SERVICE MANUAL
AC Power Source/Analyzers
Agilent Models 6811A, 6812A, and 6813A
6811B, 6812B, and 6813B
Harmonic/Flicker Test Systems
Agilent Models 6841A and 6842A
For instruments with Serial Numbers:
AGILENT 6811A: US37290101 and up
AGILENT 6811B: US38390481 and up
AGILENT 6812A: US37290101 and up
AGILENT 6812B: US38390451 and up
AGILENT 6813A: US37290101 and up
AGILENT 6813B: US38390285 and up
AGILENT 6841A: US37340101 and up
AGILENT 6842A: US37340101 and up
For instruments with higher serial numbers, a change page may be included.
Agilent Part No. 5962-0859 Printed in U.S.A.
Microfiche No. 6962-0860 September, 2000
Warranty Information
CERTIFICATION
Agilent Technologies certifies that this product met its published specifications at time of shipment from the factory.
Agilent Technologies further certifies that its calibration measurements are traceable to the United States National
Bureau of Standards, to the extent allowed by the Bureau's calibration facility, and to the calibration facilities of other
International Standards Organization members.
WARRANTY
This Agilent Technologies hardware product is warranted against defects in material and workmanship for a period
of three years from date of delivery. Agilent Technologies software and firmware products, which are designated by
Agilent Technologies for use with a hardware product and when properly installed on that hardware product, are
warranted not to fail to execute their programming instructions due to defects in material and workmanship for a
period of 90 days from date of delivery. During the warranty period Agilent Technologies will, at its option, either
repair or replace products which prove to be defective. Agilent Technologies does not warrant that the operation for
the software firmware, or hardware shall be uninterrupted or error free.
For warranty service, with the exception of warranty options, this product must be returned to a service facility
designated by Agilent Technologies. Customer shall prepay shipping charges by (and shall pay all duty and taxes)
for products returned to Agilent Technologies. for warranty service. Except for products returned to Customer from
another country, Agilent Technologies shall pay for return of products to Customer.
Warranty services outside the country of initial purchase are included in Agilent Technologies’ product price, only if
Customer pays Agilent Technologies international prices (defined as destination local currency price, or U.S. or
Geneva Export price).
If Agilent Technologies is unable, within a reasonable time to repair or replace any product to condition as warranted,
the Customer shall be entitled to a refund of the purchase price upon return of the product to Agilent Technologies.
LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the
Customer, Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the
environmental specifications for the product, or improper site preparation and maintenance. NO OTHER
WARRANTY IS EXPRESSED OR IMPLIED. AGILENT TECHNOLOGIES. SPECIFICALLY DISCLAIMS THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER'S SOLE AND EXCLUSIVE REMEDIES. AGILENT
TECHNOLOGIES SHALL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES, WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.
ASSISTANCE
The above statements apply only to the standard product warranty. Warranty options, extended support contacts,
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
GENERAL -
This is a Safety Class 1 instrument (provided with a terminal for connection to protective earth ground).
OPERATION - BEFORE APPLYING POWER:
Verify that the product is set to match the available line voltage, the correct line fuse is installed, and all safety
precautions (see following warnings) are taken. In addition, note the instrument's external markings described under
"Safety Symbols"
WARNING -
a Servicing instructions are for use by service-trained personnel. To avoid dangerous electrical shock, do not
perform any servicing unless you are qualified to do so.
a Before switching on the instrument, the protective earth terminal of the instrument must be connected to the
protective conductor of the (mains) power cord. The mains plug shall be inserted only in an outlet socket that is
provided with a protective earth contact. This protective action must not be negated by the use of an extension
cord (power cable) that is without a protective conductor (grounding). Grounding one conductor of a twoconductor outlet is not sufficient protection.
a If this instrument is to be energized via an auto-transformer (for voltage change), make sure the common
terminal is connected to the earth terminal of the power source.
a 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.
a Whenever it is likely that the protective earth connection has been impaired, this instrument must be made
inoperative and be secured against any unintended operation.
a Only fuses with the required rated current, voltage, and specified type (normal blow, time delay, etc.) should be
used. Do not use repaired fuses or short-circuited fuseholders. To do so could cause a shock or fire hazard.
a Do not operate this instrument in the presence of flammable gases or fumes.
a Do not install substitute parts or perform any unauthorized modification to the instrument.
a Some procedures described in this manual are performed with power supplied to the instrument while its
protective covers are removed. If contacted, the energy available at many points may result in personal injury.
a Any adjustment, maintenance, and repair of this instrument while it is opened and under voltage should be
avoided as much as possible. When this is unavoidable, such adjustment, maintenance, and repair should be
carried out only by a skilled person who is aware of the hazard involved.
a Capacitors inside this instrument may hold a hazardous charge even if the instrument has been disconnected
from its power source.
SAFETY SYMBOLS
Refer to the table on the following page
WARNING The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which,
Caution The CAUTION sign denotes a hazard. It calls attention to an operating procedure, or the like,
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.
which, if not correctly performed or adhered to, could result in damage to or destruction of part or
all of the product. Do not proceed beyond a CAUTION sign until the indicated conditions are fully
understood and met.
3
Safety Symbol Definitions
Symbol Description Symbol Description
Direct current Terminal for Line conductor on
permanently installed equipment
Alternating current Caution, risk of electric shock
Both direct and alternating current Caution, hot surface
Three-phase alternating current Caution (refer to accompanying
documents)
Earth (ground) terminal In position of a bi-stable push control
Protective earth (ground) terminal
Out position of a bi-stable push control
(Intended for connection to external
protective conductor.)
Frame or chassis terminal On (supply)
Terminal for Neutral conductor on
Off (supply)
permanently installed equipment
Terminal is at earth potential
(Used for measurement and control
circuits designed to be operated
with one terminal at earth
potential.)
Standby (supply)
Units with this symbol are not completely
disconnected from ac mains when this switch is
off. To completely disconnect the unit from ac
mains, either disconnect the power cord or have
a qualified electrician install an external switch.
Notice
Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential
damages in connection with the furnishing, performance or use of this material.
This document contains proprietary information which is protected by copyright. All rights are reserved. No part of
this document may be photocopied, reproduced, or translated into another language without the prior written consent
of Agilent Technologies. The information contained in this document is subject to change without notice.
ã Copyright 1995, 1997, 2000 Agilent Technologies, Inc.
