Agilent Technologies 6680A, 6682A, 6684A, 6683A, 6681A User Manual

SERVICE MANUAL

GPIB DC Power Supplies

Agilent Series 668xA

For instruments with Serial Numbers:

Agilent Model 6680A: US36480101 and Above *

Agilent Model 6681A: US36400101 and Above *

Agilent Model 6682A: US36440101 and Above *

Agilent Model 6683A: US36420101 and Above *

Agilent Model 6684A: US36410101 and Above *

* This manual also applies to instruments with the older serial number format described on page 7. For instruments with higher serial numbers, a change page may be included.

For instruments with lower serial numbers, see Appendix A.

5

Agilent Part No. 5960-5590	Printed in USA
Microfiche Part No. 5960-5591	September, 2000

CERTIFICATION

Agilent Technologies certifies that this product met its published specifications at time of shipment from the factory. Agilent Technologies further certifies that its calibration measurements are traceable to the United States National Bureau of Standards, to the extent allowed by the Bureau's calibration facility, and to the calibration facilities of other International Standards Organization members.

WARRANTY

This Agilent Technologies hardware product is warranted against defects in material and workmanship for a period of three years from date of delivery. Agilent Technologies software and firmware products, which are designated by Agilent Technologies for use with a hardware product and when properly installed on that hardware product, are warranted not to fail to execute their programming instructions due to defects in material and workmanship for a period of 90 days from date of delivery. During the warranty period Agilent Technologies will, at its option, either repair or replace products which prove to be defective. Agilent Technologies does not warrant that the operation of the software, firmware, or hardware shall be uninterrupted or error free.

For warranty service, with the exception of warranty options, this product must be returned to a service facility designated by Agilent Technologies. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products returned to Agilent Technologies for warranty service. Except for products returned to Customer from another country, Agilent Technologies shall pay for return of products to Customer.

Warranty services outside the country of initial purchase are included in Agilent Technologies product price, only if Customer pays Agilent Technologies international prices (defined as destination local currency price, or U.S. or Geneva Export price).

If Agilent Technologies is unable, within a reasonable time to repair or replace any product to condition as warranted, the Customer shall be entitled to a refund of the purchase price upon return of the product to Agilent Technologies.

LIMITATION OF WARRANTY

The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the Customer, Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental specifications for the product, or improper site preparation and maintenance. NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. AGILENT TECHNOLOGIES SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

EXCLUSIVE REMEDIES

THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER'S SOLE AND EXCLUSIVE REMEDIES. AGILENT 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 CONSIDERATIONS

GENERAL. This is a Safety Class 1 instrument (provided with 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.

•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.

•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 two-conductor outlet is not sufficient protection.

•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.

•Any interruption of the protective (grounding) conductor (inside or outside the instrument), or disconnecting of the protective earth terminal will cause a potential shock hazard that could result in personal injury.

•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.

•Only fuses with the required rated current, voltage, and specified type (normal blow, time delay, etc.) should be used. Do not use repaired fuses or short-circuited fuseholders. To do so could cause a shock or fire hazard.

•Do not operate this instrument in the presence of flammable gases or fumes.

•Do not install substitute parts or perform any unauthorized modification to this instrument.

•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.

•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.

•Capacitors inside this instrument may hold a hazardous electrical charge even if the instrument has been disconnected from its power source.

SAFETY SYMBOLS.

Instruction manual symbol. The instrument will be marked with this symbol when it is necessary for you to refer to the instruction manual in order to protect against damage to the instrument.

This sign indicates hazardous voltages.

This sign indicates an earth terminal (sometimes used in the manual to indicate circuit common connected to a ground chassis).

The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which, if not correctly performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the indicated conditions are fully understood and met.

The CAUTION sign denotes a hazard. It calls attention to an operating procedure, or the like, which, if not correctly performed or adhered to, could result in damage to or destruction of part or all of the product. Do not proceed beyond a CAUTION sign until the indicated conditions are fully understood and met.

.

3

Safety Symbol Definitions

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		Standby (supply)
	(Used for measurement and control		Units with this symbol are not completely
	circuits designed to be operated with		disconnected from ac mains when this switch is
	one terminal at earth potential.)		off. To completely disconnect the unit from ac
			mains, either disconnect the power cord or have
			a qualified electrician install an external switch.

Printing History

The edition and current revision of this manual are indicated below. Reprints of this manual containing minor corrections and updates may have the same printing date. Revised editions are identified by a new printing date. A revised edition incorporates all new or corrected material since the previous printing date. Changes to the manual occurring between revisions are covered by change sheets shipped with the manual. Also, if the serial number prefix of your power supply is higher than those listed on the title page of this manual, then it may or may not include a change sheet. That is because even though the higher serial number prefix indicates a design change, the change may not affect the content of the manual.

Edition 1	April 1994
Edition 2	September, 2000

© Copyright 1993, 2000 Agilent Technologies, Inc.

This document contains proprietary information protected by copyright. All rights are reserved. No part of this document may be photocopied, reproduced, or translated into another language without the prior consent of Agilent Technologies, Inc. The information contained in this document is subject to change without notice.

