Agilent Model 6023A; Serials US36490101 and above
Agilent Model 6028A; Serials US36520101 and above
For instruments with higher serial numbers, a change page may be included.
Microfiche Part No. 5964-8284 Printed in USA: July 2001
CERTIFICATION
Agilent Technologies certifies that this product met its published specifications at time of shipment from the factory. Agilent
Technologies further certifies that its calibration measurements are traceable to the United States National Institute of
Standards and Technology, to the extent allowed by the Institute’s calibration facility, and to the calibration facilities of
other International Standards Organization members.
WARRANTY
This Agilent Technologies hardware product is warranted against defects in material and workmanship for a period of three
years from date of delivery. Agilent Technologies software and firmware products, which are designated by Agilent
Technologies for use with a hardware product and when properly installed on that hardware product, are warranted not to
fail to execute their programming instructions due to defects in material and workmanship for a period of 90 days from date
of delivery. During the warranty period Agilent Technologies will, at its option, either repair or replace products which
prove to be defective. Agilent Technologies does not warrant that the operation of the software, firmware, or hardware shall
be uninterrupted or error free.
For warranty service, with the exception of warranty options, this product must be returned to a service facility designated
by Agilent. Technologies. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products
returned to Agilent Technologies. for warranty service. Except for products returned to Customer from another country,
Agilent Technologies s hall p a y for return of products to Customer.
Warranty services outside the country of initial purchase are included in Agilent Technologies’ product price, only if
Customer pays Agilent Technologies international prices (defined as destination local currency price, or U.S. or Geneva
Export price).
If Agilent Technologies is unable, within a reasonable time to repair or replace any product to condition as warranted, the
Customer shall be entitled to a refund of the purchase price upon return of the product to Agilent Technologies.
LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the Customer,
Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental
specifications for the product, or improper site preparation and maintenance. NO OTHER WARRANTY IS EXPRESSED
OR IMPLIED. AGILENT TECHNOLOGIES SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER’S SOLE AND EXCLUSIVE REMEDIES. AGILENT
TECHNOLOGIES SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.
ASSISTANCE
The above statements apply only to the standard product warranty. Warranty options, extended support contracts, product
maintenance agreements and customer assistance agreements are also available. Contact your nearest Agilent
Technologies Sales and Service office for further information on Agilent Technologies’ full line of Support Programs.
2
SAFETY SUMMARY
The following general safety precautions must be observed during all phases of operation, service and repair of this
instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety
standards of design, manufacture, and intended use of the instrument. Agilent Technologies, Inc. assumes no liability for the
customer's failure to comply with these requirements.
BEFORE APPLYING POWER.
Verify that the product is set to match the available line voltage and the correct fuse is installed.
GROUND THE INSTRUMENT.
This product is a Safety Class 1 instrument (provided with a protective earth terminal). To minimize shock hazard, the instrument chassis
and cabinet must be connected to an electrical ground. The instrument must be connected to the ac power supply mains through a threeconductor power cable, with the third wire firmly connected to an electrical ground (safety ground) at the power outlet. For instruments
designed to be hard wired to the ac power lines (supply mains), connect the protective earth terminal to a protective conductor before any
other connection is made. Any interruption of the protective (grounding) conductor or disconnection of the protective earth terminal will
cause a potential shock hazard that could result in personal injury. If the instrument is to be energized via an external autotransformer for
voltage reduction, be certain that the autotransformer common terminal is connected to the neutral (earth pole) of the ac power lines
(supply mains).
INPUT POWER MUST BE SWITCH CONNECTED.
For instruments without a built-in line switch, the input power lines must contain a switch or another adequate means for disconnecting
the instrument from the ac power lines (supply mains).
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.
Do not operate the instrument in the presence of flammable gases or fumes.
KEEP AWAY FROM LIVE CIRCUITS.
Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made by qualified
service personnel. Do not replace components with power cable connected. Under certain conditions, dangerous voltages may exist even
with the power cable removed. To avoid injuries, always disconnect power, discharge circuits and remove external voltage sources before
touching components.
DO NOT SERVICE OR ADJUST ALONE.
Do not attempt internal service or adjustment unless another person, capable of rendering first aid and resuscitation, is present.
DO NOT EXCEED INPUT RATINGS.
This instrument may be equipped with a line filter to reduce electromagnetic interference and must be connected to a properly grounded
receptacle to minimize electric shock hazard. Operation at the line voltage or frequencies in excess of those stated on the data plate may
cause leakage currents in excess of 5.0mA peak.
SAFETY SYMBOLS.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.
Because of the danger of introducing additional hazards, do not install substitute parts or perform any unauthorized modification to the
instrument. Return the instrument to a Agilent Technologies, Inc. Sales and Service Office for service and repair to ensure that safety
features are maintained.
Instruction manual symbol: the product will be marked with this symbol when it is necessary for the user to refer to the
instruction manual (refer to Table of Contents) .
Indicates hazardous voltages.
Indicate earth (ground) terminal.
The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which, if not correctly
performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the indicated
conditions are fully understood and met.
The CAUTION sign denotes a hazard. It calls attention to an operating procedure, or the like, which, if not correctly
performed or adhered to, could result in damage to or destruction of part or all of the product. Do not proceed beyond
a CAUTION sign until the indicated conditions are fully understood and met.
Instruments which appear damaged or defective should be made inoperative and secured against unintended operation until they can be
repaired by qualified service personnel.
3
SAFETY SYMBOL DEFINITIONS
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) terminalOut position of a bi-stable push control
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.
This document contains proprietary information protected by copyright. All rights are reserved. No part of this document
may be photocopied, reproduced, or translated into another language without the prior consent of Agilent Technologies,
Inc. The information contained in this document is subject to change without notice.
Off (supply)
Standby (supply)
Units with this symbol are not completely
disconnected from ac mains when this switch is
off. To completely disconnect the unit from ac
mains, either disconnect the power cord or have
a qualified electrician install an external switch.
Calibration and Verification .............................................................................................................................................7
Principles of Operation ..................................................................................................................................................... 7
Calibration and Verification.................................................................................................................................................. 9
Test Equipment Required ..................................................................................................................................................... 9
Constant Voltage (CV) Tests..........................................................................................................................................15
Constant Current (CC) Tests...........................................................................................................................................21
Repair and Replacement ..................................................................................................................................................... 25
A2 Control Board Removal............................................................................................................................................ 26
A4 Power Mesh Board Removal .................................................................................................................................... 27
A1 Main Board Removal................................................................................................................................................ 27
Using the Tables ............................................................................................................................................................. 28
Main Troubleshooting Setup ..........................................................................................................................................29
Power Section Blocks ..................................................................................................................................................... 35
Troubleshooting CC Circuit............................................................................................................................................38
Troubleshooting Down Programmer ..............................................................................................................................39
Principles of Operation ........................................................................................................................................................43
Down Programmer..........................................................................................................................................................47
Bias Voltage Detector.....................................................................................................................................................50
Component Location and Circuit Diagrams ...................................................................................................................... 69
System Option 002 ................................................................................................................................................................ 79
General Information............................................................................................................................................................ 79
Status Indicators..............................................................................................................................................................90
AC Dropout Buffer Circuit.............................................................................................................................................93
Multiple Supply System Shutdown ................................................................................................................................93
Troubleshooting Resistance and Voltage Programming.................................................................................................95
Troubleshooting Current Programming.......................................................................................................................... 95
This manual contains information for troubleshooting the Agilent 6023A or 6028A 200W Autoranging Power Supply to the
component level. Wherever applicable, the service instructions given in this manual refer to pertinent information provided
in the Operation Manual. Both manuals cover Agilent Models 6023A/28A; differences between models are described as
required.
The following information is contained in this manual.
Calibration and Verification
Contains calibration procedures for Agilent Models 6023A/28A. Also contains verification procedures that check the
operation of the supplies to ensure they meet the specifications of Chapter 1 in the Operating Manual.
Troubleshooting
Contains troubleshooting procedures to isolate a malfunction to a defective component on the main circuit board or to a
defective assembly (front-panel, power transformer, or cable assembly). Board and assembly level removal and
replacement procedures are also given in this section.
Principles of Operation
Provides block diagram level descriptions of the supply's circuits. The regulation & control, protection, input power, dc
power conversion and output circuits are described. These descriptions are intended as an aid in troubleshooting.
Replaceable Parts
Provides a listing of replaceable parts for all electronic components and mechanical assemblies for Agilent Models
6023A/28A.
Circuit Diagrams
Contains functional schematics and component location diagrams for all Agilent 6023A/28A circuits. The names that
appear on the functional schematics also appear on the block diagrams in Chapter 4. Thus, the descriptions in Chapter 4 can
be correlated with both the block diagrams and the schematics.
Safety Considerations
This product is a Safety Class 1 instrument, which means that it is provided with a protective earth terminal. Refer to the
Safety Summary page at the beginning of this manual for a summary of general safety information. Safety information for
specific procedures is located at appropriate places in the manual.
7
Manual Revisions
Agilent Technologies instruments are identified by a 10-digit serial number. The format is described as follows: first two
letters indicate the country of manufacture. The next four digits are a code that identify either the date of manufacture or of
a significant design change. The last four digits are a sequential number assigned to each instrument.
ItemDescription
USThe first two letters indicates the country of manufacture, where US = USA; MY = Malaysia.
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 B for backdating information.
8
2
Calibration and Verification
Introduction
This section provides test and calibration procedures. The operation-verification tests comprise a short procedure to verify
that the unit is performing properly, without testing all specified parameters. After troubleshooting and repair of a defective
power supply you can usually verify proper operation with the turn-on checkout procedure in the Operating Manual.
Repairs to the A1 main board and the A2 control board can involve circuits which, although functional, may prevent the
unit from performing within specified limits. So, after A1 or A2 board repair, decide if recalibration and operation
verification tests are needed according to the faults you discover. Use the calibration procedure both to check repairs and
for regular maintenance.
When verifying the performance of this instrument as described in this chapter, check only those specifications for which a
performance test procedure is included.
Test Equipment Required
Table 2-1 lists the equipment required to perform the tests of this section. You can separately identify the equipment for
performance tests, calibration and troubleshooting using the USE column of the table.
Operation Verification Tests
To assure that the unit is performing properly, without testing all specified parameters, first perform the turn-on checkout
procedure in the Operating Manual. Then perform the following performance tests, in this section.
CV Load Effect
CC Load Effect
Calibration Procedure
Calibrate the unit twice per year and when required during repair. The following calibration procedures which follow
should be performed in the sequence given. Table 2-2 describes in detail these calibration procedures and lists the expected
results to which each adjustment must be made.
Note: Some of the calibration procedures for this instrument can be performed independently, and some
procedures must be performed together and/or in a prescribed order. If a procedure contains no references
to other procedures, you may assume that it can be performed independently.
To return a serviced unit to specifications as quickly as possible with minimal calibration, the technician
need only perform calibration procedures that affect the repaired circuit. Table 2-3 lists various power
supply circuits with calibration procedures that should be performed after those circuits are serviced.
P,AAgilent 6060B
Current range: 60Adc
Power range: 300 watts
Open and short switches
CC PARD Test & I
Cal Resistive Load*
Value: 0.25 ohms >250W
P
Accuracy: 1%
P,A
Rheostat or Resistor Bank
Current-Monitoring
Resistors
6023A
Value: 30mV @ 30A (1mΩ )
P,A
Accuracy: 1%
TC: 30ppm/°C
Value: 30mV @ 30A (1mΩ)
Accuracy: 0.05% **
TC: 30ppm/°C (A,P)
6028A
Value100MΩ ± 0.04% @ 25W
Guidline 9230/15
Accuracy: 1%
PC: 0.0004% 1W
Calibration and Test
Resistors
Terminating
Resistors (4)
Blocking
Capacitors (2)
Common-mode
Toroidal Core
10
Value: 100Ω, 5%, 1W
1Ω, 5%, 1/2W
1KΩ, 5% 1/4W
5KΩ, 5% 1/4W (6023A)
2KΩ, 0.01% 1/4W
Value: 50Ω ±5%, noninductive
Value: 0.01µF, 100Vdc
A,T
P
P
PFerrox-Cube
500T600-3C8,
Agilent 9170-0061
Table 2-1. Test Equipment Required (continued)
TYPEREQUIRED CHARACTERISTICSUSERECOMMENDED MODEL
SwitchSPST, 30A @ 20VP
DC Power SupplyVoltage range: 0-60Vdc
Current range: 0-3Adc
T,PAgilent 6296A
Variable Voltage
Transformer
(autotransformer)
P = performance testing A = calibration adjustmentsT = troubleshooting
* Resistors may be substituted for test where an electronic load is not available.
** Less accurate, and less expensive, current-monitor resistors can be used, but the accuracy to which current programming
and current meter reading can be checked must be reduced accordingly.
Range greater than -13% to +6% of
nominal input AC voltage
1KVA
P,A
Initial Setup
Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by service trained
personnel who are aware of the hazards involved (for example, fire and electrical shock).
Turn off ac power when making or removing connections to the power supply. Where
maintenance can be performed without power applied, the power should be
removed.
a. Unplug the line cable and remove the top cover by removing three screws; the rear handle screw and the two top-rear
corner screws. Do not remove the front handle screw as the retaining nut will fall into the unit.
b. Slide the cover to the rear.
c. Plug a control board test connector A2P3 onto the A2J3 card-edge fingers.
d. Turn OVERVOLTAGE ADJUST control A3R59 fully clockwise.
e. Disconnect all loads from output terminals.
f. Connect power supply for local sensing, and ensure that MODE switches are set as shown below.
g. Reconnect the line cable and turn on ac power.
h. Allow unit to warm up for 30 minutes.
i. When attaching the DVM, the minus lead of the DVM should be connected to the first node listed, and the plus lead
should be connected to the second node listed.
j. At the beginning of each calibration procedure, the power supply should be in its power-off state, with no external
circuitry connected except as instructed.
k. The POWER LIMIT adjustment (A2R25) must be adjusted at least coarsely before many of the calibration procedures
can be performed. If you have no reason to suspect that the Power Limit circuit is out of adjustment, and you do not
intend to recalibrate it, do not disturb its setting. Otherwise, center A2R25 before you begin to calibrate the power
supply.
l. To disable the power supply, short INHIBIT line A2J3 pin 8 to COMMON A2J3 pin 4.
11
Table 2-2. Calibration Procedure
TESTTESTED
VARIABLE
Meter F/S
Adjust.
Resistance
Programming
F/S
Adjust.
V-MON
Zero
Adjust.
Common
Mode
Adjust.
I-MON
Zero
Adjust.
I-MON
F / S
Adjust.
*IR = Initial Reading
Meter Ref.
Voltage
Prog. VoltageVP ( + )
V-MON VM ( + )
Residual
Output
Voltage
VM( + )
I-MONIM ( + )
I-MONIM ( + )
TEST POINTSTEST SEQUENCE AND ADJUSTMENTSEXPECTED
RESULTS
A2J3 pin 6 ( + )
M ( - )
P ( - )
M ( - )
VM ( + )
M ( - )
M (-)
M ( - )
Rm ( + )
Rm ( - )
a. Connect DVM across test points and turn on
ac power.
b. Adjust A2R24 to obtain the voltage range
specified in the results.
a. Connect a 2KΩ 0.01%, ¼W programming
resistor and DVM between test points.
b. Set MODE switch as in Figure 2-1 and turn on
ac power.
c. Adjust A2R23 to obtain the voltage range
specified in the results.
a. Set voltage and current controls to minimum
settings.
b. Disable power supply as in Initial Setup step i.
c. Short circuit output terminals and connect the
DVM between test points. Turn on power
supply.
d. Adjust V-MON Zero trim pot A2R22 to
voltage range specified in the results.
a. Set voltage and current controls to minimum.
b. Disable power supply as Initial Setup step i.
c. Turn on ac power and record the initial
voltage (IR) with DVM across test points.
d. Remove the - S( + ) and – OUT( - ) and
connect a 1Vdc power supply between - S( + )
and – OUT( - ). See Figure 2-1.
e. Adjust A2R21 to the voltage range specified.
f. Remove the 1V supply and replace jumpers.
a. Set voltage and current controls to minimum.
b. Turn on ac power.
c. Connect DVM across test points and adjust
I-MON Zero trim pot A2R8 as shown in
results.
a. Perform I-MON Zero Adjust before
proceeding .
b. Connect a 0.001Ω 0.05% (6023A), 0.100Ω
0.05% (6028A) current monitoring resistor
Rm across the output terminals.
c. Turn on ac power and using the “Display
Setting”, set current control to 30A (6023A),
10A (6028A), and voltage control to 5V.
d. Connect DVM across test points and take an
initial reading (IR).
e. Connect DVM across Rm monitoring
terminals and adjust A2R9 as shown in the
results.
