pins J3-5 (V. Monitor) and J3-1 (D COMMON).
Observe the caution described in Local Programming paragraph, page 85 (Figure A-3).

Output impedance is l0K ohm: the monitoring device input impedance should be at least 1M ohm to limit error to 1% +
basic accuracy; 10M ohm to limit error to 0.1% + basic accuracy.
The I. MON signal from the mainframe is also brought out through the 002 Option board. A 0 to full scale current-monitor
output is available between pins J3-3 (I. MON) and J3-1 (D COMMON). Output impedance is l0K ohms: the monitoring
device input impedance should be at least 1M ohm to limit error to 1% + basic accuracy.
In some applications it may be desirable to install a noise-suppression capacitor on these monitor outputs to lessen the
effects of noise induced in the monitor leads. The capacitors should be ceramic or tantalum type, from 0.1 to 1µF. The
capacitor is installed directly across the monitor device input terminals .

Status Indicators
Six optically isolated lines provide open collector digital outputs which indicate certain modes and conditions of power
supply operation. For proper supply operation of the opto-isolators, the user must supply the bias voltage, (ISOLATOR
BIAS). This voltage can be from +4.75V to + 16V depending upon the user's interface circuits, refer to the specifications
Table A-1. Connect the bias voltage ( + ) between J3-37, (ISOLATOR BIAS) and J3-34 (ISOLATOR COMMON). The
status indicator outputs are open collector (referenced to ISOLATOR common); therefore, it is necessary to connect a
pull-up resistor from each output to ISOLATOR BIAS. When choosing the resistor value observe the current sink
capabilities of these lines as described in the Specifications Table A-1.
Because of the relatively slow rise and fall times of opto-isolators, Schmitt-triggered devices should be used to interface
these output lines to logic circuits.
The following signals are in active low-form:
a. CV MODE , J3-36, indicates that the power supply is in constant voltage operation.
b.

CC MODE , J3-35, indicates that the power supply is in constant current operation.

OUTPUT UNREGULATED , J3-18, indicates that the power supply is in neither constant voltage nor constant
current operation and cannot be guaranteed to meet specifications.
OVERVOLTAGE , J3-17, indicates power supply shutdown because of: the voltage output exceeding the OV trip
point set at the front-panel; or, a system-initiated shutdown as described in multiple supply system shutdown section,
page 93.
OVERTEMPERATURE , J3-16, indicates power supply shutdown due to an excessive temperature rise on the FET or
output diode heatsink.

The Low Bias AC DROPOUT signal, J3-19, is in active high form. This signal indicates: loss of primary power,
momentary AC dropout. or "brownout'' conditions where the AC line voltage drops below approximately 70% nominal.

Remote Control
For operation of the opto-isolators, the user must supply the bias voltage (CONTROL ISOLATOR BIAS). This voltage
can be from + 4.75V to + 16V depending on the requirements of the driving circuits. The type of driving logic and bias
voltage will determine the amplitude of the high and low logic levels, refer to the Specification Table A-1 under Remote
Control.
Connect the bias voltage ( + ) to J3-10 CONTROL ISOLATOR BIAS, and reference the input signals to this bias supply's
negative terminal.
Two optically isolated methods of remote control are available. They are described in the following paragraphs.

Remote Trip. A negative-going edge applied to terminal J3-30 ( REMOTE TRIP ) will shut down the power supply,
reducing the output voltage to near zero. For minimum pulse duration and timing considerations with respect
to REMOTE RESET , See Table A-1. The following paragraph provides a brief circuit description (See schematic diagram
and Figure A-8).

A negative going edge at REMOTE TRIP coupled through opto-isolator (U9) causes one-shot U13B to set the
TRIP/RESET latch (U5A) low. This sets terminal J1-13 ( INHIBIT ) low, thus inhibiting the Pulse Width Modulator of the
power supply. It also lights the unregulated indicator on the front-panel and generates an unregulated signal from the
opto-isolator U3.
The low signal generated by the Trip/Reset Latch is also coupled through opto-isolator U2 and appears at J3-17 as an
OVERVOLTAGE status signal. This signal does not affect the state of the power supply's OVP circuit.
Remote Reset. A negative-going edge applied to terminal J3-29 ( REMOTE RESET ) will return the supply to its initial
state following a system-initiated shutdown or an OVP shutdown caused by a temporary over voltage condition. For
minimum pulse duration and timing considerations with respect to REMOTE TRIP See Table A-1 under Remote Control.
The following paragraphs provide a brief description of this circuit (See schematic diagram and Figure A-8).