4

Table of Contents
Introduction ............................................................................................................................................................................	7
Scope...................................................................................................................................................................................	7
Organization.....................................................................................................................................................................	7
Instrument Identification.....................................................................................................................................................	7
Related Documents ..........................................................................................................................................................	8
Change Sheet.................................................................................................................................................................	8
Operating Manual..........................................................................................................................................................	8
Manual Revisions.............................................................................................................................................................	8
Firmware Revisions .........................................................................................................................................................	8
Safety Considerations .........................................................................................................................................................	9
Conventions ........................................................................................................................................................................	9
Electrostatic Discharge .......................................................................................................................................................	9
Verification............................................................................................................................................................................	11
Introduction.......................................................................................................................................................................	11
Tests..................................................................................................................................................................................	11
Test Equipment Required..................................................................................................................................................	11
List of Equipment...........................................................................................................................................................	11
Current-Monitoring Resistor ..........................................................................................................................................	11
Electronic Load ..............................................................................................................................................................	12
Programming The Tests ....................................................................................................................................................	13
General Considerations ..................................................................................................................................................	13
Programming Parameters ............................................................................................................................................	13
General Measurement Techniques....................................................................................................................................	13
Performance Test Record Sheets ......................................................................................................................................	13
Operation Verification Tests.............................................................................................................................................	14
Performance Tests.............................................................................................................................................................	14
Constant Voltage (CV) Tests .........................................................................................................................................	14
Test Setup....................................................................................................................................................................	14
Test Procedures ...........................................................................................................................................................	14
Constant Current (CC) Tests..........................................................................................................................................	19
Test Setup....................................................................................................................................................................	19
Test Procedures ...........................................................................................................................................................	19
Averaging the CC Measurements...................................................................................................................................	24
Troubleshooting ....................................................................................................................................................................	31
Introduction.......................................................................................................................................................................	31
Localizing the Problem ..................................................................................................................................................	31
Chapter Organization .....................................................................................................................................................	31
Test Equipment Required..................................................................................................................................................	32
Troubleshooting Procedures .............................................................................................................................................	32
Power-On Selftest ..........................................................................................................................................................	32
Description ..................................................................................................................................................................	32
Disabling The Power-On Selftest................................................................................................................................	32
Using the *TST? Query (GPIB Systems Supplies Only) ............................................................................................	32
Troubleshooting Charts..................................................................................................................................................	34
Troubleshooting Test Points...........................................................................................................................................	34
Bias and Reference Supplies ..........................................................................................................................................	34
CV/CC Status Annunciators Troubleshooting ...............................................................................................................	53
A3 FET Board Troubleshooting.....................................................................................................................................	53
Signature Analysis ............................................................................................................................................................	56
Introduction....................................................................................................................................................................	56
Firmware Revisions .......................................................................................................................................................	56
Test Headers...................................................................................................................................................................	57

5

Post-Repair Calibration.....................................................................................................................................................	62
When Required ..............................................................................................................................................................	62
Inhibit Calibration Jumper .............................................................................................................................................	62
Calibration Password .....................................................................................................................................................	62
Restoring Factory Calibration Constants .......................................................................................................................	62
EEPROM Initialization.....................................................................................................................................................	63
Transferring Calibration Constants To Factory Preset Locations .....................................................................................	63
Disassembly Procedures ...................................................................................................................................................	68
Tools Required...............................................................................................................................................................	68
Top Cover ......................................................................................................................................................................	69
Removing Protective RFI Shield (Galvanized Sheet Metal)..........................................................................................	69
GPIB Board....................................................................................................................................................................	69
A4 AC Input Assembly..................................................................................................................................................	70
A5 DC RAIL Assembly .................................................................................................................................................	70
A6 BIAS Assembly........................................................................................................................................................	70
A3 FET Board................................................................................................................................................................	70
A10 Control Assembly...................................................................................................................................................	71
Front Panel Assembly ....................................................................................................................................................	71
S1 Line Switch ...............................................................................................................................................................	71
A1 Front Panel Board.....................................................................................................................................................	71
A1DSP1 LCD Display ...................................................................................................................................................	72
A1G1 and A1G2 Rotary Controls..................................................................................................................................	72
A1KPD Keypad .............................................................................................................................................................	72
Output Bus Boards A7, A81 and A9 & Chassis Components........................................................................................	72
Principles Of Operation .......................................................................................................................................................	81
Introduction.......................................................................................................................................................................	81
A2 GPIB Board.................................................................................................................................................................	81
A1 Front Panel Assembly .................................................................................................................................................	82
A10 Control Board............................................................................................................................................................	82
Secondary Interface (P/O A10 Board) ...........................................................................................................................	82
A4 AC Input Board...........................................................................................................................................................	85
A5 DC Rail Board.............................................................................................................................................................	85
A3 FET Board...................................................................................................................................................................	85
Output Circuits..................................................................................................................................................................	86
Replaceable Parts..................................................................................................................................................................	89
INTRODUCTION ............................................................................................................................................................	89
Chapter Organization .....................................................................................................................................................	89
Reading the Tables.........................................................................................................................................................	89
How To Order Parts ..........................................................................................................................................................	90
Diagrams..............................................................................................................................................................................	115
Introduction.....................................................................................................................................................................	115
Chapter Organization ......................................................................................................................................................	115
General Schematic Notes ................................................................................................................................................	119
Backdating...........................................................................................................................................................................	149
Index ....................................................................................................................................................................................	155

6

1

Introduction

Scope

Organization

This manual contains information for troubleshooting and repairing to the component level Agilent Series 668xA, 5-kilowatt power supplies. The remaining chapters of this manual are organized as follows:

Chapter	Description
Chapter 2	Verification procedures to determine the performance level of the supply either before or after repair.
Chapter 3	Troubleshooting procedures for isolating a problem, procedures for replacing the defective component
	and, if required, post-repair calibration and EEPROM initialization procedures.
Chapter 4	Principles of power supply operation on a block-diagram level.
Chapter 5	Replaceable parts, including parts ordering information.
Chapter 6	Diagrams, including schematics, component location drawings, and troubleshooting test points.
Appendix A	Backdating information for power supplies with serial numbers below those listed in the title page of
	this manual.