0.5V ± 50µV
2.5V ±4mV
0 ± 20µV
IR ± 20µV
0 ± 100µV
(6023A)
0 ± 25µV
(6028A)
IR*
0.006 IR*
+40µV (6023A),
0.200 ± 1µV
(6028A)
12
Table 2-2. Calibration Procedure (continued)
TESTTESTED
VARIABLE
Power
Limit
Adjust.
V(OUT)
I(OUT)
TEST POINTSTEST SEQUENCE AND ADJUSTMENTSEXPECTED
RESULTS
a. Perform I-MON F/S Adjust before
proceeding.
b. Connect the unit to the ac power line via the
external variable auto-transformer which is set
to nominal line voltage.
c. Connect a 0.25Ω, 250W (6023A), 2.3Ω,
250W (6028A) resistor across the unit's output
and turn on ac power.
d. Set voltage control to 9V (6023A) 9V≥ 3V
(6028A) and current control to 30.2A
(6023A), 10.2A (6028A)
e. Set auto-transformer to minimum line
voltage.
f. Turn A2R25 fully counterclockwise.
g. Slowly adjust A2R25 clockwise until CC
LED just lights.
30.2A 7.55V for
CC operation
(6023A)
10.2A, 23V for
CC operation
(6028A)
Figure 2-1. Common Mode Setup
13
Table 2-3. Guide to Recalibration After Repair
Printed Circuit
Board
A1 Main BoardR34
A1 Main BoardT14 then 5
A4 Power MeshT34 then 5 Board
A4 Power MeshCR74 then 5 Board
A2 Control BoardConstant Voltage
A2 Control BoardConstant Voltage
A2 Control BoardConstant Current
A2 Control BoardPower Limit
A2 Control BoardBias Power Supplies
A2 Control BoardU9, R79, R80, R247
1. V-MON Zero Calibration
2. Common-Mode Calibration
3. I-MON Full Scale (F/S) Zero Calibration
Block NameCircuit Within
Block
All Except Current
(CV) Circuit
(CV) Circuit
(CC) Circuit
Comparator
* Code To Calibration Procedure To Be Performed
Source
Current SourceAll6
± 15V Supplies
4. I-MON Full Scale (F/S) Calibration
5. Power Limit Calibration
6. Resistance Programming Full Scale (F/S) Calibration
7. Meter Full Scale (F/S) Calibration
Ref.
Designator
All1 then 2
All3 then 4
All4 then 5
AllAll
Perform These
Procedures*
Performance Tests
The following paragraphs provide test procedures for verifying the unit's compliance with the specifications of Table 1-1 in
the Operating Manual. Please refer to CALIBRATION PROCEDURE or TROUBLESHOOTING if you observe
out-of-specification performance.
Measurement Techniques
Setup For All Tests. Measure the output voltage directly at the + S and - S terminals. Connect unit for local sensing, and
ensure that MODE switches are set as shown below. Select an adequate wire gauge for load leads using the procedures
given in the Operating Manual for connecting the load.
Electronic Load. The test and calibration procedures use an electronic load to test the unit quickly and accurately. If an
electronic load is not available, you may substitute a 2Ω 250W load resistor for the electronic load in these tests:
CV Source Effect (Line Regulation)
CC Load Effect (Load Regulation)
You may substitute a 0.25Ω 250W load resistor in these tests:
CV Load Effect (Load Regulation)
CV PARD (Ripple and Noise)
CC Source Effect (Line Regulation)
CC PARD (Ripple and Noise)
14
The substitution of the load resistor requires adding a load switch to open and short the load in the CC or CV load
regulation tests. The load transient recovery time test procedure cannot be performed using load resistors.
An electronic load is considerably easier to use than a load resistor. It eliminates the need for connecting resistors or
rheostats in parallel to handle the power, it is much more stable than a carbon-pile load, and it makes easy work of
switching between load conditions as is required for the load regulation and load transient-response tests.
Current-Monitoring Resistor Rm. To eliminate output current measurement error caused by voltage drops in the leads
and connections, connect the current-monitoring resistor between -OUT and the load as a four-terminal device. Figure 2-2
shows correct connections. Select a resistor with stable characteristics: 0.001, 1% accuracy, 30 ppm/°C or lower
temperature coefficient and 20W power rating (20 times actual power if other than 0.001Ω is used).
Figure 2-2. Current-Monitoring Resistor Setup
Constant Voltage (CV) Tests
CV Setup. If more than one meter or a meter and an oscilloscope are used, connect each to the + S and - S terminals by a
separate pair of leads to avoid mutual coupling effects. Connect only to + S and -S (except for peak-to-peak PARD)
because the unit regulates the output voltage between + S and - S, not between + OUT and - OUT. Use coaxial cable or
shielded 2-wire cable to avoid pickup on test leads. For all CV tests set the output current at full output to assure CV
operation.
Load Effect (Load Regulation). Constant-voltage load effect is the change in dc output voltage (Eo) resulting from a
load-resistance change from open-circuit to full-load. Full-load is the resistance which draws the maximum rated output
current at voltage Eo. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:
7.0Vdc (6023A)
20.0Vdc (6028A)as read on the digital voltmeter.
15
Figure 2-3. Basic Test Setup
d.Reduce the resistance of the load to draw an output current of:29Adc (6023A)10Adc (6028A)Check that the unit's CV LED remains lighted.
e. Record the output voltage at the digital voltmeter.
f. Open-circuit the load.
g. When the reading settles, record the output voltage again. Check that the two recorded readings differ no more than:
± 0.0027Vdc (6023A)
± 0.0090Vdc (6028A)
Source Effect (Line Regulation). Source effect is the change in dc output voltage resulting from a change in ac input
voltage from the minimum to the maximum value as specified in Input Power Requirements in the Specifications Table, in
the Operating Manual. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Connect the unit to the ac power line through a variable autotransformer which is set for low line voltage (104Vac for
120Vac).
c. Turn the unit's power on, and turn up current setting to full output.
d. Turn up output voltage to:
20.0Vdc (6023A)
60Vdc (6028A)
as read on the digital voltmeter.
e. Reduce the resistance of the load to draw an output current of:
10Adc (0.010Vdc across Rm) (6023A)
3.3Adc(0.33Vdc across Rm) (6028A)Check that the unit's CV LED remains lighted.
16
f. Record the output voltage at the digital voltmeter.
g. Adjust autotransformer to the maximum for your line voltage.
h. When the reading settles record the output voltage again. Check that the two recorded readings differ no more than:
± 0.0030Vdc (6023A)
± 0.0080Vdc (6028A)
PARD (Ripple And Noise). Periodic and random deviations (PARD) in the unit's output-ripple and noise-combine to
produce a residual ac voltage superimposed on the dc output voltage. Constant-voltage PARD is specified as the
root-mean-square (rms) or peak-to-peak (pp) output voltage in a frequency range of 20Hz to 20MHz.
RMS Measurement Procedure. Figure 2-4 shows the interconnections of equipment to measure PARD in Vrms. To
ensure that there is no voltage difference between the voltmeter's case and the unit's case, connect both to the same ac
power outlet or check that the two ac power outlets used have the same earth-ground connection.
Use the common-mode choke as shown to reduce ground-loop currents from interfering with measurement. Reduce noise
pickup on the test leads by using 50Ω coaxial cable, and wind it five turns through the magnetic core to form the
common-mode choke. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-4. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:
7Vdc (6023A)20Vdc (6028A)d.Reduce the resistance of the load to draw an output current of:29Adc (6023A)10Adc (6028A)Check that the unit's CV LED remains lighted.
e. Check that the rms noise voltage at the true rms voltmeter is no more than:
3.0mV rms (6023A)
3.0mV rms (6028A)
Figure 2-4. RMS Measurement Test Setup, CV PARD Test
Peak Measurement Procedure. Figure 2-5 shows the interconnections of equipment to measure PARD in Vpp. The
equipment grounding and power connection instructions of PARD rms test apply to this setup also. Connect the
oscilloscope to the + OUT and - OUT terminals through 0.01µF blocking capacitors to protect the oscilloscope's input from
17
the unit's output voltage. To reduce common-mode noise pickup, set up the oscilloscope for a differential, two-channel
voltage measurement. To reduce normal-mode noise pickup, use twisted, 1 meter or shorter, 50Ω coaxial cables with
shields connected to the oscilloscope case and to each other at the other ends. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:
7.0Vdc (6023A)20Vdc (6028A)d.Reduce the resistance of the load to draw an output current of:
29.0Adc (6023A)10Adc (6028A)Check that the unit's CV LED remains lighted.
e. Set the oscilloscope's input impedance to 50Ω and bandwidth to 20MHz. Adjust the controls to show the 20KHz and
higher frequency output-noise waveform of Figure 2-6.
f. Check that the peak-to-peak is no more than 30mV.
18
Figure 2-5. Peak-To-Peak Measurement Test Setup, CV PARD Test
6023A6028A
Figure 2-6. 20KHz Noise, CV Peak-to-Peak PARD
Load Transient Recovery Time. Specified for CV operation only; load transient recovery time is the time for the output
voltage to return to within a specified band around its set voltage following a step change in load.
Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant-current mode and set for minimum
current.
b. Turn the unit's power on, and turn up current setting to full output.
c. Turn up output voltage to:
6.70Vdc (6023A)
20.0Vdc (6028A)as read on the digital voltmeter.d.Set the load to vary the load current between:27 and 30Adc (6023A)9 and 10Adc (6028A)at a 30Hz rate.
e. Set the oscilloscope for ac coupling, internal sync and lock on either the positive or negative load transient.
f. Adjust the oscilloscope to display transients as in Figure 2-7.
g. Check that the pulse width of the transient pulse is no more than:
50mV (6023A)
75mV (6028A)
19
Temperature Coefficient. (6023A) Temperature coefficient (TC) is the change in output voltage for each °C change in
ambient temperature with constant ac line voltage, constant output voltage setting and constant load resistance. Measure
temperature coefficient by placing the unit in an oven, varying the temperature over a range within the unit's operating
temperature range, and measuring the change in output voltage. Use a large, forced air oven for even temperature distribution.
Leave the unit at each temperature measurement for half hour to ensure stability in the measured variable. Measure the output
voltage with a stable DVM located outside the oven so voltmeter drift does not affect the measurement accuracy. To measure
offset TC, repeat the procedure with output voltage set to 0.10Vdc.
Proceed as follows:
a. Connect DVM between +S and -S.
b. Place power supply in oven, and set temperature to 30°C.
c. Turn the unit's power on and turn up current setting to full output.
d. Turn up output voltage to 20Vdc as read on the DVM.
e. After 30 minutes stabilization record the temperature to the nearest 0.1°C. Record the output voltage at the DVM.
f. Set oven temperature to 50°C.
g. After 30 minutes stabilization, record the temperature to the nearest 0.1°C. Record output voltage.
h. Check that the magnitude of the output voltage change is no greater than 32mV.
6023A6028A
Figure 2-7. Load Transient Recovery Waveform
Drift (Stability) (6023A). Drift is the change in output voltage beginning after a 30-minute warm-up during 8 hours operation
with constant ac input line voltage, constant load resistance and constant ambient temperature. Use a DVM and record the
output at intervals, or use a strip-chart recorder to provide a continuous record. Check that the DVM's or recorder's specified
drift during the 8 hours will be no more than 0.001%. Place the unit in a location with constant air temperature preferably a
large forced-air oven set to 30°C and verify that the ambient temperature does not change by monitoring with a thermometer
near the unit. Typically the drift during 30 minute warm-up exceeds the drift during the 8-hour test. To measure offset drift,
repeat the procedure with output voltage set to 0.10Vdc.
a. Connect DVM between + S and - S.
b. Turn the unit's power on and turn up current setting to full output.
c. Turn up output voltage to 20Vdc as read on the digital voltmeter.
d. After a 30 minute warmup, note reading on DVM.
e. The output voltage should not deviate more than 5mV from the reading obtained in step d over a period of 8 hours.
20
Constant Current (CC) Tests
CC Setup. Constant-current tests are analogous to constant-voltage tests, with the unit's output short circuited and the
voltage set to full output to assure CC operation. Follow the general setup instructions.
Load Effect (Load Regulation). Constant current load effect is the change in dc output current (Io) resulting from a
load-resistance change from short-circuit to full-load, or full-load to short-circuit. Full-load is the resistance which develops
the maximum rated output voltage at current Io. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Turn the unit's power on, and turn up voltage setting to full output.
c. Turn up output current to:
10.0Adc (0.010Vdc across Rm) (6023A). Check that the AMPS display reads about 10 amps.
3.3Adc (0.335Vdc across Rm) (6028A) Check that the AMPS display reads about 3.3 amps.
d. Increase the load resistance until the output voltage at +S and -S increases to:
20Vdc (6023A).
60Vdc (6028A).
Check that the CC LED is lighted and AMPS display still reads ≈ current setting.
e. Record voltage across Rm.
f. Short circuit the load.
g. When the reading settles (≈ 10s), record the voltage across Rm again. Check that the two recorded readings differ no
more than:
± 0.010mVdc (6023A)
± 0.0053mVdc (6028A)
h. Disconnect the short across the load.
Source Effect (Line Regulation). Constant current source effect is the change in dc output current resulting from a
change in ac input voltage from the minimum to the maximum values listed in the Specifications Table in the Operating
Manual. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-3. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Connect the unit to the ac power line through a variable autotransformer set for low line voltage (e.g. 104Vac for
120Vac).
c. Switch the unit's power on and turn up output voltage setting to full output.
d. Turn up output current to:
29.0Adc (0.029Vdc across Rm) (6023A)
10.0Adc (1.0Vdc across Rm) (6028A)Check that the AMPS display reads ≈ current setting.e.Increase the load resistance until the output voltage between + S and - S increases to:
7.0Vdc (603A)
20.0Vdc (6028A)Check that the CC LED is still on and the AMPS display still reads ≈ current setting.
f. Record the voltage across Rm.
g. Adjust autotransformer to the maximum for your line voltage.
h. When the reading settles record the voltage across Rm again. Check that the two recorded readings differ no more than:
± 0.0090mVdc (6023A)
± 0.030mVdc (6028A)
PARD Ripple And Noise. Periodic and random deviations (PARD) in the unit's output (ripple and noise) combine to
produce a residual ac current as well as an ac voltage super-imposed on the dc output. The ac voltage is measured as
constant-voltage PARD. Constant-current PARD is specified as the root-mean-square (rms) output current in a frequency
range 20Hz to 20MHz with the unit in CC operation. To avoid incorrect measurements, with the unit in CC operation,
caused by the impedance of the electronic load at noise frequencies, use a:
21
0.25Ω (6023A)
2.0Ω (6028A)
load resistor that is capable of safely dissipating 250 watts. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-8.
b. Switch the unit's power on and turn the output voltage all the way up.
c. Turn up output current to:
29.0Vdc (6023A)10Vdc (6028A)Check that the unit's CC LED remains lighted.
d. Check that the rms noise current measured by the current probe and rms voltmeter is no more than:
15mA rms (6023A).
5mA rms (6028A)
Figure 2-8. CC PARD Test Setup
22
Troubleshooting
Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by service-trained personnel who are aware of the
hazards involved (for example, fire and electrical shock). Where maintenance can be performed without
power applied, the power should be removed.
Introduction
Before attempting to troubleshoot this instrument, ensure that the fault is with the instrument itself and not with an
associated circuit. The performance test enables this to be determined without having to remove the covers from the supply.
The most important aspect of troubleshooting is the formulation of a logical approach to locating the source of trouble. A
good understanding of the principles of operation is particularly helpful, and it is recommended that Chapter 4 of this
manual be reviewed before attempting to troubleshoot the unit. Often the user will then be able to isolate a problem simply
by using the operating controls and indicators. Once the principles of operation are understood, refer to the following
paragraphs.
Table 2-1 lists the test equipment for troubleshooting. Chapter 6 contains schematic diagrams and information concerning
the voltage levels and waveforms at many of the important test points. Most of the test points used for troubleshooting the
supply are located on the control board test "fingers", which are accessible close to the top of the board. See Table 3-1.
3
If a component is found to be defective, replace it and re-conduct the performance test. When a component is replaced,
refer to Calibration Procedure (Chapter 2). It may be necessary to perform one or more of the adjustment procedures after a
component is replaced.
