Agilent Technologies 6023A, 6028A User Manual

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 s hall p a y 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.

2

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.

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.

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.

Instruments which appear damaged or defective should be made inoperative and secured against unintended operation until they can be
repaired by qualified service personnel.

3

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

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

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.

Off (supply)

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.

4

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

5

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

6

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.

7

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

US 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.

8

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.

9

Table 2-1. Test Equipment Required

TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL

Oscilloscope Sensitivity: 1 mV

Bandwidth: 20MHz & 100MHz
Input: differential, 50Ω & 10MΩ

P,T Agilent 1740A

RMS Voltmeter True rms, 10MHz bandwidth

P Agilent 3400B
Sensitivity: 1 mV
Accuracy: 5%

Logic Pulser 4.5 to 5.5Vdc @ 35mA T Agilent 546A

Multimeter Resolution: 100nV

P,A,T Agilent 3458A
Accuracy: 0.0035%, 6½ digit

CC PARD Test
Current Probe

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

P Tektronix P6303

Probe/AM503 Amp/
TM500 Power Module

Electronic Load* Voltage range: 60Vdc

P,A Agilent 6060B
Current range: 60Adc
Power range: 300 watts
Open and short switches

CC PARD Test & I
Cal Resistive Load*

Value: 0.25 ohms >250W

P

Accuracy: 1%

P,A

Rheostat or Resistor Bank

Current-Monitoring
Resistors

6023A
Value: 30mV @ 30A (1mΩ )

P,A

Accuracy: 1%
TC: 30ppm/°C

Value: 30mV @ 30A (1mΩ)

Accuracy: 0.05% **

TC: 30ppm/°C (A,P)
6028A
Value 100MΩ ± 0.04% @ 25W

Guidline 9230/15

Accuracy: 1%

PC: 0.0004% 1W

Calibration and Test
Resistors

Terminating
Resistors (4)

Blocking
Capacitors (2)
Common-mode
Toroidal Core

10

Value: 100Ω, 5%, 1W

1Ω, 5%, 1/2W

1KΩ, 5% 1/4W

5KΩ, 5% 1/4W (6023A)

2KΩ, 0.01% 1/4W

Value: 50Ω ±5%, noninductive

Value: 0.01µF, 100Vdc

A,T

P

P

P Ferrox-Cube

500T600-3C8,
Agilent 9170-0061

Table 2-1. Test Equipment Required (continued)

TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL

Switch SPST, 30A @ 20V P
DC Power Supply Voltage range: 0-60Vdc

Current range: 0-3Adc

T,P Agilent 6296A

Variable Voltage
Transformer
(autotransformer)

P = performance testing A = calibration adjustments 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.

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

P,A

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. 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.

b. Slide the cover to the rear.
c. Plug a control board test connector A2P3 onto the A2J3 card-edge fingers.
d. Turn OVERVOLTAGE ADJUST control A3R59 fully clockwise.
e. Disconnect all loads from output terminals.
f. Connect power supply for local sensing, and ensure that MODE switches are set as shown below.

g. Reconnect the line cable and turn on ac power.
h. Allow unit to warm up for 30 minutes.
i. 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.

j. 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.

k. 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.

l. To disable the power supply, short INHIBIT line A2J3 pin 8 to COMMON A2J3 pin 4.

11

Table 2-2. Calibration Procedure

TEST TESTED

VARIABLE

Meter F/S
Adjust.

Resistance
Programming
F/S
Adjust.

V-MON
Zero
Adjust.

Common
Mode
Adjust.

I-MON
Zero
Adjust.

I-MON
F / S
Adjust.

*IR = Initial Reading

Meter Ref.
Voltage

Prog. Voltage VP ( + )

V-MON VM ( + )

Residual
Output
Voltage
VM( + )

I-MON IM ( + )

I-MON IM ( + )

TEST POINTS TEST SEQUENCE AND ADJUSTMENTS EXPECTED

RESULTS

A2J3 pin 6 ( + )

M ( - )

P ( - )

M ( - )

VM ( + )

M ( - )

M (-)

M ( - )

Rm ( + )
Rm ( - )

a. Connect DVM across test points and turn on

ac power.

b. Adjust A2R24 to obtain the voltage range

specified in the results.

a. Connect a 2KΩ 0.01%, ¼W programming

resistor and DVM between test points.

b. Set MODE switch as in Figure 2-1 and turn on

ac power.

c. Adjust A2R23 to obtain the voltage range

specified in the results.

a. Set voltage and current controls to minimum

settings.

b. Disable power supply as in Initial Setup step i.
c. Short circuit output terminals and connect the

DVM between test points. Turn on power
supply.

d. Adjust V-MON Zero trim pot A2R22 to

voltage range specified in the results.

a. Set voltage and current controls to minimum.
b. Disable power supply as Initial Setup step i.
c. Turn on ac power and record the initial

voltage (IR) with DVM across test points.

d. Remove the - S( + ) and – OUT( - ) and

connect a 1Vdc power supply between - S( + )
and – OUT( - ). See Figure 2-1.

e. Adjust A2R21 to the voltage range specified.
f. Remove the 1V supply and replace jumpers.
a. Set voltage and current controls to minimum.
b. Turn on ac power.
c. Connect DVM across test points and adjust

I-MON Zero trim pot A2R8 as shown in
results.

a. Perform I-MON Zero Adjust before

proceeding .

b. Connect a 0.001Ω 0.05% (6023A), 0.100Ω

0.05% (6028A) current monitoring resistor
Rm across the output terminals.

c. Turn on ac power and using the “Display

Setting”, set current control to 30A (6023A),
10A (6028A), and voltage control to 5V.

d. Connect DVM across test points and take an

initial reading (IR).

e. Connect DVM across Rm monitoring

terminals and adjust A2R9 as shown in the
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)

12

Table 2-2. Calibration Procedure (continued)

TEST TESTED

VARIABLE

Power
Limit
Adjust.

V(OUT)
I(OUT)

TEST POINTS TEST SEQUENCE AND ADJUSTMENTS EXPECTED

RESULTS

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.

30.2A 7.55V for
CC operation
(6023A)

10.2A, 23V for
CC operation
(6028A)

Figure 2-1. Common Mode Setup

13

Table 2-3. Guide to Recalibration After Repair

Printed Circuit

Board

A1 Main Board R3 4
A1 Main Board T1 4 then 5
A4 Power Mesh T3 4 then 5 Board
A4 Power Mesh CR7 4 then 5 Board
A2 Control Board Constant Voltage

A2 Control Board Constant Voltage

A2 Control Board Constant Current

A2 Control Board Power Limit

A2 Control Board Bias Power Supplies
A2 Control Board U9, R79, R80, R24 7

1. V-MON Zero Calibration

2. Common-Mode Calibration

3. I-MON Full Scale (F/S) Zero Calibration

Block Name Circuit Within

Block

All Except Current

(CV) Circuit

(CV) Circuit

(CC) Circuit

Comparator

* Code To Calibration Procedure To Be Performed

Source

Current Source All 6

± 15V Supplies

4. I-MON Full Scale (F/S) Calibration

5. Power Limit Calibration

6. Resistance Programming Full Scale (F/S) Calibration

7. Meter Full Scale (F/S) Calibration

Ref.

Designator

All 1 then 2

All 3 then 4

All 4 then 5

All All

Perform These

Procedures*

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)

14

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.

15

Figure 2-3. Basic Test Setup

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. Record the output voltage at the digital voltmeter.
f. Open-circuit the load.
g. 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.

16

f. Record the output voltage at the digital voltmeter.
g. Adjust autotransformer to the maximum for your line voltage.
h. 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

17

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. Connect the test equipment as shown in Figure 2-5. 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)
20Vdc (6028A)
d. 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.

e. 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.

f. Check that the peak-to-peak is no more than 30mV.

18

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. Connect the test equipment as shown in Figure 2-3. Operate the load in constant-current mode and set for minimum

current.

b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:

6.70Vdc (6023A)

20.0Vdc (6028A)
as read on the digital voltmeter.
d. Set the load to vary the load current between:
27 and 30Adc (6023A)
9 and 10Adc (6028A)
at a 30Hz rate.

e. Set the oscilloscope for ac coupling, internal sync and lock on either the positive or negative load transient.
f. Adjust the oscilloscope to display transients as in Figure 2-7.
g. Check that the pulse width of the transient pulse is no more than:

50mV (6023A)
75mV (6028A)

19

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

6023A 6028A

Figure 2-7. Load Transient Recovery Waveform

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

20

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. 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. Turn the unit's power on, and turn up voltage setting to full output.
c. 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.

d. 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.

e. Record voltage across Rm.
f. Short circuit the load.
g. 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)

h. 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:

21

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

22

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.

3

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. Check that input power is available, and check the power cord and rear-panel circuit breaker.
b. Check that the settings of mode switch A2S1 are correct for the desired mode of operation. (See Operating Manual).
c. Check that all connections to the power supply are secure and that circuits between the supply and external devices are

not interrupted.

d. 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.

23

Table 3-1. Control Board Test Connector, A2J7

PIN NO. SIGNAL NAME Vdc WAVEFORM/CONDITIONS SOURCE

Digital-Circuits Bias & Reference Voltages

1 +5V 5.0 A2Q3 (emitter)
22 + 20V(5V UNREG) 20.0 with 120Hz & 45KHz ripple A1CR6, A1CR7
14 2.5V ref 2.50 A2U9 (OUT)
6 0.5V ref 0.50 A2R79,A2R80

Analog-Circuits Bias Voltages

2 + 15V 15.0 A2U12 (OUT)
21 - 15V -15.0 A2U4 (OUT )

Status Signals

17

16

13

11

12

Control Signals

CV

CC

OV

DROPOUT

OT

25 PWM OFF <0.5
26 PWM ON <1.0

TTL Lo if in CV operation A2Q6C-7 (collector)

TTL Lo if in CC operation A2Q6F-14 (collector)

TTL Hi if not OVP shutdown A2U11D-11

TTL Hi if ac mains okay A2U17D-11

TTL Hi if not overtemp shutdown A2U11B-6

1.7

µs TTL pulses, 20KHz

1.7

µs TTL pulses, 20KHz

U1A-5

U2B-6
18 Ip MONITOR <0.5 1V pk, ½ sawtooth, 20KHz A2CR26 (cathode)
8

15

INHIBIT

DOWN PROGRAM

TTL hi if not remotely inhibited A2R185C, U19A-2

1.2-3.0 A2CR21, A2CR27

7 OVP PROGRAM 1/10 OVP (6023A) e.g.: 2Vdc if OVP set to 20 A3R6 (wiper)

1/30 OVP (6028A)

5

19

Commons & Current-Monitor

CLR OV

2 PCLR

4 L COMMON 0.0 common return for all bias

+5V inverted OV reset line A7U29-5

+5V if +5V bias OK A2Q60-9

A2C20 (-), A2R50,

voltages, and status and control

A2U6-4

signals

9 M COMMON 0.0 common return for 2.5V ref.

A2R83, A21-20

and 0.5V ref.