Instrument Identification

Agilent Technologies instruments are identified by a 10-digit serial number. The format is described as follows: first two letters indicate the country of manufacture. The next four digits are a code that identify either the date of manufacture or of a significant design change. The last four digits are a sequential number assigned to each instrument.

Item	Description
US	The first two letters indicates the country of manufacture, where US = USA.
3648	This is a code that identifies either the date of manufacture or the date of a significant design
	change.
0101	The last four digits are a unique number assigned to each power supply.

If the serial number prefix on your unit differs from that shown on the title page of this manual, a yellow Manual Change sheet may be supplied with the manual. It defines the differences between your unit and the unit described in this manual. The yellow change sheet may also contain information for correcting errors in the manual.

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 A for backdating information.

Introduction 7

Related Documents

Change Sheet

There may or may not be a Manual Change sheet included with this manual (see Manual Revisions). If one is included, be sure to examine it for changes to this manual.

Operating Manual

Each power supply is shipped with an operating manual (see Replaceable Parts, Chapter 5 for part numbers) that covers the following topics:

•Options, accessories, specifications, supplementary characteristics, output characteristic curve, typical output impedance curves.

•Connecting the power cord, load, and remote sensing.

•Connecting power supplies in series or autoparallel.

•Connecting the remote controller and setting the GPIB address.

•Configuring the digital port for remote inhibit, relay link, or digital I/O operation.

•Connecting the analog port for external voltage programming control.

•Turn-on tests, including selftest errors and runtime errors.

•Front panel operation.

•SCPI programming, an introduction to syntax, language dictionary, and status register operation.

•Compatibility-language programming for operation with Agilent Series 603xA power supplies.

•Replacement of line fuse and conversion of line voltage.

•Calibration procedure (front panel and remote).

Manual Revisions

This manual was written for power supplies that have the same serial prefixes (first part) as those listed on the title page and whose serial numbers (second part) are equal to or higher than those listed in the title page.

	Note	1)	If the serial prefix of your supply is higher than that shown in the title page then the supply was made
			after the publication of this manual and may have hardware and/or firmware differences not covered in
			the manual.
		2)	If they are significant to the operation and/or servicing of the power supply, those differences are
			documented in one or more Manual Changes sheets included with this manual.
		3)	If the serial prefix on the power supply is lower than that shown on the title page, then the supply was
			made before the publication of this manual and can be different from that described here. Such
			differences are covered in "Appendix A – Manual Backdating Changes".

Firmware Revisions

The power supply's firmware resides in the A10 control board microprocessor chip and in ROM chips on the A2 GPIB and A1 Front Panel boards. You can obtain the firmware revision number by either reading the integrated circuit label, or query the power supply using the GPIB *IDN query command (see Chapter 3 - Troubleshooting). Also, see Chapter 3, Firmware Revisions for the actual Agilent BASIC program that does this.

8 Introduction

Safety Considerations

This power supply 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, ground receptacle. Refer to the "Safety Summary" page at the beginning of this manual for general safety information. Before operation or repair, check the power supply and review this manual for safety warnings and instructions. Safety warnings for specific procedures are located at appropriate places in the manual.

Hazardous voltage exist within the power supply chassis, at the output terminals, and at the analog programming terminals.

Conventions

•In diagrams, the name of a complementary signal is sometimes shown with a bar above the signal mnemonic. In other diagrams and in the text, complementary signals are shown with an asterisk (*) after the mnemonic (such as PCLR*). A mnemonic with a bar over it or an asterisk after it represents the same signal.

•In this manual, all Agilent 668xA series supplies are referred to as system supplies.

Electrostatic Discharge

The power supply 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 power supply observe all standard, antistatic work practices. These include, but are not limited to:

•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).

•using a conductive wrist strap, such as Agilent P/N 9300-0969 or 9300-0970.

•grounding all metal equipment at the station to a single common ground.

•connecting low-impedance test equipment to static-sensitive components only when those components have power applied to them.

•removing power from the power supply before removing or installing printed circuit boards.

Introduction 9

2

Verification

Introduction

This chapter provides test procedures for checking the operation of Agilent Series 668xA power supplies. The required test equipment is specified and sample performance test record sheets are included. Instructions are given for performing the tests either from the front panel or from a controller over the GPIB.

Tests

Two types of procedures are provided: Operation Verification tests and Performance tests.

Type of Test	Purpose
Operation Verification	These tests do not check all parameters, but comprise a short procedure to verify that the power
	supply is performing properly.
Performance	These tests verify all the Specifications (not Supplementary Characteristics) listed in Table 1-1
	of the Power Supply Operating Manual.

If you encounter failures or out-of-specification test results, see Troubleshooting Procedures (Chapter 3). The procedures will determine if repair and/or calibration is required.

Note	The power supply must pass the selftest at power-on before the following tests can be performed. If the
	power supply fails selftest, go to Chapter 3.

Test Equipment Required

List of Equipment

Table 2-1 lists the equipment required to perform the tests given in this chapter. Only the equipment marked with the superscript "1'' is needed for the Operation Verification test.

Current-Monitoring Resistor

The four-terminal, current-monitoring resistor (current shunt) listed in Table 2-1 is required to eliminate output current measurement error caused by voltage drops in leads and connections. The specified current shunts have special current-monitoring terminals inside the load connection terminals. The accuracy of the current shunt must be 0.04% or better. When using the 1000 amp 0.05% current shunt the measurement uncertainty should be stated for all calibrations. Connect the current monitor directly to these current-monitoring terminals.