Initial Troubleshooting Procedures
If a problem occurs, follow the steps below in sequence:
a. Check that input power is available, and check the power cord and rear-panel circuit breaker.
b. Check that the settings of mode switch A2S1 are correct for the desired mode of operation. (See Operating Manual).
c. Check that all connections to the power supply are secure and that circuits between the supply and external devices are
not interrupted.
d. If the power supply fails turn-on self-test or gives any other indication of malfunction, remove the unit from the
operating system before proceeding with further testing.
Some circuits on the power mesh are connected directly to the ac power line. Exercise extreme caution
when working on energized circuits. Energize the supply through an isolation transformer to avoid
shorting ac energized circuits through the test instrument's input leads. The isolation transformer must
have a power rating of at least 1KVA. During work on energized circuits, the safest practice is to
disconnect power, make or change the test connections, and then re-apply power.
Make certain that the supply's ground terminal (┴) is securely connected to an earth ground before applying
power. Failure to do so will cause a potential shock hazard that could result in personal injury.
U2B-6
18Ip MONITOR<0.51V pk, ½ sawtooth, 20KHzA2CR26 (cathode)
8
15
INHIBIT
DOWN PROGRAM
TTL hiif not remotely inhibitedA2R185C, U19A-2
1.2-3.0A2CR21, A2CR27
7OVP PROGRAM1/10 OVP (6023A)e.g.: 2Vdc if OVP set to 20A3R6 (wiper)
1/30 OVP (6028A)
5
19
Commons & Current-Monitor
CLR OV
2 PCLR
4L COMMON0.0common return for all bias
+5Vinverted OV reset lineA7U29-5
+5Vif +5V bias OKA2Q60-9
A2C20 (-), A2R50,
voltages, and status and control
A2U6-4
signals
9M COMMON0.0common return for 2.5V ref.
A2R83, A21-20
and 0.5V ref.
10I-TEST
≈0.005 ( Iout)
inboard-side monitoring res.A1R3,A1T2
3NOT USED
24
Electrostatic Protection
The following caution outlines important precautions which should be observed when working with static sensitive
components in the power supply.
This instrument uses components which can be damaged by static charge. Most semiconductors can
suffer serious performance degradation as a result of static charges, even though complete failure may
not occur. The following precautions should be observed when handling static-sensitive devices.
a. Always turn power off before removing or installing printed-circuit boards.
b.
Always stored or transport static-sensitive devices (all semiconductors and thin-film devices) in conductive material.
Attach warning labels to the container or bag enclosing the device.
c.
Handle static-sensitive devices only at static-free work stations. These work stations should include special conductive
work surfaces (such as Agilent Part No. 9300-0797) grounded through a one-megohm resistor. Note that metal table
tops and highly conductive carbon-impregnated plastic surfaces are too conductive; they can act as large capacitors and
shunt charges too quickly. The work surfaces should have distributed resistance of between 10
d.
Ground all conductive equipment or devices that may come in contact with static-sensitive devices or subassemblies
containing same.
e.
Where direct grounding of objects in the work area is impractical, a static neutralizer should be used (ionized air
blower directed at work). Note that this method is considerably less effective than direct grounding and provides less
protection for static-sensitive devices.
f.
While working with equipment on which no point exceeds 500 volts, use a conductive wrist strap in contact with skin.
The wrist strap should be connected to ground through a one-megohm resistor. A wrist strap with insulated cord and
built-in resistor is recommended, such as 3M Co. No. 1066 (Agilent Part No. 9300-0969 (small) and 9300-0970
[large]).
6
and 10l2 Ω per square.
Do not wear a conductive wrist strap when working with potentials in excess of 500 volts; the one-megohm
resistor will provide insufficient current limiting for personal safety.
g. All grounding (device being repaired, test equipment, soldering iron, work surface, wrist strap, etc.) should be done to
the same point.
h.
Do not wear nylon clothing. Keep clothing of any kind from coming within 12 inches of static-sensitive devices.
i.
Low-impedance test equipment (signal generators, logic pulsers, etc.) should be connected to static-sensitive inputs
only while the components are powered.
j.
Use a mildly activated rosin core solder (such as Alpha Metal Reliacor No. 1, Agilent Part No. 8090-0098) for repair.
The flux residue of this type of solder can be left on the printed circuit board. Generally, it is safer not to clean the
printed-circuit board after repair. Do not use Freon or other types of spray cleaners. If necessary, the printed-circuit
board can be brushed using a natural-bristle brush only. Do not use nylon-bristle or other synthetic-bristle brushes. Do
not use high-velocity air blowers (unless ionized).
k.
Keep the work area free of non-conductive objects such as Styrofoam-type cups, polystyrene foam, polyethylene bags,
and plastic wrappers. Non-conductive devices that are necessary in the area can be kept from building up a static
charge by spraying them with an anti-static chemical (Agilent Part No. 8500-3397).
l.
Do not allow long hair to come in contact with static-sensitive assemblies.
m.
Do not exceed the maximum rated voltages specified for the device.
Repair and Replacement
Repair and replacement of most components in the power supply require only standard techniques that should be apparent
to the technician. The following paragraphs provide instructions for removing certain assemblies and components for which
the procedure may not be obvious upon inspection.
25
To avoid the possibility of personal injury, remove the power supply from operation before opening the
cabinet. Turn off ac power and disconnect the line cord, load, and remote sense leads before attempting
any repair or replacement.
When replacing any heatsink-mounted components except thermostat, smear a thin coating of heatsink
compound between the component and heatsink. If a mica insulator is used, smear a thin coating of
heatsink compound on both sides of the mica insulator.
Do not use any heatsink compound containing silicone, which can migrate and foul electrical contacts
elsewhere in the system. An organic zinc oxide cream, such as American Oil and Supply Company
Heatsink Compound #100, is recommended.
Most of thc attaching hardware in this unit is metric. The only non-metric (sometimes called English or
inch) fittings are listed below. Be careful when both types of screws are removed not to get them
mixed up.
a. Lock-link/shelf-mounting blocks (4 on rear panel, one at each corner).
b.
Rear-panel fuse holder.
c.
Rear-panel ground binding post.
d.
Strap-handle screws (2).
e.
Screws that secure side chassis to front-frame casting (8, 4 on each side).
f.
Screws that secure front-panel to front-frame casting (4, 2 on top and 2 on bottom).
Top Outside Cover Removal. Remove three screws, the rear handle screw (Phillips, 10x32) and two top-rear corner
screws (Pozidriv, M4x.7) using a Size 1, Pozidriv screwdriver. A Phillips head screwdriver does not fully seat into
Pozidriv screws and risks stripping the heads. Do not remove the front handle screw, as the retaining nut will fall into the
unit. Remove the top cover by sliding it to the rear and lifting at the front.
Bottom Cover Removal. Remove only for repair of main board. Remove two bottom-rear corner screws. (Pozidriv,
M4x.7) and remove the bottom cover by sliding it to the rear. You do not need to remove the unit's feet.
Inside Top Cover Removal. The unit includes an inside cover which secures the vertical board assemblies. Remove the
inside cover for repair but not for calibration. Remove the six mounting screws (Pozidriv, M4x.7) – three on each side and
five board fastening screws (Pozidriv, M4x.7) all on top. Remove the inside cover by lifting at the front edge.
When installing the inside cover, insert it first at the right side. While holding it tilted up at the left, reach through the
cutouts in the cover and fit the top tabs of the A2 control board into the mating slots in the cover. With the top cover in
place reach through the cutout above the A4 power mesh board, align the board-fastening screw holes, and replace the rearmost screw to secure the A4 board. Press the inside cover down firmly while tightening screws that secure cover to chassis.
Complete the installation by replacing the remaining ten screws. Be careful when replacing printed-circuit assemblies and
covers not to bend any boards or components.
A2 Control Board Removal
After removing the inside cover, remove the A2 board by lifting first at the front edge and than pulling it up and out of the
unit. Two connectors hold the A2 board at its bottom edge.
When installing the A2 board, insert it first at the rear of the unit. While holding it tilted up at the front, fit the A2TB1
terminal strip into the mating cutout in the rear panel. Then lower the A2 board's bottom connectors into the mating
connectors on the main board. Press the A2 board into the connectors.
26
A4 Power Mesh Board Removal
After removing the inside cover, remove the A4 power mesh board by lifting, using the large aluminum heatsink as a
handle. Two connectors hold the A4 board at its bottom edge.
When installing the A4 power mesh board, lower it vertically into its connectors and press in place.
A3 Front-Panel Board Removal
Remove the A3 front-panel board by first removing the entire front-panel assembly. You do not need to remove the top
cover. Follow this procedure:
a.
Remove the top plastic insert by prying up with a flat-blade screwdriver, and remove the front feet by lifting the tabs
and sliding toward the front of the unit.
b.
Remove the four front-panel assembly mounting screws (Phillips 8-32) on the top and bottom at the corners using a
Pozidriv or Phillips head screwdriver (Phillips head screwdriver may be used only with these four screws).
c.
Gently pull the front-panel assembly away from the unit as far as permitted by the connecting cables.
d.
Remove the ground-wire screw (Pozidriv, M4x.7) holding the green-yellow ground wire.
e.
Note the locations of the four power-wire connections to the power switch and then unplug the quick-connect plugs.
f.
Unplug the W3 3-wire cable from connector A1J3 on the A1 main board.
g.
Remove the A3 board from the front-panel assembly by removing the five mounting screws (Pozidriv, M4x.7)
Install the A3 Board by reversing the steps above. The power wires are correctly connected to the power switch wires if
they do not cross each other.
A1 Main Board Removal
Removing the A1 main board requires removing the rear panel, all boards except the A3 front-panel board, and 17 A1
board mounting screws. Component-access cutouts in the bottom inside cover allow unsoldering most A1-board
components for repair without removing the A1 board.
To remove the A1 board, proceed as follows:
a.
Remove the A2 and A4 boards according to the above instructions.
b.
Detach the rear panel by removing the four mounting screws (Pozidriv, M4x.7) two on each side. Gently pull the rear
panel away from the unit as far as permitted by the four wires connected to the A1 board.
c.
Unplug the W1 ribbon cable from connector A1J1.
d.
Remove the A1 board by removing the 17 mounting screws (Pozdriv, M4x.7).
e.
Note locations and the unplug the two ac power wires and the two fan wires to the A1 board.
Overall Troubleshooting Procedure
Perform the troubleshooting and repair procedures which follow only if you are trained in equipment
service and are aware of the danger from fire and electrical-shock hazards. Some of the procedures include
removing the unit's protective covers which may expose you to potentially lethal electrical shock.
Whenever possible, make test connections and perform service with the power removed.
After performing the Initial Troubleshooting Procedures, focus on developing a logical approach to locating the source of
the trouble. The underlying strategy for the troubleshooting procedures here is to guide you to the faulty circuit nodes
which have improper signals or voltages. It relies on you to identify the particular functional circuit to troubleshoot from
symptom tables and by understanding how the unit works. It then relies on you to discover the defective component or
components which cause the faulty circuit nodes. So, read the BLOCK DIAGRAM overview in Chapter 4 and read the
functional circuit descriptions for the circuits that you suspect may be defective. Then return to this section for help finding
the faulty circuit nodes.
27
Table 3-1 gives the signals for each of the test points on the control board test connector. This connector is provided in
service kit P/N 06033-60005. The measurements given here include bias and reference voltages as well as power supply
status signals and waveform information.
Table 3-2 provides troubleshooting information based on the status of the PWM-ON and PWM-OFF signals which drive
the PFETs. This table is used for no-output failures.
Tables 3-3 and 3-4 give measurements for the test points on the A3 front-panel board and possible failure symptoms
respectively.
Table 3-5 describes possible symptoms for overall performance failures of the power supply. It is necessary to have a
properly working front-panel before using this table.
Chapter 6 contains schematic diagrams and voltage levels, and component location diagrams to help you locate components
and test points.
Make most voltage measurements (except DC-to-DC Converter and ac mains-connected circuits) referenced to the unit's
output common which is accessible at rear-panel terminal VM. All voltages are
± 5% unless a range is given.
Using the Tables
Typically there will be two types of power supply failures; no-output and performance failures.
1.
No-OUTPUT FAILURE: Start with the TROUBLESHOOTING NO-OUTPUT FAILURES section which references
Tables 3-1 and 3-3.
2.
PERFORMANCE FAILURE: If the power supply produces an output but does not perform to specifications, begin by
verifying the measurements at the A2J7 test connector using Table 3-1. Next, verify the front-panel by doing the
procedure outlined in the FRONT-PANEL TROUBLESHOOTING section. After the front-panel has been verified
consult Table 3-5 for the performance failure symptom which seems closest to the one observed and proceed to the
functional circuit given for that failure.
The circuits referenced in Tables 3-2 and 3-5 are derived from functional blocks of circuits in the power supply. These
blocks are given in the Power Supply Blocks section starting on page 35. Troubleshooting information for each block will
include a brief description of the circuit involved. The columns provided in each block are as follows:
NODE:This column lists the nodes where the measurements should be taken. In some cases this will be
stated as NODE ( + ) and NODE (- ) where the first is the test node and the second is the
reference.
SETUP:If a certain setup is required for the measurement, it will be given in this column.
MEASUREMENT:This column indicates what the expected measurement is for the given node.
SOURCE:If applicable, the components which generate the signal will be provided in this column .
Some blocks will have Input and Output sections. The input section will have a source column to indicate which
components generated the measured signal. The output section will list all the important output signals from that block.
However, because the outputs of one block are the inputs to another, the schematic should be consulted if an output
measurement is incorrect. This will indicate the next circuit block to be trouble shot.
28
Main Troubleshooting Setup
Figure 3-1 shows the troubleshooting setup for troubleshooting all of the unit except the front-panel and initial no output
failures (See page 31). The external power supply provides the unit's internal bus voltage. The ac mains cord connects to
the unit's A1T3 bias transformer via an isolation transformer, thereby energizing the bias supplies, but it does not connect to
the input rectifier and filter because that would create the bus voltage. With the external supply the unit operates as a
dc-to-dc converter. The supply biases the A4Q3 and A4Q4 PFETs with a low voltage rather than the 320Vdc bus voltage.
This protects the PFETs from failure from excess power dissipation if the power-limit comparator or the off-pulse circuitry
are defective. It also reduces the possibility of electrical shock to the troubleshooter.
Figure 3-1. Main Troubleshooting Setup
The troubleshooting setup of Figure 3-1 connects high ac mains voltage to the A1F2 fuse, the A1S2 Mains-
Voltage Select Switch, the fan and printed-circuit traces at the left edge of the A1 main board. Be
extremely careful when working on the unit with the protective inside cover removed to avoid touching the
ac mains voltage.
29
As a convenience in implementing the troubleshooting setup, prepare cord sets as shown in Figure 3-2. This facilitates
connecting the unit's input power receptacle to the external supply and connecting the bias transformer to the ac mains.
Figure 3-2. Modified Mains Cord Set For Troubleshooting
With the mains cord unplugged proceed as follows:
a.
Remove the top cover and the inside cover as described on page 26. Set switch S4 (front-left corner of the A1 main
board) in TEST position.
If switch is not in the TEST position and remains in the NORM position, completion of step e below will
allow the unit to develop its 320Vdc bus voltage across PFETs A3Q3 and A3Q4 and will connect the ac
mains voltage to the output of the external power supply. This will probably damage the external supply
and is a shock hazard to you.
b. Install control board test connector onto the A2J3 card edge fingers.
c.
Connect a 50Ω, 10W, load resistor to the unit's output terminals.
30
d. With the LINE switch off, connect an external dc supply to the outside prongs of the unit’s power receptacle. Ignore
polarity as the unit’s input rectifying diodes steer the dc power to the correct nodes.
e.
Complete the setup of Figure 3-1 by attaching an ac mains cord to test points TP1 (L, black wire) and TP2 (N, white
wire) and connect the green ground wire to the unit's case ground terminal or a suitably grounded cabinet screw. TP1
and TP2 are accessible through the cutout on the left side of the unit and are at the left edge of the A1 main board.
Troubleshooting No-Output Failures
No-output failures often include failure of the A4Q3 and A4Q4 PFETs and their fuses, A4F1 and A4F2. When either the
off-pulses or the power-limit comparator fails, the PFETs can fail from excessive power dissipation. The strategy for
localizing no-output failures is to check the voltages and waveforms at the control board test connector to predict if that
circuit failure would cause the PFETs to fail. This makes it possible to develop your troubleshooting approach without an
extensive equipment setup. Proceed as follows:
a.
With the mains cord unplugged remove the A4 power mesh board as described on page 27. Plug in the mains cord
and switch on power.
b.
