For instruments with higher serial numbers, a change page may be included.
5
Agilent Part No. 5959-3344 Printed in USA
Microfiche Part No. 5959-3345 September, 2000
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 Bureau of
Standards, to the extent allowed by the Bureau's calibration facility, and to the calibration facilities of other International
Standards Organization members.
WARRANTY
This Agilent Technologies hardware product is warranted against defects in material and workmanship for a period of three
years from date of delivery. Agilent Technologies software and firmware products, which are designated by Agilent
Technologies for use with a hardware product and when properly installed on that hardware product, are warranted not to
fail to execute their programming instructions due to defects in material and workmanship for a period of 90 days from date
of delivery. During the warranty period Agilent Technologies will, at its option, either repair or replace products which
prove to be defective. Agilent Technologies does not warrant that the operation of the software, firmware, or hardware shall
be uninterrupted or error free.
For warranty service, with the exception of warranty options, this product must be returned to a service facility designated
by Agilent Technologies. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products returned
to Agilent Technologies for warranty service. Except for products returned to Customer from another country, Agilent
Technologies shall pay for return of products to Customer.
Warranty services outside the country of initial purchase are included in Agilent Technologies product price, only if
Customer pays Agilent Technologies international prices (defined as destination local currency price, or U.S. or Geneva
Export price).
If Agilent Technologies is unable, within a reasonable time to repair or replace any product to condition as warranted, the
Customer shall be entitled to a refund of the purchase price upon return of the product to Agilent.Technologies.
LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the Customer,
Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental
specifications for the product, or improper site preparation and maintenance. NO OTHER WARRANTY IS EXPRESSED
OR IMPLIED. AGILENT TECHNOLOGIES. SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER'S SOLE AND EXCLUSIVE REMEDIES. AGILENT
TECHNOLOGIES SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.
ASSISTANCE
The above statements apply only to the standard product warranty. Warranty options, extended support contracts, product
maintenance agreements and customer assistance agreements are also available. Contact your nearest Agilent
Technologies Sales and Service office for further information on Agilent Technologies' full line of Support Programs.
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 an Agilent Technologies Sales and Service Office for service and repair to ensure that safety features
are maintained.
Instruments which appear damaged or defective should be made inoperative and secured against unintended operation until they can be
repaired by qualified service personnel.
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.
3
Safety Symbol Definitions
SymbolDescriptionSymbolDescription
Direct currentTerminal for Line conductor on permanently
installed equipment
Alternating currentCaution, risk of electric shock
Both direct and alternating currentCaution, hot surface
Three-phase alternating currentCaution (refer to accompanying documents)
Earth (ground) terminalIn position of a bi-stable push control
Protective earth (ground) terminal
(Intended for connection to external
protective conductor.)
Frame or chassis terminalOn (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.
Out position of a bi-stable push control
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.
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.
Calibration and Verification ............................................................................................................................................. 9
Principles of Operation ..................................................................................................................................................... 9
Calibration and Verification................................................................................................................................................ 11
Test Equipment Required ................................................................................................................................................... 11
Voltage Monitor Zero Calibration .................................................................................................................................. 15
Common Mode Calibration ............................................................................................................................................ 15
Remote Readback Zero Calibration................................................................................................................................ 15
Constant Voltage Full Scale Calibration......................................................................................................................... 17
Voltage Monitor and Remote Readback Full Scale Calibration ..................................................................................... 17
Constant Voltage Zero Calibration ................................................................................................................................. 18
Current Monitor Zero Calibration................................................................................................................................... 18
Constant Current Zero Calibration.................................................................................................................................. 18
Current Monitor Full Scale Calibration .......................................................................................................................... 19
Constant Current Full Scale Calibration .........................................................................................................................19
Power Limit Calibration.................................................................................................................................................. 20
Resistance Programming Full Scale Calibration............................................................................................................. 21
Constant Voltage (CV) Tests.......................................................................................................................................... 22
Constant Current (CC) Tests........................................................................................................................................... 28
Repair and Replacement ..................................................................................................................................................... 34
A2 Control Board Removal............................................................................................................................................ 35
A4 FET Board Removal ................................................................................................................................................. 35
A1 Main Board Removal................................................................................................................................................ 36
Voltage and Current DAC............................................................................................................................................... 41
Primary SA ..................................................................................................................................................................... 45
Front Panel SA................................................................................................................................................................ 45
Secondary SA .................................................................................................................................................................46
Power Section Troubleshooting.......................................................................................................................................... 51
Main Troubleshooting Setup........................................................................................................................................... 52
Power Section Blocks ..................................................................................................................................................... 54
Troubleshooting Down Programmer............................................................................................................................... 61
Troubleshooting CC Circuit............................................................................................................................................ 62
Principles of Operation ........................................................................................................................................................65
Analog Multiplexer......................................................................................................................................................... 67
Status Inputs.................................................................................................................................................................... 67
Front Panel Board............................................................................................................................................................... 68
Address Latches and Decoders....................................................................................................................................... 68
Volts and Amps Output Ports and Displays.................................................................................................................... 68
RPG and Latches ............................................................................................................................................................68
Front-Panel Switches and Input Port............................................................................................................................... 68
Power Clear ....................................................................................................................................................................70
Power Mesh and Control Board.......................................................................................................................................... 70
Power Mesh .................................................................................................................................................................... 71
Control Board ................................................................................................................................................................. 73
Component Location and Circuit Diagrams .................................................................................................................... 101
6
l00 Vac Input Power Option 100 .......................................................................................................................................119
General Information.......................................................................................................................................................... 119
Scope of Appendix A.................................................................................................................................................... 119
Suggestions for Using Appendix A............................................................................................................................... 119
Chapter 5 and 6 Manual Changes: ................................................................................................................................ 126
7
1
Introduction
Scope
This manual contains information for troubleshooting the Agilent 6030A, 6031A, 6032A, or 6035A 1000 W 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 (P/N 5959-3301). Both manuals cover Agilent Models
6030A/31A/32A/35A; differences between models are described as required.
The following information is contained in this manual.
Calibration and Verification
Contains calibration procedures for Agilent Models 6030A/31A/32A/35A. 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 primary interface, secondary interface, and the power
mesh and control 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
6030A/31A/32A/35A.
Circuit Diagrams
Contains functional schematics and component location diagrams for all Agilent 6030A/31A/32A/35A circuits. The names
that appear on the functional schematics also appear on the block diagrams in Chapter 2. Thus, the descriptions in Chapter 2
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.
9
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.
ItemDescription
USThe first two letters indicates the country of manufacture, where US = USA.
3648This is a code that identifies either the date of manufacture or the date of a significant design change.
0101The 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 G for backdating information.
Firmware Revisions
The primary and secondary interface microcomputer chips inside of your supply are identified with labels that specify the
revision of the supply's firmware. This manual applies to firmware revisions A.00.00, A.00.01, and A.00.02.
10
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, the A2 control board and the A8 GPIB board can involve circuits which, although functional, may
prevent the unit from performing within specified limits. So, after A1, A2 or A8 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.
Voltage Programming And Readback Accuracy
Current Programming And Readback Accuracy
CV Load Effect
CC Load Effect
Calibration Procedure
Calibrate the unit twice per year and when required during repair. The following calibration procedures should be
performed in the sequence given.
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 2-2 lists various power
supply circuits with calibration procedures that should be performed after those circuits are serviced.
If the GPIB board (A8) has been replaced, you must first initialize the board before you can calibrate the
unit. Refer to Page 31.
P = performance testing C = calibration adjustmentsT = troubleshooting
* Not required if using electronic load.
** Less accurate, and less expensive, current-monitor resistors can be used, but the accuracy to which current programming
and readback can be checked must be reduced accordingly.
12
Table 2-2. Guide to Recalibration After Repair
Printed Circuit
Board
A1 Main BoardR3Current Monitor Full Scale Calibration
A1 Main BoardT1, T2Power Limit Calibration
A5 Diode BoardCR4Power Limit Calibration
A2 Control BoardConstant Voltage CircuitAllVoltage Monitor Zero Calibration
(All Except Current Source)Common Mode Calibration
A2 Control BoardConstant Voltage CircuitAllResistance Programming Full Scale Calibration
(Current Source)
A2 Control BoardConstant Current CircuitAllCurrent Monitor Zero Calibration
Block NameRef.
Desig.
Perform These Procedures
Constant Current Full Scale Calibration
Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
Constant Current Zero Calibration
Current Monitor Full Scale Calibration
Constant Current Full Scale Calibration
A2 Control BoardPower Limit ComparatorAllPower Limit Calibration
A2 Control BoardBias Power SuppliesAllAll Calibration procedures
( + & -15V Supplies)
A8 GPIB BoardVoltage Monitor BufferAllVoltage Monitor Zero Calibration
Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
A8 GPIB BoardAnalog MultiplexerAllRemote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
A8 GPIB BoardReadback DACAllRemote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
13
Table 2-2. Guide to Recalibration After Repair (continued)
Printed Circuit
Board
A8 GPIB BoardVoltage DACAllRemote Readback Zero Calibration
A8 GPIB BoardCurrent DACAllConstant Current Zero Calibration
A8 GPIB BoardU5Remote Readback Zero Calibration
Block NameRef.
Desig.
Perform These Procedures
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
Constant Current Full Scale Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
Constant Current Full Scale Calibration
Initial Setup
a. Unplug the line cable.
b. Remove the top cover by removing the two top-rear screws. Slide the cover to the rear, and pull up.
c. Plug a control board test connector onto the A2J7 card edge fingers.
d. Turn OVERVOLTAGE ADJUST control A3R72 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. Connect a GPIB controller to the power supply.
h. Reconnect line cable and turn on ac power.
i. Allow unit to warm up for 30 minutes with the internal cover on. The cover should remain in place during all
calibrations.
j. 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.
k. At the beginning of each calibration procedure, the power supply should be in its power-on state (turn ac power off and
back on), with no external circuitry connected except as instructed.
l. 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, do not change its
setting. Otherwise, center A2R25 before you begin to calibrate the power supply.
m. Turn off ac power when making or removing connections to the power supply.
14
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.
Voltage Monitor Zero Calibration
a. Send string "VSET 0; ISET 0; OUT OFF".
b. Short power supply output terminals.
c. Attach the DVM from
d. Adjust A2R22 (V-MON ZERO) to 0V ±20µV. ( ± 40µV 6035A).
M on the rear panel through a 1kΩ resistor to A2J7 pin 3 (V-MON buffered).
Common Mode Calibration
a. Send string ''VSET 0; ISET 0; OUT OFF".
b. Short power supply sense terminals ( + S to - S) at rear panel.
c. Attach the DVM from
d. Take initial reading from DVM.
e. Remove both local sensing straps from rear-panel terminal block, and connect a 1-volt external power supply with its +
lead to - S and its--lead to - Out. See Figure 2-1.
g. Replace local sense straps after removing external power supply.
M on the rear panel through a 1kΩ resistor to A2J7 pin 3 (V-MON buffered).
Note:Common mode calibration is not required for Agilent Model 6035A.
Remote Readback Zero Calibration
Note:
a. Connect an external supply to the power supply as shown in Figure 2-2.
b. Send string "VSET 0; ISET 5; OUT ON''.
c. Attach the DVM from
d. Adjust A8R40 (CV PROG ZERO) to 625µV ± 30µV.
e. Remove the DVM.
f. Enter and run the following program and begin noting the controller's display:
10 OUTPUT 705; "VOUT''20 ENTER 705; A30 DISP A40 GOTO 1050 END
This procedure and the following three procedures must be done as a set, without omitting any of the four
procedures. Also, the following four procedures require that V-MON ZERO (A2R22) be adjusted within
specifications. If it is not, perform the Voltage Monitor Zero Calibration before proceeding.