Verification 11

Table 2-1. Test Equipment Required

Type	Required Characteristics	Recommended Model
Digital Voltmeter1	Resolution: 10 nV @ 1V	Agilent 3458A
	Readout: 8 1/2 digits
	Accuracy: 20 ppm
Current Monitor Resistor1	Agilent 6682A, 6683A, Agilent 6684A:	Guildline 9230/300
	0.001Ω ± 0.04%, 300A, 100W
	Agilent 6680A, 6681A	Burster Type 1280
	100 µΩ ± 0.05%, 1000A
DC Power Supply	DC Power Source with current capability	Agilent 6680A
	equal to UUT
Electronic Load	Range: Voltage and current range must	3 each Agilent 6050A, w/3 each
	exceed that of supply under test. Power:	Agilent 60504B per Agilent 6050A
	5.4KW minimum	for all units
	or
Resistor Load	5 Kilowatt minimum
	Agilent 6680A = 5.7 milliohms 4375W
	Agilent 6681A = 13.8 milliohms 4640W
	Agilent 6682A = 87.5 milliohms. 5040W
	Agilent 6683A = 200 milliohms 5120W
	Agilent 6684A = 312 milliohms 5120W
Oscilloscope	Sensitivity: 1mV	Agilent 54504A
	Bandwidth Limit: 20MHz
	Probe: 1:1 with RF tip
RMS Voltmeter	True RMS Bandwidth: 20MHz	Agilent 3400B
	Sensitivity: 100 µV
Current Transformer	0.1Volt per ampere: 1Hz to 20MHz	Pearson Model 411
Variable-Voltage	Power: 3 Phase 24KVA; Range:	Superior Powerstat
Transformer (AC Source)	180-235V 47 - 63Hz; 360440V	1156DT-3Y, 0-280V, 50A,
	47 - 63Hz	24.2 KVA or equivalent .
GPIB Controller2	Full GPIB capabilities	HP Series 200/300

1 Required for Operation Verification Tests.

2 Required for remote testing of 668xA models.

Electronic Load

Many of the test procedures require the use of a variable load capable of dissipating the required power. If a variable resistor is used, switches must be used for connecting, disconnecting, and shorting the load resistor. For most tests, an electronic load (see Table 2-1) is easier to use than a variable resistor. However, an electronic load may not be fast enough for testing transient recovery time or may be too noisy for testing noise (PARD). In these cases, fixed load resistors of suitable power dissipation can be used with minor changes to the test procedures given in this chapter.

12 Verification

Programming The Tests

General Considerations

Procedures are given for programming these tests either from the front panel keypad or from a GPIB controller. The procedures assume you know how to use the front panel keypad or how to program over the GPIB (see the Power Supply Operating Manual for more information). When using computer-controlled tests, you may have to consider the relatively slow (compared to computer and system voltmeters) settling times and slew rates of the power supply. Suitable WAIT statements can be inserted into the test program to give the power supply time to respond to the test commands.

This power supply can provide more than 240VA at more than 2 volts. If the output connections touch each other, severe arcing can occur resulting in burns, ignition or welding of parts. DO NOT ATTEMPT

TO MAKE CONNECTIONS WHILE OUTPUT POWER IS ON. These connections should be performed only by qualified electronics personnel.

Programming Parameters

Table 2-2 lists the programming voltage and current values for each model. You can enter these values either from the front panel or from a controller over the GPIB.

Table 2-2. Programming Voltage and Current Values

Agilent Model	Full Scale	Max. Prog.	Full Scale	Max. Prog.	Max. Prog.
Agilent 6680A	Voltage	Voltage	Current	Current	Overvoltage
	5V	5.125V	875A	895A	6.25V
Agilent 6681A	8V	8.190V	580A	592A	10.0V
Agilent 6682A	21V	21.50V	240A	246A	25.2V
Agilent 6683A	32V	32.75V	160A	164A	38.4V
Agilent 6684A	40V	41.00V	128A	131A	48.0V

General Measurement Techniques

Figure 2-1 shows the setup for the Constant Voltage tests. Measure the dc output voltage directly at the sense (+S and -S) terminals. Connect these terminals for remote sensing (to the +S and -S terminals). Connect these terminals for local sensing. Be certain to use load leads of sufficient wire gauge to carry the output current (see Chapter 4 of the Power Supply Operating Manual). To avoid noise pickup, use coaxial cable or shielded pairs for the test leads. If you use more than one meter or a meter and an oscilloscope, connect separate leads for each instrument to avoid mutual-coupling effects.

Performance Test Record Sheets

When performing the tests in this chapter, refer to the Performance Test Record sheets supplied at the end of this chapter. Table 2-6 is for recording common information, such as, the test equipment used and the environmental conditions. Tables 2-7 through 2-11 are dedicated to specific models. Each sheet lists the acceptable test ranges for the model and provides a place to record the results of the test.

Note	It is recommended that before you perform the tests in either Table 2-4 or Table 2-5, that you first locate
	the appropriate Performance Test Record sheet from Tables 2-7 through Table 2-11 for your specific
	model. Make a copy of this sheet, and record the actual observed values in it while performing the tests.
	Use the sheets in Tables 2-7 through Table 2-11 as master reference sheets to run copies at any time.

Verification 13

Operation Verification Tests

Table 2-3 lists the requirements for operation verification, which is a subset of the performance tests.

Table 2-3. Operation Verification Tests

	Test	Refer To
1	Turn-On Checkout	Power Supply Operating Manual
2	Voltage Programming and Readback Accuracy	Table 2-4
3	Current Programming and Readback Accuracy	Table 2-5

Note: Record the results of Tests 2 and 3 in the appropriate Performance Test Record sheets

Performance Tests

Performance tests check all the specifications of the power supply. The tests are grouped into constant-voltage mode tests (Table 2-4) and constant-current mode tests (Table 2-5).

Constant Voltage (CV) Tests

Test Setup

Connect your dc voltmeter leads to only +S and -S (see Figure 2-1), because the power supply regulates the voltage between these points, not between the + and - output terminals .