Using Table 3-1 check the bias voltages, the PWM-OFF, PWM-ON and other signals of interest at the A2 control
board test fingers, A2J3.
c.
Check for the presence of program voltages, VP and IP, at the rear panel.
d.
Check for presence of the 320Vdc rail voltage between the cathodes of diodes A1CR3 and A1CR4. If there is no rail
voltage, check diodes A1CR1 through A1CR4.
Diodes A1CR1 through A1CR4 connect to the ac mains voltage. Use a voltmeter with both input terminals
floating to measure the rail voltage.
e. Select the functional circuit for troubleshooting based on your measurements and Table 3-2, which provides direction
based on the status of the PWM OFF and PWM ON signals .
Front-Panel Troubleshooting
The A3 front-panel board can be troubleshot by first doing the following setup.
a.
Remove the top cover of the unit.
b.
Remove the 4 side screws holding the front-panel assembly to the power supply chassis and pull the entire assembly
forward.
c.
Disconnect the W1 ribbon cable from connector A1J1 on the A1 main board and remove the ground wire screw
holding the green/yellow ground wire. Unplug the four wires to the LINE switch noting the configuration.
d.
Detach the A3 board from the front-panel assembly by removing the five mounting screws.
e.
Reconnect the W1 jumper to connector A1J1 and place the A3 board vertically against the supply with a piece of
insulating material between. The test connector can then be attached to the A3 board. The rest of the front-panel
assembly can stand vertically so that the pots and the switches can be accessed while troubleshooting.
f.
Attach the external line cord and place switch A1S4 in the TEST position.
The ac mains voltage connects directly to the LINE switch and to components and traces at the front of
the A1 main board. Be extremely careful to avoid touching the ac mains voltage.
Start troubleshooting by performing the tests given in Table 3-3. This table provides the measurements for the test points on
the test connector as well as the source components for that measurement. Switch A1S4 should be in the TEST position for
all measurements except where noted. Table 3-4 gives front-panel symptoms as well as the circuits or components that
may cause the supply to exhibit those symptoms. Both Tables 3-3 and 3-4 should be used to check out and troubleshoot the
front-panel.
31
Table 3-2. No-Output Failures
(Bias supplies and AC turn-on circuit functioning)
NhiA2 & A4off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed
NNA2 & A4Power-Limit Comparator and DC-to-DC: A4Q3 and A4Q4 probably
failed
lo= TTL low hi= TTL high N = normal 20KHz pulse train, TTL levels
* Decide which to troubleshoot -- the CV Circuit, the CC Circuit, or the PWM and Off-Pulse & On-Pulse Oneshots -- by
measuring the CV CONTROL (A2CR24, cathode) and the CC CONTROL (A2CR19 cathode) voltages. Troubleshoot
whichever is negative, and if neither is negative, troubleshoot the PWM. Make these voltage measurements after you have
implemented the Main Troubleshooting Setup.
Table 3-3. Front-Panel Board Tests
.
Pin
No
Signal NameMeasureme
nt
DescriptionSource
1+7.5V7.5VDerived from + 15V bias.A3VR2, A3R3
2-1V-1.0VDerived from –15V bias.A3R86, A3R85, A3C17
*3CV VOLTAGE0-5VFor 0 to full scale output voltage.A3U2-2, A3R1, A3R87.
*4CC VOLTAGE0-5VFor 0 to full scale output current.A3U3A-1, A3R67
5VOLTS test-1888 on
Jumper to + 5V on A3 board.A3U4-37
volts display
6AMPS test-1888 on
Jumper to + 5V on A3 board.A3U5-37
amps display
*7VOLTS input0-1VFor 0 to full scale output voltage.A3R8,A3U7-2,3,10
8VOLTS low range TTL highIf VOLTS display is below 20 volts
A3U9C-13, A3U6B
(press DISPLAY SETTINGS).
9DISPLAY
SETTINGS
10DISPLAY OVPTTL highIf DISPLAY OVP switch on front-
TTL highIf DISPLAY SETTINGS switch on
front-panel is depressed.
A3S1,A3R80
A3S2,A3R82, A3U6C-8
panel is depressed.
*11AMPS input0-150mVFor 0 to full scale output current.A3R65,A3R66,A3R67
12-5 V-5.0VDerived from -15 V bias.A3VR1, A3R2
13buffered OVP0-2.2V1/10 of OVP voltage setting when
A3U3B-6,A3CR5,A3R72
DISPLAY OVP switch is
depressed. Varies with OVP
ADJUST pot.
* Switch A1S4 should be in the NORM position for these tests.
32
Troubleshooting Bias Supplies
+5V on A2 Control Board. The PWM A2U6 includes a clock generator (45KHz set by A2R53 and A2C26), and a current
limit (2Adc set by 0.15Vdc across A2R50). It turns off each output pulse using the difference between the voltage at
voltage divider A2R46-A2R47 and the 2.5Vdc set by voltage regulator A2U5.
Circuit Included. + 5Vdc bias supply circuitry from connector pin A2P1-15 through jumper A2W3 on A2 control board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and set the external
To check if load on + 5 V is shorted, remove jumper A2W3
Table 3-4. A3 Front-Panel Board Failure Symptoms
SYMPTOMSDEFECTIVE CIRCUITCHECK COMPONENTS
Error when pressing DISPLAY SETTINGSLimits display.A3U1, A3U9
Error in VOLTS or AMPSInput ranging or DVMS.A3U1,A3U2,A3U4,A3U5,A3U7
* one or more display digits outDisplay LEDs.A3DS1 through A3DS7
Unable to adjust VOLTAGE or CURRENT
or always max
VOLTS decimal point errorDecimal drivers.A3U6
* Note that the Volts and Amps tests (Table 3-3 pins 5 and 6) verify that all the current and voltage display segments light
To check if load on -15V is shorted, remove jumper A2W3.
Refer to Down Programmer, page 39, for the + 8.9V bias supply, and refer to OVP Circuit, page 39, for the +2.5V bias
supply.
≈ -24Vdc
A1U1, AlC1 ( + )
Power Section Blocks
This section contains the blocks referenced in Tables 3-2 and 3-5.
Troubleshooting AC-Turn-on Circuits
Relay A1K1 closes at 1.0 seconds and DROPOUT goes high at 1.1 seconds after 20V (5V UNREG) reaches about 11Vdc.
DROPOUT high enables the PWM if OVERVOLTAGE, and OVERTEMPERATURE are also high.
Circuits Included. AC-Surge-&-Dropout Detector, Bias Voltage Detector, U11A, 1-Second Delay and Relay Driver--all
on A2 control board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and set the external
A2U20-5cycle powertransition 0 to 13.5Vdc
A2U20-2cycle powertransition 0 to 1.4Vdc
A2Q6-1cycle powertransition 0 to 5.0 to 0.3Vdc
A2Q6-9cycle powertransition 0 to 0.3 to 5.0Vdc
A2U20-6wait 2s< 0.25Vdc
A2U20-1,14wait 2shi (5Vdc)
A2U11-3cycle powertransition lo to hi to lo
A2U18-10cycle powerburst 1.25 KHz sq. wave 1.1s
35
A2U18-13cycle powerfive 100ms pulses then hi
A2U18-12cycle powertwo 200ms pulses then hi
A2U18-15cycle powertransition lo to hi at 800 msec
A2U17-8cycle powertransition lo to hi at 1.0 sec
A2U17-11cycle powertransition lo to hi at 1.1 sec
DROPOUT A2Q5 (col)
(RELAY ENABLE)
cycle powertransistion 5.0 to 0.3Vdc at 1.0s
Troubleshooting PWM & Clock
The inputs to inhibit Gate A2U19A and PWM gate A2U19B are the keys to PWM troubleshooting. The 20KHz clock starts
each PWM output pulse, and the pulse stops when any of the inputs to A2U19A or A2U19B goes low. The PWM is
inhibited and prevented from initiating output pulses as long as any of the eight inputs is low.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer and switch on the
LINE switch. Adjust the units current setting above 1.0Adc. Set the external supply (EXTERNAL) and adjust the unit's
voltage setting (INTERNAL) as instructed below.
+ OUT40103.8Vdc (OVERRANGE)
+ OUT4022.0Vdc (CV)
+ OUT402short A2J3-4 to
A2J3-8
0.0Vdc
Troubleshooting DC-To-DC Converter
Parallel NOR gates A4U2A, A4U2B and A4U1A act as drivers and switch on FETs A4Q3 and A4Q4 through pulse
transformer A4T1. NOR gate A4U1B turns off the PFETs through pulse transformer A4T2 and transistors A4Q1 and
A4Q2.
Circuits Included. On-Pulse Driver, Off-Pulse Driver, PFET Switches and Drivers on A4 power mesh board.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, set the external
supply to 40Vdc and switch on the LINE switch. Set the unit's output voltage to 20Vdc and current to above 1Adc. Verify
the UNREGULATED LED lights.
NoteThe Gate (G) and Source (S) leads of PFETs A4Q3 and A4Q4 can be accessed from the circuit side of the
board and used as test points. The Drain (D) of A4Q3 can be picked up at its case or from the cathode of
A4CR13. The Drain of A4Q4 can be picked up at its case or from the anode of A4CR14.
If all the INPUT measurements are correct but the OUTPUT Vgs waveform (3) is incorrect, the problem may be caused by
weak PFETs. Two 6800pF capacitors (Agilent P/N 0160-0159) can be substituted for the PFETs (G to S) to check
waveform 3. If the waveform is still incorrect, the problem may be located in the drive components.
The PFETs are static sensitive and can be destroyed by relatively low levels of electrostatic voltage.
Handle the A4 power mesh board and the PFETs only after you, your work surface and your equipment
are properly grounded with appropriate resistive grounding straps. Avoid touching the PFET's gate and
source pins.
37
Troubleshooting CV Circuit
V-MON, the output of CV Monitor Amp A2U7, is 1/4 the voltage between + S and - S. CV Error Amp A2U8 compares
V-MON to CV PROGRAM. Innerloop Amp A2U10A stabilizes the CV loop with IVS input from A2U10C. The
measurements below verify that the operational amplifier circuits provide expected positive and negative dc voltage
excursion when the CV loop is open and the power mesh shut down.
Circuits Included. Constant Voltage (CV) Circuit and buffer amplifier A2U10C.
Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer, and disconnect the
external supply Remove the + S jumper and connect A2J3-2 ( + 15V) to + S. Set MODE switch settings B4, B5 and B6 all
to 0. Set VP to 0Vdc by connecting to
If the failure symptoms include output voltage oscillation, check if the CV Error Amp circuit is at fault by shorting A2U8-6
to A2U8-2. If oscillations stop, the CV Error Amp circuit is probably at fault.
P or set VP to + 5Vdc by connecting to A2J3-1 according to SETUP below.
Troubleshooting CC Circuit
I-MON, the output of CC Monitor Amp A2U1, in volts is 1/6 the output current in amperes. CC Error Amp A2U2B
compares I-MON to CC PROGRAM. Differentiator circuit A2U3D and A2U3C stabilizes the CC loop. It differentiates
IVS and has a voltage gain of 16. Its output is summed with CC PROGRAM at CC Error Amp A2U2B.
The measurements below verify that the operational amplifier circuits provide expected positive and negative do voltage
gain when the CC loop is open and the power mesh shut down.
Circuits Included. Constant Current (CC) Circuit on A2 control board.
Setup. The Main Troubleshooting Setup, page 29, except connect the external supply with polarity reversed to the unit's +
OUT ( - ) and - OUT ( + ) terminals. Apply the ac mains voltage to the bias transformer. Set the external supply to 3.0Adc
constant current with a voltage limit in the range 5 to 20Vdc.Set IP to 0Vdc by connecting to
connecting to A2J3-1 according to SETUP below.
If the failure symptoms include output current oscillation, check if the differentiator circuit is at fault by removing resistor
A2R16 (3.3M ohm ). If oscillations stop, the differentiator is probably at fault.
Troubleshooting Down Programmer
The down programmer decreases the output when either MASTER ENABLE is low or CV ERROR is more negative than
about - 6Vdc. Comparator A4U3B triggers down programming when the voltage at A4U3B-5 is less than about 3Vdc. The
collector-emitter current through transistor A4Q6 increases as the output voltage decreases because of feedback from
voltage divider A4R24-A4R27 at A4U3A-2
Circuit Included. Down programmer and 8.9V bias supply on A4 power mesh board.
Setup. The Main Troubleshooting Setup, Paragraph 5-73, except connect the external supply to the unit's + OUT ( + ) and -
OUT ( - ) terminals. Apply the ac mains voltage to the bias transformer. Set the external supply (EXTERNAL) and adjust
unit’s voltage setting (INTERNAL) as instructed below.
Comparator A2U14D sets and gate A2U17A resets, flipflop A2U14B-A2U14C. TTL low at A2U14-1,8,13 inhibits the
PWM.
Circuit included. OVP Circuit and 2.5V bias supply on A2 control board.
Setup. The Main Troubleshooting Setup, page 29, except connect the external supply to the unit's + OUT ( + ) and - OUT
( - ) terminals. Apply the ac mains voltage to the bias transformer. Adjust the unit's OVP limit to 15Vdc. Set the external
supply (EXTERNAL) as instructed below.
NoteConnecting a test probe to either input of either comparator in the OV Flip flop (pins A2U14-1, 6, 7, 8, 9,
14 or A2U11-13) may cause the flip flop to change states and cause the probed input to be low.
41
4
Principles of Operation
Autoranging Power
Autoranging allows the unit to be compact and light weight and yet to deliver a range of output voltage current
combinations which otherwise would require the use of more than one supply or a higher rated-power supply. Autoranging
is a name for circuitry which automatically makes full power available at all but low rated output voltages and currents. By
comparison, a conventional constant-voltage/constant-current (CV/CC) power supply can provide full output power only at
maximum rated output voltage and current. For example the power available from a 200 watt, 20V, 10A CV/CC supply
adjusted to deliver 10V is only 100 watts.
The power available from the unit when adjusted to 10V is more than 200 watts. The permitted maximum voltage and
current of the unit change as current and voltage are adjusted by the user. Thus the unit can be a 20V, 10A supply; a 10V,
20A supply; a 6.7V 30A supply, or any other supply in the range shown graphically in Figure 4-1.
Figure 4-1. Output Characteristics: Typical CV/CC and Autoranging Power Supplies
Block Diagram Overview
This section is an overview. Using the block diagram, Figure 4-2, it explains how the unit works, how major circuits are
interconnected and what signals are called. The next section, explains more thoroughly how major circuits operate and uses
the simplified schematic, Figure 4-3. Power flows from the ac mains at the left of the block diagram through circuit blocks
connected by heavy lines to the load on the output terminals at the right. The Down Programmer lowers the output voltage
when required by the CV Circuit. Overvoltage Protection senses the output and shuts down the unit by inhibiting the Pulse
Width Modulator (PWM) through the MASTER ENABLE input when an overvoltage is detected. Other protection circuits
(not shown) can also inhibit the PWM through the Inhibit Gate.
43
44
Figure 4-2. Block Diagram
Control signals flow from right to left with separate circuits for constant-voltage, constant-current and power-limit control.
These three control circuits jointly provide the Autoranging characteristic of Figure 4-lB. AC Turn-on Circuits limit inrush
current to the input filter and assure transient free turn-on. Internal Bias Supplies provide five bias and two reference
voltages to the unit's circuits and provide input signals to the AC Turn-on Circuits.
The unit is a flyback switching power supply. The power transformer stores energy in its magnetic field while current flows
in its primary, and energy transfers to the secondary when current flow in the primary turns off. A pair of PFET switches in
series with the primary turns on and off at a 20KHz rate controlling the current flow; and the PWM varies the on-time of
the PFET switches to regulate the output voltage or current.
In CV or CC operation the PWM turns the PFET switches on at each clock pulse and turns them off when the IpRAMP
VOLTAGE exceeds the CP control-port voltage. The IpRAMP VOLTAGE is derived from a sensing transformer in series
with the power transformer primary and is proportional to the primary current. The CP control-port voltage is determined
by the CV Control Circuit when the unit is in constant-voltage operation and is determined by the CC Control Circuit when
in constant-current operation. Follow the block diagram from right to left to see how the output voltage is regulated during
CV mode of operation. The output voltage is monitored both at the output sense terminals + S and--S (OVS outerloop
voltage) and also before the two stages of output filter (IVS innerloop voltage). Sensing with output sense terminals
provides accurate load-voltage control, and sensing before the output filter stabilizes the supply and permits it to power
highly reactive loads.