10 I-TEST

≈0.005 ( Iout)

inboard-side monitoring res. A1R3,A1T2

3 NOT USED

24

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. Always turn power off before removing or installing printed-circuit boards.
b.

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.

c.

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 10

d.

Ground all conductive equipment or devices that may come in contact with static-sensitive devices or subassemblies

containing same.

e.

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.

f.

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]).

6

and 10l2 Ω per square.

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.

g. 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.

25

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. Lock-link/shelf-mounting blocks (4 on rear panel, one at each corner).
b.

Rear-panel fuse holder.

c.

Rear-panel ground binding post.

d.

Strap-handle screws (2).

e.

Screws that secure side chassis to front-frame casting (8, 4 on each side).

f.

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.

26

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.

27

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: Start with the TROUBLESHOOTING NO-OUTPUT FAILURES section which references

Tables 3-1 and 3-3.

2.

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.

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.

28

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 Mains-

Voltage 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.

29

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. Install control board test connector onto the A2J3 card edge fingers.
c.

Connect a 50Ω, 10W, load resistor to the unit's output terminals.

30

d. 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.

e.

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.

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.

b.

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.

c.

Check for the presence of program voltages, VP and IP, at the rear panel.

d.

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.

e. 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.

31

Table 3-2. No-Output Failures

(Bias supplies and AC turn-on circuit functioning)

Status of PFET on/off-Pulses

PWM-ON

A2J7-26

PWM-OFF

A2J7-25

DEFECTIVE

BOARD

CHECK FUNCTIONAL CIRCUITS

lo lo A2 Control ckts: CV & CC thru on- & off-Pulse Oneshots *

lo hi A2 & A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

hi lo A2 & A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

hi hi A2 & A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

lo N A2 A2U17B,on-Pulse Oneshot and A2Q6A

N lo A2 & A4 Off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

hi N A2 & A4 A2U17A, on-Pulse Oneshot & DC-to-DC: A4Q3, and A4Q4 probably

failed

N hi A2 & A4 off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

N N A2 & A4 Power-Limit Comparator and DC-to-DC: A4Q3 and A4Q4 probably

failed

lo= TTL low hi= TTL high 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

Signal Name Measureme

nt

Description Source

1 +7.5V 7.5V Derived from + 15V bias. A3VR2, A3R3
2 -1V -1.0V Derived from –15V bias. A3R86, A3R85, A3C17
*3 CV VOLTAGE 0-5V For 0 to full scale output voltage. A3U2-2, A3R1, A3R87.
*4 CC VOLTAGE 0-5V For 0 to full scale output current. A3U3A-1, A3R67
5 VOLTS test -1888 on

Jumper to + 5V on A3 board. A3U4-37

volts display

6 AMPS test -1888 on

Jumper to + 5V on A3 board. A3U5-37

amps display
*7 VOLTS input 0-1V For 0 to full scale output voltage. A3R8,A3U7-2,3,10
8 VOLTS low range TTL high If VOLTS display is below 20 volts

A3U9C-13, A3U6B

(press DISPLAY SETTINGS).

9 DISPLAY

SETTINGS

10 DISPLAY OVP TTL high If DISPLAY OVP switch on front-

TTL high If DISPLAY SETTINGS switch on

front-panel is depressed.

A3S1,A3R80

A3S2,A3R82, A3U6C-8

panel is depressed.
*11 AMPS input 0-150mV For 0 to full scale output current. A3R65,A3R66,A3R67
12 -5 V -5.0V Derived from -15 V bias. A3VR1, A3R2
13 buffered OVP 0-2.2V 1/10 of OVP voltage setting when

A3U3B-6,A3CR5,A3R72
DISPLAY OVP switch is
depressed. Varies with OVP
ADJUST pot.

* Switch A1S4 should be in the NORM position for these tests.

32

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 + MEASUREMENT SOURCE

A2J3-22

Outputs

NODE MEASUREMENT

A2U6-6
A2U6-12,13
A2Q3 (emit)
A2U5 (OUT) 2.5 Vdc
A2R50, A2CR11 (anode)
A2R161, A2R163 2.5 Vdc

≈ 2 to 4Vdc sawtooth, 45KHz
≈ 19Vpk, 15µs pulses, 45KHz
≈ 20Vpk, 5µs pulses, 45KHz

≈ 0 > V > -0.07Vdc

≈ 20Vdc

A1CR6,A1CR7

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
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 DEFECTIVE

Unexplained OVP shutdowns A2 OVP Circuit, CV Circuit

No current limit A2 CC Circuit

Max current < 30Adc A2 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

Potentiometers. A3R4, A3R5

CHECK FUNCTIONAL CIRCUITS

BOARD

Select switch A1S2

33

Table 3 5. Performance Failure Symptoms (continued)

SYMPTOMS DEFECTIVE

BOARD

CHECK FUNCTIONAL CIRCUITS

CV overshoots A2 A2U10A, A2CR20, A2R94

Output noise ( < 1KHz) A2, A1 CV Circuit

Output noise ( > 1KHz) A1, A4 Transformer A1T1, Output Filter, snubbers A4R7

/R8 /C5 / CR5, A4R13/ 14 / C6 /CR6, A4R33 /C13
CV regulation, transient response,
programming time

A2, A1 Wrong sensing (paragraph 3-40), low ac mains

voltage, CV Circuit
CC regulation A2 Low ac mains voltage, CC circuit

CV oscillates with capacitive loads A2 A2U10, A2C51, A2R95, A2R96, A2R86, A2C47,

A2R71, A2C36
CC oscillates with inductive loads A2 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 (+ ) MEASUREMENT SOURCE

A2U12(IN), A2C17(+)

Outputs:

NODE ( + ) N0DE ( - ) MEASUREMENT

≈ 24Vdc

A1U1, AlC1 (+)

A2U12 (OUT) A2U12 (ADJ) 1.25Vdc
A2U12 (cath.)
A2U12 (anode.) 11.7Vdc
A2VR1 (anode.)
A2R34, A2R33 2.05Vdc
A2LR3 (cath.)
A2VR3 (anode.) 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.

34

Input:

NODE ( + ) MEASUREMENT SOURCE

A2U4 (IN), A2C16 (-)

Outputs:

NODE ( + ) N0DE ( - ) MEASUREMENT

A2U4 (ADJ) A2U4 (OUT) 1.25Vdc
A2VR2 (cath.) A2VR2 (anode) 11.7Vdc
A2R33, A2R34 A2VR2 (cath.) 2.05Vdc

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.

≈ -24Vdc

A1U1, AlC1 ( + )

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 ( + ) * SETUP MEASUREMENT SOURCE

A2J3-1 wait 2s 5.0Vdc A2Q3 (emit.)
A2J3-22 20Vdc A1CR6, AlCR7
A2U20-8,10 f.w.rect.,1-2Vpk A1CR8,AlCR9
A2U22-13 TTL sq wave, 20KHz A2U22-6

Outputs:

NODE ( + ) * SETUP MEASUREMENT

A2U20-5 cycle power transition 0 to 13.5Vdc
A2U20-2 cycle power transition 0 to 1.4Vdc
A2Q6-1 cycle power transition 0 to 5.0 to 0.3Vdc
A2Q6-9 cycle power transition 0 to 0.3 to 5.0Vdc
A2U20-6 wait 2s < 0.25Vdc
A2U20-1,14 wait 2s hi (5Vdc)
A2U11-3 cycle power transition lo to hi to lo
A2U18-10 cycle power burst 1.25 KHz sq. wave 1.1s

35

A2U18-13 cycle power five 100ms pulses then hi
A2U18-12 cycle power two 200ms pulses then hi
A2U18-15 cycle power transition lo to hi at 800 msec
A2U17-8 cycle power transition lo to hi at 1.0 sec
A2U17-11 cycle power transition lo to hi at 1.1 sec

DROPOUT A2Q5 (col)

(RELAY ENABLE)

cycle power 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 ( + ) SETUP MEASUREMENT SOURCE

A2J3-1 5.0Vdc A2Q3 (emitter)
A2U19-1 Hi A2U17D-11
A2U19-2 Hi remote inhibit
A2U19-4 Hi A2U14-1,8
A2U19-5 Hi A2U11B-6
A2U19-10 Hi A2U16-7
A2U19-12 POWER LIMIT fully CCW Lo A2U14-2
A2U19-12 POWER LIMIT fully CW Hi A2U14-2

Outputs:

SET VOLTAGE (Vdc)

NODE ( + ) EXTERNAL INTERNAL SETUP MEASUREMENT

A2U21-7 0 0 TTL sq wave, 320KHz
A2U22-3 0 0 TTL sq wave, 160KHz
A2U22-6 0 0 TTL sq wave, 20KHz
A2U13-5 0 0
A2U13-9 0 0
A2U14-2 40 0 POWER LIMIT

fully CCW
A2U19-5 40 0 lo
A2U13-9 40 0 lo
A2U17-6 40 0 lo
A2U15-13 40 0 lo
A2U15-5 40 0 lo
A2U17-6 40 0 POWER LIMIT

fully CW

A2U17-5 40 0

23.5

µs TTL pulses, 20KHz

23.5

µs TTL pulses, 20KHz

lo

groups of 4 pulses 1.7

1.7

µs, TTL, 20KHz

µs, TTL, 20KHz

36

+ OUT 40 10 3.8Vdc (OVERRANGE)
+ OUT 40 2 2.0Vdc (CV)
+ OUT 40 2 short A2J3-4 to

A2J3-8

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 ( + ) NODE ( - ) MEASUREMENT SOURCE

A2J3-26
(PWM-ON)
A2J3-25
(PWM-OFF)
A4Q2-D A4Q4-S 39Vdc A1C4 (+), A4P1-10, A,C

VM waveform 1 A2U17-6, A2P1-7, A4P1-24,C

VM waveform 2 A2U15-5, A2P1-13, A4P1-26,A

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

Outputs:

NODE ( + ) NODE ( - ) MEASUREMENT

A4Q3-G A4Q3-S Waveform 3
A4Q4-G A4Q4-S Waveform 3
A4Q3-D A4Q3-S Waveform 4
A4Q4-D A4Q4-S Waveform 4
A2J3-18 A2J3-4 Waveform 5

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.

37

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

Outputs:

NODE ( + ) SETUP MEASUREMENT

VM 3.75Vdc
A2U10C-8 4.7Vdc
A2U8-6 VP = 0 -14Vdc
A2U10A-1 VP = 0 -14Vdc
A2U8-6 VP = 5 4.7Vdc
A2U10A-1 VP = 5 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.

P or set VP to + 5Vdc by connecting to A2J3-1 according to SETUP below.

