HP 6033A series User manual

SERVICE MANUAL
AUTORANGING
SYSTEM DC POWER SUPPLY
HP MODELS 6033A and 6038A
HP Part No. 5959-3346
FOR INSTRUMENTS WITH SERIAL NUMBERS
HP Model 6033A; Serials US38320231 and above
HP Model 6038A; Serials US38310401 and above
For instruments with higher serial numbers, a change page may be included.
Microfiche Part No. 5959-3347 Printed in USA: December, 1999

2
CERTIFICATION
Hewlett-Packard Company certifies that this product met its published specifications at time of shipment from the factory.
Hewlett-Packard 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 Hewlett-Packard hardware product is warranted against defects in material and workmanship for a period of three years
from date of delivery. HP software and firmware products, which are designated by HP 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 Hewlett-
Packard Company will, at its option, either repair or replace products which prove to be defective. HP 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 HP. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products returned to HP for
warranty service. Except for products returned to Customer from another country, HP shall pay for return of products to
Customer.
Warranty services outside the country of initial purchase are included in HP’s product price, only if Customer pays HP
international prices (defined as destination local currency price, or U.S. or Geneva Export price).
If HP 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 HP.
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. HP 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. HP 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 Hewlett-Packard
Sales and Service office for further information on HP’s full line of Support Programs.

3
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. Hewlett-Packard Company 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 three-
conductor 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).
FUSES
Only fuses with the required rated current, voltage, and specified type (normal blow, time delay, etc.) should be used. Do not use
repaired fuses or short circuited fuseholders. To do so could cause a shock or fire hazard.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.
Do not operate the instrument in the presence of flammable gases or fumes.
KEEP AWAY FROM LIVE CIRCUITS.
Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made by qualified
service personnel. Do not replace components with power cable connected. Under certain conditions, dangerous voltages may exist even
with the power cable removed. To avoid injuries, always disconnect power, discharge circuits and remove external voltage sources before
touching components.
DO NOT SERVICE OR ADJUST ALONE.
Do not attempt internal service or adjustment unless another person, capable of rendering first aid and resuscitation, is present.
DO NOT EXCEED INPUT RATINGS.
This instrument may be equipped with a line filter to reduce electromagnetic interference and must be connected to a properly grounded
receptacle to minimize electric shock hazard. Operation at the line voltage or frequencies in excess of those stated on the data plate may
cause leakage currents in excess of 5.0mA peak.
SAFETY SYMBOLS.
Instruction manual symbol: the product will be marked with this symbol when it is necessary for the user to refer to the
instruction manual (refer to Table of Contents) .
Indicates hazardous voltages.
Indicate earth (ground) terminal.
The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which, if not correctly
performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the
indicated conditions are fully understood and met.
The CAUTION sign denotes a hazard. It calls attention to an operating procedure, or the like, which, if not correctly
performed or adhered to, could result in damage to or destruction of part or all of the product. Do not proceed
beyond a CAUTION sign until the indicated conditions are fully understood and met.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.
Because of the danger of introducing additional hazards, do not install substitute parts or perform any unauthorized modification to the
instrument. Return the instrument to a Hewlett-Packard 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.