The CV Monitor Amplifier buffers the OVS outerloop voltage to produce the VMON output monitoring voltage. A buffer
amplifier (not shown) monitors the voltage before the output filter to produce the IVS innerloop voltage. CV Error and
Innerloop Amplifiers compare V-MON and IVS with the CV PROGRAM Voltage which is set by the front-panel
VOLTAGE control or by remote programming to develop the CV CONTROL Voltage. When the CV CONTROL Voltage
is lower than the CC CONTROL Voltage, CV determines CP and regulates the output voltage by controlling the turn-off of
the PWM.
While the PWM turns off when any of the four inputs shown go low, in CV and CC operation it is controlled by the
CONTROL V LIMIT input from the Control Voltage Comparator. When the Ip-RAMP VOLTAGE exceeds CP,
CONTROL V LIMIT goes low and the PWM turns off the PFET switches. The next clock pulse causes the PWM to turn
on the PFET switches, and thus the cycle repeats at a 20KHz rate. Power is transferred through the transformer as required
to produce the output voltage determined by the CV PROGRAM Voltage.
When in CC operation, the output current is regulated in a similar manner. Output current is sensed as the OCS outerloop
voltage across a Current Monitoring resistor. OCS is buffered to produce I-MON. IVS is differentiated to produce an
innerloop current-sensing voltage; and CC Error amplifier compares these to the CC PROGRAM Voltage from the frontpanel CURRENT control or remote programming to develop the CC CONTROL Voltage.
Simplified Schematic
The simplified schematic, Figure 4-3, shows the basic operating circuits of the unit. Detailed descriptions follow for major
circuits and components in clockwise order. The circuit names and layout of the simplified schematic are the same as used
on the complete schematic in Section 7. The heavy lines are the path of power flow through the unit. Please see Figure 4-5
for the display circuits.
Primary power comes to the Input Rectifier through a resistor which limits turn-on inrush current to the input filter. Jumper
A1W1 connects the Input Rectifier and Filter as a voltage doubler for 120Vac mains. This jumper is not used for
220/240Vac; thus the Input Filter develops a dc bus voltage of about 300Vdc for either 120 or 220/240Vac ac mains
voltages. Primary power also comes through Mains-Voltage Select switches to the Bias Power Supplies which provide the
internal operating voltages for the unit. The Mains-Voltage Select switches connect the primary windings of the bias
supplies transformer for operation at 120, 220, or 240Vac.
45
46
Figure 4-3. Simplified Schematic
The unit checks that the + 5Vdc bias voltage and the ac mains voltage are within acceptable limits as part of its turn on
sequence. When + 5Vdc comes up, the Bias Voltage Detector resets the Overvoltage-Protection circuit, enables the On
Pulse Driver for the PFET switches, and with the AC Surge-Dropout Detector starts the 1-Second-Delay circuit. After one
second, relay A1K1 bypasses the Inrush-Current Limiting resistor. After 0.1 seconds more, the 1-Second-Delay circuit
enables the PWM through the DROPOUT signal. The unit is then ready to deliver power.
When the AC-Surge and Dropout Detector detects high or low mains voltage, the unit shuts down until an acceptable ac
mains voltage returns. Then it repeats the above turn-on sequence. This protects the unit from damage from ac mains surges
and brownouts.
DC-to-DC Converter
PFET switches A4Q3 and A4Q4 control current flow from the Input Filter through power transformer T1. The PWM
triggers on-pulses and off-pulses for the PFETs. A train of on-pulses comes through diodes A4CR4 and A4CR3 to the
PFETs' gates to turn on the PFETs. The PFETs' input capacitances hold the PFETs on between on-pulses. Off-pulses turn
on transistors A4Q1 and A4Q2 which then short the PFETs input capacitances and turn off the PFETS .
The on-Pulse one-shot A2U15B and off-Pulse one-shot A2U15A generate the on- and off-pulses. A2U15B produces a train
of up-to four 160KHz on-pulses during the PWM output pulse. A2U15A triggers an off-pulse at each trailing edge of the
PWM pulses. Figure 4-4 shows the timing.
When the PFETs turn on, current flows through the primary of power transformer A1T1 and primary-current monitor
transformer, A4T3. The Output Rectifier, A4CR7, is reverse biased and blocks current flow in the A1T1 secondary.
consequently, the A1T1 transformer stores energy. When the PFETs apply the dc bus voltage to the primary, the primary
current ramps up storing more and more energy. The A4T3 transformer senses the A1T1 primary current, and the
secondary of A4T3 develops the Ip-Ramp Voltage across resistor A2R108. This linearly increasing voltage predicts the
correction in the supply's output voltage or current which will occur when the PFETs are turned off. Comparators
monitoring the Ip-Ramp Voltage signal the PWM to turn off the PFETs when it exceeds either the CP control-port voltage
or the Power-Limit reference voltage.
When the PFETs turn off, the collapsing magnetic field reverses the polarity of the voltages across the AlT1 primary and
secondary, and current flows from the AlT1 secondary through output Rectifier A4CR7 to charge output capacitors A1C8,
A1C9 and A1C10. When the PFETs turn off, the leakage inductance of Tl forces current to continue to flow in the primary.
Flyback Diodes A4CR13 and A4CR14 protect the PFETs from excess reverse voltage by conducting this current around
the PFETs and back to the input filter.
Down Programmer
The Down Programmer lowers the output voltage by rapidly discharging the output-filter capacitors. The Down
Programmer causes the output voltage to drop more quickly than it would if only the load discharged the capacitors. Its
negative resistance load characteristic discharges the output-filter capacitors at about a 1 ampere rate when the output
voltage is high 60Vdc and increases to about a 4 ampere rate when the output voltage is low (1Vdc). Five conditions can
trigger down programming: Programming of a lower output voltage, an overvoltage, an overtemperature, a remote disable,
or a primary power failure.
The Down-Programmer's input circuit is the diode-OR connection of the Master enable output from Inhibit Gate A2U19B
and the CV Error Voltage from CV Error Amplifier A2U8. The Down Programmer turns on when either the Master Enable
is low or when the CV Error Voltage is more negative than about -6Vdc. The + 8.9Vdc bias supply for the Down
Programmer stores enough energy in its input capacitor to operate the Down Programmer after loss of primary power. This
ensures that the Down Programmer will be able to discharge the output circuit when primary power is turned off.
47
Figure 4-4. PFET Control Signals Timing Diagram
Constant-Voltage (CV) Circuit
The Constant-Voltage Circuit compares the output voltage to the user-set CV PROGRAM Voltage to produce the CV
CONTROL Voltage. Two comparison amplifier loops accomplish the comparison. In the outerloop, CV Error Amplifier
A2U8 compares V-MON, a buffered fraction of the sensed output voltage OVS, to the program voltage from the CV
Programming Switches to create the CV ERROR Voltage. Then in the innerloop, Innerloop Amplifier A2U10A compares
this error voltage to IVS, a buffered fraction of the innerloop output voltage, to produce the CV CONTROL Voltage. The
CV ERROR Voltage is also diode-OR connected through diode A2CR21 as an input to the Down Programmer.
V-MON also connects through protective circuitry to rear-panel terminal VM for remote monitoring of the output voltage.
It is equal to 1/4 of the sensed output voltage OVS, and is 5Vdc for 60Vdc full output.
Settings of the CV Programming Switches, the B6, B5, and B4 MODE switch settings allow the CV PROGRAM Voltage
to come from the front-panel VOLTAGE Control; from an external voltage applied between rear-panel terminals VP and
sP; or from an external resistor between VP and sP. When using either the VOLTAGE Control or external resistor,
current from the CV Constant-Current Source flows through the applicable resistance to develop the CV PROGRAM
Voltage.
In CV mode, the CV CONTROL Voltage varies between about -0.5Vdc and about + 1.0Vdc. It is most negative when the
load is drawing no power. As the load draws more power, the voltage becomes more positive. The CV CONTROL Voltage
is at the cathode of diode A2CR24, part of the diode-OR input to the Control-Voltage Comparator. Diode A2CR20 prevents
voltage overshoots during transient load changes and program changes.
48
Constant-Current (CC) Circuit
The Constant-Current Circuit compares the output current to the user-set CC PROGRAM Voltage to produce the CC
CONTROL Voltage. As with the CV Circuit, two comparison amplifier loops accomplish the comparison. OCS is the
voltage across Current-Monitoring resistor A1R3, and it senses the output current for the outer loop which is the unit's
output current.
To compensate for the fraction of the output current which flows through the unit's output-voltage sensing resistors and not
through the load, CC Monitor Amplifier A2U1 adds a fraction of V-MON to OCS. It amplifies that sum to produce the
outerloop current-sense voltage, I-MON. I-MON also connects through protective circuitry to rear-panel terminal IM for
remote monitoring of the output current. In volts it is equal to 1/6 of the output current in amperes, and is 5Vdc for 10Adc
full output.
Differentiation of IVS develops a current-proportional voltage which senses the innerloop current flowing into the
capacitive output filter. CC Error Amplifier A2U2B sums this differentiated innerloop voltage with I-MON and subtracts
the sum from the CC PROGRAM Voltage to produce the CC CONTROL Voltage. In CC mode the CC CONTROL
Voltage varies from about--0.5Vdc to +1.0Vdc at the cathode of diode A2CR19. CC Clamp A2U2A limits the CC
PROGRAM Voltage to about 5.6 peak volts.
Settings of the rear-panel CC Programming Switches the B3, B2 and B1 MODE switch settings allow the CC PROGRAM
Voltage to come from the front-panel CURRENT Control, from an external voltage applied between terminals IP and /P, or
from an external resistor between IP and /P. When using either the CURRENT Control or external resistor, current from the
CC Constant-Current Source flows through the applicable resistance to develop the CC PROGRAM Voltage.
Overvoltage Protection (OVP) Circuit
The Overvoltage Protection Circuit (OVP) shuts down the unit when a monitored 1/30 fraction of the output voltage
exceeds the limit voltage set by the front-panel op ADJUST Control. If the output voltage exceeds the preset limit, the OVP
inhibits the PWM, triggers the Down Programmer, lights the OV LED and latches itself on until the unit is turned off. The
Bias Voltage Detector resets the OVP at turn-on of the unit.
option 002 allows remote reset of OVP.
Power-Limit Comparator
Two comparisons with the Ip-RAMP VOLTAGE provide POWER LIMIT and CONTROL V LIMIT, two of the four
inputs for the PWM. POWER LIMIT is the output of the Power Limit Comparator A2U14A. The comparator compares the
IpRAMP VOLTAGE with the power-limit reference voltage of about 1.0Vdc. The reference is adjustable with the POWER
LIMIT calibration trim pot A2R25. The POWER LIMIT sets the maximum primary current in power transformer A1T1 by
going low and turning off the PWM when the Ip-RAMP VOLTAGE exceeds the reference.
Primary current is proportional to output power, and POWER LIMIT turns off the PWM when the CONTROL V LIMIT
would otherwise allow the unit to deliver more than about 200 watts. This occurs during transient load increases, step
increases in CV Program Voltage and when the combination of the CV PROGRAM Voltage and the CC PROGRAM
Voltage calls for more than 200 watts. The Power-Limit Comparator produces the power-limited portion of the unit's output
characteristic curve in Figure 4-1 and is the essence of the unit's Autoranging power.
Control-Voltage Comparator
The Control-Voltage Comparator A2U16 produces the CONTROL V LIMIT input to the PWM by comparing the IpRAMP
VOLTAGE to the CP control-port voltage. In CV or CC operation CP is one diode-drop more than the lower of the CV and
CC CONTROL Voltages. CONTROL V LIMIT goes low and turns off the PWM when the Ip-RAMP VOLTAGE exceeds
CP. The A2R113-A2R114 voltage divider steers control of CP by its connection at the anodes of series diodes A2CR19 and
49
A2CR24. The A2R113-A2R114 voltage divider sets the maximum CP voltage to + 1.5Vdc and assures that the diode with
the lower control voltage will be forward biased when its control voltage is less than + 1.5Vdc. As an illustration of CV-CC
selection, suppose the unit is in CV operation and diode A2CR24 is forward biased by a low CV CONTRL Voltage: Then
CV sets CP to less than + 1.5Vdc.
CV keeps diode A2CR19 reverse biased and prevents CC control until the CC CONTROL Voltage is even lower.
The lower of the control voltages varies between about--0.5Vdc and + 1.0Vdc regulating the unit's output. The higher
control voltage has no effect on the output and increases in response to the error voltage in its circuit. When higher, the CC
CONTROL Voltage limits at about 6Vdc. When higher, the CV CONTROL Voltage increases only slightly. In CV or CC
mode CP remains one diode-drop more than the lower control voltage and varies from about 0.0 to + 1.5Vdc. In
UNREGULATED mode CP is +1.5Vdc and both control voltages are more than about + 1.0Vdc.
Initial-Ramp Circuit
The Control Voltage and Ramp Voltage waveforms in Figure 4-4 show that there is a time delay between when the control
voltage is exceeded and when the PFETs turn off. This cumulative circuit delay would cause the PFETs to deliver power
even when no power is requested by the control circuits. To eliminate the delay, the Initial-Ramp Circuit adds a ramp
voltage to the Ip-RAMP VOLTAGE at the input to the Control Voltage Comparator. The added ramp voltage starts with
the 20KHz clock pulse and causes the combined-ramp voltage to exceed the control voltage earlier thereby essentially
eliminating the PFET turn-off delay. A two-stage RC integrating network consisting of resistors A2R116 and A2R117 and
capacitors A2C59 and A2C61 creates the Initial-Ramp by shaping the 20KHz clock pulses.
Pulse-Width Modulator (PWM)
The PWM generates 20KHz repetition-rate pulses which vary in length according to the unit's output requirements. The
pulses start 1.5
Control-Voltage Comparator (CONTROL V LIMIT), the output of the Power-Limit Comparator (POWER LIMIT), the
20KHz clock pulse (50%-DUTY-CYCLE LIMIT), or the output of the Inhibit Gate A2U19A (MASTER ENABLE). As
discussed earlier, the PFETs turn on during, and turn off at the trailing edges of PWM output pulses.
The PWM generates pulses as follows: A 20KHz clock pulse holds the 1.5
trailing edge of the 20KHz pulse, the next pulse from the 320KHz Clock oscillator clocks the output of A2U13B high, and
this initiates the PWM pulse from PWM Flip-flop A2U13A. When one of the above four inputs to AND-gate A2U19B goes
low. A2U19B resets A2U13A, and the PWM pulse turns off.
µ after each 20KHz clock pulse and turn off when any of these four inputs go low. The output of the
µ Delay Flip-flop A2U13B reset; 1.5µ after the
Bias Voltage Detector
The Bias Voltage Detector prevents spurious operation which might occur at power-on of the unit if circuits tried to operate
before the + 5Vdc bias voltage is at the clock, PWM, and logic circuits. After power-on, as the output of the + 5Vdc bias
supply rises from 0Vdc through about 1Vdc, three transistor switches in the Bias Voltage Detector turn on. They inhibit the
Relay Driver and the on-Pulse Driver, and they create the power-clear signal, PCLR2. The transistors inhibit the circuits
and hold PCLR2 low until the unregulated input to the +5Vdc bias supply is greater than about 11Vdc, an input voltage
sufficient to assure + 5Vdc bias output. PCLR2 resets the OVP at turn-on, and
DROPOUT, OVERVOLTAGE, and POWER-ON RESET outputs.
Option 002 uses PCLR2 in creating its
AC-Surge Dropout Detector
Dropout Detector protects the unit from damage from ac mains voltage surges and dropouts by shutting down the unit when
there is either a 40% overvoltage or a 20 ms voltage interruption in the ac mains voltage. The detector shuts down the unit
50
by inhibiting the PWM through the DROPOUT signal from the l-Second-Delay Circuit. Mains Detect signal, which is
fullwave-rectified ac from the + 5Vdc secondary of the bias-supplies transformer, senses the ac mains voltage. The Dropout
Detector, including comparators A2U20A and A2U20C, operates by enabling a capacitor-timing ramp when Mains-Detect
ceases. Comparator A2U20D monitors the amplitude of Mains-Detect to provide ac surge voltage detection.
1-Second-Delay Circuit
The l-Second-Delay Circuit is the heart of the unit's controlled turn-on. It causes relay A1K1 to bypass inrush
current-limiting resistor A1R1 one second after turn-on, and it enables the PWM 0.1 seconds later. When either the output
of the AC-Surge and Dropout Detector or PCLR2 is low, NAND gate A2U11A holds the circuit reset. The circuit starts
counting at 1/16 the clock frequency (1.25 kHz) when both inputs to A2U11A are high and causes Relay Enable to go high
in 1.0 seconds and DROPOUT to go high in 1.1 seconds. When DROPOUT goes high, it stops the count, and it enables the
PWM.
option 002 uses DROPOUT in creating its DROPOUT output.