M on the rear panel through a 1KΩ resistor to A2J7 pin 3 (V-MON buffered).
15
g.Adjust A8R51 (READBACK ZERO) until the value displayed on the controller toggles between:0 and 50mV (6030A)0 and 5mV (6031A)0 and 15mV (6032A)0 and 125mV (6035A)
h. After adjusting A8R51 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration. Remember to disconnect the external power supply and resistor.
Figure 2-1. Common Mode Setup
Figure 2-2. Remote Readback Zero And CV Zero Calibration Setup
16
Constant Voltage Full Scale Calibration
Note:Perform this procedure only after completing Remote Readback Zero Calibration.
a. Remove all external test circuits.
b. Send string:
"VSET 200; ISET 5; OUT ON" (6030A)''VSET 20; ISET 5; OUT ON" (6031A)"VSET 60; ISET 5; OUT ON" (6032A)"VSET 500; ISET 5; OUT ON" (6035A)
c. Attach the DVM from - S to + S terminals on rear panel.
d. Adjust A8R58 (CV PROG F.S.) to:
200.025 ±6mV (6030A)
20.0025 ±0.6mV (6031A)
60.0075 ±1.82mV (6032A)
500.063 ±6mV (6035A)
e. After adjusting A8R58 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration.
Voltage Monitor and Remote Readback Full Scale Calibration
Note:Perform this procedure only after completing Constant Voltage Full Scale Calibration.
a. Attach the DVM from M on the rear panel to A2J7 pin 3 (V-MON buffered). See DVM connection in Figure 2-1.
b. Send string:''VSET 200; ISET 5; OUT ON'' (6030A)
''VSET 20; ISET 5; OUT ON'' (6031A)''VSET 60; ISET 5; OUT ON'' (6032A)''VSET 500; ISET 5; OUT ON" (6035A)
c. Adjust A8R75 (V-MON F.S.) to 5.000625V ±100µV.
d. Disconnect the DVM.
e. Enter and run the following program and begin noting the controller's display.
10 OUTPUT 705; ''VOUT?''20 ENTER 705; A30 DISP A40 GOTO 1050 ENDf.Adjust A8R61 (READBACK F.S.) until the value displayed on the controller toggles between:
200.000 and 200.050 Vdc (6030A)
20.000 and 20.005 Vdc (6031A)
60.000 and 60.015 Vdc (6032A)
500.000 and 500.125 Vdc (6035A)
g. After adjusting A8R61 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration.
17
Constant Voltage Zero Calibration
Note:Perform this procedure only after completing Voltage Monitor and Remote Readback Full Scale
Calibration.
a. Send string "VSET 0; ISET 5; OUT ON".
b. Connect an external supply to the power supply as shown in Figure 2-2.
c. Attach the DVM from - S to + S on the rear panel.
d. Adjust A8R40 (CV PROG ZERO) to 0 ±120µV.
Current Monitor Zero Calibration
a. Send string "VSET 0; ISET 0; OUT OFF''.
b. Connect a short across power supply output terminals.
c. Attach the DVM from
d. Allow several minutes (3 or more) to ensure thermal settling.
e. Adjust A2R8 (I-MON ZERO) to 0 ±100 µV.
M to IM on the rear panel.
Constant Current Zero Calibration
a. Connect the test setup shown in Figure 2-3.
b. Send string ''VSET 5; ISET 0; OUT ON''.
c. Allow several minutes (3 or more) to ensure thermal settling.
d. Adjust A8R29 (CC PROG ZERO) to:
0.05% or better across power supply output terminals.b.Send string:"VSET 5; ISET 17; OUT ON" (6030A)"VSET 5; ISET 120; OUT ON" (6031A)"VSET 5; ISET 50; OUT ON" (6032A)"VSET 5; ISET 5; OUT ON" (6035A)
c. Attach DVM from
d. Take initial reading from DVM.
e. Attach DVM across Rm. Allow several minutes (3 or more) to ensure thermal settling. This can be noted as a stable
reading on the DVM.
f. Adjust A2R9 (I-MON F.S.) to:
0.034 * initial reading ±33.5µV (6030A)
0.024 * initial reading ±80.0µV (6031A)
0.100 * initial reading ±0.4mV (6032A)
0.100 * initial reading ±67.0µV (6035A)
M to IM on the rear panel. Use six-digit display on Agilent 3458A DVM.
Constant Current Full Scale Calibration
Note:This procedure requires that CC PROG ZERO (A8R29) and I-MON F. S. (A2R9) be adjusted within
specifications. If they are not, perform Constant Current Zero and/or Current Monitor Full Scale
Calibration before proceeding.
0.05% or better across power supply output terminals.b.Send string:"VSET 5; ISET 17; OUT ON" (6030A)"VSET 5, ISET 120; OUT ON'' (6031A)"VSET 5, ISET 50; OUT ON" (6032A)''VSET 5; ISET 5; OUT ON" (6035A)
c. Attach DVM across Rm. Allow several minutes (3 or more) to ensure thermal settling.
d. Adjust A8R55 (CC PROG F.S.) to:
1.70V ±0.1mV (6030A)
0.12V ±3.0µV (6031A)
0.50V ±30µV (6032A)
0.50V ±40µV (6035A)
19
Power Limit Calibration
Note:This procedure requires that CC PROG F. S. (A8R55) be adjusted within specifications. If it is not,
perform Constant Current Full Scale Calibration before proceeding.
a. Connect the power supply to the ac power line through a variable autotransformer. Connect a DVM across the input
power rails, with the + lead to the rear of A1R3 and the - lead to the rear of A1R1. Adjust the autotransformer for
240Vdc on the input power rail. The input power rail must be maintained at 240Vdc during calibration.
The top inside cover must be removed to connect the DVM. Disconnect the ac mains power cord before
connecting or disconnecting the DVM.
a. Connect a electronic load across the output terminals, or use a:
3.8 ohm 1500W resistor (6030A)
0.066 ohm 1500W resistor (6031A)
0.44 ohm 1500 W resistor (6032A)39 ohm 1500 W resistor (6035A)b.Set the electronic load for:17 amperes (6030A)120 amperes (6031A)51 amperes (6032A)5 amperes (6035A)in the constant Current mode.
c. Turn A2R25 (LOWER KNEE) fully counterclockwise.
d. Turn on power supply and send string:
"VSET 65; ISET 17.4; OUT ON" (6030A)''VSET 8; ISET 121; OUT ON'' (6031A)"VSET 22; ISET 51; OUT ON" (6032A)''VSET 200; ISET 5.1; OUT ON'' (6035A)e.Adjust A2R25 (LOWER KNEE) clockwise until CV LED on front panel turns on. Power supply output should be:65 ±0.2V @17A in CV mode (6030A)8 ±0.08V @120A in CV mode (6031A)22 ±0.2V @50A in CV mode (6032A)200 ±0.5V @5A in CV mode (6035A)f.Turn off power supply. Reset the electronic load for:
5.25A in CC mode (6030A)51A in CC mode (6031A)
18.2A in CC mode (6031A)
2.2A in CC mode (6035A)or change the resistor to:38ohm 1500W (6033A)
0.4ohm 1500W (6031A)
3.3ohm 1500W(6032A)227ohm 1500W(6035A)
g. Turn A2R26 (UPPER KNEE) fully counterclockwise.
h. Turn on power supply. Send string
"VSET 200; ISET 5.5; OUT ON" (6030A)"VSET 20.5; ISET 55; OUT ON" (6031A)"VSET 60; ISET 19; OUT ON" (6032A)"VSET 500; ISET 2.2; OUT ON" (6035A)
20
i. Adjust A2R26 (UPPER KNEE) clockwise until front panel CV LED turns on. Power supply output should be:
200 ±0.4V @5.25A in CV mode (6030A)
20.5 ±0.5V @55A in CV mode (6031A)
60 ±0.4V @18.2A in CV mode (6032A)
500 ±0.4V @2.2A in CV mode (6035A)
Resistance Programming Full Scale Calibration
a. Send string ''OUT OFF".
b. Connect a 2K ohm calibration resistor from
c. Set rear-panel MODE switches for resistance programming:
d. Attach the DVM from
e. Adjust A2R23 (R-PROG F.S.) to 2.5V ±4mV.
f. Remember to reset MODE switches to original settings.
P to VP on the rear panel.
P to VP on rear panel.
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. The performance test specifications are listed in the Performance Test Record in
Appendix C through F. You can record the actual measured values in the columns provided.
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:
40Ω 1000W load resistor (6030A)
0.4Ω 1000W load resistor (6031A)
3.5Ω 1000W load resistor (6032A)
250Ω 1000W load resistor (6035A)
for the electronic load in these tests:
CV Source Effect (Line Regulation)
CC Load Effect (Load Regulation)
21
You may substitute:
3.5Ω 1000W load resistor (6030A)
0.069Ω 1000W load resistor (6031A)
0.4Ω 1000W load resistor (6032A)
40Ω 1000W load resistor (6035A)
in these tests:
CV Load Effect (Load Regulation)
CV PARD (Ripple and Noise)
CC Source Effect (Line Regulation)
CC PARD (Ripple and Noise)
The substitution of the load resistor requires adding a load switch and making minor changes to the procedures. The load
transient recovery time test procedure is not amenable to modification for use with 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. 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 2-4
shows correct connections. Connect the current-monitoring test leads inside the load-lead connections directly at the
monitoring resistor element.
Note:A current-monitoring resistor with 1% accuracy is suitable for all tests except current programming
accuracy and current readback accuracy. For these tests, use the shunt listed in Table 2-1.
Figure 2-4. Current-Monitoring Resistor Setup
GPIB Controller. Most performance tests can be performed using only front-panel controls. However, a GPIB controller is
required to perform the voltage and current programming accuracy tests and the voltage and current readback accuracy tests.
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 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.
Voltage Programming And Readback Accuracy. This procedure verifies that the voltage programming and readback
functions are within specifications. A GPIB controller must be used for this test.
a. Connect digital voltmeter between + S and - S.
b. Turn on ac power to the power supply.
c. Send string:
"VSET 0.5; ISET 17" (6030A)
22
''VSET 0.1; ISET 120'' (6031A)''VSET 0.09; ISET 50" (6032A)''VSET 1.0; ISET 5'' (6035A)d.The DVM reading should be in the range:
0.354 to 0.645Vdc (6030A)
0.085 to 0.115Vdc (6031A)
0.050 to 0.130Vdc (6032A)
0.598 to 1.400Vdc (6035A)Note the reading.e.Enter and run the following program:10 OUTPUT 705; "VOUT?"20 ENTER 705;A30 DISP A40 GOTO 1050 ENDf.The value displayed by the controller should be the value noted in step d:± 0.080Vdc (6030A)± 0.007Vdc (6031A)± 0.020 Vdc (6032A)± 0.205 Vdc (6035A)g.Send string:"VSET 200; ISET 17" (6030A)''VSET 20; ISET 120'' (6031A)''VSET 60; ISET 50" (6032A)''VSET 500; ISET 5" (6035A)h.The DVM reading should be in the range:
199.785 to 200.215Vdc (6030A)
19.978 to 20.022Vdc (6031A)
59.939 to 60.061 Vdc (6032A)
498.350 to 501.650 Vdc (6035A)Note the reading.i.Run the program listed in step e. The value displayed by the controller should be the value noted in step h:
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 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
60Vdc (6030A)
7.0Vdc (6031A)
20.0Vdc (6032A)200Vdc (6035A)as read on the digital voltmeter.