5
TABLE OF CONTENTS
Introduction ............................................................................................................................................................................ 9
Scope .................................................................................................................................................................................... 9
Calibration and Verification ............................................................................................................................................. 9
Troubleshooting................................................................................................................................................................ 9
Principles of Operation..................................................................................................................................................... 9
Replaceable Parts.............................................................................................................................................................. 9
Circuit Diagrams............................................................................................................................................................... 9
Safety Considerations ........................................................................................................................................................... 9
Manual Revisions ............................................................................................................................................................... 10
Firmware Revisions............................................................................................................................................................ 10
Calibration and Verification................................................................................................................................................11
Introduction ........................................................................................................................................................................ 11
Test Equipment Required ................................................................................................................................................... 11
Operation Verification Tests...............................................................................................................................................11
Calibration Procedure......................................................................................................................................................... 11
Initial Setup..................................................................................................................................................................... 14
Voltage Monitor Zero Calibration.................................................................................................................................. 15
Common Mode Calibration ............................................................................................................................................ 15
Remote Readback Zero Calibration................................................................................................................................ 16
Constant Voltage Full Scale Calibration......................................................................................................................... 16
Voltage Monitor and Remote Readback Full Scale Calibration..................................................................................... 17
Constant Voltage Zero Calibration................................................................................................................................. 17
Current Monitor Zero Calibration................................................................................................................................... 17
Constant Current Zero Calibration.................................................................................................................................. 18
Current Monitor Full Scale Calibration.......................................................................................................................... 18
Constant Current Full Scale Calibration......................................................................................................................... 19
Power Limit Calibration ................................................................................................................................................. 19
Resistance Programming Full Scale Calibration............................................................................................................. 19
Performance Tests .............................................................................................................................................................. 20
Measurement Techniques ............................................................................................................................................... 20
Constant Voltage (CV) Tests.......................................................................................................................................... 21
Constant Current (CC) Tests........................................................................................................................................... 26
Initialization Procedure....................................................................................................................................................... 28
Troubleshooting.................................................................................................................................................................... 29
Introduction ........................................................................................................................................................................ 29
Initial Troubleshooting Procedures..................................................................................................................................... 29
Electrostatic Protection....................................................................................................................................................... 30
Repair and Replacement..................................................................................................................................................... 30
A2 Control Board Removal............................................................................................................................................ 31
A4 FET Board Removal................................................................................................................................................. 31
A8 HP-IB Board Removal.............................................................................................................................................. 32
A3 Front-Panel Board Removal...................................................................................................................................... 32
A1 Main Board Removal................................................................................................................................................ 32
Overall Troubleshooting Procedure.................................................................................................................................... 33
HP-IB Section Troubleshooting.......................................................................................................................................... 33
Primary Interface Troubleshooting..................................................................................................................................... 36
Secondary Interface Troubleshooting................................................................................................................................. 38
Voltage and Current DAC .............................................................................................................................................. 38
Readback DAC Circuits.................................................................................................................................................. 39
Readback Multiplexer (U20):......................................................................................................................................... 39

6
Signature Analysis.............................................................................................................................................................. 41
Primary SA ..................................................................................................................................................................... 41
Front Panel SA................................................................................................................................................................ 41
Secondary SA ................................................................................................................................................................. 42
Power Section Troubleshooting.......................................................................................................................................... 47
Main Troubleshooting Setup ..........................................................................................................................................48
Troubleshooting No-Output Failures.............................................................................................................................. 49
Power Section Blocks..................................................................................................................................................... 50
Troubleshooting AC-Turn-On Circuits........................................................................................................................... 53
Troubleshooting DC-To-DC Converter.......................................................................................................................... 53
Troubleshooting Bias Supplies....................................................................................................................................... 54
Troubleshooting Down Programmer ..............................................................................................................................57
Troubleshooting CV Circuit ........................................................................................................................................... 58
Troubleshooting CC Circuit............................................................................................................................................ 58
Troubleshooting OVP Circuit......................................................................................................................................... 59
Troubleshooting PWM & Clock..................................................................................................................................... 59
Principles of Operation ........................................................................................................................................................ 61
Introduction ........................................................................................................................................................................ 61
HP-IB Board....................................................................................................................................................................... 61
Primary Microprocessor ................................................................................................................................................. 61
Address Switches........................................................................................................................................................... 61
EEPROM........................................................................................................................................................................ 63
Isolation.......................................................................................................................................................................... 63
Secondary Microprocessor ............................................................................................................................................. 63
Digital-to-Analog Converters ......................................................................................................................................... 63
Analog Multiplexer......................................................................................................................................................... 63
Status Inputs ................................................................................................................................................................... 63
Front Panel Board...............................................................................................................................................................64
Address Latches and Decoders....................................................................................................................................... 64
Volts and Amps Output Ports and Displays.................................................................................................................... 64
RPG and Latches ............................................................................................................................................................ 64
Front-Panel Switches and Input Port .............................................................................................................................. 64
Mode Indicators.............................................................................................................................................................. 66
OVP Adjust Control ....................................................................................................................................................... 66
Power Clear .................................................................................................................................................................... 66
Power Mesh and Control Board.......................................................................................................................................... 66
Overview ........................................................................................................................................................................ 66
AC Turn-On Circuits...................................................................................................................................................... 68
DC-to-DC Converter....................................................................................................................................................... 68
Down Programmer.......................................................................................................................................................... 69
Bleeder Circuit (6038A only) ......................................................................................................................................... 69
Constant-Voltage (CV) Circuit....................................................................................................................................... 69
Constant-Current (CC) Circuit........................................................................................................................................ 70
Overvoltage Protection (OVP) Circuit............................................................................................................................ 70
Power-Limit Comparator................................................................................................................................................ 70
Control-Voltage Comparator.......................................................................................................................................... 70
Initial-Ramp Circuit........................................................................................................................................................ 71
Pulse-Width Modulator (PWM) ..................................................................................................................................... 71
Bias Voltage Detector..................................................................................................................................................... 71
AC-Surge-&-Dropout Detector....................................................................................................................................... 71
1-Second-Delay Circuit .................................................................................................................................................. 72
Replaceable Parts ................................................................................................................................................................. 73
Introduction ........................................................................................................................................................................ 73