Display Circuits
Figure 4-5 is a simplified schematic for the display circuits. The named signals from the CV and CC Circuits are connected
through semiconductor bilateral switches to the VOLTS digital voltage display and to the AMPS digital current display.
Either a blank display or a depressing of the DISPLAY OVP switch changes the VOLTS display from low range to high
range. A blank display occurs when the Voltage DVM A3U4 receives an over-range voltage, a voltage greater than
0.999Vdc. The blank display is detected by the Voltage-Range Switching Circuit. The diode-AND connection at inverting
amplifier A3U9A senses when two selected segments of the 7-segment LED for the second digit are both not lighted. The
detection scheme works because at least one of the selected segments is lighted for all digits 0 though 9.
The normal display is the actual output voltage and current and has bilateral switches A3U1A and A3U1D closed. Switch
A3UlA connects V-MON through buffer amplifier A3U2 and range-switching bilateral switches to the VOLTS DVM.
Switch A3Ul D connects I-MON through buffer amplifier A3U3A to the AMPS DVM. Depress the DISPLAY LIMITS
Switch, and CV and CC PROGRAM Voltages connect through bilateral switches A3U1B and A3U1C to display the
programmed output voltage and current. Depress the DISPLAY OVP Switch, and OV PROGRAM Voltage from the OVP
ADJUST Control connects through buffer amplifier A3U3B and bilateral switch A3U7B to display the programmed OVP
voltage limit. The CV and CC CONTROL Voltages also control the front-panel mode LEDs. When CV CONTROL
Voltage is more negative than CP, transistor A2Q6C lights CV LED A3DS9 showing that the unit is operating in
constant-voltage mode. When CC CONTROL is more negative than CP, transistor A2Q6F lights CC LED A3DS10
showing that the unit is operating in constant-current mode. And when both CV and CC are more positive than CP,
NAND-gate A2U11C lights UNREGULATED LED A3DS11 showing the unit is operating in power-limited, unregulated
mode.
51
5
Replaceable Parts
Introduction
This chapter contains information for ordering replacement parts. Table 5-3 lists parts in alpha-numeric order by reference
designators and provides the following information:
a.
Reference Designators. Refer to Table 5-1.
b.
Agilent Model in which the particular part is used.
c.
Agilent Part Number.
d.
Description. Refer to Table 5-2 for abbreviations.
Parts not identified by reference designator are listed at the end of Table 5-3 under Mechanical and/or Miscellaneous.
* Reference designator following "X" (e.g. XA2) indicates assembly or device mounted in socket.
53
Ordering Information
To order a replacement part, address order or inquiry to your local Agilent Technolgies sales office. Specify the following
information for each part: Model, complete serial number, and any option or special modification (J) numbers of the
instrument; Agilent part number; circuit reference designator; and description. To order a part not listed in Table 5-3, give a
complete description of the part, its function, and its location.
S16023A3101-0402Switch DPST rocker (mounted on front-
panel)
S2All3101-1914Switch 2-DPDT slide
S4All3101-2046Switch DPDT slide
T16023A5080-1978Transformer, power
T16028A06038-80090Transformer, power
T2All9170-1264Core magnetic (used with primary wire
CR1,2All1901-0033Diode general purpose 180V 200mA
CR3,4All1901-0050Diode switching 80V 200mA
CR5All1901-0033Diode general purpose 180V 200mA
DS1-86023A1990-0985Display kit
DS16028A1990-0681Display, analog
DS2-46028A1990-0540Display, numeric
DS56028A1990-0681Display, analog
DS6-86028A1990-0540Display, numeric
DS9,10All1990-0951LED, green
J1All1251-5055Connector, post type 26-contacts
R1All0683-3925
R2All0683-6815
R3All0683-2025
Resistor, fixed film 1K
Resistor, fixed film 9K
Resistor, fixed film 40K
Resistor, fixed film 6.66K
Resistor, fixed film 19K
Resistor, fixed film 34K
Resistor, fixed film 1K
Resistor, fixed film 6.00K
Resistor, fixed film 1K
Ω 0.1% 1/8W
Ω 0.1% 1/8W
Ω 0.1% 1/8W
Ω 0.1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 5% 1/4W
Resistor, fixed composition 3K
Resistor, fixed film 51.1K
Resistor, fixed film 26.1K
Resistor, fixed film 8.25K
Resistor, fixed film 5.11K
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω +1% 1/8W
Resistor, fixed composition 51K
Resistor, fixed composition 1K
Resistor, fixed composition 5.1K
Resistor, fixed composition 1K
Resistor, fixed film 1K
Resistor, fixed film 4K
Resistor, fixed film 80K
Resistor, fixed film 20K
Resistor, fixed film 20K
Resistor, fixed film 30.1K
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Ω 1% 1/8W
Resistor, fixed composition 51K
Resistor, fixed film 21.5K
Ω + 1% 1/4W
Resistor, fixed composition 51K
Resistor, fixed film 27.4K
Ω 1% 1/8W
S1,2All5060-9436Switch lighted pusbutton
U1All1826-0502IC switch analog quad
U2All1826-0493IC op amp lo-bias hi-impedance
U3All1826-0346IC op amp dual general purpose
U4,5All1826-0876IC A/D CMOS 3-1/2 DGT
U6All1820-1144IC gate TTL LS NOR quad
U7All1826-0502IC switch analog quad
U9All1826-0138IC comparator GP quad
VR1All1902-3092Diode zener 4.99V 2%
VR2All1902-0064Diode zener 7.5V 5%
W4All7175-0057Wire 22 AWG
W76028A7175-0057Wire 22 AWG
W86023A7175-0057Wire 22 AWG
W11All7175-0057Wire 22 AWG
Ω 5% 1/4W
Ω ± % 1/4W
Ω 5% 1/4W
Ω ~5% 1/4W
Ω 5% 1/4W
Ω 5% 1/4W
Ω 5% 1/4W
64
Table 5-6. A4 Power Mesh Parts List
Ref. Desig.Agilent ModelAgilent Part NumberDescription
Ref. Desig.Agilent ModelAgilent Part NumberDescription
A1 Board Mechanical Parts
6023A1251-0600Contact-conn M (Ref Fan)
A1J1All1251-5927Connector post type header
A1J2All1251-5384Connector post type header
A1J3All1251-8676Connector post type
XA2P1All1251-8665Connector post type
XA2P2All1251-8667Connector post type
XA4P1,P2All1251-8806Din Connector
All1251-5613Single contact connector (ref. AC line
voltage select)
All1480-0552Pin, escutcheon (ref. L1)
All2110-0269Fuseholder, clip type (ref. F2)
A1TB1All0360-2192Barrier block
All0360-2190Jumper, barrier block
A2 Board Mechanical Parts
A2P1All1251-8664Connector post type
A2P2All1251-8666Connector post type
A2J1, J2All1251-8417Din Connector
All0380-1489Spacer, snap in
All0370-1091Knob, base round
All0403-0282Bumper feet
All1510-0044Binding post, single
6023A2110-0564Fuseholder body (chassis fuse)
6023A2110-0565Fuseholder cap (chassis fuse)
6023A2110-0569Fuseholder nut (chassis fuse)
6028A2110-0926Fuseholder assembly, (chassis fuse)
All3160-0309Finger guard (ref. fan)
67
Table 5-7. Other Replacement Assemblies (continued)
Ref. Desig.Agilent ModelAgilent Part NumberDescription
All4040-1954Window, display
6023A5020-8847Trim strip
All5041-8803Trim strip, top
All5001-0540Trim, side 7in
All5021-8417Frame front
All5041-8801Foot
All5041-8819Retainer, strap handle
All5041-8820Retainer, strap handle
All5041-0309Key cap, quarter
All5062-3703Assembly, handle strap
All7120-1254Nameplate
All7120-8572Canadian Standards Association Label (ref.
rear panel)
All7121-2527Metric and Inch Label (ref. rear panel)
All7121-2794Serial Identification Label (ref. rear panel)
6023A06023-00016Chassis
6028A06023-00001Chassis
All06023-00020Cover, top
All06023-00022Cover, bottom
6023A06023-00004Bracket, upper
6023A06023-00014Panel, sub
6023A06023-00018Sub panel, front
6023A06023-00007Bus bar, negative
6023A06023-00008Bus bar, positive
All06028-00021Front-panel, screened
All06023-81003Line Voltage Label (ref. rear panel) 28480
6023A06023-90001Operating and Service manual
6028A06028-90001Operating and Service manual
6023A1990-0521Cover, terminal block
Option 220 (220V Operation)
68
All2110-0055Fuse 4A 250V (rear chassis)
All2110-0383Fuse 8A 250V (rear chassis)
All7120-8572Label, info
All06023-81001Label, info
Option 240 (240V Operation)
All2110-0055Fuse 4A 250V (rear chassis)
All2110-0383Fuse 8A 250V (rear chassis)
All7120-8572Label, info
All06023-81002Label, info
Component Location and Circuit Diagrams
This chapter contains component location diagrams, schematics, and other drawings useful for maintenance of the power
supply. Included in this section are:
a.
Component location illustrations (Figures 6-1 through 6-5), showing the physical location and reference designators of
almost all electrical parts. (Components located on the rear panel are easily identified.)
b.
Notes (Table 6-1) that apply to all schematic diagrams.
c.
Figures 6-6 and 6-7 illustrate the detailed schematic of the unit. Test points are called out and short explanatory notes
are positioned close to the related circuit to enhance schematic readibility.
AC line voltage is present on the A1 Main Board Assembly whenever the power cord is connected to an ac
power source.
6
69
Table 6-1. Schematic Diagram Notes
1.denotes front-panel marking.
2.
denotes rear-panel marking.
3.Complete reference designator consists of component reference designator prefixed with assembly number
(e.g.: A2R14).
4.Resistor values are in ohms. Unless otherwise noted, resistors are either 1/4W, 5% or 1/8W, 1%. Parts list provides
power rating and tolerance for all resistors.
5.Unless otherwise noted, capacitor values are in microfarads.
6.Square p.c. pads indicate one of the following:
a. pin 1 of an integrated circuit.
b. the cathode of a diode or emitter of a transistor.
c. the positive end of a polarized capacitor.
7.In schematic symbols drawn to show right-to-left signal flow, blocks of information are still read left to right. For
example:
indicates shift away from control block (normally down and to right). indicates shift toward control block
(normally up and to left).
8.
indicates multiple paths represented by only one line. Reference designators with pin
numbers indicate destination, or signal names identify individual paths. Numbers
indicate number of paths represented by the line.
9.Inter-board commons have letter identifications (e.g. : ); commons existing on a single assembly have number
identifications (e.g.: ).
10.For single in-line resistor packages, pin 1 is marked with a dot. For dual in-line integrated circuit packages, pin 1 is
either marked with a dot, or pin 1 is to the left (as viewed from top) of indication at end of integrated circuit
package. e.g.:
70
Table 6-1. Schematic Diagram Notes (continued)
Pin locations for other semi-conductors are shown below:
Figure 6-5. Power Mesh Board (A4) Component Location
A
System Option 002
General Information
This option facilitates the operation of the power supply in an automated system. Four major circuit blocks provide:
1 ) remote analog programming of the supply's output by three different control methods; 2) signals indicating the power
supply modes and conditions; 3) two different digital methods of remote control; and 4) the outputs of three bias supplies
for use with external circuitry.
The power supply equipped with this option can be operated from either a 6940B Multiprogrammer equipped with a
69520A power supply programming card or a 6942A Multiprogrammer equipped with a 69709A power supply
programming card.
Remote Programming. Through this interface both the output voltage and current can be remote programmed by either an
external voltage source, resistance, or a current sink.
Status Indicators. Six optically isolated lines provide open-collector digital outputs which indicate the following states:
constant voltage mode, constant current mode, output unregulated, ac dropout, overvoltage, and overtemperature.
Remote Control. Two optically isolated methods of remote control are available. 0ne method requires a negative going
edge, which sets a latch on the 002 card to inhibit the power supply. The latch and OVP are reset by a negative-going pulse
on another input line. The second method of remote control requires a low logic level to inhibit the power supply for the
duration of the low level.
Bias Supplies. The outputs of three bias supplies are also available at the option connector. These outputs are + 15V, -15V,
and +5V.
Monitoring. The 002 Option Board provides two monitoring outputs (I.MON. and V.MON) available at the option
connector. They both vary from 0 to 5V corresponding to a 0 to full scale output.
Other modes of operation, such as multiple supply system control, are described in detail in later paragraphs. Modes such as
Auto Series, Auto Parallel, and Auto Tracking Operation are described in the Operating Manual.
Specifications
Table A-1 provides specifications for the Option 002. This table is referred to periodically throughout the text of this
Appendix.
Option 002 Hardware
The Option 002 hardware consists of a single printed circuit board installed at the right side (facing the front-panel) of the
chassis. Two cables connect the option board to the A2 control board at A2J1 and A2J2. Connections between the option
board and external circuits are made via the 37-pin connector mounted on the option board and available at the rear of the
power supply. A mating connector is also included for the user's convenience.
79
Remote Programming
Table A-1. Specifications, Option 002
Resistance Programming:
Accuracy:@25°C
0 to 4K ohm provides 0 to maximum rated voltage or current output.
CV: 0.5% + 12mV (6023A)0.5% + 70mV (6028A)
CC: 1.0% + 110mA (6023A)1.0% + 500mA (6028A)
Voltage Programming: 0 to 5V provides 0 to maximum rated voltage or current output.
Current Programming: 0 to 2mA current sink provides 0 to maximum rated voltage or current output.
Accuracy: @25°C
CV: 0.38% + 16mV (6023A)0.43%
± 500mA (6028A)
± 71mV (6028A)
CC: 0.43% + 115mA (6023A)0.50% + 500mV (6028A)
Input Compliance Voltage: ± 1V
Current Programming Enable:
Relays K2 (CV) and K1 (CC) are biased from the Control Isolator Bias input (See Remote Shutdown and OVP Clear).
Relay Bias Voltage: +4V minimum + 7V maximum
Relay Resistance: 500Ω ± 10%
Note
For Control Isolator Bias voltages greater than 7V, a series resistor must be used to maintain the relay bias voltage within
specified limits.
Enabling either relay is accomplished by bringing CV or CC enable line to Control Isolator Bias common via a suitable
driver; maximum driver off-state leakage =5mA.
Output Voltage and Current Monitor: 0 to 5V output indicates 0 to maximum rated output voltage or current.
Status Isolator Bias input (referred to Status Isolator Common).
80
Table A-1. Specifications, Option 002 (continued)
Voltage Range:
+4.75V to 16V
Current Drain: 20mA maximum
Status Indicator output:
Open collector output:
Maximum Output Voltage (logic high): + 16V
Logic Low output: + 0.4V maximum at 8mA
Remote Control (Trip, Reset, Inhibit) Control Isolator Bias Input
Voltage Range: +4.75V to 16V
Remote Control Inputs (
TripRemote, ResetRemote ) Inhibit Remote.
On State (logic low):
Minimum forward current required (I
): 1.6mA Isolator forward voltage (V
f
maximum
For Control Isolator Bias voltage greater than
± 5V, an optional resistor (Ropt) may be added to reduce drive current .
Off state ( logic high) maximum leakage current: 100µA.
REMOTE TRIP and REMOTE RESET Timing
) at 1.6mA (If): 1.4V typical, 1.75
f
Pulse duration (TL): 15µS minimum
Reset time (TH): 125
Set-up time (Ts): 25
OVP clear delay: 1 sec
µs minimum
µs minimum
± 30%
Power-on Preset
Output Ratings:
open collector output (referred to power supply common)
Maximum output voltage (logic high): + 16V
Logic low output: +0.4V maximum at 8mA
81
Table A-1. Specifications, Option 002 (continued)
Pulse Timing
Low Bias or AC DROPOUT will go false after 5V supply stabilizes.
Bias Supplies
DC Output Ratings: (25°C ± 5)
No Load to Full Load 104V to 127V line.
+ 5V ± 3% at 100mA
± 3% at 75mA
+15V
± 4% at 75mA
-15V
Short Circuit Output Current:
+5V 125mA ± 6%
+ 15V103mA
-15V103mA
PARD (Typical):
± 6%
± 6%
+ 5V 25mV pk-pk1.5mV Rms
+ 15V SameSame
-15VSameSame
Isolation:
Status Indicator lines and Remote Control lines may be floated a maximum of 240Vdc (6010A, 250Vdc, 6011A, 6012B)
from ground from the power supply or from each other. These lines may not be connected to any primary circuits.