A negative-going pulse applied to terminal J3-29 ( REMOTE RESET ) is coupled through opto-isolator U10. One-Shot
U13A then triggers and resets the TRIP/RESET latch output high. This sets terminal J1-13 ( INHIBIT ) high, thus enabling
the power supply's Pulse Width Modulator.
The REMOTE RESET signal will also reset the power supply OVP circuit in the event that an overvoltage condition has
shut down the supply. When a REMOTE RESET signal is present, ONE SHOT U13A goes low, this will produce an OV
CLEAR pulse at terminal J1-12. The OV CLEAR pulse will cause the output of A2U2 to go low thus, resetting the OV
FLIP FLOP. When this occurs the output of A2U24D goes high and simultaneously causes the front-panel OV LED to turn
off and the OV signal (J1-6) to go high. The OVERVOLTAGE signal to U4B also goes high and enables the PWM of the
power supply .

Note

By observing the OVERVOLTAGE status indicator or the power supply's output while applying a reset
pulse to REMOTE RESET , the user can determine the cause of shutdown. If the output returns and
OVERVOLTAGE goes high immediately, this indicates a controller-initiated shutdown. If the output
takes about one second to return, this indicates that the output voltage had exceeded the OVP trip point. If
the OVP circuit trips continually, check the load and/or the trip point setting.

Alternate Method of Remote Control. The REMOTE INHIBIT input, J3-31, provides an alternate method of remote

shutdown. By maintaining a low logic level at this input, the supply's output will be inhibited until REMOTE INHIBIT is
returned to its initial high state. The following paragraph provides a brief description of this circuit (See schematic diagram
and Figure A-8).
A low logic level applied to terminal J3-31 ( REMOTE INHIBIT ) is coupled through opto-isolator U8 and causes U4B to
inhibit the power supply's (PWM) Pulse Width Modulator. If jumper W1 is used (See Figure A-8) while a
REMOTE INHIBIT signal is applied, an OVERVOLTAGE signal will appear at terminal J3-17 OVERVOLTAGE thus,
indicating the power supply shut down.

Figure A-8. Remote Control

Power-On Preset
This open collector output line J3-6, provides a logic low pulse ( Power - On - Preset ) to the user that can be used to
initialize or delay a system's operation until + 5V Reg. supply has stabilized. The pulse is generated after primary power is
turned on and also after resumption of power following momentary ac dropout or conditions in which line voltage drops
below approximately 70% of the nominal. See Table Al for Power - On - Preset signal specifications.
The Power - On - Preset circuit also ensures that terminal J3-17 ( OVERVOLTAGE ) will be high when the supply is
turned on. This protects against unwanted Multiple Supply System Shutdowns when using J3-17 ( OVERVOLTAGE ) to
remote trip additional power supplies.
The following paragraphs provide a brief description of the power-on preset circuit, refer to schematic diagram:
Circuits on the Power Supply's A2 Control Board produce a power-clear signal, ( PCLR ), when the supply is turned on.
These circuits hold PCLR low until the unregulated input to the A2 Board's + 5Vdc bias supply is greater than about
11Vdc, an input voltage sufficient to assure + 5Vdc bias output.
This PCLR signal is coupled through terminal J1-15 to the 002 Option board's power-on preset circuit. When the power-on
preset circuit receives the PCLR signal, transistors U14A and U14C turn off.
Turning U14A off causes a DROPOUT signal to appear at terminal J3-19 ( DROPOUT ). Turning U14C off causes U14B
and U14D to turn on. When U14B is on, it holds output J3-17 ( OVERVOLTAGE ) high. Holding J3-17 high will prevent
any unwanted Multiple Supply Shutdowns from occurring when the supply is wired for such an application. When U10D is

on, it causes J3-6 ( Power - On - Preset ) to be low thus, if used, can initialize or delay a customer's system operation.