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
connecting to A2J3-1 according to SETUP below.

Outputs:

NODE ( + ) SETUP MEASUREMENT

IM 0.50Vdc
A2U2B-7 IP = 0 -14Vdc
A2U2B-7 IP = 5 +14Vdc
A2U3D-13 +0.015Vdc
A2U3C-9 +0.015Vdc
A2U3C-8 +0.25Vdc

P or set IP to + 5Vdc by

38

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:

SET VOLTAGE (Vdc)

NODE ( + ) EXT INT SETUP MEASUREMENT

A4U4(OUT) - - 8.9Vdc
A4U3B-7 0 2 unplug TS1 0Vdc
A4U3B-7 10 0 reconnect TS1 0Vdc
A4U3B-7 0 2 0Vdc
A4U3A-2 0 2 unplug TS1 0.43Vdc
A4F1 0 2 0.2Vdc
A4Q6(base) 0 2 1.0Vdc
A4U3A-1 20 2 4.0Vdc
A4F1 20 2 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.

39

40

Figure 3-3. Waveforms

Outputs:

NODE ( - ) = A2J7-4

SET VOLTAGE (Vdc)

NODE ( + ) EXTERNAL INTERNAL SETUP MEASUREMENT

A2U9 (OUT) - 2.5Vdc
A2U14-10 10 1.0Vdc
A2U14-11 - 1.5Vdc
A2J3-13 10 hi
A2J3-13 20 lo
A2J3-13 10 lo
A2J3-13 10 cycle power hi

Note 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.

41

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.

43

44

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.

45

46

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.

47

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.

48

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

49

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 1.5
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 1.5
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.

µ after each 20KHz clock pulse and turn off when any of these four inputs go low. The output of the

µ Delay Flip-flop A2U13B reset; 1.5µ after the

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
DROPOUT, OVERVOLTAGE, and POWER-ON RESET outputs.

Option 002 uses PCLR2 in creating its

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

50

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.

51

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.

Reference Designators. Refer to Table 5-1.

b.

Agilent Model in which the particular part is used.

c.

Agilent Part Number.

d.

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 Assembly
BBlower
C Capacitor
CR Diode
DS Signaling Device (light)
FFuse
FL Filter
G Pulse Generator
J Jack
KRelay
L Inductor
Q Transistor
RResistor
RT Thermistor Disc
S Switch
TTransformer
TB Terminal Block
TS Thermal Switch
U Integrated Circuit
VR Voltage Regulator (Zener diode)
W Wire (Jumper)
XSocket*
Y Oscillator

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

53

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 Addressable
ASSY Assembly
AWG American Wire Gauge
BUFF Buffer
CER Ceramic
COMP Carbon Film Composition
CONV Converter
DECODER/DEMULTI Decoder/Demultiplexer
ELECT Electrolytic
EPROM Erasable Programmable Read-Only Memory
FET Field Effect Transistor
FF Flip-Flop
FXD Fixed
IC Integrated Circuit
INP Input
LED Light Emitting Diode
MET Metalized
MOS Metal-Oxide Silicon
OP AMP Operational Amplifier
OPTO Optical
OVP Over Voltage Protection
PCB Printed Circuit Board
PORC Porcelain
POS Positive
PRIOR Priority
ROM Read-Only Memory
RAM Random Access Memory
RECT Rectifier
REGIS Register
RES Resistor
TBAX Tube Axial
TRIG Triggered
UNI Universal
VAR Variable
VLTG REG Voltage Regulator
WW Wire Wound

54

Table 5-3. A1 Main Board Parts List

Ref. Desig. Agilent Model Agilent Part Number Description

ELECTRICAL PARTS

Al 6023A 06038-60021 Main Board Assembly
Al 6028A 06038-61021 Main Board Assembly

C1 All 0160-4962
C2,3 All 0180-3426
C4 All 0180-3427
C5 All 0160-4962
C6,7 All 0160-5933
C8-10 6023A 0180-3425
C8-10 6028A 0160-3548
C11-12 6023A 0160-5377
C11-12 6028A 0160-6167
C13,14 6023A 0160-7731
C13,14 6028A 0160-5933
C15,16 All 0160-4355
C17 6023A 0160-5422
C17 6028A 0160-4834
C20,21 All 0180-3428
C22,23 All 0160-4439
C24,25 6028A 0160-4281
C26 6028A 0160-4323

Capacitor, 1
Capacitor, 590
Capacitor, 300
Capacitor, l
Capacitor, 0.022
Capacitor, 5500
Capacitor, 1700
Capacitor, 2.2
Capacitor, 2.2
Capacitor, 0.22
Capacitor, 0.022
Capacitor, 0.01
Capacitor, 0.047
Capacitor, 0.047
Capacitor, 1000
Capacitor, 4700
Capacitor, 2200
Capacitor, 0.047

µF + 10% 50Vac

µF + 50-10% 400V
µF + 50-10% 200V

µF + 10% 50V

µF + 10% 1500V
µF +50-10% 40V
µF 75V

µF +10% 6.3V
µF 63V

µF + 10% 1500V

µF + 10% 1500V

µF + 10% 250V

µF + 20% 50V

µF + 20% 50V
µF 50V
µF 20% 250V
µF 20% 250V

µF 20% 250V

CR1-4 6023A 1901-1199 Diode power rectifier 600V 3A
CR1 6028A 1901-1087 Diode power rectifier 600V 3A
CR2 6028A 1901-0759 Diode power rectifier 600V 3A
CR3 6028A 1901-1087 Diode power rectifier 600V 3A
CR4 6028A 1901-0759 Diode power rectifier 600V 3A
CR6, 7 All 1901-0731 Diode power rectifier 600V 3A
CR8, 9 All 1901-0050 Diode power rectifier 600V 3A
CR13, 15 All 1901-0731 Diode power rectifier 600V 3A
F2 All 2110-0007 Fuse 1A 250V
F3 6028A 2110-0763 Fuse 1/4A 125V
J1 All 1251-5927 Connector, 26-contact
J2 All 1251-5384 Connector, 3-contact
J3 All 1251-8676 Connector, 5-contact
K1 All 0490-1417 Relay, DPST
L1 All 06024-80094 Choke RFI 3A (magnetic core 9170-0721)
L3 6023A 5080-1981
L3 6028A 9140-0987

Choke, output 0.5
Choke 3

µH

µH

Q1 6028A 1854-0087 Transistor NPN SI
Q2 6028A 1854-0799 Transistor NPN SI TIP41C
R1 All 0811-3667
R2 All 0811-1865

Resistor 20
Resistor 2k

Ω 5% 7W
Ω 10% 5W

R3 6023A 5080-2007 Sensing resistor 0.005
R4 All 0683-1025

Resistor 1K

Ω 5% 1/4W

R5 6023A 8151-0013 Wire, 22 AWG
R5 6028A 7175-0057 Wire, tinned copper, AWG 22
R6 All 0683-1025
R7 6028A 0699-1210

Resistor 1K
Resistor 80K

Ω 5% 1/4W

Ω 0.1% 0.1W

R8-10 6023A 8151-0013 Wire, 22 AWG

55

Table 5-3. A1 Main Board Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

R8 6028A 0699-0118

Resistor 20

Ω 0.1% 0.1W

R9 6028A 7175-0057 Wire tinned copper AWG 22
R10 6028A 0698-6359
R11 All 0698-6322
R12 All 0698-8695
R14 6023A 0698-3572

Resistor 80K
Resistor 4K
Resistor 36K
Resistor 60.4

Ω 0.1% 1/8W

Ω 0.1% 1/8W

Ω 0.1% 1/8W

Ω 1% 1/8W

R15 6023A 8151-0013 Wire 22 AWG
R15 6028A 0757-0270
R17,18 All 0683-1005
R19 All 0683-1055
R20,21 All 0811-1867
R22.23 All 0686-1065
R24,25 All 0686-1035
R26 All 0683-3315
R27A,28B 6028A 0811-3823
R29 6028A 0686-3335
R30 6028A 0811-1865
R31 6028A 0812-0098
R32 6028A 0683-1035
R33 6028A 0683-4745
R34 6028A 0683-2035

Resistor 249K
Resistor 10
Resistor 1M

Ω 5% 1/4W

Ω 5% 1/4W

Resistor 15K
Resistor 10M
Resistor 10K
Resistor 330
Resistor 0.1

Ω 5% 20W

Resistor 33K
Resistor 2K

Ω 1% 5W

Resistor 135
Resistor 10K
Resistor 470
Resistor 20K

Ω 1% 1/4W

Ω 5% 5W

Ω 5% 1/2W

Ω 5% 1/2W

Ω 5% 1/4W

Ω 5% 1/2W

Ω 5% 5W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

S1 6023A 3101-0402 Switch DPST rocker (mounted on front-

panel)
S2 All 3101-1914 Switch 2-DPDT slide
S4 All 3101-2046 Switch DPDT slide
T1 6023A 5080-1978 Transformer, power
T1 6028A 06038-80090 Transformer, power
T2 All 9170-1264 Core magnetic (used with primary wire

06023-80004)
T3 All 9100-4864 Transformer bias
T4 All 5080-1984 Choke line 2mH
TP1, 2 All 1251-5613 Connector single contact
U1 All 1906-0006 Rectifier bridge 400V 1A
VR1, 2 6028A 1902-1377 Diode zener 6.19V 2%
W1, 2 All 06023-80003 Jumper output 10 AWG
XA2P1 All 1251-8665 Connector, 30-contact
XA2P2 All 1251-8667 Connector, 20 contact
XA4P1, 2 All 1251-8806 Connector, DIN 32-contact

56

MECHANICAL PARTS
6028A 1480-0552 Pin, escutcheon (L1)
6028A 0380-1489 Snap-in-spacer
6028A 2110-0269 Fuseholder, clip type F2
6028A 0360-2190 Jumper, locai sensing (2)
6028A 0360-1833 Barrier block, 6-position
6023A 0515-0964 screw
6023A 2190-0586 washer, lock
6023A 3050-0893 washer, flat

Table 5-4. A2 Control Board Parts List

Ref. Desig. Agilent Model Agilent Part Number Description

ELECTRICAL PARTS

A2 06038-61023 Control Board Assembly
A2 06023-60023 Control Board Assembly

C1 All 0160-5469
C2 All 0160-5422

Capacitor, l
Capacitor, 0.047

µF + 10% 50V

µF 20% 50V

C3 6023A 0160-4801 Capacitor, 100pF 5% 100V
C3 6028A 0160-4812 Capacitor, 220pF 5%
C7 All 0160-5422

Capacitor, 0.047

µF 20% 50V

C8 All 0160-4812 Capacitor, 220pF 5% 100V
C9 All 0160-5377
C10,11 All 0160-5469
C12,13 All 0160-5422
C14 All 0180-0291
C15 All 0180-1731
C16,17 All 0180-0230
C18,19 6023A 0180-0291
C18,19 6028A 0180-0230
C20 All 0180-2624
C21 All 0180-5098
C22 All 0180-4832