7
Ordering Information.......................................................................................................................................................... 74
Component Location and Circuit Diagrams ...................................................................................................................... 91
l00 Vac Input Power Option 100.........................................................................................................................................99
General Information............................................................................................................................................................ 99
Description ..................................................................................................................................................................... 99
Scope of Appendix A...................................................................................................................................................... 99
Suggestions for Using Appendix A.................................................................................................................................99
Chapter 1 Manual Changes............................................................................................................................................. 99
Chapter 2 Manual Changes............................................................................................................................................. 99
Chapter 3 Manual Changes:..........................................................................................................................................101
Chapter 4 Manual Changes:..........................................................................................................................................101
Chapter 5 and 6 Manual Changes................................................................................................................................. 102
Blank Front Panel Option 001...........................................................................................................................................103
Introduction ...................................................................................................................................................................... 103
Troubleshooting............................................................................................................................................................ 103
Chapter 2 Manual Changes:..........................................................................................................................................103
Chapter 3 Manual Changes:..........................................................................................................................................104
Chapter 5 and 6 Manual Changes:................................................................................................................................ 104

9
1
Introduction
Scope
This manual contains information for troubleshooting the HP 6033A/6038A 200W Autoranging Power Supply to the
component level. Wherever applicable, the service instructions given in this manual refer to pertinent information provided
in the Operation Manual (P/N 5959-3301). Both manuals cover HP Models 6033A/6038A; differences between models are
described as required.
The following information is contained in this manual.
Calibration and Verification
Contains calibration procedures for HP Models 6033A/6038A. 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 HP Models
6033A/6038A.
Circuit Diagrams
Contains functional schematics and component location diagrams for all HP 6033A/6038A 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.

10
Manual Revisions
Hewlett-Packard instruments are identified by a 10-digit serial number. The format is described as follows: first two letters
indicate the country of manufacture. The next four digits are a code that identify either the date of manufacture or of a
significant design change. The last four digits are a sequential number assigned to each instrument.
Item Description
US The first two letters indicates the country of manufacture, where US = USA.
3648 This is a code that identifies either the date of manufacture or the date of a significant design change.
0101 The last four digits are a unique number assigned to each power supply.
If the serial number prefix on your unit differs from that shown on the title page of this manual, a yellow Manual Change
sheet may be supplied with the manual. It defines the differences between your unit and the unit described in this manual.
The yellow change sheet may also contain information for correcting errors in the manual.
Note that because not all changes to the product require changes to the manual, there may be no update information required
for your version of the supply.
Older serial number formats used with these instruments had a two-part serial number, i.e. 2701A-00101. This manual also
applies to instruments with these older serial number formats. Refer to Appendix E 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.

11
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 HP-IB 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.
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 HP-IB board (A8) has been replaced, you must first initialize the board before you can calibrate the
unit. Refer to Page 28.