AC Dropout Buffer Circuit
This circuit couples, inverts and isolates the DROPOUT signal (received from the A2 Control Board) of status output
terminal J3-19 ( DROPOUT ). The dropout signal indicates loss of primary power, momentary AC dropout, or "brownout"
conditions where the AC line voltage drops below approximately 70% normal. The following paragraph provides a brief
description of the AC Dropout Buffer circuit. Refer to the Schematic Diagram
The AC Dropout Buffer Circuit receives a DROPOUT signal from the A2 Control Board. This causes the bias voltage
supplied to the Dropout Buffer U14A to be pulled down through diode CR4 thus, turning U14A off. This in turn will cause
opto-isolator U3 to turn off. Since external pull up resistors are used, terminal J3-19 (DROPOUT) will go high and remain
high until the dropout signal from the A2 Control Board is removed.

Multiple Supply System Shutdown
When using more than one 002 Option equipped power supply in a system, it may be desirable to implement a system
shutdown. In this configuration, an OVP trip or remote shutdown of a single unit will cause all of the supplies to shut down

Figure A-9. System Shutdown using Controller Power Supply

Figure A-9 shows one method of system shutdown. The advantages of this method are that one common is used for all
status and control lines (useful for controller-operated systems), and the capability of system reset. As shown in Figure A-9,
one supply's OVERVOLTAGE line is connected to the next supply's REMOTE TRIP line, and so on in a continuous
chain.

Note

+5V REG/POWER SUPPLY common from Supply 1 can be used instead of the bias voltage from the
controller. However, because of current limits of the + 5V REG, no more than four units can be
connected together in this configuration. To prevent ground loops, do not parallel connect + 5V REG
from more than one supply.

The note on page 91 tells how to determine if a shutdown was initiated through the remote trip line or by a supply's OVP. This
allows the controller to determine which supply initiated the shutdown. Following a multiple supply shutdown, each unit can
be reset individually or all the REMOTE RESET lines can be tied together for a system reset.

If it is necessary to have all the supplies come up simultaneously after a system shutdown, follow this procedure:
a.

First bring the REMOTE INHIBIT line low.

Provide a negative-going pulse to the REMOTE RESET .

After at least one second, return REMOTE INHIBIT to a high level.

Figure A-10. System Shutdown Using Bias Supply Output

Figure A-10 shows a second method of system shutdown. This method is appropriate in systems which are not
controller-operated and in which more than four supplies must be shutdown simultaneously. Because each supply derives
its CONTROL ISOLATOR BIAS from the previous supply's + 5V REG, there is no limit to the number of supplies that can
be shutdown. Each supply must be reset individually.
Using either method of system shutdown, PCLR inhibits the OVERVOLTAGE indicator from going low and shutting
down succeeding supplies upon initial sum-on. After the supplies have stabilized, PCLR returns to a high state.

Bias Supplies
The outputs of three current-limited bias supplies are available for user-supplied circuitry. These are + 15V @ 75mA at
J3-4, -15V @ 75mA at J3-20, and +5 V @ 100mA at J3-23; all with respect to J3-7, L Common.
It may be desirable to install noise-suppression capacitors on the bias supply outputs near the load circuits. The capacitors
should be ceramic or tantalum type, approximately 0.1µF to 10µF.

Maintenance
The following paragraphs provide procedures and setups to aid in checking and troubleshooting the 002 Option Board. This
information, used in conjunction with the schematic drawing and the Operation section of this Appendix, will help in the
isolation and repair of faulty circuits.
When testing the option, use of the test connector on page 83 will allow easier access to the J3 contacts.

Troubleshooting
Before attempting to troubleshoot the 002 Option Board, ensure that the fault is with the option itself and not with the main
power supply. This can be accomplished by removing the top cover, inside cover and disconnecting the two ribbon cables
from the A2 Control board and checking the operation of the main supply. Otherwise troubleshoot the option board as
described in the following paragraphs.
Removal of the Option Board. To facilitate troubleshooting the 002 Option the board can be removed from the power
supply and electrically connected via the ribbon cables from Service Kit's 06033-60005 or 5060-2665. To remove the
circuit board proceed as follows:

Turn off power supply and disconnect line cord.

Disconnect option I/O cable from J3 on rear panel and remove the two screws that secure option board to rear panel.

Disconnect the ribbon cables from the A2 Control board.

Remove option board by lifting the board by the front edge and sliding the board toward the front of the power supply.