Printing History
First Edition ............October, 1995
Second Edition ...... ... July, 1997
Third Edition ......... September, 2000
4
Table of Contents
Warranty Information 2
Safety Summary 3
Notice 4
Printing History 4
Table of Contents 5
1 INTRODUCTION 7
Organization 7
Safety Considerations 7
Related Documents 7
Revisions 8
Instrument Identification 8
Manual Revisions 8
Firmware Revisions 8
Electrostatic Discharge 8
2 PERFORMANCE TESTS 9
Introduction 9
Test Equipment Required 9
Current Monitoring Resistor 10
Constant Voltage Tests 10
Procedures 11
3 PRINCIPLES OF OPERATION 17
Introduction 17
General Description 17
A1 Front Panel Assembly 17
A2 GPIB / RS-232 Interface Assembly 18
A3 FET Assembly 18
A4 AC Input Assembly 18
A5 DC Rail Asembly 18
A6 Bias Assembly 19
A7 Inverter Assembly 19
A8 Digital Signal Processing (DSP) Assembly 19
A9 Output / Filter Assembly 19
A10 Control Assembly 20
A11 Trigger ( BNC ) Assembly 20
5
4 TROUBLESHOOTING 21
Introduction 21
Test Equipment Required 21
Troubleshooting Hints 21
Power-on Self-test Failures 22
Run-Time Errors 22
Overall Troubleshooting Flowchart 24
A1 Front Panel Assembly Troubleshooting 26
A2 GPIB/RS-232 Board Troubleshooting 26
A3 FET Board Troubleshooting 27
A5 DC Rail Assembly Troubleshooting 29
A6 Bias Assembly Troubleshooting 31
A7 Inverter Assembly Troubleshooting 33
Slow-Start Procedure 39
A8 DSP and A10 Control Assembly Troubleshooting 38
A9 Output/Filter/Relay Assembly Troubleshooting 41
A11 Trigger/BNC Board Troubleshooting 42
Initialization 44
ROM Upgrade 44
Identifying the Firmware 44
Upgrade Procedure 44
Post-repair Calibration 45
Inhibit Calibration Switch 45
Disassembly Procedures 46
List of Required Tools 47
Top Cover ( outer cover ) Removal 47
Inner Top Cover Removal 47
A1 Front Frame / Panel Assembly Removal and Replacement 47
A2 HI-IB / RS 232 Board Removal and Replacement 48
A3 AC FET Assembly Removal and Replacement 48
A4 AC Input Board Removal and Replacement 48
A5 DC Rail Board Removal and Replacement 48
A6 Bias Board Removal and Replacement 49
A7 Inverter Assembly Removal and Replacement 49
A8 DSP Board and A10 Control Board Removal and Replacement 49
A11 Trigger ( BNC ) Board Removal and Replacement 50
A9 Output Board Removal and Replacement 50
5 REPLACEABLE PARTS LIST 51
Introduction 51
Reading the Tables 51
How to Order Parts 51
6 DIAGRAMS 63
Introduction 63
General Schematic Notes 63
List of Figures 64
INDEX 115
6
1
Introduction
Organization
This manual contains information for troubleshooting and repairing to the component level models Agilent 6811A/B,
6812A/B, and 6813A/B Power Source/Analyzers, and models Agilent 6841A and 6842A Harmonic Flicker Test
Systems. All models will hereafter be referred to as the ac source. This manual is organized as follows:
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Introduction
Performance tests
Principles of operation on a block-diagram level
Troubleshooting
Replaceable parts
Diagrams
Safety Considerations
This ac power source is a Safety Class I instrument, which means it has a protective earth terminal. This terminal
must be connected to earth ground through a power source equipped with a 4-wire (3-wire for Agilent 6811A/B),
ground receptacle. Refer to the "Safety Summary" page at the beginning of this manual for general safety
information. Before operation or repair, check the ac source and review this manual for safety warnings and
instructions. Safety warnings for specific procedures are located at appropriate places in the manual.
WARNING: Hazardous voltages exist within the ac power source chassis, at the output terminals, and at
the analog programming terminals. Only qualified personnel who have been trained in
working with high voltage power equipment are to service this unit.
Related Documents
The following documents are shipped with your ac source:
a a Quick-Start Guide, to help you quickly get started using the ac source
a a User's Guide, containing detailed installation, checkout, and front panel information
a a Programming Guide, containing detailed GPIB programming information
a a Quick Reference Card, designed as a memory jogger for the experienced user
7
1 - Introduction
Revisions
Instrument Identification
The ac source is identified by a 10-digit serial number. The items in this serial number are explained as follows:
US
3729
0101
The first two letters indicates the country of manufacture, where US = USA.
This is a code that identifies either the date of manufacture, or the date of a significant design change.
The last four digits are a unique number assigned to each unit.
Manual Revisions
This manual was written for ac sources that have the same or higher serial numbers as those listed on the title page.
NOTE: If the serial number of your unit is higher than that shown on the title page, your unit was made
after the publication of this manual and may have hardware or firmware differences not covered in
this manual. If they are significant to the operation and/or servicing of the ac source, those
differences are documented in one or more Manual Change sheets included with this manual.
If the serial number of your unit is lower than those shown on the title page, your unit was made
before the publication of this manual and can be different from that described here. The previous
versions of this manual (print date October, 1995 or July, 1997) applies to these units.
Firmware Revisions
You can obtain the firmware revision number by either reading the integrated circuit label, or query the ac source
using the GPIB *IDN?' query command (see Chapter 4, Troubleshooting).
Electrostatic Discharge
CAUTION: The ac source has components that can be damaged by ESD (electrostatic discharge). Failure to
observe standard antistatic practices can result in serious degradation of performance, even when
an actual failure does not occur.
When working on the ac source, observe all standard, antistatic work practices. These include, but are not limited to:
a Working at a static-free station such as a table covered with static-dissipative laminate or with a conductive
table mat (Agilent P/N 9300-0797, or equivalent).
a Using a conductive wrist strap, such as Agilent P/N 9300-0969 or 9300-0970.
a Grounding all metal equipment at the station to a single common ground.
a Connecting low-impedance test equipment to static-sensitive components only when those components have
power applied to them.
a Removing power from the ac source before removing or installing printed circuit boards.
8
2
Performance Tests
Introduction
This chapter provides test procedures for checking the operation of a model Agilent 6811AB, 6812A/B, 6813A/B
AC Power Source/Analyzer and Agilent 6841A, 6842A Harmonic/Flicker Test System. The required test equipment
is specified and sample performance test record sheets are included. Instructions are given for performing the tests
using the front panel keypad.
Test Equipment Required
Table 2-1 lists the equipment required to perform the performance tests in this chapter. A test record sheet with
specification limits and measurement uncertainties (when test using the recommended test equipment) may be found
at the back of this section.
WARNING: SHOCK HAZARD. These tests should only be performed by qualified personnel. During the
performance of these tests, hazardous voltages may be present at the output of the unit.
Table 2-1. Test Equipment Required for Verification and Performance Tests
Type Specifications Recommended Model
Digital Voltmeter Resolution: 10 nV @ 1V
Readout: 8 1/2 digits
Accuracy: 20 ppm
Current Monitor 0.01 ohms +/-200 ppm 10 Watts Guildline 7320/15
Audio Analyzer
Frequency Counter Accuracy @1 KHZ < 0.001% Agilent 5316B
Ratio Transformer130:1 ratio < 50 ppm
Variable-Voltage
Transformer
Load Resistors 20 ohms, 5 A, 1000 W minimum
GPIB Controller Full GPIB capabilities HP Series 300 or equivalent
1
A ratio transformer is not required for a valid MIL-STD-5622A 4:1 test. The 30:1 ratio transformer is only required
when a 4:1 test equipment ratio is desired using the Agilent 3458A voltmeter in the 1000 volt range.
Input Voltage: 50mV TO 300V
Distortion Accuracy: +/-1db 20Hz to 20khz
Residual Distortion/Noise: -80db (0.01%) 20Hz to 20kHz
Power: 1 Phase 3.4KVA
Range: 104-127V 47-63 Hz / 207-253V 47-63 Hz
250 ohms, 2 A, 500 W minimum
120 ohms, 2.5 A, 750 W minimum
51 ohms, 6 A, 1800 W minimum
Agilent 3458A
Agilent 8903A
Superior Powerstat
9
2 - Performance Tests
Current Monitoring Resistor
A 4-terminal current monitoring resistor (current shunt ) listed in Table 2-1 is required to eliminate output current
measurement error caused by voltage drops in the load leads and connections.