23
Figure 2-5. Basic Test Setup
d.Reduce the resistance of the load to draw an output current of:
17.0Adc (6030A)120Adc (6031A)50 Adc (6032A)
5.0 Adc (6035A)Check that the unit's CV LED remains lighted.
e. Open-circuit the load.
f. Record the output voltage at the digital voltmeter.
g. Reconnect the load.
h. When the reading settles, record the output voltage again. Check that the two recorded readings differ no more than:
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 2-5. 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 nominal line voltage.
c. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
d. Turn up output voltage to:
200Vdc (6030A)
20.0Vdc (6031A)
60.0Vdc (6032A)500Vdc (6035A)as read on the digital voltmeter.
24
e.Reduce the resistance of the load to draw an output current of:
5.0Adc (6030A)50 Adc (6031A)
16.5 Adc (6032A)
2.0 Adc (6035A)Check that the unit's CV LED remains lighted.
f. Adjust autotransformer to the minimum for your line voltage.
g. Record the output voltage at the digital voltmeter.
h. Adjust autotransformer to the maximum for your line voltage.
i. When the reading settles record the output voltage again. Check that the two recorded readings differ no more than:
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 20 Hz to 20 MHz.
RMS Measurement Procedure. Figure 2-6 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 2-6. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
60Vdc (6030A)7Vdc (6031A)20Vdc (6032A)200Vdc (6035A)d.Reduce the resistance of the load to draw an output current of:
17.0Adc (6030A)120Adc (6031A)50Adc (6032A)
5.0Adc (6035A)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:
Figure 2-6. RMS Measurement Test Setup, CV PARD Test
Peak Measurement Procedure. Figure 2-7 shows the interconnections of equipment to measure PARD in Vpp. The
equipment grounding and power connection instructions of Paragraph 2-36 apply to this setup also. Connect the
oscilloscope to the + S and - S terminals through 0.01µF blocking capacitors to protect the oscilloscope's input from the
unit's output voltage. To reduce common-mode noise pickup, set up the oscilloscope for a differential, two-channel voltage
measurement. To reduce normal-mode noise pickup, use matched-length, 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 2-7. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
d.Turn up output current setting to full output and reduce the resistance of the load to draw an output current of:
17.0Adc (6030A)120Adc (6031A)50Adc (6032A)
5.0Adc (6035A)Check that the unit's CV LED remains lighted.
e. Set the oscilloscope's input impedance to 50Ω and bandwidth to 20MHz. Check that the peak-to-peak is no more than:
50mV (6030A/31A)
40mV (6032A)
160mV (6035A)
26
Figure 2-7. Peak-To-Peak Measurement Test Setup, CV PARD Test
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.
Use the equipment setup of Figure 2-5 to display output voltage transients while switching the load between 10% with the
output set at:
60Vdc (6030A)
7Vdc (6031A)
20Vdc (6032A)
200Vdc (6035A)
Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant-current mode and set for minimum
current.
b. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
60Vdc (6030A)7Vdc (6031A)
20.0Vdc (6032A)200Vdc (6035A)as read on the digital voltmeter.d.Set the load to vary the load current between:
15.3 and 17Adc (6030A)108 and 120Adc (6031A)45 and 50Adc (6032A)
4.5 and 5.0 Adc (6035A)at a 30Hz rate for the 10% RECOVERY TEST.
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 2-8.
27
.
g. Check that the amplitude of the transient pulse at 1 ms is no more than:
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 of Pages 21 and 22.
Current Programming And Readback Accuracy. This procedure verifies that the current programming and readback
functions are within specifications. A GPIB controller must be used for this test. The accuracy of the current shunt resistor
(Rm) must be 0.02% or better. Proceed as follows:
a. Connect test setup shown in Figure 2-5, except replace the load with a short circuit.
b. Turn on ac power to the power supply.
c. Send string:
"VSET 200; ISET 0.5" (6030A)"VSET 20; ISET 0.5" (6031A)''VSET 60; ISET 0.5" (6032A)''VSET 500; ISET 0.10" (6035A)d.Check that the voltage across Rm is in the range:
4.75 to 5.25mV (6030A)248 to 751µV (6031A)
4.14 to 5.86mV (6032A)
1.5 to 1.85mV (6035A)Note the reading.e.Enter and run the following program:10 OUTPUT 705; "IOUT?''20 ENTER 705; A30 DISP A40 GOTO 1050 ENDf.The value displayed by the controller should be the actual output current:
± 17mA (6030A)
± 102mA (6031A)
± 36mA (6032A)
± 50 mA (6035A)
28
g.Send string:"VSET 200; ISET 17" (6030A)''VSET 20; ISET 120" (6031A)''VSET 60; ISET 50" (6032A)''VSET 500; ISET 5" (6035A)h.Check that the voltage across Rm is in the range:
169.72 to 170.28mV (6030A)
119.4 to 120.55mV (6031A)
498.1 to 501.8 mV (6032A)490 to 510 mV (6035A)Note the reading.
i. Run the program listed in step e.
j. The value displayed by the controller should be the actual output current:
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 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Turn the unit's power on, and, using DISPLAY SETTINGS pushbutton switch, turn up voltage setting to full output.
c. Turn up output current to:
5.0Adc (6030A)50Adc (6031A)
16.5Adc (6032A)
2.0Adc (6035A)d.Increase the load resistance until the output voltage at +S and -S decreases to:200Vdc (6030A).20Vdc (6031A).60Vdc (6032A)500Vdc (6035A)Check that the CC LED is lighted and AMPS display still reads ≈ current setting.
e. Short-circuit the load and allow the voltage across Rm to stabilize.
f. Record voltage across Rm.
g. Disconnect short across load.
h. When the reading settles (≈ 10s), record the voltage across Rm again. Check that the two recorded readings differ no
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 2-5. 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 nominal line voltage.
c. Switch the unit's power on and turn up output voltage setting to full output.
29
d.Turn up output current to:
17.0Adc (6030A)120Adc (6031A)50Adc (6032A)
5.0 Adc (6035A)e.Increase the load resistance until the output voltage between + S and - S decreases to:60Vdc (6030A)
7.0Vdc (6031A)
20.0Vdc (6032A)200 Vdc (6035A)Check that the CC LED is still on.
f. Adjust autotransformer to the minimum for your line voltage.
g. Record the voltage across Rm.
h. Adjust autotransformer to the maximum for your line voltage.
i. When the reading settles record the voltage across Rm again. Check that the two recorded readings differ no more than:
6mA (6030A)
37mA (6031A)
15mA (6032A)
18 mA (6035A)
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, Page 23. 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:
3.5Ω (6030A)
0.069Ω (6031A)
0.4Ω (6032A)
40Ω (6035A)
load resistor that is capable of safely dissipating 1000 watts. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-9.
Note: For Agilent 6031A units, use a 30Adc power supply in the test setup to subtract from the 120Adc of the Agilent
603lA unit under test. This will prevent the current probe specified in Table 2-1 from saturating. Makesure the rms noise of the 30Adc supply is less than 10mA rms.
b. Switch the unit's power on and turn the output voltage all the way up.
c. Turn up output current to:
17.0Adc (6030A)120Adc (6031A)50 Adc (6032A)
5.0 Adc (6035A)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:
3. Turn the power off, wait 5 seconds, then turn the power back on.
4. If the GPIB assembly has been replaced, calibrate the unit.
31
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 3-9.
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. Check that the rear-panel GPIB address switch A8S1 is properly set. (See Operating Manual).
e. 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 4KVA. 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.
33
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.
34
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, GPIB plug, 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 the 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. Screws that secure the input and output capacitors to A1 main board and output bus bars.
b. Rear-panel circuit breaker.
c. Rear-panel ground binding post.
d. Strap-handle screws (2).
e. Screws that secure side chassis to front-frame casting (4, 2 on top and 2 on bottom).
Top Outside Cover Removal. Remove the two top rear screws using a Size 2, Pozidriv screwdriver. A Phillips head
screwdriver does not fully seat into Pozidriv screws and risks stripping the heads. Remove the top cover by sliding it to the
rear and lifting at the front.
Bottom Cover Removal. Remove the handles from both sides of the unit and remove the bottom cover by sliding it to the
rear. Use a Phillips head #2 screwdriver to remove the handle screws. 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 nine mounting screws (Pozidriv, M4x.7) -two on the left side, three on the right side, four 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 A8 GPIB board into the mating slots in the cover. Then repeat the process for
the A2 control board, the A4 FET board, and the A5 Diode board. Press the inside cover down firmly while tightening
screws that secure cover to chassis. Be careful not to bend any boards or components.
A2 Control Board Removal
After removing the inside cover, unplug the W5 and W6 ribbon cables at the top edge of the A2 control board. Then unplug
the W7 and W8 ribbon cables from the lower center of the board. Remove the A2 board by lifting first at the front edge and
than pulling it up and out of the unit.
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, and reinstall the W5, W6, W7, and W8 ribbon
cables.
A4 FET Board Removal
After removing the inside cover, remove the A4 mesh board by lifting, using the large aluminum heatsink as a handle. One
connector and one tab holds the A4 board at its bottom edge.
35
When installing the A4 power mesh board, lower it vertically, placing its tab into the A1 board slot, align the connector and
press in place.
A5 Diode Board Removal
After removing the cover, remove the A5 Diode board by first removing the two screws (Pozidriv) that hold heatsinks to the
A1 board, then lift vertically to remove the A5 board from the connector.
When installing the A5 Diode board, lower it vertically into the mating connector on the A1 board, then install a screw
between each heatsink and Al board.
A8 GPIB Board Removal
Remove the A8 board as follows:
a. Remove the two screws (Pozidriv, M3x.5) which attach the A8 GPIB board to the rear panel. Remove the single screw
(Pozidriv, M4x.7) that secures the GPIB board to the side frame near the front corner.
b. After removing the inside cover, unplug the W5 and W6 ribbon cables at the top edge of the A8 board, the W2 3-wire
cable from connector A8J10 and the W1 ribbon cable from connector A8J9.
c. Remove the A8 board lifting it straight up.
Install the A8 board by reversing the above steps. Lower the rear side of the board into the unit first and fit the bottom tabs
into their mating slots.
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.
b. Remove the four front-panel assembly mounting screws (Pozidriv M4) on the top and bottom at the comers.
c. Gently pull the front-panel assembly away from the unit as far as permitted by the connecting cables.
d. Note the locations of the four power-wire connections to the power switch and then unplug the quick-connect plugs.
e. Unplug the W3 3-wire cable from connector A1J4 on the A2 control board, and unplug the W1 ribbon cable from
connector A8J9 on the A8 GPIB board.
f. Remove the A3 board from the front-panel assembly by removing the six mounting screws (Pozidriv, M4x.7)
Install the A3 Board by reversing the steps above.
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, four standoffs, and two bus bar mounting screws. Component-access cutouts in the bottom inside
cover allow unsoldering most A1-board components for repair without removing the A1 board.
Proceed as follows
a. Remove the A2, A4, A5, and A8 boards according to the above instructions.
b. Remove the AC power cord from the cooling fan and the four AC Input Power wires.
c. Remove the following mounting screws, all Pozidriv:
2 (1 each) from the output bus bars7 from the A1 board4 from transformer AlT24 from transformer AlT32 from relay AlK14 inside-cover mounting posts 5/16 hex
d.Lift the A1 board up and toward the rear, then remove the wires from the front panel switch A3S1.