Reconnect the option board to the A2 Control board using the extended ribbon cables from the Service Kit, and pace
the option board on an insulated surface next to the power supply.

Be careful that the option board lies securely on insulating material and does not touch any part of the main power
supply.

Isolating Faulty Circuit. It is apparent which function is not operating properly, proceed to the appropriate paragraph. If
the problem involves more than one function check the bias voltages from connectors J1 and J2 and the ± 11.8V on the
option board.

Troubleshooting Resistance and Voltage Programming
a.

Confirm that the problem is on the option board by disconnecting the ribbon cables from the A2 Control Board and
attempting to program the supply via the rear panel terminal strip.

Check ± 15V and ± 11.8V supplies.

Check for a problem in the programming protection circuit. This circuit should draw about 2µA from the programming
lines.

Check that W3 and W4 are installed and S1 is in proper position .

Troubleshooting Current Programming
a.

Check ± 15V and ± 11.8V supplies.

Proceed to test set-up shown in Figure A-11 and/or A-12.

Put S1 in V, R position and see if varying the 0-20V voltage source produces a 0-5 volt DC level across R44 or R39. If
not, check op-amps and associated circuitry.

Put S1 in I position and see if varying voltage source from 0 to 20 volts produces a 0-5Vdc level at W3 or W4. If not
check relay and programming protection circuit.

Figure A-11. Troubleshooting Current Programming of CV Mode

Figure A-12. Troubleshooting Current Programming of CC Mode
Troubleshooting Status Indicators. The test set-up shown in Figure A-13 can be used to check each of the six status
indicators. This set-up will temporarily defeat the isolation of the status lines. Before attempting to troubleshoot a status
indicator, check for + 5V Bias for proper operation of the opto-couplers.

Figure A-13. Troubleshooting Status Indicators

To check CV Mode proceed as follows:
a. Using test set-up, Figure A-13, connect to end of 2KΩ resistor to J3-36.
b. Turn on power supply.
c. Using "Display Setting'' set voltage and current or power supply for 1 volt and 1 amp.
d. DVM should read between 0 and 0.4Vdc.
e. Turn off power supply and short to output terminals.
f. Turn on power supply.
g. DVM should read approximately 5Vdc.
To check CC Mode proceed as follows:
a. Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-35.
b. Turn on power supply.
c. Using "Display Settings'' set voltage for 1 volt and current for 1 Amp.
d. DVM should read = 5Vdc.
e. Turn off power supply and short the output terminals.
f. Turn on power supply.
g. DVM should read between 0 and 0.4Vdc.
To check OVERVOLTAGE proceed as follows:
a. Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-17.
b. Turn "OVP Adjust" fully clockwise and voltage control fully counter clockwise.
c. Open power supply output terminals and turn on power.
d. DVM should read approximately 5Vdc.
e. Press "Display Settings" and increase voltage control for 15Vdc output.
f. Turn "OVP Adjust'' counterclockwise until supply goes into overvoltage.
g. DVM should read between 0 and 0.4Vdc.
h. Turn "OVP Adjust" fully clockwise and turn off input power for 5 seconds.
i. Turn on input power and DVM should read approximately 5Vdc.
To check OUTPUT UNREGULATED proceed as follows:
a. Using test set-up, Figure A-13, connect to end of 2KΩ to J3-18.
b. Connect output terminals of power supply to an electronic load capable of exceed the power supplies output power
rating by 50%.

c.
d.
e.
f.
a.

Turn on power supply.
DVM should read approximately 5Vdc.
Set voltage and current controls of power supply to maximum.
Decrease resistance of electronic load until "UNREGULATED" LED on front-panel lights.
DVM should now read between 0 and 0.4Vdc.

To check LOW BIAS or AC Dropout proceed as follows:
a. Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-19.
b. Substitute an oscilloscope in place of DVM. Set vertical deflection for 1 volt/div on the DC input.
c. Turn power on and observe oscilloscope trace. Voltage should increase to 5V at power-on and drop to between 0 and
0.4Vac approximately 3 sec.
d. Turn power off. Voltage should go to about 5Vdc before decaying back to 0V.

Note

In this test, the Low BIAS or AC Dropout signal decays to 0V only because of loss of power to the + 5V
REG Bias Supply used in the test set-up. If in doubt, use an external + 5V supply for this test.