Capacitor, 2.2
Capacitor, 1

µF 10% 63V

µF 10% 50V

Capacitor, 0.047
Capacitor, 1
Capacitor, 4.7
Capacitor, l
Capacitor, l
Capacitor, l

µF 10% 35V

µF 10% 50V
µF + 20% 50V
µF 10% 35V
µF 20% 50V

Capacitor, 2000
Capacitor, 0.22
Capacitor, 0.01

µF 20% 50V

µF 75-25% 10V
µF 10% 50V
µF 10% 100V

C23 All 0180-3407 Capacitor, 2200pF +50-10% 35V
C24 All 0180-5098
C25 All 0160-4833

Capacitor, 0.22
Capacitor, 0.022

µF 10% 50V

µF 10% 100V

C26 All 0160-0154 Capacitor, 2200pF 10% 200V
C27,28 All 0160-5422

Capacitor, 0.047

µF 20% 50V

C29 6023A 0160-4808 Capacitor, 470pF 5% 100V
C29 6028A 0160-4812 Capacitor, 220pF 5% 100V
C30 All 0160-4830 Capacitor, 2200pF 10% 100V
C31 6023A 0160-4808 Capacitor, 470pF 5% 100V
C31 6028A 0160-4801 Capacitor, 100pF 5% 100V
C32 All 0160-4801 Capacitor, 100pF 5% 100V
C33-37 6023A 0160-5422
C33-35 6028A 0160-5422
C36 6028A 0160-4833
C37 6028A 0160-5422

Capacitor, 0.047
Capacitor, 0.047
Capacitor, 0.022
Capacitor, 0.047

µF 20% 50V
µF 20% 50V
µF 10% 100V
µF 20% 50V

C38 6023A 0160-4801 Capacitor, 100pF 5% 100V
C38 6028A 0I60-4803 Capacitor, 68pF 5% 100V
C39,40 All 0160-5422
C41 All 0160-4835

Capacitor, 0.047
Capacitor, 0.l

µF 10% 50V

µF 20% 50V

C42 All 0160-4805 Capacitor, 47pF 5% 100V
C43 All 0160-5422

Capacitor, 0.047

µF 20% 50V

C44 All 0160-4805 Capacitor, 47pF 5% 100V
C45 6023A 0160-4808 Capacitor, 470pF 5% 100V
C45 6028A 0160-4810 Capacitor, 330pF 5% 100V
C46 All 0160-4807 Capacitor, 33pF 5% 100V
C47 All 0160-4822 Capacitor, 1000pF 5% 100V
C48 All 0160-5422
C49 6023A 0160-5644
C49 6028A 0160-4833

Capacitor, 0.047
Capacitor, 0.033
Capacitor, 0.022

µF 20% 50V
µF 10% 50V
µF 10% 100V

57

Table 5-4. A2 Control Board Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

C50 6023A 0160-0167
C50 6028A 0160-0168

Capacitor, 0.082
Capacitor, 0.l

µF 10% 200V

µF 10% 200V

C51 All 0160-4801 Capacitor, 100pF 5% 100V
C52,53 All 0160-4831 Capacitor, 4700pF 10% 100V
C54 All 0160-5422

Capacitor, 0.047

µF 20% 50V

C55,56 All 0160-4801 Capacitor, 100pF 5% 100V
C57,58 All 0160-5422

Capacitor, 0.047

µF 20% 50V

C59 All 0160-4812 Capacitor, 220pF 5% 100V
C60 All 0160-5422

Capacitor, 0.047

µF 20% 50V

C61 All 0160-4812 Capacitor, 220pF 5% 100V
C62 All 0160-5422
C63 All 0180-0116
C64,65 All 0160-5422
C66 All 0180-0376

Capacitor, 0.047
Capacitor, 6.8
Capacitor, 0.047
Capacitor, 0.47

µF 20% 50V

µF 10% 35V

µF 20% 50V

µF 10% 35V

C67,68 All 0160-4812 Capacitor, 220pF 5% 100V
C69 All 0180-4832
C70 All 0180-1980
C71 All 0160-5422
C72 6028A 0160-5422

Capacitor, 0.01
Capacitor, 1

µF 5% 35V

Capacitor, 0.047
Capacitor, 0.047

µF 10% 100V

µF 20% 50V
µF 20% 50V

CRl,2 All 1901-0033 Diode general purpose 180V 200mA
CR3 All 1901-0050 Diode switching 80V 200A
CR5-7 All 1901-0033 Diode general purpose 180V 200mA
CR8-10 All 1901-0050 Diode switching 80V 200A
CR11 All 1901-0992 Diode power rectifier 40V 3A
CR12-16 All 1901-0033 Diode general purpose 180V 200mA
CR18 All 1901-0033 Diode general purpose 180V 200mA
CR19 All 1901-0050 Diode switching 80V 200A
CR20 All 1901-0033 Diode general purpose 180V 200mA
CR21-30 All 1901-0050 Diode switching 80V 200A
J1,2 All 1251-8417 Connector, 16-contact
L1 All 06023-80090

Choke bias 820

µH

P1 All 1251-8664 Connector 30-contact
P2 All 1251-8666 Connector 20-contact
Q1,2 All 1855-0413 Transistor J-FET P-chan 2N5116
Q3 All 1854-0635 Transistor NPN SI D44H5
Q4 All 1853-0012 Transistor PNP SI 2N2904A
Q5 All 1854-0823 Transistor NPN SI
Q6 All 1858-0023 Transistor array CA3081E
Q7 6028A 1854-0087 Transistor NPN SI
R1 All 0683-5125
R2 6023A 0683-3925
R2 6028A 0757-0419
R3 6023A 0698-6329
R3 6028A 0698-6393
R4 All 0683-1035
R5 6023A 0698-7880
R5 6028A 0699-0774

Resistor 51k

Ω 1/2W

Resistor 39K
Resistor 681
Resistor 845
Resistor 585

Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W

Resistor 10K
Resistor 28.7K
Resistor 6.65K

Ω 5% 1/4W

Ω 5% 1/4W

Ω 1% 1/8W
Ω 1% 1/8W

58

Table 5-4. A2 Control Board Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

R6 All 0683-5125

Resistor 5.1K

Ω 5% 1/4W

R7 All 0683-4745 Resistor 470K 5% 1/4W
R8 All 2100-3353

Trimmer 20K

Ω side adjust

R9 6023A 2100-3350 Trimmer 200 side adjust
R9 6028A 2100-3993 Trimmer 200 side adjust
R10 6023A 0683-5625
R10 6028A 0757-0427
R11 6023A 0698-3136
R11 6028A 0683-1025
R12 All 0683-1025
R13 All 0683-2735
R14 All 0686-5125
R15 All 0683-2015
R16 6023A 0683-3355
R16 6028A 0683-2255
R17 6023A 0683-6835
R17 6028A 0757-0289
R18 6023A 0683-3035
R18 6028A 0757-0449
R19 6023A 0683-4735
R19 6028A 0757-0449
R20 All 0683-1035
R21 6023A 2100-3350
R21 6028A 2100-3273
R22 All 2100-3353
R23 All 2100-3273
R24 All 2100-3350
R25 All 2100-3207
R26 All 0683-1045
R27 All 0698-6322
R28 All 0683-1045
R29 All 0698-4416
R30 All 0683-7545
R31 All 0698-6322
R32 All 0698-4416
R33 All 0698-4447
R34 All 0757-0404
R35 All 0698-4608
R36 All 0757-0438
R37,38 All 0683-1035
R39 All 0686-2005
R40 All 0683-1005
R41,42 All 0683-6215
R43 All 0683-1515
R44 All 0757-0434
R45 All 0757-0442
R46,47 All 0757-0283

Resistor 5.6K
Resistor 1.5K
Resistor 17.8K
Resistor 12K
Resistor 1K

Ω 5% 1/4W

Resistor 27K
Resistor 5.1K
Resistor 200

Ω 5% 1/4W

Resistor 3.3M
Resistor 2.2M
Resistor 68K
Resistor 13.3K
Resistor 50K
Resistor 20K
Resistor 47K
Resistor 20K
Trimmer 200
Resistor 3.3M
Trimmer 2K

Ω side adjust

Trimmer 20K
Trimmer 2K

Ω side adjust

Trimmer 200
Trimmer 5K

Ω side adjust

Resistor 100K
Resistor 4K

Ω 0.1% 1/8W

Resistor 100K
Resistor 169

Ω 1% 1/8W

Resistor 750K
Resistor 4K
Resistor 169
Resistor 280
Resistor 130
Resistor 806

Ω 0.1% 1/8W

Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W

Resistor 5.11k
Resistor 10K
Resistor 20
Resistor 10
Resistor 620
Resistor 150

Ω 5% 1/2W
Ω 5% 1/4W

Ω 5% 1/2W
Ω 5% 1/4W

Resistor 3.65K
Resistor 10K
Resistor 2K

Ω 1% 1/8W

Ω 5% 1/4W
Ω 1% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W
Ω 5% 1/4W

Ω 5% 1/4W

Ω 1% 1/8W
Ω 5% 1/4W
Ω l% 1/8W
Ω 5% 1/4W
Ω 1% 1/8W

Ω side adjust

Ω 5% 1/4W

Ω side adjust

Ω side adjust

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 1% 1/8W

Ω 5% 1/4W

Ω 1% 1/8W
Ω 1% 1/8W

59

Table 5-4. A2 Control Board Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

R48,49 All 0686-1315
R50 All 0811-3174
R51 All 0698-6076
R52 All 0757-0280
R53 All 0698-4121
R54 All 0683-2015
R55 6023A 0683-5655
R55 6028A 0683-1055
R56 6023A 0757-0408
R56 6028A 0757-0269
R57 6023A 0683-1325
R57 6028A 0683-2015
R58 All 0683-1045
R59 All 0698-8816
R60 All 0757-0199
R61 6023A 0699-0059
R61 6028A 0698-6360
R62 6023A 0698-3432