Constant Voltage Tests
If more than one meter or a meter and an oscilloscope are used, connect each to the sense terminals by separate leads
to avoid mutual coupling effects.
Tables 2-2 through 2-8 provide the test procedures for verifying the 6811A/B, 6812A/B, 6813A/B, and the 6841A,
6842A compliance with the specifications given in Appendix A of the User’s Guide. Please refer to the
CALIBRATION PROCEDURE or TROUBLESHOOTING if you observe out-of specification performance. The
performance test specifications are listed in the Performance Test Records at the end of this chapter. You can record
the actual measured values in the columns provided. When performing the load tests select an adequate gauge wire
using the procedures given in the User’s Guide for connecting the load.
10
Figure 2-1. Test Setup
Performance Tests - 2
Procedures
In the following procedures the term "UUT" means "unit under test" which can be either the 6811A/B, 6812A/B,
6813A/B, 6841A, or 6842A AC Source.
Table 2-2. Voltage Programming and Readback Accuracy
Step Action Normal Result
This procedure verifies that the voltage programming / GPIB readback and Front Panel display functions
are within specifications.
Turn off the UUT and connect DVM and Ratio
1
Transformer as shown in Test Setup Figure 2-1.
Switch S1is open.
Turn on the UUT. Recall factory defaults with *RST then
2
program output to
VOLT 300, FREQ 45, SHAPE:SIN
Record voltage readings at DMM and on front panel
3
display.
4 Program FREQ 400
Record voltage readings at DMM and on front panel
5
display.
6 Program FREQ 1000, CURR:PEAK 40
Record voltage readings at DMM and on front panel
7
display.
Table 2-3. Constant Voltage Load Effect
Step Action Normal Result
This test measures the change in output voltage resulting from a change in output current from full-load to
no-load or no-load to full-load.
Turn off the UUT and connect DMM, Load Resistors,
1
Current shunt and Ratio Transformer as shown in Test
Setup Figure 2-1 with S1 closed.
CV annunciator on
Output current near zero
Reading within specified high range
300V / 45Hz limits
Reading within specified high range
300V / 400Hz limits
Reading within specified high range
300V / 1KHz limits
Turn on the UUT. Recall factory defaults with *RST. Set
2
ALC:DET RMS to rms then program output to VOLT
300, FREQ 60, SHAPE:SIN
3 Record voltage reading of DMM.
Open S1
4
Record voltage readings at DMM.
5
Check test results
6
CV annunciator on, output current near:
1.2 amps for 6811A/B
2.5 amps for 6812A/B
5.8 amps for 6813A/B
Output current near zero.
The difference between the DMM
readings in Step 3 & 5 are within
specified load effect limits.
11
2 - Performance Tests
Table 2-4. Constant Voltage Source Effect
Step Action Normal Result
This test measures the change in output voltage resulting from a change in AC Mains Input voltage from
minimum to maximum value within the line voltage specification.
Turn off the UUT and connect DMM, Load Resistors,
1
Current shunt and Ratio Transformer as shown in Test
Setup Figure 2-1 with S1 closed.
Connect UUT AC input through a variable voltage
2
transformer
Turn on the UUT. Recall factory defaults with *RST. Set
3
ALC:DET RMS to rms then program output to
VOLT 300, FREQ 60, SHAPE:SIN,
4
Adjust variable voltage transformer to low line condition
( 104 or 207 VAC )
Record voltage reading of DMM.
5
Adjust variable voltage transformer to high line condition
6
( 127 or 253 VAC )
Record voltage readings at DMM.
7
Check test results
8
Table 2-5. RMS Current Accuracy Test
Step Action Normal Result
This test verifies the measurement accuracy of the rms current readback.
1 Turn off the UUT and connect an 20 ohm Load Resistor,
current shunt and DMM as shown in Test Setup Figure 2-1
with S1 closed.
CV annunciator on, output current near:
1.2 amps for 6811A/B
2.5 amps for 6812A/B, 6841A
5.9 amps for 6813A/B, 6842A
The difference between the DMM
readings in Step 3 & 5 are within
specified line effect limits.
2 Turn on the UUT. Recall factory defaults with *RST. Set
ALC:DET RMS to rms and then program output voltage to
VOLT 60, FREQ 60 SHAPE:SIN, CURR 2.50 for 6811A/B;
VOLT 120, FREQ 60 SHAPE:SIN, CURR 5.00 for the
6812A/B, 6813A/B, 6841A, 6842A
3 Record DVM reading and calculate rms current Readings are within specified
4 Program CURR:RANGE LOW CC annunciator on, outp ut current
5 Record DVM reading and calculate rms current Readings are within specified
CC annunciator on, outp ut current
near 2.5 amps for 6811A/B - near 5
amps for the 6812A/B, 6813A/B,
6841A, 6842A
current high range limits.
near 2.5 or 5.0 amps
current low range limits.
12
Performance Tests - 2
Table 2-6. Harmonic Distortion Test
Step Action Normal Result
This test measures the total harmonic distortion of the output sinewave at full power
1 Turn off the UUT. Connect load resistor and DMM as
shown in Test Setup Figure 2-1 with S1 closed.
2 Turn on the UUT. Program output volta ge to
VOLT 300, FREQ 60, SHAPE:SIN, CURR MAX
3 Record the total harmonic distortion reading from the audio
analyzer and front panel display of UUT.
Table 2-7. Frequency Accuracy Test
Step Action Normal Result
This test verifies the frequency programming and measurement accuracy of the output voltage waveform.
1 Turn off the UUT. Connect the audio analyzer directly to the
UUT output terminals. Connect the frequency counter to the
Monitor Output on the rear panel of the audio analyzer.
2 Turn on the UUT. Program output volta ge to
VOLT 100, FREQ 400, SHAPE:SIN, CURR MAX
3 Select AC Level on the audio analyzer. Record the output
frequency reading from counter and front panel display of
UUT.
Table 2-8. DC Voltage Programming and Readback Accuracy
CV annunciator on, Outp ut current
at 1.2 amps for 6811A/B
2.5 amps for 6812A/B, 6841A
5.8 amps for 6813A/B, 6842A
Readings are less then maximum
specified limits.
CV annunciator on.
Readings are within specified limits
@ 400Hz.
Step Action Normal Result
This test verifies the DC voltage programming and front panel readback functions are within specifications.
1 Turn off the UUT. Connect DVM directly to the output
terminals. DVM negative lead is connected to COM output
terminal. Disconnect the 30:1 transformer. Open S1.
2 Turn on UUT. P rogram output voltage to VOLT 0,
OUTP:COUP DC, OFFSET 425
3 Record dc voltage at DVM and readback from front panel
display.
4 Program output voltage OFFSET -425 Output voltage at -425 Vdc,
5 Record dc voltage at DVM and readback from front panel
display.
Output voltage at +425 Vdc,
output current near zero.
Readings within specified dc
voltage programming and readback
limits.
output current near zero.
Readings within specified DC
voltage programming and readback
limits.