To check OVERTEMPERATURE proceed as follows:
a. Turn off power supply and disconnect line cord.
b. Wait at least two minutes for input capacitors to discharge .
c. Remove top cover and inside cover.
d. Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-16.
e. Turn on power supply.
f. DVM should read approximately 5VAC.
g. Turn off power and wait two minutes.
h. Remove the A4 FET Assembly from the unit.
i. Turn on power supply. DVM should read between 0 to 0.4Vdc.

Note

The FET heatsinks are connected to the primary circuit and hazardous voltage (up to between 300 to
400V) exists between the heatsinks and the heatsink and the chassis. These potentials remain for up to 2
minutes if the power supply is turned off. Do not touch the heatsinks or any components on the heatsink
assemblies while the power supply is turned on or for at least two minutes after primary power is
removed. Do not place any of the heatsink assemblies on extender boards.

Troubleshooting Remote Shutdown. The following procedures check the Remote Shutdown features of 002 Option.
Troubleshooting can be accomplished by using a logic probe and referring to the schematic and the circuit description on
page 93. Before attempting to troubleshoot the Remote Shutdown section of the option, check for + 5Vdc internal bias. This
voltage must be present for proper operation of these circuits

To check the REMOTE TRIP and REMOTE RESET proceed as follows:
a. Connect +5V (J3-23) to Control Isolator bias (J3-l0).
b. Turn unit on and short REMOTE TRIP (J3-30) to + 5V common (J3-7) momentarily. Output should go into
unregulated condition with output off.
c. Short REMOTE RESET (J3-29) to + 5V common (J3-7) momentarily and OUTPUT should return to its initial state.
To check REMOTE INHIBIT proceed as follows:
a. Table A-3. Replacement Connect +5V (J3-23) to control isolator bias (J3-10).
b. Turn unit on and short REMOTE INHIBIT (J3-31 ) to + 5V common (J3-7). Output should go to an unregulated
output off condition.
c. Remove short between REMOTE INHIBIT (J3-31 ) and + 5V common (J3-7) and output should return to its initial
state.

Table A-3. Replacement Parts
REF. DESIG.
A7
C1,2
C3
C4
C5
C6
C7
C8,9
C10
C11
C12,13
C14
C15
C16
C17,18
C19
C20-22
CR1-4
CR5-10
CR11-14
CR15
CR16,17
CR18,19
CR20
CR21,22
CR23
CR24,25
CR26-29
CR30
K1,2
L1-3
Q1,2
R1-3
R4
R5
R6
R7
R8,9
R10
R11
R12
R13
R14
R15,16
R17
R18
R19
R20,21

MODEL NO.
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All

PART NO.
5060-2854
0180-0230
0180-2825
0160-4835
0160-4554
0160-4835
0160-4554
0180-0230
0180-2825
0160-4801
0160-5422
0160-4801
0160-5422
0160-5422
0180-0230
0180-2825
0160-0128
1901-0050
1901-0327
1901-0033
1901-0327

1901-0050
1901-0033
1901-0050
1901-0033
1901-0050
1901-0033
1901-0327
0490-1418
9170-1223
1854-0823
0683-2015
0683-3925
0683-2035
0683-3035
0683-6225
0683-2035
0683-1035
0683-5125
0757-0984
0683-1615
0683-4715
0683-1235
0686-1525
0683-1535
0683-4715
0683-1235