A1 DesignatorWire colorA3S1 Position (Rear View)
Awhite/gray
BgrayS1
Cwhite/brown/grayB - | - A
Dwhite/red/grayC - | - D
Install the A1 board by reversing the above steps. Be careful to follow the wire color code.
Overall Troubleshooting Procedure
The overall troubleshooting procedure for the unit involves isolating the problem to one of several circuit blocks and
troubleshooting the block individually. The GPIB/microprocessor related circuit blocks are located on the A3 (front panel)
and the A8 (GPIB) boards. They are referred to collectively as the GPIB section. The power supply circuit blocks are on the
A1 (main), the A2 (control), the A4 (FET), and the A5 (diode) boards. They are referred to collectively as the power
section.
The flowchart of Figure 3-1 provides troubleshooting isolation procedures to guide you either to the appropriate circuit or to
one of the detailed troubleshooting procedures in this section. The purpose of the flowchart is only to isolate the problem to
a specific area of the power supply. If you have already isolated the problem, proceed directly to the applicable
troubleshooting section.
Table 3-1 lists the error codes that may appear on the front panel when the unit performs its internal selftest. Along with the
error codes, the table also identifies various circuits or components that may have caused that error code to appear.
In the Power Section Troubleshooting, Tables 3-10 and 3-11 give various power supply symptoms that identify the
corresponding board, circuit or components that may have caused that symptom. The symptoms in Table 3-10 may become
apparent when running the Performance Tests in Section 2.
GPIB Section Troubleshooting
The GPIB section troubleshooting consists of primary and secondary interface troubleshooting. Signature analysis is
required to troubleshoot the primary and secondary processor as well as the front panel board. Other circuits on the GPIB
board, such as the voltage and current DACs, can be checked using either signature analysis or the front panel controls. The
readback circuits cannot be checked using signature analysis. Figure 3-2 illustrates the test setup that allows access to the
GPIB board components for troubleshooting.
37
38
Figure 3-1. Troubleshooting Isolation
Figure 3-1. Troubleshooting Isolation (continued)
39
To remove the GPIB board, perform the GPIB board removal procedure discussed earlier in this section. Lay out the board
as shown in Figure 3-2 with a piece of insulating material under the board. Reconnect connectors W1, W2, W5, and W6
after the board is on the insulating material.
Note:The GPIB board can be placed alongside the unit for troubleshooting by using extender cables provided in
service kit Agilent P/N 06033-60005.
Table 3-1. Selftest Error Code Troubleshooting
Error CodeDescriptionCheck Functional Circuit
ERROR 4External RAM TestReplace A8U8
ERROR 5Internal RAM TestReplace A8U14
ERROR 6External ROM TestReplace A8U6
ERROR 7GPIB TestReplace A8U17
ERROR 8GPIB address set to 31
ERROR 10Internal ROM TestReplace A8U4
ERROR 12ADC Zero Too HighCheck U11,20,24,66,67; go to Readback DAC Troubleshooting
ERROR 13Voltage DAC Full Scale LowCheck U2,7,64,69
ERROR 14Voltage DAC Full Scale HighCheck U2,7,64,69
ERROR 15Voltage DAC Zero LowCheck U2,7,64,69
ERROR 16Voltage DAC Zero HighCheck U2,7,64,69
ERROR 17Current DAC Full Scale LowCheck U9,65,68
ERROR 18Current DAC Full Scale HighCheck U9,65,68
ERROR 19Current DAC Zero LowCheck U9,65,68
ERROR 20Current DAC Zero HighCheck U9,65,68
┐
│
│
│
├─
│
│
│
┘
Go to Secondary SA
Troubleshooting
Primary Interface Troubleshooting
Primary interface troubleshooting checks for the presence of bias voltages, clock signals (see Figure 3-3), and activity on the
data lines. Primary signature analysis may be used to further troubleshoot these circuits, but since the address and data lines
go to so many IC's, it may not be cost-effective to narrow an incorrect signature to a specific chip. GPIB board replacement
may be the most cost-effective solution.
Note:The initialization procedure in Page 31 must be performed when the GPIB board is replaced.
C7+,C8+= 12MHz (see waveform)Y2
J5-8= 6MHz (see waveform)U14
U35-12
Data Lines Check that all data and address lines are toggling. Address and data lines go to the following IC's:
Address LinesData Lines
U6: A0 to A15U6: D0 to D7
U8: A0 to A15U8: D0 to D7
U12: A0 to A4U12: D0 to D7
U14: A8 to A15U14: D0 to D7
U16: A0 to A7U16: D0 to D7
U17: A0 to A2U17: D0 to D7
U36: A7 to A15
≈ 3.5Vdc
≈50mVdc
NodeMeasurementSource
≈ 50mVdc (see waveform)
U35
Note:Data and address lines may not toggle if one line is shorted either high or low. If no short is found, replace
all socketed IC's. If the data lines still do not toggle, replace the GPIB (A8) assembly.
Node Measurement
A0 to A15 Toggling
D0 to D7 Toggling
Secondary Interface Troubleshooting
Secondary interface troubleshooting checks the operation of the voltage, current, and readback DACs as well as analog
multiplexer and secondary microprocessor. The analog multiplexer is checked in the Readback DAC troubleshooting
procedure. The secondary microprocessor can only be checked using secondary SA (refer to Signature Analysis).
Voltage and Current DAC
The voltage and current DACs can be checked either from the front panel or by secondary SA. Refer to Signature Analysis
to troubleshoot the voltage and current DACs in this manner.
Note:To troubleshoot the voltage and current DACs from the front panel if the unit has failed selftest, place
jumper A8J5 in the skip selftest position (see Table 3-2). This lets you operate the unit even though it fails
the internal selftest.
41
42
Figure 3-3. Clock and Primary SA Waveforms
Use the front panel controls to vary the output voltage and current from zero to full-scale output. Remember to turn off the
unit and connect a short across the output before programming the current from zero to full scale. Use a DMM and check
the voltages at the following nodes:
CV DAC Circuits
NodeSetupMeasurement
U69-6Voltage set to 0.0V
Voltage set to max.+ 5V
U64-6Voltage set to 0.0V
Voltage set to max.-10V
CC DAC Circuits
NodeSetupMeasurement
U68-6Current set to 0.0V
Current set to max.+ 5V
U65-6Current set to 0.0V
Current set to max.-10V
Readback DAC Circuits
Refer to Figure 3-4 for the waveforms to troubleshoot the readback circuits.
The turn-on selftest waveform at U24-7 is obtained by toggling the on/off switch repeatedly to perform the selftest routine.
If this waveform is not correct, isolate the problem either to the readback DAC or the multiplexer.
Note:To troubleshoot the readback DAC from the front panel if the unit has failed selftest, place jumper A8J5 in the
skip selftest position (see Table 3-2). This lets you operate the unit even though it fails the internal selftest.
Use the front panel controls to vary the output voltage from zero to full-scale output to obtain the waveforms at U67-6.
These waveforms check the operation of the readback DAC.
To check the multiplexer, use the front panel controls to obtain the waveforms at the output of the multiplexer (U24-2).
Remember to turn off the unit and connect a short across the output before programming the current from zero to full scale.
Press "OVP DISPLAY'' on the front panel to display the OV_MON portion of the waveforms.
If the waveforms are not correct, use the front panel controls and a DMM to check the multiplexer input voltages at the
following nodes:
Readback Multiplexer (U20):
NodeSetupMeasurement
U20-9Voltage set to 0.0V
Voltage set to max.+ 5V
U20-10Current set to 0.0V
Current set to max.+ 5V
U20-11OV set to 0.0V
OV set to max.+2.2V
43
44
Figure 3-4. Readback and Secondary SA Waveforms
Signature Analysis
Perform the signature analysis only after you have completed the Primary Processor Troubleshooting.
The easiest and most efficient method of troubleshooting microprocessor-based instruments is signature analysis. Signature
analysis is similar to signal tracing with an oscilloscope in linear circuits. Part of the microcomputer memory is dedicated to
signature analysis and a known bit stream is generated to stimulate as many nodes as possible within the circuit. However,
because it is virtually impossible to analyze a bit stream with an oscilloscope, a signature analyzer is used to compress the
bit stream into a four-character signature that is unique for each node. By comparing signatures of the unit under test to the
correct signatures for each node, faults can usually be isolated to one or two components. Note that signature analysis
provides only go/no-go information; the signature provides absolutely no diagnostic information.
The following general notes apply to signature analysis of the power supply.
1. Be certain to use the correct setup for the signature being examined.
2. Most signatures are taken on the GPIB, and front panel assemblies.
3. Note the signatures for Vcc and ground on the I.C. being examined. If an incorrect signature is the same as that of Vcc
or ground, that point is probably shorted to Vcc or ground.
4. If two pins have identical signatures, they are probably shorted together. If two signatures are similar, it is only
coincidence. For example, if the signature at a certain point should be 65C4, a signature of 65C3 is not "almost right".
No diagnostic information can be inferred from an incorrect signature.
5. If a signature is incorrect at an input pin, but is correct at its source (output of previous I.C.), check for printed circuit
and soldering discontinuity.
6. An incorrect signature at an output could be caused by a faulty component producing that output; or, a short circuit in
another component or on the board could be loading down that node.
Tables 3-2 and 3-3 show the primary, front panel, and secondary signature analyzer connections that are required to perform
the SA tests in Tables 3-4 through 3-8. Remember that the primary and secondary circuits each reference a different circuit
common.
Primary SA
Place the unit in primary SA mode by moving the J5 jumper as shown in Table 3-2. Connect the signature analyzer as
shown in the table. The front panel display should indicate: ''SA SA", and all LED's will be on. If the display is different,
replace U14.
Note:The power supply will not go into SA mode if one of the data and address lines is shorted either high or
low. Refer to Data Lines troubleshooting.
When the unit is in SA mode, check for the waveforms shown in Figure 3-3. Refer to Table 3-4 for the primary SA
signatures. Return the J5 jumper to its normal position when the primary signature analysis is complete.
Front Panel SA
To place the unit in SA mode for Front Panel SA troubleshooting, follow the procedure for Primary SA troubleshooting.
When the unit is in SA mode, check the signatures in Tables 3-5 through 3-7.
The signatures in Table 3-5 check the registers that drive the 7-segment LED displays. Most problems will involve only one
display or LED indicator. Table 3-6 checks the address latches and decoders. Address latch U15 forwards address data to
the address decoders, which enable the shift registers. Table 3-7 checks flip-flop U12, shift register U11, and gate U18. U12
decodes the output of the RPG. U11 and U18 are used by the microprocessor to read the status of the RPG and front panel
switches.
45
Return the J5 jumper to its normal position when the front panel signature analysis is complete.
Secondary SA
For secondary SA troubleshooting, connect the signature analyzer as shown in Table 3-3. Use a jumper wire and short U4
pin 21 to common (U4 pin 20). Check for the waveforms in Figure 3-4 and the signatures in Table 3-8 for the secondary
SA. When the secondary signature analysis is complete, disconnect the jumper on U4 pin 21.
Table 3-2. Primary and Front Panel Signature Analyzer Test Setups
SIGNATURE
ANALYZER INPUT
CLOCK
START
STOP
GROUND
A8J5 (in SA mode)
SIGNATURE
ANALYZER INPUT
CLOCK
START
STOP
GROUND
EDGE
SETTING
A8J5 JUMPER POSITIONS
Jumpering pins 1 and 2 skips the internal
selftest when the unit is turned on.
Jumpering pins 3 and 4 places U37 in SA mode.
Jumpering pins 5 and 6 is the normal/operating
position of the jumper.