13
2 - Performance Tests
Table 2-9. Performance Test Record - Agilent 6811A/B
Model Report No: Date:
Test Description Minimum
Specification
Voltage Programming & Readback Accuracy
300Vrms @ 45Hz
Front Panel Display
300Vrms @ 400Hz
Front Panel Display
300Vrms @ 1KHz
Front Panel Display
CV Load Effect
CV Line Effect
299.250
Vrms -190mV
298.200
Vrms -400mV
296.700
Vrms -700mV
Vout - 1.5V
Vout - 0.3V
rms Current Readback
Front Panel Display High Range (A models)
Front Panel Display Low Range (A models)
Io-0.0175A
Io-0.0045A
Results Maximum
Specification
________ V
________ V
________ V
________ V
________ V
________ V
________ V
________ V
_______A
_______A
300.750
Vrms +190mV
301.800
Vrms +400mV
303.300
Vrms +700mV
Vout + 1.5V
Vout + 0.3V
Io+0.0175A
Io+0.0045A
Meas.
Uncert.
140mV
(1.2mV)
140mV
(1.2mV)
140mV
(1.2mV)
1mA
1mA
Front Panel Display High Range (B models)
Front Panel Display Low Range (B models)
Io-0.01125A
Io-0.00275A
_______A
_______A
Io+0.01125A
Io+0.00275A
Total Harmonic Distortion
Audio Analyzer
Front Panel Display
0
0
________ %
________ %
1%
1%
Frequency Programming & Readback Accuracy
Program 400 Hz
Front Panel Display
399.960 Hz
Fo - 0.040 Hz
_______ Hz
_______ Hz
400.040 Hz
Fo + 0.040 Hz
DC Voltage Programming & Readback Accuracy
+425 VDC Output
Front Panel Display
-425 VDC Output
Front panel Display
Note: 1. Measurement uncertainties are only valid when using test equipment listed in Table 2-1.
2. Voltage Programming and Readback measurement uncertainties are for a 3458A DMM in the 1000 volt range.
3. Measurement uncertainties in parenthesis are only if a 30:1 ratio transformer is used with the 3458A DMM.
424.075 Vdc
Vo-0.363 Vdc
-424.075 Vdc
Vo-0.363 Vdc
________Vdc
________Vdc
________Vdc
________Vdc
425.925 Vdc
Vo+0.363Vdc
425.925 Vdc
Vo+0.363 Vdc
1mA
1mA
0.005Hz
4.4mV
4.4mV
14
Table 2-10. Performance Test Record - Agilent 6812A/B, 6841A
Model Report No: Date:
Performance Tests - 2
Test Description Minimum
Specification
Voltage Programming & Readback Accuracy
300Vrms @ 45Hz
Front Panel Display
300Vrms @ 400Hz
Front Panel Display
300Vrms @ 1KHz
Front Panel Display
CV Load Effect
CV Line Effect
299.250
Vrms -190mV
298.200
Vrms -400mV
296.700
Vrms -700mV
Vout - 1.5V
Vout - 0.3V
rms Current Readback
Front Panel Display High Range (A models)
Front Panel Display Low Range (A models)
Io-0.0175A
Io-0.0045A
Results Maximum
Specification
________ V
________ V
________ V
________ V
________ V
________ V
________ V
________ V
_______A
_______A
300.750
Vrms +190mV
301.800
Vrms +400mV
303.300
Vrms +700mV
Vout + 1.5V
Vout + 0.3V
Io+0.0175A
Io+0.0045A
Meas.
Uncert.
140mV
(1.2mV)
140mV
(1.2mV)
140mV
(1.2mV)
1mA
1mA
Front Panel Display High Range (B models)
Front Panel Display Low Range (B models)
Io-0.0125A
Io-0.0040A
_______A
_______A
Io+0.0125A
Io+0.0040A
Total Harmonic Distortion
Audio Analyzer
Front Panel Display
0
0
________ %
________ %
1%
1%
Frequency Programming & Readback Accuracy
Program 400 Hz
Front Panel Display
399.960 Hz
Fo - 0.040 Hz
_______ Hz
_______ Hz
400.040 Hz
Fo + 0.040 Hz
DC Voltage Programming & Readback Accuracy
+425 VDC Output
Front Panel Display
-425 VDC Output
Front panel Display
Note: 1. Measurement uncertainties are only valid when using test equipment listed in Table 2-1.
2. Voltage Programming and Readback measurement uncertainties are for a 3458A DMM in the 1000 volt range.
3. Measurement uncertainties in parenthesis are only if a 30:1 ratio transformer is used with the 3458A DMM.
424.075 Vdc
Vo-0.363 Vdc
-424.075 Vdc
Vo-0.363 Vdc
________Vdc
________Vdc
________Vdc
________Vdc
425.925 Vdc
Vo+0.363Vdc
425.925 Vdc
Vo+0.363 Vdc
1mA
1mA
0.005Hz
4.4mV
4.4mV
15
2 - Performance Tests
Table 2-11. Performance Test Record - Agilent 6813A/B, 6842A
Model Report No: Date:
Test Description Minimum
Specification
Voltage Programming & Readback Accuracy
300Vrms @ 45Hz
Front Panel Display
300Vrms @ 400Hz
Front Panel Display
300Vrms @ 1KHz
Front Panel Display
CV Load Effect
CV Line Effect
299.250
Vrms -190mV
298.200
Vrms -400mV
296.700
Vrms -700mV
Vout - 1.5V
Vout - 0.3V
rms Current Readback
Front Panel Display High Range (A models)
Front Panel Display Low Range (A models)
Io-0.0175A
Io-0.0045A
Results Maximum
Specification
________ V
________ V
________ V
________ V
________ V
________ V
________ V
________ V
_______A
_______A
300.750
Vrms +190mV
301.800
Vrms +400mV
303.300
Vrms +700mV
Vout + 1.5V
Vout + 0.3V
Io+0.0175A
Io+0.0045A
Meas.
Uncert.
140mV
(1.2mV)
140mV
(1.2mV)
140mV
(1.2mV)
1mA
1mA
Front Panel Display High Range (B models)
Front Panel Display Low Range (B models)
Io-0.0125A
Io-0.0040A
_______A
_______A
Io+0.0125A
Io+0.0040A
Total Harmonic Distortion
Audio Analyzer
Front Panel Display
0
0
________ %
________ %
1%
1%
Frequency Programming & Readback Accuracy
Program 400 Hz
Front Panel Display
399.960 Hz
Fo - 0.040 Hz
_______ Hz
_______ Hz
400.040 Hz
Fo + 0.040 Hz
DC Voltage Programming & Readback Accuracy
+425 VDC Output
Front Panel Display
-425 VDC Output
Front panel Display
Note: 1. Measurement uncertainties are only valid when using test equipment listed in Table 2-1.
2. Voltage Programming and Readback measurement uncertainties are for a 3458A DMM in the 1000 volt range.
3. Measurement uncertainties in parenthesis are only if a 30:1 ratio transformer is used with the 3458A DMM.
422.575 Vdc
Vo-0.363 Vdc
-422.575 Vdc
Vo-0.363 Vdc
________Vdc
________Vdc
________Vdc
________Vdc
427.425 Vdc
Vo+0.363Vdc
427.425 Vdc
Vo+0.363 Vdc
1mA
1mA
0.005Hz
4.4mV
4.4mV
16
Principles of Operation
Introduction
Figure 3-1 at the end of this chapter is a block diagram showing the major circuits within the AC Power Source
/Analyzer and Harmonic / Flicker Test System. These units consist of the following modules.
a A1 Front Panel Assembly
a A2 GPIB Assembly
a A3 AC FET Assembly
a A4 AC Input Assembly
a A5 DC Rail Assembly
a A6 Bias Assembly
a A7 Inverter Assembly
a A8 DSP Assembly
a A9 Output Filter Assembly
a A10 Control Assembly
3
a A11 Trigger Assembly
General Description
The 6811A/B, 6812A/B, and 6813A/B are 375VA, 750VA and 1750VA AC Source/Analyzers whereas the 6841A
and 6842A are 750VA and 1750VA power sources are used as Harmonic / Flicker Test Systems. The 6811A/B,
6812A/B and 6841A can operate from 120, 220 or 240 volt AC input main while the 6813A/B and 6842A only
operate from 220/240 volt AC input mains. All deliver regulated AC voltage and/or current from 45 to 1000 hertz.