DESCRIPTION
Opt. 002 Interface Board
fxd elect. 1µF 20% 50V
fxd elect. 22µF 50V
fxd cer. 0.1µF 10% 50V
fxd cer. 0.0µF 20% 50V
fxd cer. 0.1µF l0% 50V
fxd cer. 0.0µF 20% 50V
fxd elect. 1µF 20% 50V
fxd elect. 22µF 50V
fxd cer. 100pf 5% l00V
fxd cer. 0.047µF 20% 50V
fxd cer. 100pfF 5% l00V
fxd cer. 0.047µF 20% 50V
fxd cer. 0.047µF 20% 50V
fxd elect. 1µF 20% 50V
fxd elect. 22µF 50V
fxd cer. 2.2µF 20% 50V
switching 80V 200ma
pwr. rect. 300V 40A
gen. prp. 180V 200ma
zener 9.09V 10% PD=1.5W
NOT USED
switching 80V 200ma
gen. prp. 180V 200ma
switching 80V 200ma
gen. prp. 180V 200ma
switching 80V 200ma
gen. prp. 180V 200ma
zener 9.09V 10% PD=1.5W
relay 250ma 28V,5V –coil 3VA
core shielding bead
NPN SI PD=300mW FT=200MHZ
fxd. film 200 5% 1/4W
fxd. film 3.9K 5% 1/4W
fxd. film 20K 5% 1/4W
fxd. film 30K 5% 1/4W
fxd. film 6.2K 5% 1/4W
fxd. film 20K 5% 1/4W
fxd. film 10K 5% 1/4W
fxd. film 5.1K 5% 1/4W
fxd. film 10 1% 1/2W
fxd. film 160 5% 1/4W
fxd. film 410 5% 1/4W
fxd. film 12K 5% 1/4W
fxd. film 1.5K 5% 1/4W
fxd. film 15K 5% 1/4W
fxd. film 470 5% 1/4W
fxd. film 12K 5% 1/4W

Table A-3. Replacement Parts
REF. DESIG.
R22
R23
R24
R25,26
R27
R28
R29,30
R31
R32
R33
R34
R35
R36
R37
R38
R39
R40
R41
R42
R43
R44
R45
R46
R47
R48
R49
R50,51
R52,53
R54
R55
R56
R57
S1
U1-3
U4
U5
U6
U6
U7
U7
U8-10
U11
U12
U13
U14
U15
U15
U16
U16
U17,18

100

MODEL NO.
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
All
6023A
6028A
6023A
6028A
All
All
All
All
All
6023A
6028A
6023A
6028A
All

PART NO.
0686-1525
0683-1535
0683-4715
0683-1235
0686-1525
0683-1535
0698-4479
0686-5125
0683-5125
0686-5125
0683-5125
0757-0986
0757-0269
0683-4715
0683-1035
0698-6631
0683-4715
0813-0001
0683-4715
0683-l035
0698-6631
0683-4715
0813-0001
0683-1525
0683-3325
0683-2225
0683-3355
0683-1055
0757-0441
0757-0986
0757-0269
0698-3226
3101-2715
1990-0732
1820-1197
1820-1202
1826-0393
5060-2942
1826-0551
5060-2945
1990-0494
1820-1491
1820-1416
1820-l437
1858-0023
1826-0527
5060-2943
1826-0277
5060-2950
1826-0493

DESCRIPTION
fxd. film 1.5K 5% 1/4W
fxd. film 15K 5% 1/4W
fxd. film 470 5% 1/4W
fxd. film 12K 5% 1/4W
fxd. film 1.5K 5% 1/4W
fxd. film 15K 5% 1/4W
fxd. film 14K 1% 1/8W
fxd. comp. 5.lK 5% 1/2W
fxd. film 5.1K 5% 1/4W
fxd. comp. 5.1K 5% 1/4W
fxd. film 5.1K 5% 1/4W
fxd. film 12.1K 1% 1/2W
fxd. film 270 1% 1/8W
fxd. film 470 5% 1/4W
fxd. film 10K 5% 1/4W
fxd. film 2.5K .1% 1/8W
fxd. film 470 5% 1/4W
fxd. ww. 1K 5% 3W
fxd. film 470 5% 1/4W
fxd. film 10K 5% 1/4W
fxd. film 2.5K .1% 1/8W
fxd. film 470 5% 1/4W
fxd. ww. 1K 5% 3W
fxd. film 1.5K 5% 1/4W
fxd. film 3.3K 5% 1/4W
fxd. film 2.2K 5% 1/4W
fxd. film 3.3M 5% 1/4W
fxd. film 1M 5% 1/4W
fxd. film 8.25K 1% 1/8W
fxd. film 12.lK 1% 1/2W
fxd. film 270 1% 1/8W
fxd film 6.49K 1% 1/8W
Switch-Slide 2-lA .1A 50V
Opto-Isolator IF=20mA max.
IC NAND gate TTL LS quad
IC NAND gate TTL LS
IC Voltage Reg.
IC Voltage Reg. heatsink assy.
IC Voltage Reg.
IC Voltage Reg. heat sink assy.
Opto-Isolator IF=20mA max.
IC Buffer TTL LS, hex
IC Schmitt-Trig. TTL LS, hex
IC Multi. Vib. TTL LS
Trans. Array 16-pin
IC Voltage Reg.
IC Voltage Reg. heatsink assy.
IC Voltage Reg.
IC Voltage Reg. heatsink assy.
IC Op Amp Low-bias-High-Impd.