Table 3-3. Secondary Signature Analyzer Test Setups
EDGE
SETTING
PRIMARY SA
CONNECTIONS
A8J5 pin 8
A8U37 pin 16
A8U37 pin 16
A8J5 pin 5
SECONDARY SA
CONNECTIONS
A8U4 pin 23
A8U4 pin 22
A8U4 pin 22
A8U4 pin 20
46
A8U4 JUMPER POSITIONS
Use a jumper wire and connect A8U4 pin 21 to pin 20 (ground).
Use a 40-pin test clip (Pomona Model 5240 or eq.) to facilitate test
connections to A8U4.
Table 3-4. Primary Processor Signature Table
(A8U6 = P/N 5080-2160 REV A.00.00, A.00.01, A.00.02 and A.00.04)
U1 to U10-16H15
U1 to U10-9Cycle power to unit--Lo to Hi after approx. 160 ms
U1 to U10-2,14+5V
U1 to U10-7common
U1-8F05U
U2-850A9
U3-86F42
U4-8AH52
U5-851U7
U6-8PHFF
U7-85730
U8-88U73
U9-8HU9C
U10-85AHH
S1 LCL releasedU11-13 Lo U11-7, U16-9LoU16-8 Hi
S1 LCL depressedU11-13 Hi U11-7, U16-8,9Toggling
S2 OUTPUT ADJUST releasedU11-14 Lo U11-7, U16-9LoU16-8 Hi
S2 OUTPUT ADJUST depressedU11-14 Hi U11-7, U16-8,9Toggling
S3 DISPLAY OVP releasedU11-3 Lo U11-7, U16-9LoU16-8 Hi
S3 DISPLAY OVP depressedU11-3 Hi U11-7, U16-8,9Toggling
S4 DISPLAY SETTINGSreleasedU11-4 Lo U11-7, U16-9LoU16-8 Hi
S4 DISPLAY SETTINGSdepressedU11-4 Hi U11-7, U16-8,9Toggling
S5 FOLDBACKreleasedU11-5 Lo U11-7, U16-9LoU16-8 Hi
S5 FOLDBACKdepressedU11-5 Hi U11-7, U16-8,9Toggling
U12-5Node toggles when RPG is rotated clockwise
U12-9Node toggles when RPG is rotated in either direction
Set scope for dual trace operation, 2V/div, 10 ms/div, normal triggering, and positive edge on channel A.
Connect channel A to U12-3 and channel B to U12-2.
Table 3-9 describes the signals at each of the control board test points. The test connector provided in service kit P/N
5060-2865 allows easy connection to each test point. The measurements given here include bias and reference voltages as
well as power supply status signals. It provides conditions for these measurements and gives the components which are the
sources of the signals. Tables 3-10 and 3-11 describe possible symptoms in the power section. Both give lists of circuit
blocks or components which can cause the symptoms shown. The appropriate assembly is also given.
If the supply exhibits a symptom given in Table 3-10 or 3-11, go to the block which pertains to that symptom. If the exact
symptom seen is not in the tables, start with the symptom that seems to be closest to the one observed. The blocks are given
in the Power Section Blocks section starting in Paragraph 3-84. Troubleshooting information for each block will include a
brief description of the circuit. The columns provided 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.
51
The A4 FET Board should only be raised on an extender when using the main troubleshooting setup.
NEVER use a FET Board extender when the unit is operated with its normal ( ≈ 320Vdc) bus voltage. To
do so is a personal shock hazard and can damage the power supply.
To troubleshoot the power supply the A4 power FET board and A2 control board can be raised out of the unit using
extender boards and cables provided in service kit P/N 5060-2865.
Main Troubleshooting Setup
Figure 3-5 shows the troubleshooting setup for troubleshooting all of the unit except the front panel and initial no-output
failures (see Paragraph 3-82). The external power supply provides the unit's internal bus voltage. The ac mains connects
directly to the unit's A1T3 bias transformer via the isolation transformer, thereby energizing the bias supplies, but it does not
connect to the input rectifier and filter to create the bus voltage. With the external supply the unit operates as a dc-to-dc
converter. The supply biases A4Q1, A4Q2, 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.
52
Figure 3 5. Main Troubleshooting Setup
An isolation transformer provides ac voltage that is not referenced to earth ground, thereby reducing the
possibility of accidentally touching two points having high ac potential between them. Failure to use an
isolation transformer as shown in Figure 3-5 will cause the ac mains voltage to be connected directly to
many components and circuits within the power supply, including the FET heatsinks, as well as to the
terminals of the external dc power supply. Failure to use an isolation transformer is a definite personal injury hazard.
The troubleshooting setup of Figure 3-5 connects high ac voltage to relay K1, fan B1, fuseholder A1F1, and
other components and circuits along the front of the A1 main board.
As a convenience in implementing the troubleshooting setup, modify a spare mains cord set as shown in Figure 3-6. This
facilitates connecting the unit's power receptacle to the external supply and connecting the bias transformer to the ac mains.
With the mains cord unplugged proceed as follows:
a. Remove the top cover and the inside cover per Page 35. Remove fuse A1F1.
Failure to remove fuse AlF1 will result in damage to the power supply, damage to the external dc supply,
and is an electrical shock hazard to you.
a. Install control board test connector onto the A2J7 card-edge fingers.
b. Connect a 50Ω 10-W load resistor to the unit's output terminals.
c. The external dc power supply can be connected to the unit in either of two ways (in either case, the front panel LINE
switch should be off):
1.Remove white/gray wire from main board terminal marked "N'' (at left side, just behind relay at front left
corner), and remove white/brown, gray wire from terminal "L". Connect external dc power supply to terminals
"N" and "L''. Either polarity is correct.
OR
2.Ensure that the rear-panel circuit breaker is on. Connect external dc power supply to ac input terminals ''N"
and ''L''. Either polarity is correct.
e. Complete the setup of Figure 3-5 by attaching an ac mains cord to test points J8 (L, black wire) and J7 (N, white wire)
and connect the green ground wire to the unit's case ground terminal or a suitably grounded cabinet screw. Connect the
mains cord to an isolation transformer.
Troubleshooting No-Output Failures
No-output failures often include failure of the A4Q1, A4Q2, 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 FETs to fail. This makes it possible to develop your troubleshooting approach
without an extensive equipment setup. Proceed as follows:
a. With the mains cord disconnected remove the A4 FET board per Page 36. Connect the mains cord and switch on
power.
b. Using Table 3-9 check the bias voltages, the PWM-OFF and PWM-ON Control signals and other signals of interest at
the A2 control board test fingers, A2J7.
c. Check for the presence of program voltages, VP and IP, at the rear panel.
d. Check for presence of the 320Vdc rail voltage with + at the rear facing end of AlR3 and - at the rear facing end of
AlR1. If there is no rail voltage, check AlU1.
53
AlR1, AlR3, and AlU1 connect to the ac mains voltage. Use a voltmeter with both input terminals floating
to measure the rail voltage.
a. Select the functional circuit for troubleshooting based on your measurements and Table 3-11, which provides direction
based on the status of the PWM OFF and PWM ON signals.
Figure 3-6. Modified Mains Cord Set For Troubleshooting
Power Section Blocks
This section contains the blocks referenced in Tables 3-10 and 3-11.
3V-MON-BUFV-OUT/4 (6031A)buffered V-MON for readbackA8U25-6
20Ip-SET
OV CLEAR
PCLR
≈0.013*I0UT(6030A/35A).
≈0.0017* IOUT (6031A)
≈0.0037* IOUT (6032A)
V-OUT/12 (6032A)
V-OUT/40 (6030A)
V-OUT/100 (6035A)
+5Vinverted OV reset lineA8U4-35
+5Vif +5V bias OKA2Q11-4
status and control signals
inboard-side monitoring resA1R11,A1T2
(AlR13 (6032A))
≈0.9
A2R25 wiper
55
Table 3-10. Performance Failure Symptoms
DEFECTIVE
SYMPTOMS BOARDCHECK FUNCTIONAL CIRCUITS
unexplained OVP shutdowns A2OVP circuit, CV circuit
no current limit A2CC circuit
max current < specified A2CC Clamp, CC circuit
max power < specified A2, A1Power Limit, 20KHz clock, transformer AlT1
max voltage < specified A2, A1CV Circuit, diodes A1CR1-CR4
cycles on & off randomly A2, A1AC-Surge-&-Dropout Detector, Mains Voltage
NHiA2&A4Off-Pulse Oneshot and DC-to-DC: A4 PFETS probably failed
NNA2&A4Power-Limit Comparator and DC-to-DC: A4 PFETS 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 (A2CR11 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.
PWM-OFF
A2J7-25
DEFECTIVE
BOARD
CHECK FUNCTIONAL CIRCUITS
56
Troubleshooting AC-Turn-On Circuits
Relay AlK1 closes at 2.5 seconds and AC FAULT goes high at 2.9 seconds after 21V UNREG reaches about 13Vdc.
AC FAULT high enables the PWM if OVERVOLTAGE , INHIBIT , and OVERTEMP are also high.
Circuits Included. High AC and AC Dropout Detectors, Bias Voltage Detector, Q11A, 3-Second Delay and Relay Driver-all on A2 control board.
Setup. The Main Troubleshooting Setup, Page 53. Apply the ac mains voltage to the isolation transformer, and set the
external supply to 0Vdc.
A2U17-9cycle power
A2U17-14cycle power
A2Q11-14cycle powertransition 0 to 5Vdc at 25 sec
A2Q11-4Hi (5Vdc)
A2U9-10cycle power2.9 s burst 1.25KHz sq. wave
A2U9-15cycle powerone 840ms pulse then Hi at 2.5 sec
A2U9-14cycle powerthree 420 ms pulses then Hi at 2.9 sec
A2U9-1cycle powertransition Lo to Hi at 1.7 s
A2U15-10cycle powertransition Lo to Hi at 2.9 s
(
AC FAULT )
A2Q7-Ccycle powertransition 5.0 to 0.3Vdc at 2.5 sec
RELAY ENABLE
≈ 21Vdc
≈ 13.5Vdc
≈ 1.4Vdc
A1CR2,A1CR5
*Node( - ) = A2J7-4
Troubleshooting DC-To-DC Converter
Parallel NOR gates A4U1, A4U2 and A4U3A act as drivers and switch on FETs A4Q1,Q2,Q3 and Q4 through pulse
transformer A4T1. NOR gate A4U3B turns off the FETs through pulse transformer A4T2 and transistors A4Q5 and A4Q6.
Circuits Included. On-Pulse Driver, Off-Pulse Driver, FET Switches and Drivers on A4 FET board.
Setup. The Main Troubleshooting Setup, Paragraph 3-40. Apply the ac mains voltage to the isolation 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.
Using the DISPLAY SETTINGS switch. Verify that the OVERRANGE LED lights. See Figure 3-7 for waveforms.
57
Inputs:
NODE (+)NODE (-)MEASUREMENTSOURCE
A2J7-26(PWM-ON)M
A2J7-25(PWM-OFF)M
NODE (+)NODE (-)MEASUREMENTSOURCE
A4P1-C1A4P1-A110.6VdcAlU3-2
A4Q2-DA4Q4-S39VdcA1C51 ( + ),A4P1-22 to 25
If you replace the FETs, replace both the FETs and associated drive components as furnished in FET Service Kit. Agilent
Part No. 5060-2866.
The FETs are static sensitive and can be destroyed by relatively low levels of electrostatic voltage.