Resistor 130

Ω 5% 1/2W

Resistor 0.07
Resistor 39K
Resistor 1K

Ω 1% 1/8W

Resistor 11.3K
Resistor 200

Ω 5% 1/4W

Resistor 5.6M
Resistor 1M
Resistor 243
Resistor 270

Ω 5% 1/4W

Ω 1% 1/4W
Ω 1/4W

Resistor 1.3K
Resistor 200

Ω 5% 1/4W

Resistor 100K
Resistor 2.15
Resistor 21.5K
Resistor 5K

Ω 0.1% 0.1W

Resistor 10K
Resistor 26.1

Ω 5% 5W

Ω 1% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 1% 1/8W

Ω 1% 1/8W

Ω 0.1% 1/8W

Ω 1% 1/8W

R62 6028A 8159-0005 Wire tinned copper AWG 22
R63 6023A 0699-0059
R63 6028A 0698-6360
R64 All 0683-5125
R65,66 6023A 0699-0118
R65 6028A 0699-1210
R66 6028A 0699-1211
R67,68 All 0686-5125
R69 All 0683-2225
R70 All 0683-2015
R71 6023A 0683-2735
R71 6028A 0698-5089
R72 6023A 0757-0465
R72 6028A 0757-0470
R73,74 6023A 0683-2035
R73,74 6028A 0757-0452
R75 All 0683-7545
R76 6023A 0683-4735
R76 6028A 0757-0446
R77 6023A 0683-7545
R77 6028A 0757-0469
R78 6023A 0757-0415
R78 6028A 0698-4014
R79 All 0698-6983
R80 All 0698-6320
R81 All 0757-0459
R82 All 0683-3325
R83 All 0757-0270
R84 6023A 0683-5125
R84 6023A 0757-0442

Resistor 5K

Ω 0.1% 0.1W

Resistor 10K
Resistor 5.1K
Resistor 20K
Resistor 80K
Resistor 95K
Resistor 5.1K
Resistor 2.2K
Resistor 200

Ω 5% 1/4W

Resistor 27K
Resistor 33K
Resistor 100K
Resistor 162K
Resistor 20K
Resistor 27.4K
Resistor 750K
Resistor 47K
Resistor 15K
Resistor 750K
Resistor 150K
Resistor 475
Resistor 787

Ω 1% 1/8W
Ω 1% 1/8W

Resistor 20.4K
Resistor 5K

Ω 0.1% 1/8W

Resistor 56.2K
Resistor 3.3K
Resistor 249K
Resistor 5.1K
Resistor 10K

Ω 1/8W

Ω 5% 1/4W
Ω 0.1% 0.1W
Ω 0.1% 0.1W
Ω 0.1% 0.1W

Ω 5% 1/2W

Ω 5% 1/4W

Ω 5% 1/4W
Ω 1% 1/8W

Ω 1% 1/8W
Ω 1% 1/8W

Ω 5% 1/4W

Ω 1% 1/8W

Ω 5% 1/4W
Ω 5% 1/4W
Ω 1% 1/8W

Ω 5% 1/4W

Ω 1% 1/8W

Ω 0.1% 1/8W

Ω 0.1% 1/8W

Ω 5% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W

Ω 1% 1/8W

60

Table 5-4. A2 Control Board Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

R85 All 0698-3450
R86 All 0757-0452
R87 All 0683-2715
R88,89 All 0683-2225
R90 All 0683-2715
R91 All 0683-2225
R92 All 0683-2015
R93 All 0686-5125
R94 All 0686-1035
R95 All 0757-0472
R96 6023A 0698-3572
R96 6028A 0757-0455
R97 All 0686-5125
R98 All 0686-2735
R99 All 0686-1035
R100,101 All 1810-0365
R102,103 All 0757-0449
R104 All 0757-0280
R105 All 0698-3430
R106 All 0698-3449
R107 All 0698-3153
R108 All 0683-2035
R109 All 0683-2225
R110 All 0683-4725
R111 All 0683-2025
R112 All 0683-1125
R113 All 0757-0442
R114 All 0757-0424
R115 All 0683-1015
R116 All 0683-3498
R117 All 0757-0438
R118 All 1810-0365
R119 All 0757-0288
R120 All 0683-1005
R121 All 0757-0442
R122 All 0683-5135
R123-126 All 0683-4725

Resistor 42.2K
Resistor 27.4K
Resistor 270
Resistor 2.2K
Resistor 270
Resistor 2.2K
Resistor 200
Resistor 5.1K
Resistor 10K
Resistor 200K
Resistor 60.4K
Resistor 36.5K
Resistor 5.1K
Resistor 27K
Resistor 10K

Ω 1% 1/8W
Ω 1% 1/8W

Ω 5% 1/8W

Ω 5% 1/4W

Ω 5% 1/8W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 1% 1/8W

Ω 1% 1/8W
Ω 1% 1/8W

Ω 5% 1/4W
Ω 5% 1/4W
Ω 5% 1/4W

Network sip 2.2K
Resistor 20K
Resistor 1K
Resistor 21.5K
Resistor 28.7K
Resistor 3.38K
Resistor 20K
Resistor 2.2K
Resistor 4.7K
Resistor 2K
Resistor 1.1K
Resistor 10K
Resistor 1.1K
Resistor 100
Resistor 8.66K
Resistor 5.11K

Ω 1% 1/8W

Ω l% 1/8W

Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W
Ω 1% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W

Ω 1% 1/8W
Ω 1% 1/8W

Network sip 2.2K
Resistor 9.09
Resistor 10
Resistor 10K
Resistor 51K
Resistor 4.7K

Ω 1% 1/8W

Ω 5% 1/4W

Ω 1% 1/8W
Ω 5% 1/4W

Ω 5% 1/4W

Ω X5

Ω X5

R127 All 0683-1855 Resistor 1.8MO 5% 1/4W
R128 All 0683-6835
R129 All 0757-0439
R130 All 0683-1055
R131 All 0683-3335
R132 All 0683-2225
R133 All 0683-2735
R134 All 0757-0466
R135,136 All 0757-0442
R137 All 0698-3455
R138 All 0683-2045

Resistor 68K
Resistor 6.8K
Resistor 1M

Ω 5% 1/4W

Resistor 33K
Resistor 2.2K
Resistor 27K
Resistor 110K
Resistor 10K
Resistor 261K
Resistor 200K

Ω 5% 1/4W

Ω l% 1/8W

Ω 5% 1/4W

Ω 5% 1/4W
Ω 5% 1/4W

Ω 1% 1/8W

Ω 1% 1/8W

Ω 1% 1/8W
Ω 5% 1/4W

61

Table 5-4. A2 Control Board Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

R139 All 0757-0442
R140 All 0698-3160
R141 All 0683-1025
R142 All 0683-2225
R143 All 0683-1045
R144 All 0683-4725
R145 All 0683-4715
R146,147 All 0683-1125
R148 All 0683-3925
R149 All 1810-0365
R150,151 All 0683-1815
R152 All 0683-1025
R153 6028A 0683-1035
R155,158 6023A 8159-0005
R155 6028A 0683-1005
R156-158 6028A 0683-1005

Resistor 10K
Resistor 31.6K
Resistor 1K
Resistor 2.2K
Resistor 100K
Resistor 4.7K
Resistor 470
Resistor l.1K
Resistor 3.9K

Ω 1% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Network sip 2.2K
Resistor 180
Resistor 1K
Resistor 10K
Resistor 0
Resistor 10
Resistor 10

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω

Ω 5% 1/4W
Ω 5% 1/4W

Ω X5

S1 All 3101-2097 Switch 6-lA slide
U1 All 1826-0493 IC op amp lo-bias hi-impedance
U2 All 1826-0346 IC op amp dual general purpose
U3 All 1826-0161 IC op amp quad general purpose
U4 All 1826-0527 IC voltage regulator 1.2/37V
U5 All 1826-0544 IC voltage reference 2.5V
U6 All 1826-0428 IC voltage regulator 1/40V
U7,8 All 1826-0493 IC op amp lo-bias hi-impedance
U9 All 1826-0544 IC voltage reference 2.5V
U10 All 1826-0161 IC op amp quad general purpose
U11 All 1820-1209 IC flip flop D-type
U12 All 1826-0393 IC voltage regulator 1.2/37V
U13 All 1820-1112 IC flip flop D-type
U14 All 1820-0138 IC comparator quad
U15 All 1820-1437 IC multivibrator monostable dual
U16 All 1820-0065 IC comparator precision
U17 All 1820-1246 IC gate quad AND
U18 All 1820-0935 IC counter binary CMOS
U19 All 1820-1205 IC gate dual AND
U20 All 1826-0138 IC comparator quad
U21 All 1826-0065 IC comparator precision
U22 All 1820-2096 IC counter binary dual
VR1,2 All 1902-0018 Diode zener 11.7V 5%
VR3 All 1902-0777 Diode zener 6.2V 5%
VR4 All 1902-3110 Diode zener 5.9V 2%
VR5 All 1902-0575 Diode zener 6.5V 2%
W1-3 All 7175-0057 Jumper wire 22 AWG
Y1 All 0960-0586 Resonator 320kHz

62

MECHANICAL PARTS
6028A 5060-2942 Heatsink (Q2, U15, 16)
6028A 1200-0181 Insulator
6028A 1200-0485 Socket (S1)
6028A 0360-2195 Terminal block, 6-position
6028A 1531-0309 Clevis, tapped

Table 5-5. A3 Front-Panel Board Parts List

Ref. Desig. Agilent Model Agilent Part Number Description

ELECTRICAL PARTS

A3 6023A 06023-60020 Front-Panel Board Assembly
A3 6028A 06028-61020 Front-Panel Board Assembly

C1 All 0160-4807
C2-4 All 0160-5422
C5 All 0160-4805
C6 All 0160-4835
C7 All 0160-0168
C8 All 0160-5893
C9 All 0160-5422
C10 All 0160-4805
C11 All 0160-4835
C12 All 0160-0168
C13 All 0160-5893
C14-15 All 0160-5422

Capacitor, fixed ceramic 33pF
Capacitor, fixed ceramic 0.047
Capacitor, fixed ceramic 47pF
Capacitor, fixed ceramic 0.1
Capacitor, fixed ceramic 0.1/1F
Capacitor, fixed met 0.047
Capacitor, fixed ceramic 0.047
Capacitor, fixed ceramic 47pF
Capacitor, fixed ceramic 0.1
Capacitor, fixed ceramic 0.1
Capacitor, fixed ceramic 0.047
Capacitor, fixed ceramic 0.047

±5% 100V
µF ±20% 5OV
±5% 100V

µF ±10% 50V

±10% 200V

µF ±10% 100V

µF ±20% 50V

±5% 100V
µF ±10% 50V
µF ±10% 200V

µF ±10% 100V

µF ±20% 50V

C16 All 0160-4831 Capacitor, fixed ceramic 4700pF 10% 100V
C17 All 0160-5422
C80 All 0160-4835

Capacitor, fixed ceramic 0.047
Capacitor, fixed ceramic 0.1

µF ±10% 50V

µF ±20% 50V

CR1,2 All 1901-0033 Diode general purpose 180V 200mA
CR3,4 All 1901-0050 Diode switching 80V 200mA
CR5 All 1901-0033 Diode general purpose 180V 200mA
DS1-8 6023A 1990-0985 Display kit
DS1 6028A 1990-0681 Display, analog
DS2-4 6028A 1990-0540 Display, numeric
DS5 6028A 1990-0681 Display, analog
DS6-8 6028A 1990-0540 Display, numeric
DS9,10 All 1990-0951 LED, green
J1 All 1251-5055 Connector, post type 26-contacts
R1 All 0683-3925
R2 All 0683-6815
R3 All 0683-2025