Jumpers Designation
W1--jumpered:OV indication @ A7J3-17 is active (lo) if OVP; Remote Trip or Remote Inhibit is
active.
W1--open:OV indication is active (lo) if OVP or Remote Trip is active.
Normal operation as shipped:W3 and W4 jumpered W2 and W5 open.
OVP ProgrammableCV: W2 jumpered; W3 open or
CC: W5 jumpered; W4 open
S1A,B in open position
82
Installation
When installing the board, perform the following steps:
a.
Remove the top and inner cover of the power supply as discussed in Section 3 under Repair and Replacement.
b.
Remove the plate next to the barrier strip on the rear panel of the supply by unscrewing the 2 M3 screws.
c.
Insert the already prepared 002 board in the slot closest to the right side (looking from the front-panel) of the supply.
d.
Use the two M3 screws to connect the rear end of the 002 board to the rear panel of the supply.
Attach ribbon cables from the A2 Control Board A2J1 to A7J1 and A2J2 to A7J2.
e.
f.
Replace the inner and outer cover of the supply.
Connector Assembly Procedure
The following instructions describe assembly of the mating connector provided to interface the user's system with the
option connector, J3. Figure A-1 identifies the parts of the mating connector.
Proceed as follows:
Note:It may be desirable to set up a test interface before final assembly of the mating connector to allow
checkout of the system. A mating connector with pins accessible for temporary wiring is available from
Agilent Technologies, Agilent part number 1251-4464.
If the cable assembly presents RFI or ESD problems, a shielded cable assembly accessory Agilent Part
Number 5060-2890 can be ordered.
a. If a multi-wire cable is being used (as opposed to individual wires), remove approximately 1 1/2 inches of cable
insulation from the end. Be careful not to cut the insulation on the individual wires.
b. Strip 3/16 inch of insulation from the end of each wire to be used.
Insert each wire into a contact pin (1) and crimp firmly.
c.
Insert each pin into a proper hole in connector-pin house (2) from rear. Pins will lock into housing when fully inserted.
d.
NoteOnce the pins are locked into the connector-pin housing, they are extremely difficult to remove.
Therefore, be certain pin is in proper hole before inserting fully.
e. Screw a slotted setscrew (3) partially into a square nut (4) and place in position in connector shield assembly (6).
Place strain relief (5) in position in connector shield assembly (6), just under set screw (3). Be certain that strain relief
f.
is oriented as shown in Figure A-1.
g.
Place connector pin housing (2) in shield assembly (6) and route cable through cable entrance.
Fold connector assembly (6) and secure with three screws.
h.
Strain relief set screw (3) can now be adjusted from top of connector to clamp firmly on cable.
i.
Clip fasteners (7) onto ends of connector pin housing (2).
j.
Connector can now be plugged onto option connector J3 and secured with two screws (8) into the threaded stand-offs
k.
on either side of J3.
83
Figure A-1. Mating Connector Assembly
Operation
The following paragraphs provide the operating instructions necessary to interface a 002-equipped power supply into an
automated system. A brief description of some circuits is also provided. The unit is shipped for front-panel operation with
mode switch settings as follows:
B1B2B3B4B5B6
011011
Before beginning, switch the power supply's rear panel MODE switches B1 through B6 to their correct positions for the
programming source being used, (See Table A-2).
Next switch A1 and A2 also on the rear panel, to the correct program source function, See Figure A-2. All connections are
made at the 37-pin rear panel connector J3, and can be wired directly into the mating connector supplied for this purpose.
84
Figure A-2. 002 Option Rear Panel Connector J3 and Switches A1 and A2.
Local/Remote Programming
When switching to local/ control, remember to set Front-Panel Voltage and Current Control to safe levels.
Local Programming (Figure A-3). The supply can be switched back and forth between remote and local programming
while initially checking out a remote programming circuit. For proper operation of local programming, the user must
supply the bias voltage (CONTROL ISOLATOR BIAS). The Control Isolator Bias voltage can range from +4.75V to
+ 16V depending upon the user's interface circuits. Refer to Specifications Table A-1. For local programming, take the
Control Isolator Bias common and connect it to both of the LOC/REM terminals, and position mode switch as indicated in
Operation.
Although CONTROL ISOLATOR BIAS can be + 4. 75V to + 16V, a supply voltage of more than 7V
may damage the relays. Therefore, if CONTROL ISOLATOR BIAS exceeds 7V it is necessary to use a
resistor in series with each of the LOC/REM terminals. Figure A-4 provides a graph from which the
proper series resistance value can be determined. Note that the tolerances of both the Control Isolator
Bias and the resistor must be taken into account. The actual Control Bias used in Figure A-4 is obtained
after subtracting any driver gate voltage drop.
85
Figure A-3. Accessing Local Programming While In Remote Programming Mode
If solid state circuitry is used, connect the Control Isolator Bias to a driver capable of sinking 10mA of current, then
connect the driver's output to both of the LOC/REM terminals. Refer to Figure A-3. Either method will enable relays K1
(CV) and K2 (CC) to switch regulation to the front-panel VOLTAGE and CURRENT controls. For Control Isolator Bias
voltages greater than 7V, a resistor (Ropt) must be used in series with the Control Isolator Bias common or the Driver's
output. Figure A-4 provides a graph for determining the proper series resistance value depending on the Control Isolator
Bias voltage being used.
The supply can be returned to the remote programming mode by switching off the Control Isolator Bias common or by
increasing the Driver's output signal to within 1V of the Control Isolator Bias voltage. If remote programming is solely
desired, leave the LOC/REM terminals open and make the proper connections to the RESISTOR/VOLTAGE PROG. or
CURRENT PROG. terminals (See Figures A-5, A-6, A-7).
Table A-2. Mode Switch Settings For Enabling Different Programming Sources
Switch Pole Settings
Program Source
Mode
B1B2B3B4B5B6
Resistance
Voltage or
Current
001001
010010
86
Figure A-4. Calculating Value of Series Dropping Resistor
Remote Resistance Programming
Check switches A1 and A2 on the rear panel, they must be in their correct positions for CV and CC resistance/voltage
programming (See Figure A-2). A resistance variable from 0 to 4K ohms can be used to program the output voltage or
current from 0 to full scale. To program the output voltage, connect the variable resistance between J3-25 (CV RES/VOLT
PROG.) and J3-22 (E COM.). To program the output current, connect the variable resistance from J3-24 (CC RES/VOLT
PROG.) to J3-22 (E COM.).
If the programming lines become open circuited during resistance programming (user’s system becomes
disconnected from J3), the power supply's output will tend to rise above rating. The supply will not be
damaged if this occurs, but the user's load may be damaged. To protect the load, be sure that the
overvoltage trip point is properly adjusted. The unit includes clamp circuits to prevent it from supplying
more than about 120% of rated output voltage or current when the remote programming voltage is
greater than 5Vdc or remote programming resistance is greater than 4K ohm. Do not intentionally
operate the unit above 100% rated output. Limit your programming voltage to 5Vdc and programming
resistance to 4K ohm to assure reliable operation.
Remote Voltage Programming (Figure A-6). Check switches Al and A2 on the rear panel, they must be in the correct
positions for CV and CC resistance/ voltage programming (See Figure A-2). A voltage source variable from 0 to 5 volts,
can be used to program the output voltage or current from 0 to full scale. The load on the programming source is less than
1mA. To program voltage, the voltage source should be connected from J3-25 (CV RES & VOLT PROG) to J3-22 (E
COM). To program current, the voltage source should be connected from J3-24 (CC RES & VOLT PROG) to J3-22 (E.
COMMON). If the programming lines become open circuited (user's system becomes disconnected from J3) during voltage
programming, the Programming Protection circuit will reduce the power supply output to zero.
87
Figure A-5. Remote Resistance Programming
88
Figure A-6. Voltage Programming of Output Voltage and Current
Current Programming (Figure A-7).
for CV and CC current programming (See Figure A-2). A current sink variable from 0 to 2mA, can be used to program the
output voltage or current from 0 to full scale (See Figure A-7). The following paragraph provides a brief circuit description,
refer to schematic diagram.
Check switches A1 and A2 on the rear panel, they must be in the correct positions
Figure A-7. Current Programming of Output Voltage and Current
To program voltage, the current sink can be connected from J3-21 (CV CURRENT PROG) to J3-20 ( -15V). To program
current, the current sink can be connected from J3-2 (CC CURRENT PROG) to J3-20 ( -15V). Current sinks can either be
connected to the power supply ( -15V) or to an external negative supply that is referenced to the L. COMMON of the power
supply.
The 0 to 2mA current sink will cause the output signal of op-amps U17 and U18 to vary proportionally from 0 to 5 volts.
These signals are then coupled through relays K1 and K2 and then on to the A2 Board's CV and CC circuits which, in-turn,
will program the supply's output from 0 to full scale. If the programming lines become open circuited (user's system
becomes disconnected from J3) during current programming, the Programming Protection circuit will bring the power
supply output to zero.
Remote Monitoring
The 002 Option board provides a protected 0 to 5V output corresponding to a full scale voltage output. The voltage monitor
output is available between pins J3-5 (V. Monitor) and J3-1 (D COMMON).
Observe the caution described in Local Programming paragraph, page 85 (Figure A-3).
89
Output impedance is l0K ohm: the monitoring device input impedance should be at least 1M ohm to limit error to 1% +
basic accuracy; 10M ohm to limit error to 0.1% + basic accuracy.
The I. MON signal from the mainframe is also brought out through the 002 Option board. A 0 to full scale current-monitor
output is available between pins J3-3 (I. MON) and J3-1 (D COMMON). Output impedance is l0K ohms: the monitoring
device input impedance should be at least 1M ohm to limit error to 1% + basic accuracy.
In some applications it may be desirable to install a noise-suppression capacitor on these monitor outputs to lessen the
effects of noise induced in the monitor leads. The capacitors should be ceramic or tantalum type, from 0.1 to 1
capacitor is installed directly across the monitor device input terminals .
µF. The
Status Indicators
Six optically isolated lines provide open collector digital outputs which indicate certain modes and conditions of power
supply operation. For proper supply operation of the opto-isolators, the user must supply the bias voltage, (ISOLATOR
BIAS). This voltage can be from +4.75V to + 16V depending upon the user's interface circuits, refer to the specifications
Table A-1. Connect the bias voltage ( + ) between J3-37, (ISOLATOR BIAS) and J3-34 (ISOLATOR COMMON). The
status indicator outputs are open collector (referenced to ISOLATOR common); therefore, it is necessary to connect a
pull-up resistor from each output to ISOLATOR BIAS. When choosing the resistor value observe the current sink
capabilities of these lines as described in the Specifications Table A-1.
Because of the relatively slow rise and fall times of opto-isolators, Schmitt-triggered devices should be used to interface
these output lines to logic circuits.
The following signals are in active low-form:
a.
MODECV, J3-36, indicates that the power supply is in constant voltage operation.
MODECC, J3-35, indicates that the power supply is in constant current operation.
b.
DUNREGULATEOUTPUT, J3-18, indicates that the power supply is in neither constant voltage nor constant
c.
current operation and cannot be guaranteed to meet specifications.
d.
EOVERVOLTAG , J3-17, indicates power supply shutdown because of: the voltage output exceeding the OV trip
point set at the front-panel; or, a system-initiated shutdown as described in multiple supply system shutdown section,
page 93.
e.
ATUREOVERTEMPER, J3-16, indicates power supply shutdown due to an excessive temperature rise on the FET or
output diode heatsink.
The Low Bias AC DROPOUT signal, J3-19, is in active high form. This signal indicates: loss of primary power,
momentary AC dropout. or "brownout'' conditions where the AC line voltage drops below approximately 70% nominal.
Remote Control
For operation of the opto-isolators, the user must supply the bias voltage (CONTROL ISOLATOR BIAS). This voltage
can be from + 4.75V to + 16V depending on the requirements of the driving circuits. The type of driving logic and bias
voltage will determine the amplitude of the high and low logic levels, refer to the Specification Table A-1 under Remote
Control.
Connect the bias voltage ( + ) to J3-10 CONTROL ISOLATOR BIAS, and reference the input signals to this bias supply's
negative terminal.
Two optically isolated methods of remote control are available. They are described in the following paragraphs.
90
Remote Trip.
reducing the output voltage to near zero. For minimum pulse duration and timing considerations with respect
to
and Figure A-8).
A negative-going edge applied to terminal J3-30 (TRIPREMOTE) will shut down the power supply,
RESETREMOTE, See Table A-1. The following paragraph provides a brief circuit description (See schematic diagram
A negative going edge at
TRIP/RESET latch (U5A) low. This sets terminal J1-13 (
power supply. It also lights the unregulated indicator on the front-panel and generates an unregulated signal from the
opto-isolator U3.
The low signal generated by the Trip/Reset Latch is also coupled through opto-isolator U2 and appears at J3-17 as an
EOVERVOLTAG status signal. This signal does not affect the state of the power supply's OVP circuit.
Remote Reset. A negative-going edge applied to terminal J3-29 (RESETREMOTE) will return the supply to its initial
state following a system-initiated shutdown or an OVP shutdown caused by a temporary over voltage condition. For
minimum pulse duration and timing considerations with respect to
The following paragraphs provide a brief description of this circuit (See schematic diagram and Figure A-8).
A negative-going pulse applied to terminal J3-29 (
U13A then triggers and resets the TRIP/RESET latch output high. This sets terminal J1-13 (
the power supply's Pulse Width Modulator.
The
shut down the supply. When a
CLEAR pulse at terminal J1-12. The
FLIP FLOP. When this occurs the output of A2U24D goes high and simultaneously causes the front-panel OV LED to turn
off and the OV signal (J1-6) to go high. The
power supply .
RESETREMOTE signal will also reset the power supply OVP circuit in the event that an overvoltage condition has
TRIPREMOTEcoupled through opto-isolator (U9) causes one-shot U13B to set the
INHIBIT ) low, thus inhibiting the Pulse Width Modulator of the
TRIPREMOTE See Table A-1 under Remote Control.
RESETREMOTE) is coupled through opto-isolator U10. One-Shot
INHIBIT ) high, thus enabling
RESETREMOTEsignal is present, ONE SHOT U13A goes low, this will produce an OV
CLEAROV pulse will cause the output of A2U2 to go low thus, resetting the OV
EOVERVOLTAG signal to U4B also goes high and enables the PWM of the
NoteBy observing the EOVERVOLTAG status indicator or the power supply's output while applying a reset
pulse to RESETREMOTE, the user can determine the cause of shutdown. If the output returns and
EOVERVOLTAG goes high immediately, this indicates a controller-initiated shutdown. If the output
takes about one second to return, this indicates that the output voltage had exceeded the OVP trip point. If
the OVP circuit trips continually, check the load and/or the trip point setting.
Alternate Method of Remote Control. The INHIBITREMOTE input, J3-31, provides an alternate method of remote
shutdown. By maintaining a low logic level at this input, the supply's output will be inhibited until
returned to its initial high state. The following paragraph provides a brief description of this circuit (See schematic diagram
and Figure A-8).
A low logic level applied to terminal J3-31 (
inhibit the power supply's (PWM) Pulse Width Modulator. If jumper W1 is used (See Figure A-8) while a
INHIBITREMOTE signal is applied, an EOVERVOLTAG signal will appear at terminal J3-17 EOVERVOLTAG thus,
indicating the power supply shut down.
INHIBITREMOTE) is coupled through opto-isolator U8 and causes U4B to
INHIBITREMOTE is
91
Figure A-8. Remote Control
Power-On Preset
This open collector output line J3-6, provides a logic low pulse (Preset-On -Power ) to the user that can be used to
initialize or delay a system's operation until + 5V Reg. supply has stabilized. The pulse is generated after primary power is
turned on and also after resumption of power following momentary ac dropout or conditions in which line voltage drops
below approximately 70% of the nominal. See Table Al for
Preset-On-Power signal specifications.
The
turned on. This protects against unwanted Multiple Supply System Shutdowns when using J3-17 (
remote trip additional power supplies.
The following paragraphs provide a brief description of the power-on preset circuit, refer to schematic diagram:
Circuits on the Power Supply's A2 Control Board produce a power-clear signal, ( PCLR ), when the supply is turned on.
These circuits hold
11Vdc, an input voltage sufficient to assure + 5Vdc bias output.