Table A-3. Replacement Parts
REF. DESIG.
U19
U19
U20
U20
VR1-8
VR9
VR10
VR11
VR12
VR13
VR14
VR15
VR16
VR17
Z1

A7J3
W1
W2
W3,4
W5,6

MODEL NO.
6023A
6028A
6023A
6028A
All
All
All
All
All
All
All
All
All
All
All

PART NO.
1826-0393
5060-2942
1826-0607
5060-2946
1902-0556
1902-3185
1902-0556
1902-3256
1902-0779
1902-3180
1902-3110
1902-0575
1902-0556
1902-3256
1810-0276
Mechanical

DESCRIPTION
IC Voltage Reg.
IC Voltage Reg. heatsink assy.
IC Voltage Reg.
IC Voltage Reg. heatsink assy.
zener 20V 5% PD=1W IR=5µA
zener 12.4V 5% PD=.4W
zener 20V 5% PD=1W IR=5µA
zener 23.7V 5% PD=.4W
zener 11.8V 5% PD=.4W
zener 11.8V 2% PD=.4W
zener 5.9V 2% PD=.4W
zener 6.5V 2% PD=.4W
zener 20V 5% PD=.4W IR=5µA
zener 23.7V 5% PD=.4W
network res. 1.5K x 9

All
All
All
All
All
All
All
All
All

06023-00013
1251-6075
1205-0282
1258-0189
NOT USED
7175-0057
8120-4356
1251-8417
0360-1300

plate (ref. A7J3)
connector 37-pin
heatsink (ref. U6, 7, 15, 16, 19, 20)
jumper
jumper, solid tinned copper
ribbon cable, 16 cond.
post type header (ref. J1, J2)
solder pin

101

Definitions

High = more positive
Low = less positive
Indicator and Qualifier Symbols

OR function
Polarity indicator, shown outside logic symbol. Any marked input or output is active low; any unmarked
input or output is active high.
(Dynamic indicator) Any market input is edge-triggered, ie, active during transition between states. any
unmarked input is level sensitive.
(Schmitt trigger) indicates that hysteresis exists in device.
(Non-logic indicator) Any marked input or output does not carry logic information.
Open-collector or open emitter output
t = xSec
G
C

Monostable (one-shot) multivibrator.
Indicates pulse width usually determined by external RC network.
Gate input (a number following G indicates which inputs are gated)
Control input (clock)

R
S

Reset (clear)
Set
OLD SYMBOL

NEW SYMBOL

NOTES

Output requires external components to achieve logic state
A positive-going transition at A or a negative-going transition at B
triggers the one-shot. External timing components connect to
non-logic inputs.

Output changes state rapidly regardless of input rate of change.
Logic Symbols and Definitions

102

SCHEMATIC NOTES

ALL RESISTORS ARE IN OHMS, ± 5%, 1/4W, UNLESS OTHERWISE INDICATED.

ALL CAPACITORS ARE IN MICROFARADS, UNLESS OTHERWISE INDICATED.

WHITE SILKSCREENED DOTS ON P. C. BOARDS INDICATE ONE OF THE FOLLOWING:
A. PIN 1 OF AN I. C. (EXCEPT FOR U18 SEE NOTE 4 ).
B. POSITIVE END OF A POLARIZED CAPACITOR.
C. CATHODE OF A DIODE OR THE EMITTER OF A TRANSISTOR.

PIN LOCATIONS FOR SEMICONDUCTORS ARE SHOWN BELOW:

ON VOLTAGE REGULATOR DEVICES,
REF SUPPLY BIAS FOR REGULATORS INTERNAL REFERENCE.
REF = OUTPUT FROM REGULATORS INTERNAL REFERENCE.
BOOST OUTPUT = CONTROL FOR EXTERNAL PASS TRANSISTOR
CS = CURRENT SENSE
CL = CURRENT LIMIT
INV = INVERTING INPUT TO REGULATORS ERROR AMPLIFIER
NI = NON-INVERTING INPUT TO REGULATORS ERROR AMPLIFIER.
COMP = FREQUENCY COMPENSATION
Schematic Diagram Notes

103

1.
2.
3.
4.