Handle the A4 FET board and the FETs only after you, your work surface and your equipment are
properly grounded with appropriate resistive grounding straps. Avoid touching the FET's gate and
+5V On A2 Control Board. The PWM A2U22 includes a clock generator (40KHz set by A2R170, A2C79 and A2Q10),
and a current limit (2Adc set by 0.15Vdc across A2R172). It turns off each output pulse using the difference between the
voltage at voltage divider A2R161-A2R163 and the 2.5Vdc set by voltage regulator A2U21.
Circuit Included. +5Vdc bias supply circuitry from connector pins A2J5-1,3 through jumper A2W3 on A2 control board.
Setup. The Main Troubleshooting Setup, Page 53. Apply the ac mains voltage to the voltage transformer, and set the
external supply to 0Vdc.
Input:
NODE (+)NODE (-)MEASUREMENTSOURCE
A2J7-22A2J7-4
Outputs:
NODE ( + )NODE (-)MEASUREMENT
A2U22-7A2J7-4
A2U22-12,13"
A2Q9 (emit)"
A2U21-2"2.5 Vdc
A2R161, A2R163"2.5 Vdc
To check if load on + 5V is shorted, remove jumper A2W3
+15V On A2 Control Board. Voltage regulator A2U11 regulates the voltage across resistor A2R99 to be 1.25Vdc. That
sets the current through zener diode A2VR3 at 7.5mAdc. The output voltage is 1.25Vdc plus 11.7Vdc across A2VR3 plus
the voltage across A2R100.
Circuit Included. +15Vdc bias supply circuitry from connector pin A2J5-5 through test point A2J7-2 on A2 control board.
Setup. The Main Troubleshooting Setup, Page 53. Apply the ac mains voltage to the isolation transformer, and set the
To check if load on -15V is shorted, remove jumper A2W2.
Refer to Down Programmer, for the + 10.6Vdc bias supply, and refer to OVP Circuit, for the + 2.5V bias supply.
≈ - 25Vdc
A1U4
60
Troubleshooting Down Programmer
The down programmer discharges the output when either PWM OFF is generated or CV ERROR is more negative than
about - 3Vdc. Comparator A5U1 triggers down programming when the voltage at A5U1-5 is less than about 4Vdc.
Circuit Included. Down programmer and 10.6V bias supply on A1 main board.
Setup. The Main Troubleshooting Setup, Page 53, except connect the external supply to the unit's + OUT ( + ) and - OUT (
- ) terminals. Apply the ac mains voltage to the isolation transformer. Set the external supply for an output voltage of 10Vdc
and set current limit for 2.5 Amps. Set the power supply under test for a voltage setting of 8.0Vdc and current setting of
2.0Adc using the ''DISPLAY SETTING" switch.
Outputs:
NODE ( + ) *EXTERNAL SUPPLYMEASUREMENT
A5C1 ( + ) C3(6031A)ON/OFF10Vdc
A5VR1(K)ON/OFF6.5Vdc
A5U1-3ON/OFF0.2Vdc
A5CR1( K ) CR2(6031A)OFF0.6Vdc
A5CR1( K ) CR2(6031A)ON0.2Vdc
A5U1-1OFF0.5Vdc
A5U1-1ON5.0Vdc
A5R20 + (6030A/35)OFF< 0.001Vdc
A5R20 + (6030A/35)ON1.5Vdc
across A5R1(6031A)OFF< 0.001Vdc
across A5R1(6031A)ON0.10Vdc
across A5R14(6032A)OFF< 0.001Vdc
across A5R14(6032A)ON0.17Vdc
* NODE (-) = A2J7-4
Troubleshooting CV Circuit
V-MON, the output of CV Monitor Amp A2U2. is 1/40 (6030A); 1/4 (6031A); 1/12 (6032A); l/l00 (6035A) the voltage
between + S and - S. CV Error Amp A2U3 compares V-MON to CV PROGRAM. Innerloop Amp A2U5A stabilizes the
CV loop with input from A2U5B. 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 A2U5B.
Setup. The Main Troubleshooting Setup, Page 53. Apply the ac mains voltage to the isolation bias transformer, and
disconnect the external supply. Remove the + S jumper and connect A2J7-2 ( +15V) to + S. Set mode switch settings B4,
B5 and B6 all to 0. Set VP to 0Vdc by connecting to P or set VP to + 5Vdc by connecting to A2J7-24 according to SETUP
below. VP and P are on rear-panel terminal block.
If the failure symptoms include output voltage oscillation, check if the CV Error Amp circuit is at fault by shorting A2U3-6
to A2U3-2. If oscillations stop, the CV Error Amp circuit is probably at fault.
Troubleshooting CC Circuit
I-MON, the output of CC Monitor Amp A2U1, in volts is 5/17 (6030A); 1/24 (6031A); 1/10 (6032A); equals (6035A) the
output current in amperes. CC Error Amp A2U4C compares l-MON to CC PROGRAM. Differentiator circuit A2U4A
differentiates the inboard voltage sense and stabilizes the CC loop. Its output is summed with CC PROGRAM at CC Error
Amp A2U4C.
The measurements below verify that the operational amplifier circuits provide expected positive and negative dc 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 53, except connect the external supply with polarity reversed to the unit's +
OUT ( - ) and - OUT ( + ) terminals. Apply the ac mains voltage to the isolation transformer. Set the external supply to
3.0Adc constant current with a voltage limit in the range 5 to 20Vdc. Set IP to 0Vdc by connecting to P or set IP to +5Vdc
by connecting to A2J7-24 according to SETUP below. Set mode switches B1, B2, and B3 AU to 0.
If the failure symptoms include output current oscillation, check if the differentiator circuit is at fault by removing resistor
A2R35. If oscillations stop, the differentiator is probably at fault.
Troubleshooting OVP Circuit
Flip-flop A2U8A-A2U8D is set by comparator A2U8C and reset by OV CLEAR. TTL low at A2U18-12 inhibits the PWM.
OVP Program Voltage on A2J7-7 is equal to Eout/250 (6035A), Eout/100 (6030A), Eout/30 (6032A), Eout/10 (6031A).
Circuit included. OVP Circuit and 2.5V bias supply on A2 control board.
62
Setup. The Main Troubleshooting Setup, Page 53, except connect the external supply to the unit's + OUT ( + ) and - OUT
(-) terminals. Apply the ac mains voltage to the isolation transformer. Adjust the unit's OVP limit to 10Vdc. Set the external
supply (EXTERNAL) as instructed below.
Note: Connecting a test probe to either input of either comparator in the OV Flip Flop (pins A2U8-1, 6, 7,10,11
or 13 ) may cause the flip flop to change states and cause the probed input to be low.
Troubleshooting PWM & Clock
The inputs to gates A2U18A and A2U18B are the keys to PWM troubleshooting. The 20KHz Clock starts each PWM
output pulse, and the pulse stops when any of the inputs to A2U18A or A2U18B goes low. The PWM is inhibited and
prevented from initiating output pulses as long as any of the seven inputs is low.
This chapter contains block diagrams, simplified schematics, and related descriptions of the power supply. The instrument
can be thought of as comprising two major sections: the GPIB, microcomputer, and interface circuitry; and the power mesh
and control circuits. Block diagrams represent the GPIB board, the front panel board, and the power mesh and control
board. The descriptions associated with these block diagrams explain the function of each block without describing how
individual components within the circuit accomplish that function. Detailed descriptions are provided only for those
individual circuits whose operation may not be obvious to the user.
The circuit names and layouts of the block diagrams are the same as used on the complete schematics; however, some items,
such as bias supplies, are left off the block diagrams for clarity. In general, circuits are described as they appear on the
diagrams from left to right. Signal names that appear on the drawings are printed in capitals in the descriptions, as are
front-panel labels for indicators and controls. Signal names that describe an operating mode or condition are active when
that condition exists. For example, OT is high and
to right and top to bottom, unless arrows indicate otherwise.`
The following paragraphs describe the GPIB and the front-panel board. These circuits provide the interface between the
power mesh circuits and the controller and/or operator. The GPIB and front-panel boards are referenced to earth common.
Isolation is achieved by optical isolators on the GPIB board. Data is sent between boards serially.
OT is low if an overtemperature condition exists. Signal flow is from left
GPIB Board
Circuits on the GPIB board, see Figure 4-1, provide the interface between the power supply and the user, generate the
fault/inhibit and relay controls signals (DFI/RI), and supply the analog control and reference signals for the power mesh and
readback circuit. Two microprocessors (primary and secondary) control all data communication between the power supply
and the user. Additional circuits on the GPIB board include the serial interface ports, address switches, an EEPROM, and
status registers.
Primary Microprocessor
The primary microprocessor controls the GPIB/serial link interface, the front panel data communication, and the DFI/RI
interface. It communicates with the secondary microprocessor through two serial link data lines that are optically coupled to
provide the proper isolation of the user interface from the power mesh. The GPIB board also has a ROM, which contains
the operating firmware, and a RAM, which stores variables such as programmed voltage and current and readback values.
Address Switches
The primary microprocessor determines the GPIB address by reading the address switch settings. Two of the address
switches determine the power-on SRQ state and the DFI/RI port setting.
65
66
Figure 4-1. GPIB Block Diagram
EEPROM
The primary microprocessor determines the power supply ID, start-up parameters, calibration constants and scale factors by
reading the factory-initialized EEPROM.
Isolation
Two optical isolators transmit serial data between the primary and secondary microprocessors while maintaining electrical
isolation between the controller/user-interface and the power mesh.
Secondary Microprocessor
The secondary microprocessor translates the serial data from the primary microprocessor into a parallel data bus and other
control signals. Values are loaded into the voltage, current, and readback DAC via the data bus. The secondary
microprocessor also controls the analog multiplexer, which is used when reading back the actual output.
Digital-to-Analog Converters
Output voltage and current are controlled by two 12-bit DACs whose digital inputs are directly connected to the secondary
microprocessor. The microprocessor programs the DACs according to data received over the GPIB or from the front panel
rotary pulse generator. The DAC circuits also include buffers and compensation amplifiers.
The 12-bit readback DAC is connected to the input of a comparator where it's output is compared to the unknown voltage
output of the analog multiplexer. The secondary microprocessor programs the output of the readback DAC starting with the
MSB and continuing down to the LSB. Each bit is programmed either on or off until the output of the DAC is closest to the
unknown voltage output of the multiplexer. At this point, the microprocessor returns the programmed value of the readback
DAC.
Analog Multiplexer
The analog multiplexer selects one of five input voltages to be compared to the readback DAC. This comparison allows the
microprocessor to determine the value of the input voltage. The five inputs of the multiplexer are: CV_PROG and
CC_PROG, which are only used during selftest, at power-on, or in response to the TEST? query when the supply is
disabled; OV_MON, which represents the overvoltage trip setting; and I_MON and V_MON, which represent the measured
values of output current and voltage.
Status Inputs
The status inputs from the main board provide the following status information to the secondary microprocessor. They are:
CC, which is set when the supply is operating in constant current mode; CV, which is set when the supply is in constant
voltage mode; AC_FAULT, which signals that ac power has dropped below the minimum operating voltage of the supply;
OT, which indicates an overtemperature condition has occurred on the supply; and OV, which indicates an overvoltage has
occurred on the supply.
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Front Panel Board
The front-panel board, see Figure 4-2, contains the VOLTS and AMPS display circuits, the rotary pulse generator (RPG)
and RPG decoders, five pushbutton switches, mode indicators, and the OVP ADJUST potentiometer. Data from the
microprocessor is shifted to the display circuits via
shifted to the microprocessor via DATA UP. Circuits on the front-panel board operate from bias voltages supplied from the
GPIB board, and are referenced to the same common as the GPIB board (earth ground). The OVP ADJUST potentiometer
is part of the power mesh control circuitry (referenced to power supply negative output), and is not connected to any circuits
on the front-panel board.