Resistor, composition 3.9K
Resistor, composition 680
Resistor, composition 2K

Ω 5% 1/4W

Ω 5% 1/2W

Ω 5% 1/4W

R4,5 6023A See Chassis Electrical
R6 All 2100-1775
R7 6023A 0757-0415
R7 6028A 0698-4457
R8 All 0683-1045
R10-57 All 0683-2015
R58 All 0683-6215
R59 All 0757-0458
R60 All 0757-0270
R61,62 All 0683-5615
R63 All 0757-0458
R64 All 0757-0270
R65 All 0683-1045
R66 All 0698-8498
R67 6023A 0699-0721
R67 6028A 0757-7929

Termistor 5K
Resistor, fixed film 475
Resistor, fixed film 576

Ω 5% 1-turn side adjust

Ω 1% 1/8W
Ω 1% 1/8W

Resistor, fixed composition 100K
Resistor, fixed composition 200
Resistor, fixed composition 620
Resistor, fixed film 51.1K
Resistor, fixed film 249K

Ω 1% 1/8W

Ω 1% 1/8W

Resistor, fixed composition 560
Resistor, fixed film 51.1K
Resistor, fixed film 249K

Ω 1% 1/8W

Ω 1% 1/8W

Resistor, fixed composition 100K
Resistor, fixed film 1.02K
Resistor, fixed film 33K
Resistor, fixed film 9.09K

Ω 0.1% 1/8W

Ω 0.1% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W
Ω 5% 1/4W
Ω 5% 1/2W

Ω 5% 1/4W

Ω 5% 1/4W

63

Table 5-5. A3 Front-Panel Board Parts List

Ref. Desig. Agilent Model Agilent Part Number Description

R68 All 0698-6362
R69 All 0698-6343
R71 6023A 0698-6363
R71 6028A 0698-8861
R72 6023A 0698-7353
R72 6028A 0698-4493
R73 6023A 0757-0280
R73 6028A 0698-3476
R74 All 0683-1025
R75 All 0683-3025
R77 All 0757-0458
R78 All 0698-3159
R79 All 0757-0441
R80 All 0757-0438
R81 All 0683-5135
R82 All 0683-1025
R83 All 0683-5125
R84 All 0683-1025
R85 All 0757-0280
R86 All 0698-5808
R87 6023A 0698-3201
R87 6028A 0757-0449
R88 6023A 0757-0449
R88 6028A 0757-0453
R89 All 0683-5135
R90 All 0757-0199
R91 All 0683-5235
R92,93 All 0757-0452

Resistor, fixed film 1K
Resistor, fixed film 9K
Resistor, fixed film 40K
Resistor, fixed film 6.66K
Resistor, fixed film 19K
Resistor, fixed film 34K
Resistor, fixed film 1K
Resistor, fixed film 6.00K
Resistor, fixed film 1K

Ω 0.1% 1/8W
Ω 0.1% 1/8W

Ω 0.1% 1/8W

Ω 0.1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W

Ω 1% 1/8W

Ω 1% 1/8W

Ω 5% 1/4W

Resistor, fixed composition 3K
Resistor, fixed film 51.1K
Resistor, fixed film 26.1K
Resistor, fixed film 8.25K
Resistor, fixed film 5.11K

Ω 1% 1/8W

Ω 1% 1/8W

Ω 1% 1/8W

Ω +1% 1/8W

Resistor, fixed composition 51K
Resistor, fixed composition 1K
Resistor, fixed composition 5.1K
Resistor, fixed composition 1K
Resistor, fixed film 1K
Resistor, fixed film 4K
Resistor, fixed film 80K
Resistor, fixed film 20K
Resistor, fixed film 20K
Resistor, fixed film 30.1K

Ω 1% 1/8W
Ω 1% 1/8W

Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W

Ω 1% 1/8W

Resistor, fixed composition 51K
Resistor, fixed film 21.5K

Ω + 1% 1/4W

Resistor, fixed composition 51K
Resistor, fixed film 27.4K

Ω 1% 1/8W

S1,2 All 5060-9436 Switch lighted pusbutton
U1 All 1826-0502 IC switch analog quad
U2 All 1826-0493 IC op amp lo-bias hi-impedance
U3 All 1826-0346 IC op amp dual general purpose
U4,5 All 1826-0876 IC A/D CMOS 3-1/2 DGT
U6 All 1820-1144 IC gate TTL LS NOR quad
U7 All 1826-0502 IC switch analog quad
U9 All 1826-0138 IC comparator GP quad
VR1 All 1902-3092 Diode zener 4.99V 2%
VR2 All 1902-0064 Diode zener 7.5V 5%
W4 All 7175-0057 Wire 22 AWG
W7 6028A 7175-0057 Wire 22 AWG
W8 6023A 7175-0057 Wire 22 AWG
W11 All 7175-0057 Wire 22 AWG

Ω 5% 1/4W

Ω ± % 1/4W

Ω 5% 1/4W

Ω ~5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

Ω 5% 1/4W

64

Table 5-6. A4 Power Mesh Parts List

Ref. Desig. Agilent Model Agilent Part Number Description

A4 06038-61022 Power Mesh Assembly

C1 All 0160-5891
C2 All 0160-5422

Fixed met 0.47
Fixed cer 0.047

µF +l0% 630V

µF +20% 50V

C5,6 All 0160-4960 Fixed film 2200pF +10% 1.6kV
C7 All 0180-0155
C8 All 0160-0127
C9 All 0180-2780
C10 All 0160-4834
C11,12 All 0160-4835
C13 All 0160-0161

Fixed elect 2.2
Fixed ceramic l
Fixed elect 470
Fixed cer 0.047
Fixed cer 0.1

µF +10% 50V

Fixed poly 0.01

µF +20% 20V

µF +20% 25V

µF +75-10% 16V

µF +10% 100V

µF +10% 200V

CR1-4 All 1901-0050 Switching 80V 200mA
CR5,6 All 1901-1065 Pwr rect 400V lA
CR7 All 1901-1127 Pwr rect 150V 70A
CR10,11 All 1901-0050 Switching 80V 200mA
CR13,14 All 1901-1087 Pwr rect 600V 3A
F1,2 All 2110-0671 Axial lead, 1/8A
F3 6023A 2110-0699 Fuse, 5A 125V
F3 6028A 2110-0688 Fuse, 5A 125V
L3 All 06024-80096 Inductor, 3A
L4 All 9170-1265 Core, ferrite, 5uH
P1,2 All 1251-8807 Connector, DIN type 32-contact F
Q1,2 All 1854-0477 NPN SI
Q3,4 6023A 1855-0916 MOSFET N-channel
Q3,4 6028A 1855-0547 PFET
Q6 All 1854-0264 NPN SI
Q7 All 1855-0549 PFET
R1,2 All 0686-0275 Fixed comp. 2.7 5% 1/2W
R3 All 0683-3915 Fixed comp. 390 5% 1/4W
R4 All 0683-1015 Fixed comp. 100 5% 1/4W
R5 All 0683-4705 Fixed comp. 47 5% 1/4W
R6 All 0683-1045 Fixed comp. l00K 5% 1/4W
R7 All 0811-1857 Fixed ww 400 5% 5W
R8 All 0698-3601 Fixed met ox 10 5% 2W
R9 All 0683-3915 Fixed comp. 390 5% 1/4W
R10 All 0683-1015 Fixed comp. 100 5% 1/4W
R11 All 0683-4705 Fixed comp. 47 5% 1/4W
R12 All 0683-1045 Fixed comp. 100K 5% 1/4W
R13 All 0811-1857 Fixed ww 400 5% 5W
R14 All 0698-3601 Fixed met ox 10 5% 2W
R15 All 0757-0403 Fixed film 121 1% 1/8W
R16 All 0683-3305 Fixed comp. 33 5% 1/4W
R17 All 0683-1025 Fixed comp. 1K 5% 1/4W
R18 All 0683-0475 Fixed comp. 4.7 5% 1/4W
R19 All 0683-2025 Fixed comp. 2K 5% 1/4W
R20 All 0683-0275 Fixed comp. 2.7 5% 1/4W
R21,22 All 0683-0475 Fixed comp. 4.7 5%. 1/4W
R23 All 0683-2725 Fixed comp. 2.7K 5% 1/4W

65

Table 5-6. A4 Power Mesh Parts List (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

R24 All 0757-0464 Fixed film 90.9K 1% A 1/8W
R25 All 0686-1005 Fixed comp. 10 5% 1/2W
R26 All 0811-2490 Fixed ww 0.1 3% 5W
R27 All 0698-3225 Fixed film 1.43k 1% 1/8W
R28 All 0757-0279 Fixed film 3.16K 1%1/8W
R29 All 0698-3159 Fixed film 26.1K 1%1/8W
R30 All 0698-3202 Fixed film 1.74K 1% 1/8W
R31 All 0698-4046 Fixed film 732 1% 1/8W
R32 All 0757-0442 Fixed film 10K 1% 1/8W
R33 All 0698-3601 Fixed met ox 10 5% 2W
R34 All 0698-4484 Fixed film l9.1K 1% 1/8W
R35,36 All 0683-3305 Fixed comp. 33 5% 1/4W
R37 All 0683-3325 Fixed comp. 3.3k 5% 1/4W
R39 All 0683-1055 Fixed comp. 1M 5% 1/4W
T1,2 All 5080-1983 transformer, FET driver
T3 All 9100-4350 transformer, current
TS1 All 3103-0116 Switch, thermal 100 C
TP1-4 All 1251-0646 Contact connector, post type
U1,2 All 1820-1050 IC DRVR TTL NOR dual
U3 All 1826-0346 IC op amp GP dual
U4 All 1826-0393 IC voltage regulator 1.2/37V
VR2 All 1902-3002 Zener 2.37V 5V
VR3 All 1902-0057 Zener 6.49V 5V
VR4 All 1902-0575 Zener 6.5V 2V

CHASSIS ELECTRICAL

R4,R5 6023A 2100-4060 Resistor, variable, 5K (ref. front-panel)

All 3160-0343 Fan, axial tube
All 9135-0223 Line filter, IEC
All 8120-1348 Cable assembly (power cord) 18 AWG
All 8120-4353 Cable assembly (A1 board to A3 board)
All 8120-4383 Cable assembly (Line Cord)

66

Table 5-7. Other Replacement Assemblies

Ref. Desig. Agilent Model Agilent Part Number Description

A1 Board Mechanical Parts

6023A 1251-0600 Contact-conn M (Ref Fan)
A1J1 All 1251-5927 Connector post type header
A1J2 All 1251-5384 Connector post type header
A1J3 All 1251-8676 Connector post type
XA2P1 All 1251-8665 Connector post type
XA2P2 All 1251-8667 Connector post type
XA4P1,P2 All 1251-8806 Din Connector