They can operate below 45 hertz to DC at derated output power. (See Users Guide for operation below 45 hertz ).
They can generate sine, square, clipped sine or arbitrary waveforms. The output waveform can be controlled from
the front panel keypad or computer via GPIB or RS-232. The output characteristics or measurements ( voltage,
current, frequency, power factor, etc. ) can be readback via the front panel, GPIB or RS-232.
A1 Front Panel Assembly
The A1 Intelligent Front Panel assembly contains a circuit board, a vacuum florescent display assembly, keypad and
rotary pulse generators ( RPG ). The circuit board contains digital logic circuits including a CPU, ROM and RAM.
The front panel CPU decodes operator keystrokes and transmits the information to the A8 DSP assembly. The front
panel receives information from the A8 DSP assembly to update the display. The front panel assembly is a surface
mount ( SMT ) assembly and is not component level repairable. The A1 front panel assembly is common to all
models.
17
3 - Principles of Operation
A2 GPIB / RS-232 Interface Assembly
The A2 GPIB / RS-232 interface assembly contains the CPU and GPIB interface controller for communicating with
a GPIB controller. The A2 interface assembly also contains the logic for communicating with a computer via RS-
232. The interface type, GPIB or RS-232, is determined by the operator using front panel keystrokes. When using
the RS-232 interface the operator can select the baud rate and parity using the front panel keypad. The GPIB / RS232 interface assembly is an SMT assembly and is not component level repairable. The A2 assembly is common to
all models.
A3 FET Assembly
The 6813A/B and 6842A A3 FET assembly contains 8 power FETs and 2 bridge driver ICs. The power FETS and
power transformer form an H-Bridge converter. The A3 FET H-Bridge converts the 320 volt DC rail from the AC
Input assembly to 500 volts DC on the A9 Output assembly via the A5 DC Rail assembly. The A3 assembly power
FETs switching frequency is synchronized with the switching frequency of the A7 Inverter assembly. The A3 FET
switching frequency is approximately 42 KHz, 1/2 that of the A7 Inverter assembly.
The 6811A/B, 6812A/B and 6842A ACFET assemblies, having lower output power ratings then the 6813A/B and
6842A/B , use only 4 power FETs in the H-Bridge. These assemblies are component level repairable except for a
FET failure. Power FETs replacement requires that all FETs in the H-Bridge have the same manufacture and same
date code, therefore when a FET replacement is required it may be more practical to replace the ACFET assembly.
The 6811A/B, 6812A/B and 6841A use one common assembly, the 6813A and 6842A use a different unique
assembly. .
A4 AC Input Assembly
The AC input mains voltage is connected on the rear panel via J1049 to the A4 AC Input board. The AC input board
converts the AC mains to a nominal 320 volt DC rail for use by the AC FET assembly. Relays K1040 and K1041
prevent the DC rail from energizing until the front panel on/off switch closed. Resistors R1040, R1041, R1045 and
R1046 limit turn-on surge current to the input filter capacitors C1060 thru C1067. Relay K1040 bypasses the current
limit resistors when energized. Relay K1040 is controlled by FET Q1040 who is driven by the input_rly_iso signal
derived from the DSP assembly. Wire jumper J1047 connects the full wave bridge rectifier D1060 and input
capacitors C1060 thru C1067 as either a voltage doubler for 120 volt mains or full wave bridge for 220/240 volt
mains. Fuse F1020 is the main AC line fuse and F1080 protects the 320 volt DC rail to the AC FET assembly. The
A4 assembly is component level repairable and there are 3 unique assemblies. One for the 6811A/B, another for the
6812A/B and 6841A and another for the 6813A/B and 6842A.
A5 DC Rail Assembly
The A5 DC Rail assembly contains U447 the CV error amplifier, U491 PWM driver, U462 PWM comparator and
U475 ramp generator to control the FET H-bridge on the A3 ACFET assembly. The chassis mounted power
transformer connects the 42 KHz AC from the A3 ACFET assembly to input rectifiers D400 thru D407 on the A5
DC Rail board.
Chassis mounted rail filter 5080-2329 and capacitors C500 to C503 and C508 to C509 located on the A9 Output
Filter board convert the 42 KHz AC to a 503 volt DC rail for use by the A7 Inverter assembly. It also contains U423
bias voltage detector and high/low 503 volt rail voltage detection circuit. There is a red LED on the right side of the
A5 DC Rail assembly to warn when high voltages are present, this LED can be seen from the right side of the AC
Source without removing any covers. This assembly is component level repairable but extreme caution must be used
when troubleshooting as 1100 volts peak / 503VDC is present. The A5 DC Rail assembly is common to all models.
18
Principles of Operation - 3
A6 Bias Assembly
The A6 Bias assembly receives the AC input mains voltage via connector J1035 from the A4AC Input assembly. The
bias transformer primaries for models 6811A/B, 6812A/B, or 6841A can be configured for either 100, 120 , 200 or
230 volt nominal input and models 6813A/B and 6842A can only be configured for 200 or 230 volt nominal inputs.
The input voltage range is configured by moving jumpers on J353. A J353 jumper configuration diagram is located
on the bias assembly next to J353. Regulator U300 supplies +15 volts to the AC input relays and bias to the ACFET
assembly. Regulators U311 and U3121 supply +5 volts to the GPIB and front panel assemblies. Opto-coupler U362
transmits the input_rly_iso signal to relay K1040 on the AC input assembly. J337 supplies +5 and +/- 15 volts to the
control assembly via the Output Filter assembly and 48 volts AC via E336 to the DC rail assembly. The A6 assembly
is a component level repairable assembly. There is one unique assembly for the 6811A/B, 6812A/B and 6841A and
another unique assembly for the 6813A/B and 6842A.
A7 Inverter Assembly
The A7 Inverter ( output amplifier ) assembly is a switching H-bridge FET assembly operating at approximately 83
KHz. It receives its switching logic from the A10 control assembly. The A7 Inverter assembly can provide a sine,
square, clipped sine, arbitrary waveform or DC level to the A9 Output Filter assembly. The Agilent 6813A/B and
6842A uses twice as many power FETs as the Agilent 6811A/B, 6812A/B and 6841A assembly. Slow start
procedures, disconnecting the 503 volt DC rail, should be used when troubleshooting the Inverter assembly. See
Inverter troubleshooting for more complete information on slow start procedures. The A7 Inverter assemblies are
component level repairable except for a FET failure. Power FETs replacement requires that all FETs in the H-Bridge
have the same manufacture and same date code, therefore when a FET replacement is required it may be more
practical to replace the A7 Inverter assembly. There is one unique A7 Inverter assembly for Agilent models
6811A/B, 6812A/B and 6841A and another unique assembly for models 6813A/B and 6842A. .