DATA DOWN , and data from the front-panel controls circuits is
Address Latches and Decoders
DATA DOWN bits received while D / A is low are latched and decoded in this circuit, which then steers clock pulses to
the addressed circuit when
D / A goes high.
Volts and Amps Output Ports and Displays
These circuits display values sent by the microprocessor via DATA DOWN. Normally, these are the actual output voltage
and current readings. Pressing the DISPLAY SETTINGS switch causes the microprocessor to send the voltage and current
values that have been sent by the controller (remote) or RPG (local). If the unit is in CV mode, the voltage display should
show the same reading for actual and set values; the current display will switch from the actual value to the current limit. In
CC mode, the current readings will be the same and the voltage display will switch from actual value to the voltage limit.
Pressing the DISPLAY OVP switch causes the voltage display to show the OVP trip voltage that has been set.
The microprocessor also uses the readout to display the GPIB address switch settings, self test error messages, and readback
overrange conditions.
RPG and Latches
When rotated, the RPG products two pulse trains that are 90 degrees phase shifted from each other, with the phase
relationship determined by the direction of rotation. This circuit contains two flip-flops that monitor the RPG outputs. The
output of one flip-flop goes low to indicate that the RPG has been rotated, and the output of the other goes low to indicate
CW rotation or high to indicate CCW rotation. This data is loaded into an input port when
are set back to their quiescent state by clock pulses from the address decoder when the input port is addressed.
Because the microprocessor reads the input approximately every millisecond, it can determine if the RPG is being turned
rapidly (for a large change) or slowly (for fine adjustment), and the microprocessor varies the rate it changes the DAC
inputs accordingly.
D / A is low, and the flip-flops
Front-Panel Switches and Input Port
Five front-panel pushbutton switches plus the two RPG flip-flop outputs are connected to this input port. Data is loaded
when
D / A is low, and is shifted out by clock pulses from the address decoders. The microprocessor reads data in via
DATA UP approximately every millisecond, and checks the switches every 10 ms, thereby ensuring that even rapid switch
operations will be captured.
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Figure 4-2. Front Panel Block Diagram
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Mode Indicators
The front-panel mode indicators are controlled by the microprocessor via DATA DOWN and the mode indicator output
ports and latches. DATA DOWN signals are shifted in by clock pulses from the address decoders.
OVP Adjust Control
The OVP ADJUST potentiometer sets the voltage level at which the overvoltage protection (OVP) circuit trips.
Power Clear
The power clear signal ( PCLR ) from the GPIB board goes low when the unit is turned on, and remains low until the bias
power supplies have stabilized. This low level resets the display-circuit latches on the front panel board, causing all
indicators and display segments to turn on and remain on until the microprocessor updates the display (approximately one
second).
Power Mesh and Control Board
The basic operating concepts of the power mesh and control circuits are described in the following paragraphs. The
beginning paragraphs describe the basic difference between an autoranging power supply and a conventional CV/CC power
supply in terms of the available output, and provide an overview of the basic theory of operation. Later paragraphs describe
the functions of the individual circuits on the power mesh and control board.
Overview
The basic difference between an autoranging power supply and conventional types of Constant Voltage/Constant Current
(CV/CC) power supplies can be seen by comparing the maximum-output-power characteristics of each. A conventional
CV/CC power supply can provide maximum output power at only one combination of output voltage and current, as shown
in Figure 4-3a. The range of a power supply can be extended by designing an instrument with two or more switch-selectable
voltage/current ranges within the maximum power-output capability, as shown in Figure 4-3b. An autoranging power supply
provides maximum output power over a wide and continuous range of voltage and current combinations, as shown in Figure
4-3c, without the operator having to select the proper output range.
The unit is a flyback-type switching power supply, so-called from the flyback technique of generating high voltage in
television receivers. Energy is stored in the magnetic field within a transformer while current flows in the primary, and is
transferred to the secondary circuit when current flow in the primary is turned off. Current flow in the primary is controlled
by FET switches which are turned on and off at a 20KHz rate by a pulse width modulator. Regulation is accomplished by
controlling the on time of the FET switches. On pulses are initiated by a clock circuit. Off pulses are initiated when current
flow in the primary has stored enough energy for the output circuit, which is determined as follows.
Sense voltages representing the actual output voltage and current are compared to reference voltages set either by
front-panel controls or remote programming signals. These comparisons produce a control voltage, which represents the
amount of power required by the output circuit. Current flow in the primary circuit produces a ramp voltage that represents
the amount of energy being stored for transfer to the output circuit. An off pulse is generated when the ramp voltage exceeds
the control voltage. It can be seen that the power available in the output circuit corresponds to the duty cycle of the FET
switches.
Figure 4-4 shows the relationship of various signals associated with the FET on/off cycle.
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Figure 4-3. Output Characteristics; Typical, Dual Range, and Autoranging Supplies
Figure 4-4. FET Control Signals Timing Diagram
Power Mesh
Figure 4-5 is a block diagram of the power mesh. These circuits convert the ac input power to approximately 320Vdc, and
convert this dc voltage to the proper dc output voltage.
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Input Circuits
. Primary power is connected through the AC Input Filter to the LINE switch and to the normally open
contacts of the Inrush-Limit relay. When LINE switch is closed, current flows through the inrush current limiting resistor
and the normally closed relay contacts to the Bridge Rectifier/Voltage Doubler. This circuit is jumper connected as a
voltage doubler for 100 or 115Vac operation and as a full-wave bridge charges to about 320Vdc for any input voltage.
Current also flows through the Voltage Select Switch to the Bias Power Supplies, which provide the operating voltages for
the power supply. The Voltage Select Switch connects the primary windings of the bias transformer for operation at 100,
120, 220, or 240Vac. The Voltage Select Switch also supplies 120 Vac to the fan and Relay Circuits.
The Inrush Limit relay is energized by
RELAY ENABLE , which is generated on the control board after the unit has
checked that various operating voltages are within acceptable limits. After a delay of approximately 2-1/2 seconds, which
allows the Input Filter capacitors to charge, the relay is energized, bypassing the Inrush Limit resistor. A switch on the main
board switches in more Inrush Limit resistance for 220 or 240Vac operation.
DC To DC Conversion. Current flow from the input rails through the power transformer is controlled by FET switches. On
and off pulses for the FETs are generated on the control board, as will be described shortly. On pulses are applied through
the On Driver and pulse transformer T1 to the gates of both pairs of FETs. Although the on pulse is only about 1.7
µs
duration, the FETs' input capacitance holds the FETs on after the on pulse has disappeared.
When the FETs are turned on, current flows through the primaries of Power Transformer T2 and Primary-Current Monitor
Transformer T1. The Output Diodes are reverse biased and block current flow in the T2 secondary. Consequently, energy is
stored in the field that builds around the T2 transformer windings. The longer that voltage is applied to the primary, the
more energy is stored. Current flow in the secondary of T1 is connected to the control board, where it generates a ramp
voltage. The amplitude of this linearly increasing voltage corresponds to the amount of current flow through the T2 primary;
therefore, it represents the amount of energy being stored in the field around T2. It is this ramp voltage that is compared to a
control voltage to determine when the FETs should be turned off.
Off pulses turn on Q5 and Q6, which discharge the FET gates, thereby turning the FETs off. When the FETs are turned off,
the collapsing magnetic field reverses the polarity across the T2 primary and secondary, and current flows from T2
secondary through output diodes to charge the output filter capacitors. The level to which the output capacitors are charged
corresponds to the length of time that the FETs are on and current flows in T2 primary.
Leakage inductance of T2 attempts to maintain current flow in the primary circuit when the FETs turn off. Flyback diodes in
the FET board protect the FETs by conducting this current around the FETs and back to the input filter.
Down Programmer. This circuit allows the output voltage to be lowered rapidly when required. In order to lower the
output voltage it is necessary to discharge the output filter capacitors (typically, through the load). In situations that require
the output voltage to drop more rapidly than can be accomplished through the load, the Down Programmer discharges the
capacitors and pulls the output line low.
DOWN PROGRAM ENABLE is generated on the control board. Six conditions
can conditions can trigger down programming: programming of a lower output voltage, overvoltage, overtemperature,
remote disable, remote inhibit, or primary power failure.
The + 10.6Vdc 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 completely when primary power is turned off.
The Agilent 6030A/35A units contain an active bleed circuit, connected across the output, which allows regulation at low
output current and/or low output voltage levels. This circuit also minimizes dielectric absorption effects, which show up as
noise on the output of the supply.
Current Monitor Resistor. A highly stable resistance element in the -output line develops the CURRENT SENSE voltage,
which is proportional to the power supply output current. This signal is supplied to the CC Circuit on the control board.
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Control Board
Figure 4-6 is a block diagram of the control board. These circuits monitor the power supply operation and provide the
signals that control the power mesh.
+ 5V Bias Supply. This circuit operates from the + 5V Unregulated voltage from the main board, and generates + 5V and
+ 2.5V used by circuits on the control board. Regulated + 5V is also supplied back to the main board for use by the relay
circuits, FET Drivers, and Down Programmer. The + 5V Bias Supply is regulated by a pulse width modulator chip that is
synchronized by the 40KHz clock signal to the main Pulse Width Modulator; this eliminates the possibility of frequency
modulated signals on common lines.
Bias Voltage Detector and Relay Driver. The Bias Voltage Detector monitors + 5V Unregulated to determine when bias
voltages are sufficient to ensure proper operation. After turn-on, as the output of the + 5V bias supply rises from 0Vdc
through approximately 1Vdc, three transistor switches in the Bias Voltage Detector turn on. They inhibit the relay driver
and the on-pulse driver, and generate the power-clear signal. The switches remain on until the + 5V Unregulated input
exceeds approximately 13 volts, which is sufficient to ensure both a stable + 5V output and adequate FET drive voltage.
PCLR holds various circuits reset until after the bias voltages stabilize and control circuits are certain to be working.
RELAY ENABLE , which is delayed for approximately 2 ½ seconds by the Time Delay Circuit, drives relay circuits on the
main board that short out inrush current limiting resistors after input filter capacitors are charged up. RELAY ENABLE
cannot occur until bias voltages have stabilized and time delay has expired. ON - PULSE INHIBIT shorts ON pulses to
ground whenever bias voltage is insufficient to ensure proper operation.
Note that Bias Voltage Detector inhibits power supply operation in two circumstances: while bias voltages are stabilizing
after turn-on, and when ac input drops below an adequate level (brownout).
+ 15V Bias Supply. This circuit produces the + 15V and +5.9V bias voltages. It also produces the reference voltage used
by the CC and CV Current Sources.
Time-Delay Circuit. This circuit generates the signal that delays RELAY ENABLE for approximately 2 ½ seconds after
cessation of an ac fault (Dropout or High AC). The AC FAULT signal is extended for the duration of the time delay and
supplied to: the 1.25KHz counter in the 20KHz Clock Circuit to reset the counter, so that the time delay output of the Time
Delay Circuit will remain set; the Pulse Width Modulator (PWM) to inhibit the PWM in case of an ac fault.
AC Dropout Detector. The AC Dropout Detector operates to shut down the power mesh when primary power is turned off
or lost. The circuit monitors the 120Hz signal (full-wave rectified 60 Hz ac) from the bias transformer on the main board.
Dropout is detected by a ramp circuit that is reset by the 120 Hz pulses. If the ramp is not reset within approximately 20
milliseconds of the previous reset, the circuit generates AC FAULT, which is supplied to the Time Delay Circuit to disable
RELAY ENABLE and the PWM.