12
Table 2-1. Test Equipment Required
TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL
Oscilloscope Sensitivity: 1 mV
Bandwidth: 20MHz & 100MHz
Input: differential, 50 Ω& 10MΩ
P,T HP54504A
RMS Voltmeter True rms, 10MHz bandwidth
Sensitivity: 1 mV Accuracy: 5% P HP3400A
Logic Pulser 4.5 to 5.5Vdc @ 35mA T HP546A
Multimeter Resolution: 100nV
Accuracy: 0.0035%, 6½digit P,C,T HP 3458A
Signature Analyzer -- T HP 5004A
HP-IB Controller Full HP-IB capabilities C,T,P HP Series, 200/300
Current Probe No saturation at 30Adc
Bandwidth: 20Hz to 20MHz P Tektronix P6303 Probe/ AM503 Amp/
TM500 Power Module
Electronic Load Voltage range: 60Vdc P,C HP 6060A
Current range: 30Adc
Power range: 250W
Open and short switched
Power Resistor* Value: 0.25Ω>200W (6033A) P,C
Value: 2.3Ω>200W (6038A)
Current-Monitoring
Shunts Value: 10mΩ±0.04% @ 100W (6033A)
PC: 0.0004%/W P,C** Guildline 9230/100
Value: 100mΩ±0.04% @ 25W (6038A)
PC: 0.0004%/W Guildline 9230/15
Calibration and Test
Resistors Value: 100Ω, 5%, 1W
1Ω, 5%, ½W
1KΩ, 5%, ¼W
2KΩ, 0.01%, ¼W
C,T
Terminating
Resistors (2) Value: 50Ω±5%, noninductive P
Blocking
Capacitors (2) Value: 0.01µF, 100Vdc P
Common-mode
Toroidal Core ≥3.7µH/turn2
≅23mm I.D. P Ferrox-Cube
500T600-3C8,
HP 9170-0061
Switch* SPST, 30A @60V P
DC Power Supply Voltage range: 0-60Vdc
Current range: 0-3Adc C,T HP 6024A
P = performance testing C = calibration adjustments T = 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.

13
Table 2-2. Guide to Recalibration After Repair
Printed Circuit
Board Block Name Ref. Desig. Perform These Procedures
A1 Main Board R3 Current Monitor Full Scale Calibration
Constant Current Full Scale Calibration
A1 Main Board T1 Power Limit Calibration
A4 Power Mesh Board T3 Power Limit Calibration
A4 Power Mesh Board CR7 Power Limit Calibration
A2 Control Board Constant Voltage Circuit All Voltage Monitor Zero Calibration
(All Except Current Source) Common Mode Calibration
Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
A2 Control Board Constant Voltage Circuit All Resistance Programming Full Scale Calibration
(Current Source)
A2 Control Board Constant Current Circuit All Current Monitor Zero Calibration
Constant Current Zero Calibration
Current Monitor Full Scale Calibration
Constant Current Full Scale Calibration
A2 Control Board Power Limit Comparator All Power Limit Calibration
A2 Control Board Bias Power Supplies All All Calibration Procedures
( + & -15V Supplies)
A8 HP-IB Board Voltage Monitor Buffer All Voltage 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 HP-IB Board Analog Multiplexer All Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
A8 HP-IB Board Readback DAC All Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration

14
Table 2-2. Guide to Recalibration After Repair (continued)
Printed Circuit
Board Block Name Ref. Desig. Perform These Procedures
A8 HP-IB Board Voltage DAC All Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
A8 HP-IB Board Current DAC All Constant Current Zero Calibration
Constant Current Full Scale Calibration
A8 HP-IB Board U5 Remote Readback Zero 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 and remove the top cover by removing the three screws; the rear handle screw and the two top-
rear-corner screws. Do not remove the front handle screw as the retaining nut will fall into the unit.
b. Slide the cover to the rear.
c. Plug a control board test connector A2J3 onto the A2J3 card-edge fingers.
d. Turn OVERVOLTAGE ADJUST control A3R59 fully clockwise.
e. Disconnect all loads from output terminals.
f. Connect power supply for local sensing, and ensure that MODE switches are set as shown below.
g. Connect an HP-IB controller to the power supply.
h. Reconnect line cable and turn on ac power.
i. Allow unit to warm up for 30 minutes.
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.

15
Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by trained service 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 M on the rear panel through a 1kΩresistor to A2P3 pin 3 (V-MON1).
d. Adjust A2R22 (V-MON ZERO) to 0V ±20µV.
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 M on the rear panel through a 1kΩresistor to A2J3 pin 3 (V-MON).
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.
Adjust A2R21 (CV LOAD REG) to Initial Reading ±20µV.
f. Replace local sense straps after removing external power supply.
Figure 2-1. Common Mode Setup

16
Remote Readback Zero Calibration
Note: 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.
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 M on the rear panel through a 1KΩresistor to A2J3 pin 3 (V-MON).
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; A
30 DISP A
40 GOTO 10
50 END
g. Adjust A8R51 (READBACK ZERO) until the value displayed on the controller toggles between:
0 and 5mV (6033A).
0 and 15mV (6038A).
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 2-2. Remote Readback Zero And CV Zero Calibration Setup
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" (6033A).
"VSET 60; ISET 5; OUT ON" (6038A).