A8 Digital Signal Processing (DSP) Assembly
The A8 DSP assembly contains the CPU, ROMs, Digital-to Analog ( DACs ) circuits that control the output voltage
and output current settings. It contains Analog-to-Digital ( ADCs ) circuits to readback actual output voltage and
current. It contains all logic circuits for generating arbitrary waveforms, frequency changes and transient or pulse
level changes. At power on the A8 DSP assembly performs a self test and reports any failures via the front panel
display. The A8 assembly is an SMT assembly and is not component level repairable except for the ROMs which are
installed in sockets and are replaceable for ROM upgrades. There is one unique assembly for models 6811A/B,
6812A/B, and 6813A/B and another unique assembly for models 6841A and 6842A.
A9 Output / Filter Assembly
The A9 Output filter assembly contains U500 the remote sense amplifier and K501 remote sense relay. The rms and
peak current sense resistors, overvoltage divider and output disconnect relays K502 and K503 ( older manufactured
units use one output disconnect relay K500 ). The A9 Output assembly contains 2 notch filters to reduce the inverter
switching frequency noise in the output. It provides a communication path between the A10 Control assembly, A5
DC rail assembly and A6 Bias assembly. The A9 assembly is component level repairable. There is one unique
assembly for model 6811A/B and another unique assembly for models 6812A/B, 6813A/B, 6841A and 6842A.
19
3 - Principles of Operation
A10 Control Assembly
The A10 Control assembly contains the PWM comparator and ramp generator for controlling the A7 Inverter
assembly power FETs. It contains the voltage and current rms/dc converter circuits, voltage and current readback
amplifiers and all other analog circuits required to interface the output voltage , output current and frequency
programming and measurement capabilities with the A8 DSP assembly. The A10 assembly is an SMT assembly and
is not component lever repairable. There are three unique A10 Control assemblies, one for model 6811A/B, one for
models 6812A/B, and 6841A and one for models 6813A/B, and 6842A.
A11 Trigger ( BNC ) Assembly
The A11 Trigger or BNC assembly provides the communication and isolation path for trigger out ( U157 ) and
trigger in signals ( U156 ). The A11 assembly provides the isolation ( optical couplers ) between the A2 GPIB
interface assembly ( U153 & U154 ) and A8 DSP assembly ( J115 ). The A11 assembly is an SMT assembly and is
common to all models.
20
Figure 3-1. AC Power Source/Analyzer Block Diagram
4
Troubleshooting
Introduction
WARNING: SHOCK HAZARD. The troubleshooting procedures in this chapter are performed with
power applied and protective covers removed. These procedures should be performed only
by service trained personnel who are aware of the hazards (e.g., fire and electrical shock).
CAUTION: This instrument uses components which can either be damaged or suffer serious performance
degradation as a result of ESD (electrostatic discharge). Observe the standard antistatic precautions
to avoid damage to the components. An ESD summary is given in Chapter 1.
This chapter provides troubleshooting and repair information for the AC Power Source. Before beginning
troubleshooting procedures make certain the problem is in the AC Power Source and not with an associated circuit ,
the GPIB controller or AC input lines. Without removing the covers you can use the verification tests in Chapter 2 to
determine if the AC Power Source is operating normally.
Test Equipment Required
Table 4-1 lists the equipment required to perform the troubleshooting procedures given in this chapter.
Table 4-1. Test Equipment Requirements for Troubleshooting
Equipment Characteristics Recommended Model
GPIB Controller Communicate with AC Source via GPIB or
RS232
Digital Voltmeter Check voltages /resistances Agilent 3458A or equivalent
Function Generator Generate waveforms Agilent 3312A or equivalent
Oscilloscope Observe waveforms Agilent 54504A or equivalent
Current Shunt Check output current 0.01 ohm 10 watt
Logic Probe Check data lines Agilent 545A or equivalent
HP Series 200/300 controller or
Equivalent.
Troubleshooting Hints
a Service kit 5063-2330 contains 2 PC board holders to hold the A5 DC Rail board in a vertical position for
troubleshooting, and a PC board extender that raises the A8 DSP and A10 Control boards above the chassis for
troubleshooting.
Extender board part number 5063-2331
PC B holder part number 5020-8458
Cable part number 5080-2381
a Locate and observe the 2 red LEDs which indicate when high voltage is present on the A4 AC input board, A5
DC rail board, and A9 output board. Wait for the LEDs to extinguish before removing or installing assemblies.
a If both CV and CC annunciators are on, the peak current limit is may be set to low.
21
4 - Troubleshooting
Power-on Self-test Failures
The power-on self-test sequence tests of most of the digital and DAC circuits. If the supply fails self-test, the display
"ERR" annunciator will come on. You can then query the unit to find out what the error(s) are. When an error is
detected, the output is not disabled so you can still attempt to program the supply to help troubleshoot the unit.
Table 4-2 lists the self test errors and gives a possible remedy for each error. Table 4-3 lists the run-time errors that
can occur at any time while the unit is running.
NOTE: A partial self test is performed when the *TST? query is executed. Those tests that interfere with
normal interface operation or cause the output to change are not performed by *TST?. The return
value of *TST? will be zero if all tests pass, or the error code of the first test that failed. The power
supply will continue normal operation if *TST? returns a non-zero value.
Table 4-2. Self-Test Errors
Error # Description Possible Remedy
0 No error -
1 Non-volatile RAM RD0 section checksum failed A
2 Non-volatile RAM CONFIG section checksum failed A
3 Non-volatile RAM CAL section checksum failed A
4 Non-volatile RAM WAVEFORM section checksum failed A
5 Non-volatile RAM STATE section checksum failed A
6 Non-volatile RAM LIST section checksum failed A
7 Non-volatile RAM RST section checksum failed A
10 RAM selftest B
11 - 31 DAC selftest error, expected <n>, read <reading>
Errors 11, 12, 13, 14, 15 apply to DAC12 1A and 1B
Errors 16, 17, 18 apply to DAC12 2A
Errors 19, 20, 21 apply to DAC12 2B
Errors 22, 23 apply to DAC12 4A
Errors 24, 25 apply to DAC12 4B
Errors 26, 27, 28 apply to DAC12 3A and 3B
Errors 29, 30, 31 apply to DAC12 5A and 5B
40 Voltage selftest error C
43 Current selftest error C
70 Fan voltage failure D
80 Digital I/O selftest error D
B
A Re-initialize unit and re-calibrate. If unit still has RAM error replace A8 DSP board.
B Check A8 DSP and A10 Control assemblies
C *TST? programs 50 volts, expected readback 50+/-1volt 0+/-1amp
D Check fan and/or fan voltage or replace A8 DSP assembly.
Run-Time Errors
Run-time errors do not occur during self-test, but can occur at any time while the unit is running. (See Table 4-3).