Test Procedures

Perform the test procedures in Table 2-4. The CV tests are:

•Voltage Programming and Readback Accuracy

•CV Load Effect

•CV Source Effect

•CV Noise (PARD)

•Transient Recovery Time

Note	The tests are independent and may be performed in any order.

14 Verification

Figure 2-1. Constant Voltage (CV) Test Setup

Verification 15

Table 2-4. Constant Voltage (CV) Tests

	Action	Normal Result

Voltage Programming and Readback Accuracy

This test verifies that the voltage programming, GPIB readback (GPIB system power supplies only), and front panel display functions are within specifications. With system power supplies, values read back over the GPIB should be the same as those displayed on the front panel.

1Turn off the power supply and connect a DVM across +S and -S (see Fig. 2-1).

2Turn on the power supply with no load and program the output for 0 volts and maximum programmable current (see Table 2-2).

3Record voltage readings at DVM and on front panel display.

4Program voltage to full scale (see Table 2-2).

5Record voltage readings of DVM and on front panel display.

CV annunciator on. Output current near 0.

Readings within specified Low Voltage limits.

Readings within specified High Voltage limits.

CV Load Effect

This test measures the change in output voltage resulting from a change in output current from full-load to no-load.

1Turn off the power supply and connect a DVM across +S and -S (see Fig. 2-1).

2Turn on the power supply and program the current to its maximum programmable value and the voltage to its full-scale value (see Table 2-2).

3Adjust the load to produce full-scale current (see Table 2-2) as shown on the front panel display.

4Record voltage reading of the DVM.

5Adjust load to draw 0 amperes (open load). Record voltage reading of the DVM.

6Check test result.

CV annunciator is on. If it is not, adjust the load to slightly reduce the output current until the annunciator comes on.

The difference between the DVM readings in steps 4 and 5 are within the specified Load Effect limits.

CV Source Effect

This test measures the change in output voltage resulting from a change in ac line voltage from its minimum to maximum value within the line voltage specifications.

1Turn off the power supply and connect the ac power input through a variable-voltage transformer.

16 Verification

Table 2-4. Constant Voltage (CV) Tests (continued)

	Action	Normal Result

CV Source Effect (cont)

2Set the transformer to the nominal ac line voltage. Connect the DVM across +S and -S (see Fig. 2-1).

3Turn on the power supply and program the current to its maximum programmable value and the voltage to its full-scale value (see Table 2-2).

4Adjust the load to produce full-scale current (see Table 2-2) as shown on the front panel display.

5Adjust the transformer to decrease the ac input voltage to the lowline condition (174Vac or 191Vac). Record the output voltage reading of the DVM.

6Adjust the transformer to increase the ac input voltage to the high-line condition (220Vac or 250Vac). Record the output voltage reading on the DVM.

7Check test result.

CV annunciator is on. If it is not, adjust the load to slightly reduce the output current until the annunciator comes on.

The difference between the DVM readings in steps 5 and 6 are within the specified Source Effect limits.

CV Noise (PARD)

Periodic and random deviations (PARD) in the output (ripple and noise) combine to produce a residual ac voltage superimposed on the dc output voltage. This test measures CV PARD, specified as the rms and peak-to-peak output voltages over the frequency range of 20Hz to 20MHz.

1Turn off the power supply and connect an a-c coupled oscilloscope across the + and -output terminals (see Fig. 2-1). Set the oscilloscope bandwidth limit to 20MHz (30MHz for the Agilent 54504A) and use an RF tip on the oscilloscope probe.

2Turn on the power supply and program the current to its maximum programmable value and the voltage to its full-scale value (see Table 2-2).

3Adjust the load to produce full-scale current (see Table 2-2) as shown on the front panel display.

4Record the amplitude of the waveform.

5Replace the oscilloscope connection with an ac rms voltmeter.

6Record the reading obtained in Step 5.

CV annunciator is on. If it is not, adjust the load to slightly reduce the output current until the annunciator comes on.

Amplitude is within the specified PARD Peak-to-Peak limits.

Amplitude is within the specified PARD rms limits.

Verification 17

Table 2-4. Constant Voltage (CV) Tests (continued)

	Action	Normal Result

Transient Recovery Time

This test measures the time required for the output voltage to return to within 100mV of its final value following a 50% change in output load current. Measurements are made on both the unloading transient (from full load to 1/2 load) and the loading transient (from 1/2 load to full load).

1Turn off the power supply and connect an oscilloscope across +S and -S (see Fig. 2-1).

2Turn on the power supply and program the current to its maximum programmable value and the voltage to its full-scale value (see Table 2-2).

3Program the Electronic Load as follows:

þOperating mode to constant current.

þInput load current to 1/2 the supply's full rated output current.

þTransient current level to the supply's full rated output current.

þTransient generator frequency = 100Hz.

þTransient generator duty cycle = 50%.

4Turn on the transient and adjust the oscilloscope to display response waveform.

5Measure both the loading and unloading transients by triggering the oscilloscope on both the negative and positive slopes of the transient. Record the voltage level obtained at the 900- s interval .

See Fig. 2-2.

Specified voltage level is reached within 900 s.

Figure 2-2. Transient Response Waveform

18 Verification

Constant Current (CC) Tests

Test Setup

Connect the appropriate current monitoring resistor (see Table 2-l) as shown in Fig. 2-3. The accuracy of the resistor must be as specified in the table.

Test Procedures

The test procedures are given in Table 2-5. The tests are independent and may be performed in any order. The CC tests are:

•Current Programming and Readback Accuracy.

•CC Load Effect.

•CC Source Effect.

•CC Noise (PARD).