17
c. Attach the DVM from - S to + S terminals on rear panel.
d. Adjust A8R58 (CV PROG F.S.) to:
20.0025 ±600µV (6033A).
60.0075 ±1.82mV (6038A).
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 A2J3 pin 3 (V-MON). See DVM connection in Figure 2-1.
b. Send string: ’’VSET 20; ISET 5; OUT ON’’(6033A).
’’VSET 60; ISET 5; OUT ON’’(6038A).
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; A
30 DISP A
40 GOTO 10
50 END
f. Adjust A8R61 (READBACK F.S.) until the value displayed on the controller toggles between:
20V and 20.005V (6033A).
60V and 60.015V (6038A).
g. After adjusting A8R61 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration.
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 M to IM on the rear panel.
d. Allow several minutes (3 or more) to ensure thermal settling.
e. Adjust A2R8 (I-MON ZERO) to:
0V ±100µV (6033A).
0V ±25µV (6038A).

18
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:
0V ±1mV (6033A).
0V ±350µV (6038A).
Figure 2-3. CC Zero Calibration Setup
Current Monitor Full Scale Calibration
Note: This procedure requires that I-MON ZERO (A2R8) be adjusted within specifications. If it is not, perform
the Current Monitor Zero Calibration before proceeding.
a. Connect Rm current-monitoring shunt:
(10 milliohm, 6033A)
(100 milliohm, 6038A)
0.05% or better across power supply output terminals.
b. Send string:
"VSET 5; ISET 30; OUT ON" (6033A).
"VSET 5; ISET 10; OUT ON" (6038A).
c. Attach DVM from M to IM on the rear panel. Use six-digit display on HP 3458A DVM.
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:
0.060 x initial reading ±0.4mV (6033A).
0.200 x initial reading ±1.0mV (6038A).

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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.
a. Connect Rm current-monitoring shunt:
(10 milliohm, 6033A)
(100 milliohm, 6038A)
0.05% or better across power supply output terminals.
b. Send string:
"VSET 5; ISET 30; OUT ON" (6033A).
"VSET 5, ISET 10; OUT ON’’(6038A).
c. Attach DVM across Rm. Allow several minutes (3 or more) to ensure thermal settling.
d. Adjust A8R55 (CC PROG F.S.) to:
300mV ±30µV (6033A).
100mV ±100µV (6038A).
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 which is set to the minimum for your
line voltage (e.g. 104V for nominal 120V line).
b. Turn A2R25 (POWER LIMIT) fully counterclockwise.
c. Connect a electronic load across the output terminals, or use a:
0.25Ω200W resistor (6033A).
2.3Ω200W resistor (6038A).
d. Set the electronic load for:
30 amperes (6033A).
10 amperes (6038A).
in the constant Current mode.
e. Turn on power supply and send string:
"VSET 9; ISET 30.5; OUT ON" (6033A).
’’VSET 23; ISET 10.2; OUT ON’’(6038A).
f. Adjust A2R25 (POWER LIMIT) clockwise until CV LED on front panel turns on.
Resistance Programming Full Scale Calibration
a. Send string ’’OUT OFF".
b. Connect a 2-kilohm calibration resistor from P to VP on rear panel.
c. Set rear-panel MODE switches for resistance programming:

20
d. Attach the DVM from P to VP on the rear panel.
e. Adjust A2R23 (R-PROG F.S.) to 2.5V ±4mV.
f. Remember to reset MODE switches to original settings.
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 and D. 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:
2Ω200W load resistor (6033A).
18Ω200W load resistor (6038A).
for the electronic load in these tests:
CV Source Effect (Line Regulation).
CC Load Effect (Load Regulation).
You may substitute:
0.25Ω200W load resistor (6033A).
2.3Ω200W load resistor (6038A).
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.