Schematic Notes
W1 in normally open position.
W3 & W4 jumpered
Relays K1, K2 normally closed
S1A and S1B are located at the rear panel

Figure A-15. Option 002 Board, Component Location

104

Figure A-16. Option 002 Board, Schematic Diagram

105

B
Backdating
Manual backdating describes changes that must be made to this manual for power supplies whose serial numbers are lower
than those listed in the title page to this manual.
Look in the following table and located your Agilent Model. Then look at each serial number listed for this group. If the
serial number of your power supply is prior to any of the serial number(s) listed, perform the change indicated in the
Change column. Note that several changes can apply to your supply. You may also be instructed to update your power
supply if certain components are being replaced during repair.
Model 6023A
Serial Numbers
PREFIX
NUMBER
3332A
01839-02233
3302A
01789-01838
3215A
01709-01788
3047A
01559-01708
2845A
01069-01558
2704A
00619-01068
2541A
00364-00618
2508A
00184-00363
2428A
00139-00183
2420A
00124-00136
2407A
00101-00123

Change
1
1,2
1-3
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10

Model 6028A
Serial Numbers
PREFIX
NUMBER
3544A
00101-00165

Change
1

CHANGE 1
All

In the parts list for the A4 Power Mesh Board change Q3, Q4 to PFET p/n 1855-0547. Under A4
Power Mesh Board Mechanical change heatsink (Q3, Q4) to p/n 1205-0256. Add hex head
standoff (Q3, Q4) p/n 0380-1679.

CHANGE 2
6023A

In the parts list for the A1 Main Board Assembly change CR1, 3 to p/n 1901-1087. Change
CR2, CR4 to p/n 1901-0759.

CHANGE 3
6023A

In the parts list for the A1 Main Board Assembly change C13, C14 to 0.022µF 10% 1500V p/n
0160-5933.

CHANGE 4
6023A

In the parts list for the A1 Main Board Assembly change T3 bias transformer to p/n 5080-1982.
Delete screw p/n 0515-0964, lock washer p/n 2190-0586 and flat washer p/n 3050-0893.

CHANGE 5

107

6023A

In the parts list for the Chassis Mechanical change the following:
FROM
TO
Cover-top
06023-00020
06023-00002
Cover bottom
06023-00022
06023-00003
Trim top
5041-8803
5040-7203
Trim sides
5001-0540
5001-0440
Front Frame
5021-8417
5021-5817
Feet
5041-8801
5040-7201
Strap Handle Assy
5062-3703
5060-9803
Strap Retain Rear
5041-8820
5041-6820
Strap Retain Front
5041-8819
5041-6819

CHANGE 6
6023A

In the parts list for the Appendix A delete resistor R57 .49K 1%, 1/8W p/n 0698-3226 and solder
pin p/n 0360-1300.

CHANGE 7
6023A

In the parts list for the A2 Control Board Assembly delete R152, 1K 1/4W, R155, R158, 0 ohms
p/n 8159-0005.

CHANGE 8
6023A

In the parts list for the Chassis Mechanical change the following:
FROM
TO
Retainer Strap Handle
5041-6819
5040-7219
Retainer Strap Handle
5041-6820
5040-7220
Chassis
06023-00016
06023-00001
Rear panel screened
06023-00019
06023-00011
Front Frame
5021-5817
5020-8817
Delete sub panel, front p/n 06023-00018

CHANGE 9
6023A

In the parts list for the A3 Front-Panel Board Assembly change DS1, DS5 to p/n 1990-0681,
DS2-DS4, DS6-DS8 to p/n 1990-0050.

CHANGE 10
6023A

108

In the parts list for the Chassis change panel sub from 06023-00014 to 06023-0006, change frontpanel from 06023-00015 to 06023-00012.

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Format                          : application/pdf
Title                           : SERVICE MANUAL
Creator                         : Randi Kleiman
Author                          : Randi Kleiman

EXIF Metadata provided by EXIF.tools

Agilent Technologies Power Supply S 6023A And 6028A Users Manual SERVICE

AGILENT S 6023A and 6028A to the manual eef2d6c7-17f4-4bde-a75f-78a69ccc4e66

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