All 1251-5613 Single contact connector (ref. AC line

voltage select)
All 1480-0552 Pin, escutcheon (ref. L1)
All 2110-0269 Fuseholder, clip type (ref. F2)

A1TB1 All 0360-2192 Barrier block

All 0360-2190 Jumper, barrier block

A2 Board Mechanical Parts

A2P1 All 1251-8664 Connector post type
A2P2 All 1251-8666 Connector post type
A2J1, J2 All 1251-8417 Din Connector

All 1200-0485 Socket, IC 14-contact (ref.
All 1205-0282 Heatsink (ref. Q2, U15, U16)
All 1531-0309 Clevis (ref. A2 Board)
All 0360-2195 Barrier block

A3 Board Mechanical Parts

All 4040-2121 Plastic (ref. DS9-12)

A1J1 All 1251-5055 Connector post type header

A4 Board Mechanical Parts

A4P1,P2 All 1251-8807 Din Connector

All 0362-0335 Single contact Connector (AC)

6023A 1205-0919 Heatsink (ref. Q3, Q4)
6028A 1205-0256 Heatsink (ref. Q3, Q4)

All 1205-0282 Heatsink (ref. Q7)
All 1531-0309 Clevis (ref. A4 Board)
All 06023-20001 Heatsink (ref. CR7)
All 06023-80002 Jumper, 10 AWG

6028A 0380-1679 Hex head stand off (ref.Q3, Q4)

TP1-4 All 1251-0646 Connector single contact (pin)

CHASSIS MECHANICAL PARTS

All 0380-1489 Spacer, snap in
All 0370-1091 Knob, base round
All 0403-0282 Bumper feet
All 1510-0044 Binding post, single

6023A 2110-0564 Fuseholder body (chassis fuse)
6023A 2110-0565 Fuseholder cap (chassis fuse)
6023A 2110-0569 Fuseholder nut (chassis fuse)
6028A 2110-0926 Fuseholder assembly, (chassis fuse)

All 3160-0309 Finger guard (ref. fan)

67

Table 5-7. Other Replacement Assemblies (continued)

Ref. Desig. Agilent Model Agilent Part Number Description

All 4040-1954 Window, display

6023A 5020-8847 Trim strip

All 5041-8803 Trim strip, top
All 5001-0540 Trim, side 7in
All 5021-8417 Frame front
All 5041-8801 Foot
All 5041-8819 Retainer, strap handle
All 5041-8820 Retainer, strap handle
All 5041-0309 Key cap, quarter
All 5062-3703 Assembly, handle strap
All 7120-1254 Nameplate
All 7120-8572 Canadian Standards Association Label (ref.

rear panel)
All 7121-2527 Metric and Inch Label (ref. rear panel)
All 7121-2794 Serial Identification Label (ref. rear panel)

6023A 06023-00016 Chassis
6028A 06023-00001 Chassis

All 06023-00020 Cover, top
All 06023-00022 Cover, bottom

6023A 06023-00004 Bracket, upper
6023A 06023-00014 Panel, sub
6023A 06023-00018 Sub panel, front
6023A 06023-00007 Bus bar, negative
6023A 06023-00008 Bus bar, positive

All 06023-00009 Cover, bar block

6023A 06023-00010 Cover,(top plate screened)
6028A 06023-00026 Cover,(top plate screened)
6023A 06023-00019 Rear panel, screened
6028A 06023-00011 Rear panel, screened

All 06028-00021 Front-panel, screened
All 06023-81003 Line Voltage Label (ref. rear panel) 28480

6023A 06023-90001 Operating and Service manual
6028A 06028-90001 Operating and Service manual
6023A 1990-0521 Cover, terminal block

Option 220 (220V Operation)

68

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

Option 240 (240V Operation)

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

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.

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.)

b.

Notes (Table 6-1) that apply to all schematic diagrams.

c.

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.

6

69

Table 6-1. Schematic Diagram Notes

1. denotes front-panel marking.

2.

denotes rear-panel marking.

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

4. 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.

5. Unless otherwise noted, capacitor values are in microfarads.

6. 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.

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

 indicates shift away from control block (normally down and to right).  indicates shift toward control block

(normally up and to left).

8.

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.

9. Inter-board commons have letter identifications (e.g. : ); commons existing on a single assembly have number
identifications (e.g.: ).

10. 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.:

70

Table 6-1. Schematic Diagram Notes (continued)

Pin locations for other semi-conductors are shown below:

71

72

Figure 6-1. Top View, Top Covers Removed

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

73

74

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

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

75

76

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.

79

Remote Programming

Table A-1. Specifications, Option 002

Resistance Programming:

Accuracy: @25°C

0 to 4K ohm provides 0 to maximum rated voltage or current output.

CV: 0.5% + 12mV (6023A) 0.5% + 70mV (6028A)

CC: 1.0% + 110mA (6023A) 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) 0.33% + 70mV (6028A)
CC: 0.30% + 110mA (6023A) 0.36%

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

Accuracy: @25°C

CV: 0.38% + 16mV (6023A) 0.43%

± 500mA (6028A)

± 71mV (6028A)

CC: 0.43% + 115mA (6023A) 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) 0.39% + 15mV (6028A) TC: 10ppm +0.2mV/

CC: 0.30% + 15mA (6023A) 0.36% + 20mA (6028A) TC: 70ppm +1.5mA/

Output Impedance: 10.2 k ohm ± 5%
Temperature Coefficient:

°C
°C

CV: 70 ppm/°C +600µV/°C (6023A) 12.5 ppm/°C +810µV/°C (6028A)
CC: 100 ppm/

Status Indicators:

°C + 2.0mA/°C (6023A) 47 ppm/°C + 1.6mA/°C (6028A)

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

80

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 (

TripRemote , ResetRemote ) Inhibit Remote .

On State (logic low):
Minimum forward current required (I

): 1.6mA Isolator forward voltage (V

f

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

) at 1.6mA (If): 1.4V typical, 1.75

f

Pulse duration (TL): 15µS minimum
Reset time (TH): 125
Set-up time (Ts): 25
OVP clear delay: 1 sec

µs minimum

µs minimum

± 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

81

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

± 3% at 75mA

+15V

± 4% at 75mA

-15V

Short Circuit Output Current:

+5V 125mA ± 6%
+ 15V 103mA

-15V 103mA

PARD (Typical):

± 6%
± 6%

+ 5V 25mV pk-pk 1.5mV Rms
+ 15V Same Same

-15V 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

82

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.

Attach ribbon cables from the A2 Control Board A2J1 to A7J1 and A2J2 to A7J2.

e.
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.

a. 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.

b. 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.

c.

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

d.

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.

e. 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

f.

is oriented as shown in Figure A-1.

g.

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

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

h.

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

i.

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

j.

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

k.

on either side of J3.

83

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 B2 B3 B4 B5 B6

011011

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.

84

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.

85

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

Switch Pole Settings

Program Source

Mode

B1 B2 B3 B4 B5 B6

Resistance
Voltage or
Current

001001
010010

86

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.

87

Figure A-5. Remote Resistance Programming

88

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

Current Programming (Figure A-7).

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.

Check switches A1 and A2 on the rear panel, they must be in the correct positions

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).

89

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 1
capacitor is installed directly across the monitor device input terminals .

µF. The

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.

MODECV , J3-36, indicates that the power supply is in constant voltage operation.

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

b.

DUNREGULATEOUTPUT , J3-18, indicates that the power supply is in neither constant voltage nor constant

c.

current operation and cannot be guaranteed to meet specifications.

d.

EOVERVOLTAG , 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.

e.

ATUREOVERTEMPER , 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.

90

Remote Trip.

reducing the output voltage to near zero. For minimum pulse duration and timing considerations with respect

to

and Figure A-8).

A negative-going edge applied to terminal J3-30 ( TRIPREMOTE ) will shut down the power supply,

RESETREMOTE , See Table A-1. The following paragraph provides a brief circuit description (See schematic diagram

A negative going edge at

TRIP/RESET latch (U5A) low. This sets terminal J1-13 (
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

EOVERVOLTAG 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 ( RESETREMOTE ) 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

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 (

U13A then triggers and resets the TRIP/RESET latch output high. This sets terminal J1-13 (
the power supply's Pulse Width Modulator.

The

shut down the supply. When a

CLEAR pulse at terminal J1-12. The

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
power supply .

RESETREMOTE signal will also reset the power supply OVP circuit in the event that an overvoltage condition has

TRIPREMOTE coupled through opto-isolator (U9) causes one-shot U13B to set the

INHIBIT ) low, thus inhibiting the Pulse Width Modulator of the

TRIPREMOTE See Table A-1 under Remote Control.

RESETREMOTE ) is coupled through opto-isolator U10. One-Shot

INHIBIT ) high, thus enabling

RESETREMOTE signal is present, ONE SHOT U13A goes low, this will produce an OV

CLEAROV pulse will cause the output of A2U2 to go low thus, resetting the OV

EOVERVOLTAG signal to U4B also goes high and enables the PWM of the

Note By observing the EOVERVOLTAG status indicator or the power supply's output while applying a reset

pulse to RESETREMOTE , the user can determine the cause of shutdown. If the output returns and

EOVERVOLTAG 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 INHIBITREMOTE 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

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 (

inhibit the power supply's (PWM) Pulse Width Modulator. If jumper W1 is used (See Figure A-8) while a

INHIBITREMOTE signal is applied, an EOVERVOLTAG signal will appear at terminal J3-17 EOVERVOLTAG thus,

indicating the power supply shut down.

INHIBITREMOTE ) is coupled through opto-isolator U8 and causes U4B to

INHIBITREMOTE is

91

Figure A-8. Remote Control

Power-On Preset

This open collector output line J3-6, provides a logic low pulse ( Preset-On -Power ) 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

Preset-On-Power signal specifications.

The

turned on. This protects against unwanted Multiple Supply System Shutdowns when using J3-17 (
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
11Vdc, an input voltage sufficient to assure + 5Vdc bias output.

PCLR signal is coupled through terminal J1-15 to the 002 Option board's power-on preset circuit. When the power-on

This

preset circuit receives the

Turning U14A off causes a

and U14D to turn on. When U14B is on, it holds output J3-17 (
any unwanted Multiple Supply Shutdowns from occurring when the supply is wired for such an application. When U10D is

92

Preset-On-Power circuit also ensures that terminal J3-17 ( EOVERVOLTAG ) will be high when the supply is

EOVERVOLTAG ) to

PCLR low until the unregulated input to the A2 Board's + 5Vdc bias supply is greater than about

PCLR signal, transistors U14A and U14C turn off.

DROPOUT signal to appear at terminal J3-19 ( DROPOUT ). Turning U14C off causes U14B

EOVERVOLTAG ) high. Holding J3-17 high will prevent

on, it causes J3-6 ( Preset-On-Power ) 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 (
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

DROPOUT ). The dropout signal indicates loss of primary power, momentary AC dropout, or "brownout"

The AC Dropout Buffer Circuit receives a
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.