PCLR signal is coupled through terminal J1-15 to the 002 Option board's power-on preset circuit. When the power-on
This
preset circuit receives the
Turning U14A off causes a
and U14D to turn on. When U14B is on, it holds output J3-17 (
any unwanted Multiple Supply Shutdowns from occurring when the supply is wired for such an application. When U10D is
92
Preset-On-Power circuit also ensures that terminal J3-17 (EOVERVOLTAG ) will be high when the supply is
EOVERVOLTAG ) to
PCLR low until the unregulated input to the A2 Board's + 5Vdc bias supply is greater than about
PCLR signal, transistors U14A and U14C turn off.
DROPOUT signal to appear at terminal J3-19 ( DROPOUT ). Turning U14C off causes U14B
EOVERVOLTAG ) high. Holding J3-17 high will prevent
on, it causes J3-6 (Preset-On-Power) to be low thus, if used, can initialize or delay a customer's system operation.
AC Dropout Buffer Circuit
This circuit couples, inverts and isolates the DROPOUT signal (received from the A2 Control Board) of status output
terminal J3-19 (
conditions where the AC line voltage drops below approximately 70% normal. The following paragraph provides a brief
description of the AC Dropout Buffer circuit. Refer to the Schematic Diagram
DROPOUT ). The dropout signal indicates loss of primary power, momentary AC dropout, or "brownout"
The AC Dropout Buffer Circuit receives a
supplied to the Dropout Buffer U14A to be pulled down through diode CR4 thus, turning U14A off. This in turn will cause
opto-isolator U3 to turn off. Since external pull up resistors are used, terminal J3-19 (DROPOUT) will go high and remain
high until the dropout signal from the A2 Control Board is removed.
DROPOUT signal from the A2 Control Board. This causes the bias voltage
Multiple Supply System Shutdown
When using more than one 002 Option equipped power supply in a system, it may be desirable to implement a system
shutdown. In this configuration, an OVP trip or remote shutdown of a single unit will cause all of the supplies to shut down
Figure A-9. System Shutdown using Controller Power Supply
Figure A-9 shows one method of system shutdown. The advantages of this method are that one common is used for all
status and control lines (useful for controller-operated systems), and the capability of system reset. As shown in Figure A-9,
one supply's EOVERVOLTAG line is connected to the next supply's TRIPREMOTE line, and so on in a continuous
chain.
Note+5V REG/POWER SUPPLY common from Supply 1 can be used instead of the bias voltage from the
controller. However, because of current limits of the + 5V REG, no more than four units can be
connected together in this configuration. To prevent ground loops, do not parallel connect + 5V REG
from more than one supply.
The note on page 91 tells how to determine if a shutdown was initiated through the remote trip line or by a supply's OVP. This
allows the controller to determine which supply initiated the shutdown. Following a multiple supply shutdown, each unit can
be reset individually or all the REMOTE RESET lines can be tied together for a system reset.
93
If it is necessary to have all the supplies come up simultaneously after a system shutdown, follow this procedure:
a. First bring the INHIBITREMOTEline low.
b.
Provide a negative-going pulse to the RESETREMOTE.
c. After at least one second, return INHIBITREMOTEto a high level.
Figure A-10. System Shutdown Using Bias Supply Output
Figure A-10 shows a second method of system shutdown. This method is appropriate in systems which are not
controller-operated and in which more than four supplies must be shutdown simultaneously. Because each supply derives
its CONTROL ISOLATOR BIAS from the previous supply's + 5V REG, there is no limit to the number of supplies that can
be shutdown. Each supply must be reset individually.
Using either method of system shutdown,
down succeeding supplies upon initial sum-on. After the supplies have stabilized,
PCLR inhibits the EOVERVOLTAG indicator from going low and shutting
PCLR returns to a high state.
Bias Supplies
The outputs of three current-limited bias supplies are available for user-supplied circuitry. These are + 15V @ 75mA at
J3-4, -15V @ 75mA at J3-20, and +5 V @ 100mA at J3-23; all with respect to J3-7, L Common.
It may be desirable to install noise-suppression capacitors on the bias supply outputs near the load circuits. The capacitors
should be ceramic or tantalum type, approximately 0.1
µF to 10µF.
Maintenance
The following paragraphs provide procedures and setups to aid in checking and troubleshooting the 002 Option Board. This
information, used in conjunction with the schematic drawing and the Operation section of this Appendix, will help in the
isolation and repair of faulty circuits.
When testing the option, use of the test connector on page 83 will allow easier access to the J3 contacts.
94
Troubleshooting
Before attempting to troubleshoot the 002 Option Board, ensure that the fault is with the option itself and not with the main
power supply. This can be accomplished by removing the top cover, inside cover and disconnecting the two ribbon cables
from the A2 Control board and checking the operation of the main supply. Otherwise troubleshoot the option board as
described in the following paragraphs.
Removal of the Option Board. To facilitate troubleshooting the 002 Option the board can be removed from the power
supply and electrically connected via the ribbon cables from Service Kit's 06033-60005 or 5060-2665. To remove the
circuit board proceed as follows:
Turn off power supply and disconnect line cord.
a.
Disconnect option I/O cable from J3 on rear panel and remove the two screws that secure option board to rear panel.
b.
Disconnect the ribbon cables from the A2 Control board.
c.
Remove option board by lifting the board by the front edge and sliding the board toward the front of the power supply.
d.
Reconnect the option board to the A2 Control board using the extended ribbon cables from the Service Kit, and pace
e.
the option board on an insulated surface next to the power supply.
Be careful that the option board lies securely on insulating material and does not touch any part of the main power
f.
supply.
Isolating Faulty Circuit. It is apparent which function is not operating properly, proceed to the appropriate paragraph. If
the problem involves more than one function check the bias voltages from connectors J1 and J2 and the
option board.
± 11.8V on the
Troubleshooting Resistance and Voltage Programming
a. Confirm that the problem is on the option board by disconnecting the ribbon cables from the A2 Control Board and
attempting to program the supply via the rear panel terminal strip.
b.
Check ± 15V and ± 11.8V supplies.
c. Check for a problem in the programming protection circuit. This circuit should draw about 2µA from the programming
lines.
Check that W3 and W4 are installed and S1 is in proper position .
d.
Troubleshooting Current Programming
a. Check ± 15V and ± 11.8V supplies.
Proceed to test set-up shown in Figure A-11 and/or A-12.
b.
Put S1 in V, R position and see if varying the 0-20V voltage source produces a 0-5 volt DC level across R44 or R39. If
c.
not, check op-amps and associated circuitry.
d. Put S1 in I position and see if varying voltage source from 0 to 20 volts produces a 0-5Vdc level at W3 or W4. If not
check relay and programming protection circuit.
95
Figure A-11. Troubleshooting Current Programming of CV Mode
Figure A-12. Troubleshooting Current Programming of CC Mode
Troubleshooting Status Indicators.
The test set-up shown in Figure A-13 can be used to check each of the six status
indicators. This set-up will temporarily defeat the isolation of the status lines. Before attempting to troubleshoot a status
indicator, check for + 5V Bias for proper operation of the opto-couplers.
96
Figure A-13. Troubleshooting Status Indicators
To check Mode CV proceed as follows:
a.
Using test set-up, Figure A-13, connect to end of 2KΩ resistor to J3-36.
Turn on power supply.
b.
c.
Using "Display Setting'' set voltage and current or power supply for 1 volt and 1 amp.
d.
DVM should read between 0 and 0.4Vdc.
e.
Turn off power supply and short to output terminals.
Turn on power supply.
f.
g.
DVM should read approximately 5Vdc.
To check
a.
Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-35.
Turn on power supply.
b.
c.
Using "Display Settings'' set voltage for 1 volt and current for 1 Amp.
d.
DVM should read = 5Vdc.
Turn off power supply and short the output terminals.
e.
f.
Turn on power supply.
g.
DVM should read between 0 and 0.4Vdc.
To check
a.
Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-17.
Turn "OVP Adjust" fully clockwise and voltage control fully counter clockwise.
b.
c.
Open power supply output terminals and turn on power.
DVM should read approximately 5Vdc.
d.
e.
Press "Display Settings" and increase voltage control for 15Vdc output.
f.
Turn "OVP Adjust'' counterclockwise until supply goes into overvoltage.
g.
DVM should read between 0 and 0.4Vdc.
h.
Turn "OVP Adjust" fully clockwise and turn off input power for 5 seconds.
i.
Turn on input power and DVM should read approximately 5Vdc.
To check
a.
Using test set-up, Figure A-13, connect to end of 2KΩ to J3-18.
Connect output terminals of power supply to an electronic load capable of exceed the power supplies output power
b.
Mode CC proceed as follows:
EOVERVOLTAG proceed as follows:
ED UNREGULATOUTPUT proceed as follows:
rating by 50%.
97
c. Turn on power supply.
d.
DVM should read approximately 5Vdc.
Set voltage and current controls of power supply to maximum.
e.
f.
Decrease resistance of electronic load until "UNREGULATED" LED on front-panel lights.
a.
DVM should now read between 0 and 0.4Vdc.
To check LOW BIAS or AC Dropout proceed as follows:
a.
Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-19.
Substitute an oscilloscope in place of DVM. Set vertical deflection for 1 volt/div on the DC input.
b.
c.
Turn power on and observe oscilloscope trace. Voltage should increase to 5V at power-on and drop to between 0 and
0.4Vac approximately 3 sec.
Turn power off. Voltage should go to about 5Vdc before decaying back to 0V.
d.
NoteIn this test, the Low BIAS or AC Dropout signal decays to 0V only because of loss of power to the + 5V
REG Bias Supply used in the test set-up. If in doubt, use an external + 5V supply for this test.
To check ATUREOVERTEMPER proceed as follows:
a.
Turn off power supply and disconnect line cord.
b.
Wait at least two minutes for input capacitors to discharge .
c.
Remove top cover and inside cover.
d.
Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-16.
Turn on power supply.
e.
f.
DVM should read approximately 5VAC.
g.
Turn off power and wait two minutes.
h.
Remove the A4 FET Assembly from the unit.
Turn on power supply. DVM should read between 0 to 0.4Vdc.
i.
NoteThe FET heatsinks are connected to the primary circuit and hazardous voltage (up to between 300 to
400V) exists between the heatsinks and the heatsink and the chassis. These potentials remain for up to 2
minutes if the power supply is turned off. Do not touch the heatsinks or any components on the heatsink
assemblies while the power supply is turned on or for at least two minutes after primary power is
removed. Do not place any of the heatsink assemblies on extender boards.
Troubleshooting Remote Shutdown. The following procedures check the Remote Shutdown features of 002 Option.
Troubleshooting can be accomplished by using a logic probe and referring to the schematic and the circuit description on
page 93. Before attempting to troubleshoot the Remote Shutdown section of the option, check for + 5Vdc internal bias. This
voltage must be present for proper operation of these circuits
To check the
a.
Connect +5V (J3-23) to Control Isolator bias (J3-l0).
b.
Turn unit on and short TRIP REMOTE (J3-30) to + 5V common (J3-7) momentarily. Output should go into
unregulated condition with output off.
c.
Short REMOTE RESET (J3-29) to + 5V common (J3-7) momentarily and OUTPUT should return to its initial state.
To check
a.
Table A-3. Replacement Connect +5V (J3-23) to control isolator bias (J3-10).
b.
Turn unit on and short INHIBIT REMOTE (J3-31 ) to + 5V common (J3-7). Output should go to an unregulated
output off condition.
c.
Remove short between INHIBIT REMOTE (J3-31 ) and + 5V common (J3-7) and output should return to its initial
CR1-4All1901-0050switching 80V 200ma
CR5-10All1901-0327pwr. rect. 300V 40A
CR11-14All1901-0033gen. prp. 180V 200ma
CR15All1901-0327zener 9.09V 10% PD=1.5W
CR16,17AllNOT USED
CR18,19All1901-0050switching 80V 200ma
CR20All1901-0033gen. prp. 180V 200ma
CR21,22All1901-0050switching 80V 200ma
CR23All1901-0033gen. prp. 180V 200ma
CR24,25All1901-0050switching 80V 200ma
CR26-29All1901-0033gen. prp. 180V 200ma
CR30All1901-0327zener 9.09V 10% PD=1.5W
K1,2All0490-1418relay 250ma 28V,5V –coil 3VA
L1-3All9170-1223core shielding bead
Q1,2All1854-0823NPN SI PD=300mW FT=200MHZ
R1-3All0683-2015fxd. film 200 5% 1/4W
R4All0683-3925fxd. film 3.9K 5% 1/4W
R5All0683-2035fxd. film 20K 5% 1/4W
R6All0683-3035fxd. film 30K 5% 1/4W
R7All0683-6225fxd. film 6.2K 5% 1/4W
R8,9All0683-2035fxd. film 20K 5% 1/4W
R10All0683-1035fxd. film 10K 5% 1/4W
R11All0683-5125fxd. film 5.1K 5% 1/4W
R12All0757-0984fxd. film 10 1% 1/2W
R13All0683-1615fxd. film 160 5% 1/4W
R14All0683-4715fxd. film 410 5% 1/4W
R15,16All0683-1235fxd. film 12K 5% 1/4W
R17All0686-1525fxd. film 1.5K 5% 1/4W
R18All0683-1535fxd. film 15K 5% 1/4W
R19All0683-4715fxd. film 470 5% 1/4W
R20,21All0683-1235fxd. film 12K 5% 1/4W
99
Table A-3. Replacement Parts
REF. DESIG.MODEL NO.PART NO.DESCRIPTION
R22All0686-1525fxd. film 1.5K 5% 1/4W
R23All0683-1535fxd. film 15K 5% 1/4W
R24All0683-4715fxd. film 470 5% 1/4W
R25,26All0683-1235fxd. film 12K 5% 1/4W
R27All0686-1525fxd. film 1.5K 5% 1/4W
R28All0683-1535fxd. film 15K 5% 1/4W
R29,30All0698-4479fxd. film 14K 1% 1/8W
R31All0686-5125fxd. comp. 5.lK 5% 1/2W
R32All0683-5125fxd. film 5.1K 5% 1/4W
R33All0686-5125fxd. comp. 5.1K 5% 1/4W
R34All0683-5125fxd. film 5.1K 5% 1/4W
R35All0757-0986fxd. film 12.1K 1% 1/2W
R36All0757-0269fxd. film 270 1% 1/8W
R37All0683-4715fxd. film 470 5% 1/4W
R38All0683-1035fxd. film 10K 5% 1/4W
R39All0698-6631fxd. film 2.5K .1% 1/8W
R40All0683-4715fxd. film 470 5% 1/4W
R41All0813-0001fxd. ww. 1K 5% 3W
R42All0683-4715fxd. film 470 5% 1/4W
R43All0683-l035fxd. film 10K 5% 1/4W
R44All0698-6631fxd. film 2.5K .1% 1/8W
R45All0683-4715fxd. film 470 5% 1/4W
R46All0813-0001fxd. ww. 1K 5% 3W
R47All0683-1525fxd. film 1.5K 5% 1/4W
R48All0683-3325fxd. film 3.3K 5% 1/4W
R49All0683-2225fxd. film 2.2K 5% 1/4W
R50,51All0683-3355fxd. film 3.3M 5% 1/4W
R52,53All0683-1055fxd. film 1M 5% 1/4W
R54All0757-0441fxd. film 8.25K 1% 1/8W
R55All0757-0986fxd. film 12.lK 1% 1/2W
R56All0757-0269fxd. film 270 1% 1/8W
R57All0698-3226fxd film 6.49K 1% 1/8W
S1All3101-2715Switch-Slide 2-lA .1A 50V
U1-3All1990-0732Opto-Isolator IF=20mA max.
U4All1820-1197IC NAND gate TTL LS quad
U5All1820-1202IC NAND gate TTL LS
U66023A1826-0393IC Voltage Reg.
U66028A5060-2942IC Voltage Reg. heatsink assy.
U76023A1826-0551IC Voltage Reg.
U76028A5060-2945IC Voltage Reg. heat sink assy.
U8-10All1990-0494Opto-Isolator IF=20mA max.
U11All1820-1491IC Buffer TTL LS, hex
U12All1820-1416IC Schmitt-Trig. TTL LS, hex
U13All1820-l437IC Multi. Vib. TTL LS
U14All1858-0023Trans. Array 16-pin
U156023A1826-0527IC Voltage Reg.
U156028A5060-2943IC Voltage Reg. heatsink assy.
U166023A1826-0277IC Voltage Reg.
U166028A5060-2950IC Voltage Reg. heatsink assy.
U17,18All1826-0493IC Op Amp Low-bias-High-Impd.
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