22
Troubleshooting - 4
Table 4-3. Run-Time Errors
Error # Description Possible Remedy
200 Outgrd not responding E
201 Front panel not responding F
210 Ingrd receiver framing error E
211 Ingrd uart overrun status E
212 Ingrd received bad token E
213 Ingrd receiver buffer overrun E
214 Ingrd input buffer overrun E
215 Outgrd output buffer overrun E
216 RS-232 receiver framing error G
217 RS-232 receiver parity error G
218 RS-232 receiver overrun error G
219 Ingrd inbuf count sync error E
220 Front panel uart overrun F
221 Front panel uart framing F
222 Front panel uart parity F
223 Front panel buffer overrun F
224 Front panel timeout F
401 CAL switch prevents calibration H
402 CAL password is incorrect H
403 CAL not enabled J
404 Computed readback cal constants are incorrect J
405 Computed programming cal constants are incorrect J
406 Incorrect sequence of calibration commands J
600 Systems in mode:list have different list lengths K
601 Requested voltage and waveform exceeds peak voltage capability K
602 Requested voltage and waveform exceeds transformer volt-second rating K
603 Command only applies to RS-232 interface K
604 Trigger received before requested number of pre-trigger readings K
605 Requested RMS current too high for voltage range K
606 Waveform data not defined K
607 VOLT, VOLT:SLEW, and FUNC:SHAP modes incompatible K
608 Measurement overrange K
609 Output buffer overrun K
610 Command cannot be given with present SYST:CONF setting K
E Communication error between A1 GPIB, A8 DSP and/or A11 trigger assemblies.
F Communication error between A3 front panel, A8 DSP and /or A11 Trigger assemblies.
G RS-232 communication or programming error.
H Check CAL switch positions (see Figure 4-11).
J See Appendix B in User’s Guide for calibration procedure.
K Programming error (see applicable programming command in Programming Guide).
23
4 - Troubleshooting
Overall Troubleshooting Flowchart
Figure 4-1 gives the overall procedures to isolate a fault to a circuit board or particular circuit. See Figure 6-1 for the
location of the circuit boards.
START TROUBLESHOOTING PROCEDURES
TURN UNIT OFF. DISCONNECT LOAD
REMOVE OUTER COVER (TORX T25 )
REMOVE INNER COVER ( TORX T15 )
CHECK FOR ANY INDICATION AC POWER ON
TURN UNIT ON
IS
AC INPUT ASSY
LED ON ?
note 1
YES
IS DISPLAY ON
?
YES
NO
PRESS SHIFT KEY ON
SEE FIGURES 6-8 AND 6-9. CHECK FUSE A4F1020 / LINE SWITCH,
A4 E1048 CONNECTIONS TO L1050 LINE CHOKE
CHECK A4TP1050-2 FOR ~150VDC, +RAIL FOR ~300VDC
SEE FIGURES 6-12 & 6-13 CHECK FUSE A6 F300 & A6 F301,
+15Vpri & +12Vpri FROM A6 BIAS ASSY TO A4 ACINPUT ASSY
IS FAN ON
?
YES
FRONT PANEL
SHIFT
ANNUNICIATOR
LIGHTS
?
YES
NONO
NO
CHECK FUSE A6F301
LINE VOLTAGE SWITCH A4J353 SETTING
SEE A6 BIAS BOARD TROUBLESHOOTING
CHECK +5V TO A8 DSP
ASSY
CHECK DRDX / DTXD SIGNALS @ A11 TRIGGER ASSY.
U150-5 TO D COM J7462-2 ON A8 DSP ASSY.
U151-1 TO D COM J7462-2 ON A8 DSP ASSY.
U164-5 TO D COM J7462-2 ON A8 DSP ASSY.
U163-6 TO H COM J114-2 ON A11 TRIG ASSY.
CHECK BIAS VOLTAGES ( +5V SEC / -15V )
A6 BIAS / A9 OUTPUT / A8 DSP / A10 CONTROL ASSY
GO TO A1 FRONT PANEL TROUBLESHOOTING
24
IS ERROR
ANNUNICATOR
ON
?
YES
PRESS [ SHIFT ] [ ERROR ].
SEE TABLE 4-2 FOR SELF-TEST ERROR MESSAGE
NO
PROGRAM
"VOLT 120"
"OUTPUT ON"
Notes: 1. View LED from lower left side of power supply.
"A"
Figure 4-1. Overall Troubleshooting Procedures (sheet 1 of 2)
(
@
"A"
Troubleshooting - 4
MEASURE
120 VAC
DC RAIL J444-1 TO
OUTPUT
TERMINALS
NO
IS
DC RAIL LED
ON?
YES
MEASURE
J444-3
503 +/-4 VDC
YES
MEASURE
120 VAC
A9TP501 TO
A9TP502
NO
YES
VOL TAG E IS W ITH IN
PERFORM VERIFICATION &
CALIBRATION AS REQUIRED
NO
NO
YES
MEASURED
SPEC?
NO
DISCONNECT CABLE FROM A9E527 (OUTPUT BOARD)
TO J627 (INVERTER BOARD)
CHECK OUTPUT RELAY A9K500, A9Q501, D501
OUTPUT_RELAY (HI) @ A10J524-45
OUT_RELAY (HI) @ A10J821-22
IF THESE SIGNALS DO NOT TOGGLE WITH OUTP ON -
PROBLEM WITH A1 FRONT PANEL OR A8 DSP BOARD
YES
DC RAIL LED
PROGRAM "OUTPUT OFF" CONNECT LOAD RESISTOR
(20 OHMS) AND CURRENT SHUNT ACROSS OUTPUT
TERMINALS PROGRAM "OUTPUT ON" "CURRENT 5.00"
NO
IS
ON?
NO
YES
OUTPUT
CURRENT @ 5A
WITHIN SPEC CC
MODE?
GO TO A7 INVERTER
TROUBLESHOOTING
GO TO A3 FET/A5 DC RAIL
TROUBLESHOOTING
MEASURE
~3.5 Vpp SINEWAVE
@ A10J822-5
CONTROL
BOARD
YES
CHECK
PULSES AT
A10U1801-25
FIG X-X
YES
IF FAULT IS VOLTAGE OR CURRENT READBACK CHECK
OUTPUT AND CONTROL BOARDS
IF FA ULT IS TRIG IN, T RIG O UT, R I OR D FI GO TO A 11
TRIGGER BOARD TROUBLESHOOTING
IF FAULT IS NO OUTPUT CHECK A7 INVERTER BOARD
NO
NO
Figure 4-1. Overall Troubleshooting Procedures (sheet 2 of 2)
GO TO A8 DSP
TROUBLESHOOTING
GO TO A10 CONTROL BOARD
TROUBLESHOOTING
25
4 - Troubleshooting
A1 Front Panel Assembly Troubleshooting
Figure 4-2. Front Panel Assembly Troubleshooting
A2 GPIB/RS-232 Board Troubleshooting
Table 4-4. GPIB/RS232 Board Troubleshooting
Step Procedure Waveform
1.
2.
3.
26
Check for +5 Vdc at L100 (see Figure 6-5
for location).
Check for clock waveform at Y100.
Connect the unit to a GPIB or RS232
controller to check the GPIB/RS232
transceivers. Note that GPIB and RS232 use
separate communication transceivers.
HP-I B
CRYSTAL
2. 00 V/di v
50.0 ns/div
-250. 0 ns
Troubleshooting - 4
A3 FET Board Troubleshooting
Because test points on the FET board are not accessible when the board is installed, troubleshooting must be
performed with the board removed from the power supply. Troubleshooting procedures are provided with both
power removed and power applied. The location of different test points are shown by encircled numbers on the A3
FET Board schematic and component location diagrams.
NOTE: If any power FET (Q201-204, Q211, Q222, Q233, or Q244) is defective, you must replace all
eight with a matched set.
Table 4-5. FET Board Troubleshooting
Step Procedure Result
With all power removed
1 Turn the power supply off and remove the A3 FET board with
its heatsink assembly attached (see Disassembly Procedures).