DROPOUT signal from the A2 Control Board. This causes the bias voltage

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 EOVERVOLTAG line is connected to the next supply's TRIPREMOTE 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.

93

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

a. First bring the INHIBITREMOTE line low.

b.

Provide a negative-going pulse to the RESETREMOTE .

c. After at least one second, return INHIBITREMOTE 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,

down succeeding supplies upon initial sum-on. After the supplies have stabilized,

PCLR inhibits the EOVERVOLTAG indicator from going low and shutting

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 0.1

µF 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.

94

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.

a.

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

b.

Disconnect the ribbon cables from the A2 Control board.

c.

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

d.

Reconnect the option board to the A2 Control board using the extended ribbon cables from the Service Kit, and pace

e.

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

f.

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
option board.

± 11.8V on the

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.

b.

Check ± 15V and ± 11.8V supplies.

c. 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 .

d.

Troubleshooting Current Programming

a. Check ± 15V and ± 11.8V supplies.

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

b.

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

c.

not, check op-amps and associated circuitry.

d. 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.

95

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.

96

Figure A-13. Troubleshooting Status Indicators

To check Mode CV proceed as follows:
a.

Using test set-up, Figure A-13, connect to end of 2KΩ resistor to J3-36.

Turn on power supply.

b.
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.

Turn on power supply.

f.
g.

DVM should read approximately 5Vdc.

To check

a.

Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-35.

Turn on power supply.

b.
c.

Using "Display Settings'' set voltage for 1 volt and current for 1 Amp.

d.

DVM should read = 5Vdc.

Turn off power supply and short the output terminals.

e.
f.

Turn on power supply.

g.

DVM should read between 0 and 0.4Vdc.

To check

a.

Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-17.

Turn "OVP Adjust" fully clockwise and voltage control fully counter clockwise.

b.
c.

Open power supply output terminals and turn on power.

DVM should read approximately 5Vdc.

d.
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

a.

Using test set-up, Figure A-13, connect to end of 2KΩ to J3-18.

Connect output terminals of power supply to an electronic load capable of exceed the power supplies output power

b.

Mode CC proceed as follows:

EOVERVOLTAG proceed as follows:

ED UNREGULATOUTPUT proceed as follows:

rating by 50%.

97

c. Turn on power supply.
d.

DVM should read approximately 5Vdc.

Set voltage and current controls of power supply to maximum.

e.
f.

Decrease resistance of electronic load until "UNREGULATED" LED on front-panel lights.

a.

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.

Substitute an oscilloscope in place of DVM. Set vertical deflection for 1 volt/div on the DC input.

b.
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.

Turn power off. Voltage should go to about 5Vdc before decaying back to 0V.

d.

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 ATUREOVERTEMPER 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.

Turn on power supply.

e.
f.

DVM should read approximately 5VAC.

g.

Turn off power and wait two minutes.

h.

Remove the A4 FET Assembly from the unit.

Turn on power supply. DVM should read between 0 to 0.4Vdc.

i.

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

a.

Connect +5V (J3-23) to Control Isolator bias (J3-l0).

b.

Turn unit on and short TRIP REMOTE (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

a.

Table A-3. Replacement Connect +5V (J3-23) to control isolator bias (J3-10).

b.

Turn unit on and short INHIBIT REMOTE (J3-31 ) to + 5V common (J3-7). Output should go to an unregulated

output off condition.

c.

Remove short between INHIBIT REMOTE (J3-31 ) and + 5V common (J3-7) and output should return to its initial

state.

TRIP REMOTE and RESET REMOTE proceed as follows:

INHIBIT REMOTE proceed as follows:

98

Table A-3. Replacement Parts

REF. DESIG. MODEL NO. PART NO. DESCRIPTION

A7 All 5060-2854 Opt. 002 Interface Board

C1,2 All 0180-0230
C3 All 0180-2825
C4 All 0160-4835
C5 All 0160-4554
C6 All 0160-4835
C7 All 0160-4554
C8,9 All 0180-0230
C10 All 0180-2825

fxd elect. 1
fxd elect. 22
fxd cer. 0.1
fxd cer. 0.0
fxd cer. 0.1
fxd cer. 0.0
fxd elect. 1
fxd elect. 22

µF 20% 50V

µF 50V
µF 10% 50V
µF 20% 50V
µF l0% 50V
µF 20% 50V

µF 20% 50V

µF 50V

C11 All 0160-4801 fxd cer. 100pf 5% l00V
C12,13 All 0160-5422

fxd cer. 0.047

µF 20% 50V

C14 All 0160-4801 fxd cer. 100pfF 5% l00V
C15 All 0160-5422
C16 All 0160-5422
C17,18 All 0180-0230
C19 All 0180-2825
C20-22 All 0160-0128

fxd cer. 0.047
fxd cer. 0.047
fxd elect. 1

µF 20% 50V

fxd elect. 22
fxd cer. 2.2

µF 20% 50V

µF 20% 50V
µF 20% 50V

µF 50V

CR1-4 All 1901-0050 switching 80V 200ma
CR5-10 All 1901-0327 pwr. rect. 300V 40A
CR11-14 All 1901-0033 gen. prp. 180V 200ma
CR15 All 1901-0327 zener 9.09V 10% PD=1.5W
CR16,17 All NOT USED
CR18,19 All 1901-0050 switching 80V 200ma
CR20 All 1901-0033 gen. prp. 180V 200ma
CR21,22 All 1901-0050 switching 80V 200ma
CR23 All 1901-0033 gen. prp. 180V 200ma
CR24,25 All 1901-0050 switching 80V 200ma
CR26-29 All 1901-0033 gen. prp. 180V 200ma
CR30 All 1901-0327 zener 9.09V 10% PD=1.5W
K1,2 All 0490-1418 relay 250ma 28V,5V –coil 3VA
L1-3 All 9170-1223 core shielding bead
Q1,2 All 1854-0823 NPN SI PD=300mW FT=200MHZ
R1-3 All 0683-2015 fxd. film 200 5% 1/4W
R4 All 0683-3925 fxd. film 3.9K 5% 1/4W
R5 All 0683-2035 fxd. film 20K 5% 1/4W
R6 All 0683-3035 fxd. film 30K 5% 1/4W
R7 All 0683-6225 fxd. film 6.2K 5% 1/4W
R8,9 All 0683-2035 fxd. film 20K 5% 1/4W
R10 All 0683-1035 fxd. film 10K 5% 1/4W
R11 All 0683-5125 fxd. film 5.1K 5% 1/4W
R12 All 0757-0984 fxd. film 10 1% 1/2W
R13 All 0683-1615 fxd. film 160 5% 1/4W
R14 All 0683-4715 fxd. film 410 5% 1/4W
R15,16 All 0683-1235 fxd. film 12K 5% 1/4W
R17 All 0686-1525 fxd. film 1.5K 5% 1/4W
R18 All 0683-1535 fxd. film 15K 5% 1/4W
R19 All 0683-4715 fxd. film 470 5% 1/4W
R20,21 All 0683-1235 fxd. film 12K 5% 1/4W

99

Table A-3. Replacement Parts

REF. DESIG. MODEL NO. PART NO. DESCRIPTION

R22 All 0686-1525 fxd. film 1.5K 5% 1/4W
R23 All 0683-1535 fxd. film 15K 5% 1/4W
R24 All 0683-4715 fxd. film 470 5% 1/4W
R25,26 All 0683-1235 fxd. film 12K 5% 1/4W
R27 All 0686-1525 fxd. film 1.5K 5% 1/4W
R28 All 0683-1535 fxd. film 15K 5% 1/4W
R29,30 All 0698-4479 fxd. film 14K 1% 1/8W
R31 All 0686-5125 fxd. comp. 5.lK 5% 1/2W
R32 All 0683-5125 fxd. film 5.1K 5% 1/4W
R33 All 0686-5125 fxd. comp. 5.1K 5% 1/4W
R34 All 0683-5125 fxd. film 5.1K 5% 1/4W
R35 All 0757-0986 fxd. film 12.1K 1% 1/2W
R36 All 0757-0269 fxd. film 270 1% 1/8W
R37 All 0683-4715 fxd. film 470 5% 1/4W
R38 All 0683-1035 fxd. film 10K 5% 1/4W
R39 All 0698-6631 fxd. film 2.5K .1% 1/8W
R40 All 0683-4715 fxd. film 470 5% 1/4W
R41 All 0813-0001 fxd. ww. 1K 5% 3W
R42 All 0683-4715 fxd. film 470 5% 1/4W
R43 All 0683-l035 fxd. film 10K 5% 1/4W
R44 All 0698-6631 fxd. film 2.5K .1% 1/8W
R45 All 0683-4715 fxd. film 470 5% 1/4W
R46 All 0813-0001 fxd. ww. 1K 5% 3W
R47 All 0683-1525 fxd. film 1.5K 5% 1/4W
R48 All 0683-3325 fxd. film 3.3K 5% 1/4W
R49 All 0683-2225 fxd. film 2.2K 5% 1/4W
R50,51 All 0683-3355 fxd. film 3.3M 5% 1/4W
R52,53 All 0683-1055 fxd. film 1M 5% 1/4W
R54 All 0757-0441 fxd. film 8.25K 1% 1/8W
R55 All 0757-0986 fxd. film 12.lK 1% 1/2W
R56 All 0757-0269 fxd. film 270 1% 1/8W
R57 All 0698-3226 fxd film 6.49K 1% 1/8W
S1 All 3101-2715 Switch-Slide 2-lA .1A 50V
U1-3 All 1990-0732 Opto-Isolator IF=20mA max.
U4 All 1820-1197 IC NAND gate TTL LS quad
U5 All 1820-1202 IC NAND gate TTL LS
U6 6023A 1826-0393 IC Voltage Reg.
U6 6028A 5060-2942 IC Voltage Reg. heatsink assy.
U7 6023A 1826-0551 IC Voltage Reg.
U7 6028A 5060-2945 IC Voltage Reg. heat sink assy.
U8-10 All 1990-0494 Opto-Isolator IF=20mA max.
U11 All 1820-1491 IC Buffer TTL LS, hex
U12 All 1820-1416 IC Schmitt-Trig. TTL LS, hex
U13 All 1820-l437 IC Multi. Vib. TTL LS
U14 All 1858-0023 Trans. Array 16-pin

U15 6023A 1826-0527 IC Voltage Reg.
U15 6028A 5060-2943 IC Voltage Reg. heatsink assy.
U16 6023A 1826-0277 IC Voltage Reg.
U16 6028A 5060-2950 IC Voltage Reg. heatsink assy.
U17,18 All 1826-0493 IC Op Amp Low-bias-High-Impd.

100