Table 2-5. Constant Current (CC) Tests

	Action	Normal Result

Current Programming and Readback Accuracy

This test verifies that the current programming and readback are within specification.

1Turn off the power supply and connect the current monitoring resistor as shown in Fig. 2-3. Connect a DVM across the resistor .

2Turn on the power supply and program the output for 5 volts and 0 amperes.

3Short the load.

4Observe the DVM voltage reading. Divide this by the resistance of the current monitor resistor. Record the result as the Low Current value.

5Record the front panel display readback.

6Program output current to full scale (see Table 2-2).

7Repeat Steps 4 and 5.

Value within specified Low Current limits.

Value within specified readback limits.

Both current readings within specified High Current and readback limits.

CC Noise (PARD)

Periodic and random deviations (PARD) in the output (ripple and noise) combine to produce a residual ac current superimposed on the dc output current. This test measures CC PARD, specified as the rms output current over the frequency range of 20 Hz to 20 MHz.

1Turn off the power supply and connect the current transformer, resistor, capacitor and rms voltmeter (see Fig. 2-4).

Verification 19

Table 2-5. Constant Current (CC) Tests (continued)

	Action	Normal Result

CC Noise (PARD) (cont)

2Measure the residual noise on the DVM with the power supply turned off. Noise generated by other equipment may affect this measurement and should be removed or factored out.

3Turn on the power supply and program the current to its full scale value and the voltage to its maximum programmable value (see Table 2-2).

4Adjust the load in the CV mode for full-scale voltage (see Table 2-2) as shown on the front panel display.

5Observe the reading on the rms voltmeter. Multiply rms voltage by 0.1 to obtain the rms noise current.

The power supply output current should be at its full-scale value and the CC annunciator on. If it is not, adjust the load to slightly reduce the output voltage until the annunciator comes on.

Current is within the specified PARD rms limits (see Table 2-6).

CC Load Effect

This test measures the change in output current resulting from a change in load from full-load voltage to a short circuit. It is recommended that you use averaged readings for Steps 5 and 6 of this test (see Averaging AC Measurements at the end of this chapter).

Note: Refer to Figure 2-4. If you are using Agilent 60504B Eloads, a series DC power source is required to supply the minimum 3 volt input required by the Agilent 60504B Eloads. The series DC source must be capable of 3VDC at a current level greater than the output current of the supply being tested. A switch can be used in place of the series supply if the Eloads are used in place of a load resistor as shown in Fig. 2-4(b).

1Turn off the power supply and connect a DVM across the current monitoring resistor (see Fig. 2-3).

2Turn on the power supply and program the current to its full scale value and the voltage to its maximum programmable value (see Table 2-2).

3Set the Electronic Load to CV mode and its voltage to full scale as indicated on its front panel display. Set the series supply for 3VDC and a current greater than that being tested. Series source should be in CV mode.

4Observe the DVM reading. Divide this by the resistance of the current monitoring resistor to obtain the output current. Record the result.

5Program the Electronic Load input to 3 volts or short the Electronic Load input and repeat Step 5.

6Check the result.

Power supply output current is full scale and its CC annunciator is on. If not, reduce the Electronic Load voltage slightly until the annunciator comes on.

You may want to use an averaged reading for this measurement.

You may want to use averaged reading for this measurement.

The difference between the current readings taken in Step 5 and Step 6 must be within specified “Load Effect” limits (see Table 2-2).

20 Verification

Table 2-5. Constant Current (CC) Tests (continued)

	Action	Normal Result

CC Source Effect

This test measures the change in output current resulting from a change in ac line voltage from its minimum to its maximum value within the line voltage specifications. It is recommended that you use averaged readings for Steps 6 and 8 of this test (see "Averaging AC Measurements" at the end of this chapter) .

1Turn off the power supply and connect the ac power input through a variable-voltage transformer.

2Set the transformer to the nominal ac line voltage. Connect the DVM across the current monitoring resistor (see Fig. 2-3).

3Turn on the power supply and program the current to its full-scale value and the voltage to its maximum programmable value (see Table 2-2).

4Set the Electronic Load to CV mode and its voltage to full scale.

5Adjust the transformer to decrease the ac input voltage to the low-line condition (180Vac or 360Vac).

6Observe the DVM reading. Divide this voltage by the resistance of the current monitoring resistor to obtain the output current. Record the result.

7Adjust the transformer to increase the ac input voltage to the high-line condition (235Vac or 440Vac).

8Observe the DVM reading. Divide this voltage by the resistance of the current monitoring resistor to obtain the output current. Record the result.

9Check the test result.

The power supply output current is full scale and its CC annunciator is on. If not, reduce the Electronic Load voltage slightly until the annunciator comes on.

You may want to use an averaged reading for this measurement.

You may want to use an averaged reading for this measurement.

The difference between the current readings found in Step 6 and Step 8 is within the specified current Source Effect limits.

Verification 21

Figure 2-3. CC Load Effect Test Setup

22 Verification

Figure 2-4. CC rms Noise Test Setup

Verification 23

Averaging the CC Measurements

The CC Load Effect and CC Source Effect tests measure the dc regulation of the power supply's output current. When doing these tests, you must be sure that the readings taken are truly dc regulation values and not instantaneous ac peaks of the output current ripple. You can do this by making each measurement several times and then using the average of the measurements as your test value. Voltmeters such as the Agilent 3458A System Voltmeter can be programmed to take just such statistical average readings as required by these tests.

The following steps show how to set up the voltmeter from its front panel to take a statistical average of l00 readings. represents the unlabeled shift key in the FUNCTION/RANGE group.

1.Program 10 power line cycles per sample by pressing .

2.Program 100 samples per trigger by pressing .