High AC Detector. The High AC Detector protects the power supply from damage from ac power line surges. The circuit
contains a comparator that monitors the voltage level of the 120Hz signal. If this voltage exceeds a safe operating level, the
circuit generates the
FAULT signal.
Turn-On Overshoot Control. The Turn-On Overshoot Control Circuit prevents output overshoot when the Pulse Width
Modulator is turned back on after having been turned off. The circuit monitors the
Modulator. If the PWM is turned off because of INHIBIT (from GPIB), AC FAULT , OT (overtemperature), or OV
(overvoltage), the power supply output will be down programmed to zero, and both the CC and CV Circuit outputs will
increase to maximum in an attempt to restore the output level. This circuit holds the CONTROL PORT at a low level to
prevent output overshoot when
HIGH AC signal, which is ORED with AC DROPOUT . Either can cause generation of the AC
PWM OFF signal from the Pulse Width
PWM OFF is removed.
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Constant Current (CC) Circuit.
The Constant Current Circuit compares the CURRENT SENSE voltage level to CC
PROGRAMMING VOLTAGE to produce CC CONTROL SIGNAL. CURRENT SENSE is developed across the
current-monitor resistor on the main board, and is proportional to the power supply output current. CC PROGRAMMING
VOLTAGE comes from one of a number of sources as selected by the rear-panel mode switches, and represents the desired
output current or current limit.
CC CONTROL SIGNAL varies from approximately -1 to +0.5 volts when the power supply is in constant current mode,
and is most positive when the CC Circuit is calling for maximum power supply output. CC CONTROL SIGNAL is
connected through an output diode, CR11, shown at the wired-OR gate that is the CONTROL PORT.
The amplified current-sense signal is brought out of the CC Circuit as I-MON (current monitor). I-MON is connected to the
rear-panel IM terminal, and varies from 0 to + 5 volts as the output current varies from zero to full scale.
A differentiator circuit in the CC Circuit block provides increased stability for highly reactive loads.
Constant Voltage (CV) Circuit. Operation of the CV Circuit is similar to the CC Circuit. The CV Circuit compares the
output SENSE voltage to the CV PROGRAMMING VOLTAGE to produce the CV CONTROL SIGNAL. + OUT and OUT are also supplied to the circuit as protection in case the sense leads are inadvertently disconnected. CV CONTROL
SIGNAL also varies between approximately -1 to + 0.5 volts, and is connected through diode CR24 to the CONTROL
PORT.
The buffered voltage-sense signal is brought out of the CV Circuit as V_MON (voltage monitor). V_MON is connected to
the rear-panel VM terminal, and varies from 0 to + 5 volts as the output voltage varies from zero to full scale. Both V-MON
and I-MON are referenced to monitor common ( M).
The CV Circuit also produces the
DOWN PROGRAM ENABLE signal when the CV PROGRAMMING VOLTAGE is
changed quickly from a relatively high level to a relatively low level. This allows the power supply output voltage to be
lowered more rapidly than if the output filter capacitors had to be discharged solely through the load.
CC And CV Current Sources. This circuit generates constant currents that are connected to front-panel VOLTAGE and
CURRENT potentiometers of non-- GPIB units to develop the CC and CV programming voltages.
Mode Switches. The rear-panel mode switches select the source of the CC and CV PROGRAMMING VOLTAGES. For
GPIB units, the programming voltages are supplied via the GPIB board, and are connected through mode switches B1 and
B4 to the CC and CV Circuits. For non-- GPIB units, mode switches B2, B3, and B5, B6 are closed. The CC and CV
Current Source outputs are connected through B2 and B5 to the front-panel CURRENT and VOLTAGE potentiometers,
and the voltages developed across the potentiometers are connected through B3 and B6 to the CC and CV Circuits.
Remote analog programming voltages can be supplied to the CC and CV Circuits from the rear-panel IP and VP terminals.
IP and VP are referenced to program common ( P).
Primary Current Ramp. The output from the primary current-monitor transformer on the main board is developed across
R116 and R117 to produce a ramp voltage that represents the amount of energy being stored in the power transformer for
transfer to the power supply output circuits. This ramp voltage is connected to the Power Limit Comparator and to the
Control Voltage Comparator.
Power Limit Comparator. The power supply maximum output power curve (shown in Specifications Table in the
Operating Manual) is defined by this circuit. The PRIMARY CURRENT RAMP voltage, which represents the amount of
power being supplied to the power supply output, is compared to a voltage which represents the maximum amount of power
that the power supply can supply safely. If the ramp voltage exceeds the limit voltage, the POWER LIMIT signal is
produced to turn off the PWM.
The Power Limit Comparator Circuit includes a dynamic primary-current-limit circuit, which decreases the primary current
limit to maintain the output power curve at specified limits.
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Control Voltage Comparator.
This circuit compares the voltage at the CONTROL PORT (represents power required at
output) with PRIMARY CURRENT RAMP voltage (represents energy being stored for transfer to output). When RAMP
voltage exceeds CONTROL PORT voltage, the Control Voltage Comparator generates the
CONTROL LIMIT signal to
turn the PWM off. The CONTROL PORT is biased to approximately + 1.3 volts. Whichever control signal, CC or CV, is
more negative (calling for less output power) forward biases its output diode and determines the voltage at the CONTROL
PORT.
As can be seen from the waveforms in Figure 4-4, there is a delay between the time when PRIMARY CURRENT RAMP
voltage exceeds the CONTROL PORT voltage and the time when the FETs turn off. This delay consists of the comparator
switching time, gate delays, transformer delay, and FET turn-off time, and it results in a certain amount of power being
transferred to the output after the desired off time. If the CONTROL PORT voltage is at a very low level (unit supplying
little or no output power), this power may exceed the amount required by the load. To eliminate the delay, the Control
Voltage Comparator includes an initial ramp circuit that generates a small ramp voltage before the FETs are turned on. The
added ramp voltage starts with the 20KHz clock pulse, and causes the combined-ramp voltage to exceed the CONTROL
PORT voltage earlier, thereby effectively eliminating the FET turn-off delay.
Status Drivers. Inputs from the CC and CV Circuits indicate which circuit, if either, is regulating the power supply output.
If neither circuit is regulating the output (load calling for more power than the power supply can deliver), logic circuits
within Status Driver block determine that output is unregulated.
In GPIB units, CC and CV signals go to the microcomputer, which will take appropriate action, including lighting
front-panel indicators. In non-- GPIB units, Status Driver outputs go to front-panel indicators.
20KHz Clock. This circuit contains a 320KHz crystal oscillator and dividers that produce 40KHz, 20KHz, and 1.25KHz
signals. Both the 320KHz and 20KHz signals are supplied to the PWM, with the 20KHz signal controlling the repetition
rate of the PWM.
The 40 KHz signal is supplied to the +5V Bias Supply Circuit to synchronize the PWM in that circuit to the main power
supply PWM. The 1.25KHz output is supplied to the Time Delay Circuit for generating the time delay used to control the
power supply turn-on sequence.
The 1.25KHz signal is subsequently disabled by the AC FAULT output from the Time Delay Circuit at the end of the time
delay.
Pulse Width Modulator (PWM). The PWM generates the ON and OFF pulses that control the power FETs in the power
mesh. ON pulses are generated at a 20KHz rate, and, as can be seen in Figure 4-4, are initiated by the first 320KHz dock
pulse after the start of the 20KHz clock pulse. When the FET switches turn on, current flows through the Primary Current
Monitor transformer on the main board, and the Primary CURRENT RAMP voltage starts to rise. OFF pulses are normally
initiated when CONTROL LIMIT becomes active (low), indicating that the ramp voltage has exceeded the CONTROL
PORT voltage. However, an off pulse can be initiated by any one of a number of other signals.
An overtemperature (
OT ), overvoltage ( OV ), remote inhibit, AC FAULT condition or an INHIBIT signal from GPIB
will initiate an OFF pulse, and will also trigger the Down Programmer to reduce output voltage to zero. These conditions
will also cause
OFF pulses can also be initiated by
PWM OFF to be sent to the TurnOn Overshoot Control Circuit.
POWER LIMIT and by the trailing edge of the 20KHz clock signal. The 20KHz clock
signal ensures that even if nothing else, such as CONTROL LIMIT or POWER LIMIT , initiates an OFF pulse, the FET
duty cycle will be limited to less than 50%.
Overvoltage Protection (OVP). The OVP circuit monitors the power supply output voltage and compares it to a preset
limit determined by a front-panel OVP ADJUST potentiometer. If the output voltage exceeds the limit, the OVP Circuit
initiates a PWM OFF pulse, which also triggers the Down Programmer. The OVP Circuit lathes itself until it receives OV
CLEAR or ac power is turned off.
75
76
Figure 4-5. Power Mesh Block Diagram
Figure 4-6. Control Board Block Diagram
77
Replaceable Parts
Introduction
This chapter contains information for ordering replacement parts. Table 5-1 lists parts in alpha-numeric order by reference
designators and provides the following information:
a.
Reference Designators. Refer to Table 5-1.
b.
Agilent Technologies model in which the particular part is used.
c.
Agilent Technologies Part Number.Description. Refer to Table 5-2 for abbreviations.
d.
Parts not identified by reference designator are listed at the end of Table 5-4 under Mechanical and/or Miscellaneous.
* Reference designator following "X" (e.g. XA2) indicates assembly or device mounted in socket.
79
Ordering Information
To order a replacement part, address order or inquiry to your local Agilent Technologies 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 Technologies part number; circuit reference designator; and description. To order a part not listed in
Table 5-4, give a complete description of the part, its function, and its location.
Ref. DesigAgilent ModelAgilent Part NumberDescription
Chassis Mechanical
(cont)
all06032-00010output buss bar (2)
all0340-1095insulator for bus bar (4)
all0380-1362standoff, 12mrn (buss bar) (2)
all1510-0044binding post, rear panel ground
all0400-0086insulated bushing (under A6) (2)
all5001-6739cover, top
all5001-6738cover, bottom
all06032-00024cover, internal (lettered)
all5040-1626cover, dc output
all5040-1627cover, ac input
all5040-1625strain relief (line cord)
all5062-3703strap handle (2)
all5041-8819handle retainer, front (2)
all5041-8820handle retainer, back (2)
all5041-8801foot (4)
100
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 6-9), 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.Schematic diagrams (Figures 6-10 through 6-13).
c.
AC line voltage is present on the A1 Main Board Assembly whenever the power cord is connected to an ac
power source.
Table 6-1. Schematic Diagram Notes
6
1.
2.
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.Schematic components marked with an asterisk (*) indicate that different values are used in each model. Refer to the
parts list for the applicable values.
8.Schematic components marked with a dagger (
9.This capacitor is only used on 6030A and 6035A units. C6 is mounted on the chassis on 6030A units. C3 is mounted
on the A9 board on 6035A units.
10.
denotes front-panel marking.
.
denotes rear-panel marking.
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.
† ) are listed under chassis, electrical in the parts list.
11.
Inter-board commons have letter identifications (e.g.:
identifications (e.g.:
).
); commons existing on a single assembly have number
101
Table 6-1. Schematic Diagram Notes (continued)
For single in-line resistor packages, pin 1 is marked with a dot. For integrated circuit packages, pin 1 is either marked with
a dot, or pin 1 is to the left (as viewed from top) of indentation on the integrated circuit package (except for A8U6 and
A8U8).
102
Figure 6-1. Top View, Top Covers Removed
103
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