2 Measure the resistance between the +Rail (E502) and the - Rail
(E501) and common (-Rail).
3 Measure the resistance between the gate of each FET (Q201-
204, Q211, Q222, Q233, and Q244) and common (-Rail).
4 Measure the resistance across capacitor C201.
5 Measure the resistance across the 15 V bias input (E506 to
E507).
With signal from external waveform generator applied
6 Short the collectors of Q251 and Q252 by connecting the
collector (case) of each transistor to common (E507).
8 Connect a waveform generator to J200-1 and J200-2.
9 Set generator to produce a 20kHz, 20Vp-p triangular waveform. See Figure 4-3A.
10 Connect 15 V from an external supply to E506 (positive) and
E507 (common).
Note: All of the following measurements are taken with respect
to E507 common (same as TP 26 on A3 FET Board).
11 Check bias voltage at U203-1 (TP 27). +5V
12 While adjusting the external 15 V supply input, check the bias
trip point at U204-1 (TP 28).
13 Set external supply input to + 15V and check drive 1 waveform
at U201-10 (TP 29), and drive 2 waveform at U201-12 (TP 30).
14 Check that pulses are present at U201-1(TP 31), U201-7 (TP
32), U202-1 (TP 33), and U202-7 (TP 34)
15 Pulses should be present on both sides of inductors L201-204
and L213-216 as follows:
Check the pulses on the driver transistor side (Q251-Q254) of
each inductor.
Check the pulses on the FET regulator side (Q201-Q204,
Q211,Q222, Q233, and Q244) of each inductor.
If the waveforms do not have the fast step as shown in Figure
4-3, then the associated FET gate input has an open circuit.
16 Measure the VREF voltage at U204-4 (TP 35). approx. 1.7 V.
17
Check the peak current limit by connecting a 68 kΩ resistor
from +5 V (U201-9) to U204-5.
See Disassembly Procedures
Value should be >20 MΩ
Value should be >15 kΩ
Value should be approx. 150Ω
Value should be approx. 1 kΩ in the
forward direction and 490Ω reversed.
Value should be approx. 1 kΩ in the
forward direction and 490Ω reversed.
Voltage goes from low of 0V to high of
5V at an input of approx. 12V, and from
high to low at an input of approx. 13V
See Figure 4-3B.
See Figure 4-3C.
See Figure 4-3D.
See Figure 4-3E.
All pulses turned off.
27
4 - Troubleshooting
-
-
Figure 4-3. FET Assembly Test Waveforms
-
-
28
Troubleshooting - 4
A5 DC Rail Assembly Troubleshooting
CAUTION: This board contains hazardous voltages during some troubleshooting procedures. Use
extreme caution.
Before troubleshooting the A5 DC Rail board, refer to the previous procedure and determine that the A3 AC FET
Assembly is good. The 503 Vdc rail (+/-4Vdc) is generated from the 300 Vac input board rail, the A3 FET board,
and the power transformer. The A5 DC Rail board contains the PWM and CV error amplifiers for controlling the
FET switches. Troubleshooting the bias, PWM, and CU error amplifiers must be done with the 300 Vdc rail
disconnected from the A3 FET assembly
DISCONN ECT CABLE FROM A3 FET BOARD TO J1042 ON A4 AC INPUT BOARD.
DISCONN ECT CABLE FROM A9 O UTPUT BOAR D TO J627 ON A7 INVE RTER BOA RD.
REMOVE 5 SCREWS HOLDING A5 DC RAIL BOARD AND HOLD A5 DC RAIL BOARD IN VERTICAL
POSITION USING BOARD HOLDERS.
JUMPER TP#1 & TP X
TURN ON AC INPUT
START
MEASURE BIAS VOLTAGE S: TP404 = COM MON
MEASURE +10V RA IL_REF @ C454+ = 10.00VDC
EXT_CLK_ISO
THE CV ERROR AMPLIFIER, PWM COMPARATOR, PWM DRIVER, RAMP GENERATOR AND
HV/LOW RAIL DETECT CIRCUIT CAN BE CHECKED BY APPLYING 0V OR 10V TO RAIL_VMON.
CHECK RAMP GENERATOR AT U475-1 AND U 475-7 (SEE FIGURES 4-5C AND 4-5D).
0V applied
+15V
+5V
+5V
PULSE
PULSE
PULSE
PULSE
+5V
+5V
10V applied
CV ERROR AMP
-15V
PWM COMPARATOR
0
RAIL_OV_INH
+5V
0
PULSE
0
0
RAIL_INH_ISO
0
RAMP PULSE
1/2 EXT_CLK_ISO
+5V
PWM DRIVER (disconnected)
0
PWM DRIVER (normal)
0
RAIL_OV_INH
0
RAIL_LOW_W ARN
+1.2V
LRFIN
5V
LRFDEL
0
TP401 = +15VDC
TP402 = -15VDC
TP403 = +5VDC
PWM_EN
@ +5V ?
YES
WAVEFORM
U436-6
OK?
YES
U447-7
U462-7
U463-3 (LOW WHE N RAIL OVER VOLTAGE IS TRUE)
U463-4 (HIGH INHIBITS P WM D RIVER)
U463-14 (SEE FIGURE 4-5B)
U463-15 (SEE FIGURE 4-5A)
U491-8,9 (SEE FIGURE 4-5E)
U491-8,9 (SEE FIGURE 4-5F)
U424-14 (TOGGLES A T APPROX. 10.6V @ RAIL_VMO N)
U424-14 (TOGGLES A T APPROX. 9.3V @ RAIL_VMO N)
U424-1
U433-1
NO
NO
(TOGGLES AT APPROX. 8.4V @ RAIL_VMON)
CHECK U 423 BIAS DETEC T CIRCUIT
PWM_EN WILL INHIBIT A8 DSP BOARD
CHECK EXT_SYNC U436-3 TO X
CHECK E XT_CLK_SYN C A10 J824-1 CONTR OL BOARD
IF SIGNAL NOT PR ESENT @ A10 J824-1, THEN
A10 CONTROL OR A8 DSP BOARD FAULT
Figure 4-4. DC Rail Assembly Troubleshooting
29
4 - Troubleshooting
O
(
)
P
R
R
(
)
R
7
(
)
D
R
D
(
A
)
T
T
X
R
8
O
M
R
9
A
BCD
EXT CL K IS
U436-6
R459
TO
TP404
RAMP
GENERATO
U475-1
R487
TO
TP404
2.00 V/div
83 kHz EXTERNAL CLOCK
2.00 V/div 5.00 us/div
5.00 us/div
RAM
GENERATO
PULSE
R483/R489
TO
TP404
RAMP
GENERATO
U475-
R480
TO
TP404
1.00 V/div
2.00 V/div
5.00 us/div
RAMP PULSE
5.00 us/div
PWM DRIVE
U491 -8
TO
U491 -9
RAIL
DISCONNECT E
FROM AC FET
PULL J1042
C INPUT
SHOR
RAIL LO FAUL
TP#1
TO
RAMP GENERATOR NO. 2
5.00 V/di v 10.00 us/div
PWM DRIVER - AC FET RAIL DISCONNECTE
Figure 4-5. DC Rail Assembly - Test Waveforms
PWM DRIVE
U491-
T
U491-
500 V DC RAIL
DISCONNECTED
FRO
INVERTE
RAMP GENERATOR NO. 1
5.00 V /div
PWM DRIVER - NORMAL OPERATION
5.00 us/div
F
30
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