3.Set up voltmeter to take measurements in the statistical mode as follows:

a.	Press	.
b.	Press	until MATH function is selected, then press	.
c.	Press	until STAT function is selected, then press	.

4.Now set up voltmeter to read the average of the measurements as follows:

a.	Press	.
b.	Press	until RMATH function is selected, then press		.
c.	Press	until MEAN function is selected, then press		.
5. Execute the average reading program by pressing						.

6. Wait for 100 readings and then read the average measurement by pressing .

Record this as your result.

24 Verification

Table 2-6. Performance Test Record Form

Test Facility:

__________________________________________	Report No.__________________________________________
__________________________________________	Date______________________________________________
__________________________________________	Customer___________________________________________
__________________________________________	Tested By___________________________________________
Model_____________________________________	Ambient Temperature (°C)______________________________
Serial No.__________________________________	Relative Humidity (%)_________________________________
Options ____________________________________	Nominal Line Frequency (Hz)___________________________
Firmware Revision ___________________________
Special Notes:

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

____________________________________________________________________________________________

Test Equipment Used:
Description		Model No.	Trace No.	Cal. Due Date
1.	AC Source	_______________	_______________	_________________
2.	DC Voltmeter	_______________	_______________	_________________
3.	RMS Voltmeter	_______________	_______________	_________________
4.	Oscilloscope	_______________	_______________	_________________
5.	Electronic Load	_______________	_______________	_________________
6.	Current Monitoring	_______________	_______________	_________________
	Shunt

Verification 25

Table 2-7. Performance Test Record for Agilent Model 6680A

MODEL Agilent _____________		Report No.______________		Date_____________________
Test Description		Minimum	Results	Maximum	Measurement
		Spec.	*	Spec.	Uncertainty
		Constant Voltage Tests
Voltage Programming
and Readback
Low Voltage (0V) Vout		-5mV	________mV	+5mV	1.6 V
Front Panel Display Readback		Vout - 7.5mV	________mV	Vout + 7.5mV	1.6 V
High Voltage (5V) Vout		4.993V	_________V	5.007V	56 V
Front Panel Display Readback		Vout - 10mV	_______mV	Vout + 10mV	56 V
Load Effect		Vout - 0.3mV	_______mV	Vout + 0.3mV	750 nV
Source Effect		Vout - 0.3mV	_______mV	Vout + 0.3mV	750 nV
PARD (Ripple and Noise)
Peak-to-Peak		0	_______mV	10mV	904 V
RMS		0	_______mV	1.5mV	150 V
Transient Response Time		0	_______mV	150mV	23mV
(at 900 s)
		Constant Current Tests
Current Programming
and Readback
Low Current (0A) Iout		-450mA	_______mA	+450mA	15 A
Front Panel Display Readback		Iout - 600mA	_______mA	Iout + 600mA	15 A
High Current (875A) Iout		873.675A	_________A	+876.325A	462mA
Front Panel Display Readback		Iout - 1.475mA	_______mA	Iout + 1.475mA	462mA
PARD (Ripple and Noise)		0	________mA	290mA	3.8mA
RMS
Load Effect		Iout - 108mA	________mA	Iout + 108mA	937 A
Source Effect		Iout - 108mA	________mA	Iout + 108mA	937 A
	*Enter your test results in this column.

26 Verification

Table 2-7. Performance Test Record for Agilent Model 6681A

MODEL Agilent_____________		Report No.______________		Date_____________________
Test Description		Minimum	Results	Maximum	Measurement
		Spec.	*	Spec.	Uncertainty
		Constant Voltage Tests
Voltage Programming
and Readback
Low Voltage (0V) Vout		-8mV	________mV	+8mV	1.6 V
Front Panel Display Readback		Vout - 12mV	________mV	Vout + 12mV	1.6 V
High Voltage (8V) Vout		7.988V	_________V	8.011V	88 V
Front Panel Display Readback		Vout - 16mV	_______mV	Vout + 16mV	88 V
Load Effect		Vout - 0.5mV	_______mV	Vout + 0.5mV	900 nV
Source Effect		Vout - 0.5mV	_______mV	Vout + 0.5mV	900 nV
PARD (Ripple and Noise)
Peak-to-Peak		0	_______mV	10mV	904 V
RMS		0	_______mV	1.5 mV	150 V
Transient Response Time		0	_______mV	150mV	23mV
(at 900 s)
		Constant Current Tests
Current Programming
and Readback
Low Current (0A) Iout		-300mA	_______mA	+300mA	15mA
Front Panel Display Readback		Iout -400mA	_______mA	Iout +400mA	15mA
High Current (580A) Iout		579.120A	_________A	+580.880A	311mA
Front Panel Display Readback		Iout -980mA	________A	Iout + 980mA	311mA
PARD (Ripple and Noise)
RMS		0	________mA	190mA	3.8mA
Load Effect		Iout - 69mA	________mA	Iout +69mA	790 A
Source Effect		Iout - 69mA	________mA	Iout + 69mA	790 A
	*Enter your test results in this column.

Verification 27

Table 2-7. Performance Test Record for Agilent Model 6682A

MODEL Agilent_____________		Report No.______________		Date_____________________
Test Description		Minimum	Results	Maximum	Measurement
		Spec.	*	Spec.	Uncertainty
		Constant Voltage Tests
Voltage Programming
and Readback
Low Voltage (0V) Vout		-21mV	________mV	+21mV	1.7 V
Front Panel Display Readback		Vout - 32mV	________mV	Vout + 32mV	1.7 V
High Voltage (21V) Vout		20.970V	_________V	21.029V	347 V
Front Panel Display Readback		Vout -42mV	_______mV	Vout + 42mV	347 V
Load Effect		Vout - 1mV	_______mV	Vout + 1mV	20 V
Source Effect		Vout - 1mV	_______mV	Vout +1mV	20 V
PARD (Ripple and Noise)
Peak-to-Peak		0	_______mV	10mV	904 V
RMS		0	_______mV	1.75 mV	150 V
Transient Response Time		0	_______mV	150mV	23 V
(at 900 s)
		Constant Current Tests
Current Programming
and Readback
Low Current (0A) Iout		-125mA	_______mA	+125mA	1.5mA
Front Panel Display Readback		Iout - 165mA	_______mA	Iout + 165mA	1.5mA
High Current (240A) Iout		239.635A	_________A	+240.365A	84mA
Front Panel Display Readback		Iout - 405mA	_______mA	Iout + 405mA	84mA
PARD (Ripple and Noise)
RMS		0	________mA	80mA	0.8mA
Load Effect		Iout - 24mA	________mA	Iout + 24mA	172 A
Source Effect		Iout - 24mA	________mA	Iout + 24mA	172 A
	*Enter your test results in this column.

28 Verification

Table 2-7. Performance Test Record for Agilent Model 6683A

MODEL Agilent_____________		Report No.______________		Date_____________________
Test Description		Minimum	Results	Maximum	Measurement
		Spec.	*	Spec.	Uncertainty
		Constant Voltage Tests
Voltage Programming
and Readback
Low Voltage (0V) Vout		-32mV	________mV	+32mV	1.9 V
Front Panel Display Readback		Vout - 48mV	________mV	Vout + 48mV	1.9 V
High Voltage (32V) Vout		31.995V	_________V	32.044V	488 V
Front Panel Display Readback		Vout - 64mV	_______mV	Vout + 64mV	488 V
Load Effect		Vout - 1.7mV	_______mV	Vout + 1.7mV	26 V
Source Effect		Vout - 1.7mV	_______mV	Vout + 1.7mV	26 V
PARD (Ripple and Noise)
Peak-to-Peak		0	_______mV	10mV	904 V
RMS		0	_______mV	2.0mV	150 V
Transient Response Time		0	_______mV	150mV	23 V
(at 900 s)
		Constant Current Tests
Current Programming
and Readback
Low Current (0A) Iout		-85mA	_______mA	+85mA	1.5mA
Front Panel Display Readback		Iout - 110mA	_______mA	Iout + 110mA	1.5mA
High Current (160A) Iout		159.755A	_________A	+160.245A	36mA
Front Panel Display Readback		Iout - 270mA	_______mA	Iout + 270mA	36mA
PARD (Ripple and Noise)		0	________mA	55mA	0.56mA
RMS
Load Effect		Iout - 18mA	________mA	Iout + 18mA	148 A
Source Effect		Iout - 18mA	________mA	Iout + 18mA	148 A
	*Enter your test results in this column.

Verification 29

Table 2-7. Performance Test Record for Agilent Model 6684A

MODEL Agilent_____________		Report No.______________		Date_____________________
Test Description		Minimum	Results	Maximum	Measurement
		Spec.	*	Spec.	Uncertainty
		Constant Voltage Tests
Voltage Programming
and Readback
Low Voltage (0V) Vout		-40mV	________mV	+40mV	2 V
Front Panel Display Readback		Vout - 60mV	________mV	Vout + 60mV	2 V
High Voltage (40V) Vout		39.944V	_________V	40.056V	590 V
Front Panel Display Readback		Vout - 80mV	_______mV	Vout + 80mV	590 V
Load Effect		Vout - 2.3mV	_______mV	Vout + 2.3mV	30 V
Source Effect		Vout -2.3mV	_______mV	Vout + 2.3mV	30 V
PARD (Ripple and Noise)
Peak-to-Peak		0	_______mV	10mV	904 V
RMS		0	_______mV	2.5mV	150 V
Transient Response Time		0	_______mV	150mV	23 V
(at 900 s)
		Constant Current Tests
Current Programming
and Readback
Low Current (0A) Iout		-65mA	_______mA	+65mA	1.5mA
Front Panel Display Readback		Iout - 90mA	_______mA	Iout + 90mA	1.5mA
High Current (128A) Iout		127.807A	_________A	+128.193A	24mA
Front Panel Display Readback		Iout - 218mA	_______mA	Iout + 218mA	24mA
PARD (Ripple and Noise)		0	________mA	45mA	0.23mA
RMS
Load Effect		Iout - 15mA	________mA	Iout + 15mA	138mA
Source Effect		Iout - 15mA	________mA	Iout + 15mA	138mA
	*Enter your test results in this column.

30 Verification

3

Troubleshooting

Shock Hazard: Most of the procedures in this chapter must be performed with power applied and protective covers removed. These procedures should be done only by trained service personnel aware of the hazard from electrical shock.

This instrument uses components that can be damaged or suffer serious performance degradation due to ESD (electrostatic discharge). Observe standard antistatic precautions to avoid damage to the components (see Chapter 1).

Introduction

Localizing the Problem

This chapter provides troubleshooting and repair information for the power supply. Before beginning troubleshooting procedures, make certain the problem is in the power supply and not with an associated circuit, the GPIB controller (for GPIB system power supplies), or ac input line. Without removing the covers, you can use the Verification tests in Chapter 2 to determine if the power supply is operating normally.

Chapter Organization

The information in this chapter is organized as follows:

Topic	Information Given
Test Equipment Required	Equipment required for completing all the tests in this chapter.
Troubleshooting Procedures	A series of flow charts for systematic location of defective boards, circuits, and
	components. An explanation of the error codes and messages generated during the
	power-on selftest. Signature analysis techniques for troubleshooting the digital circuits
	on the front panel, primary GPIB, and secondary interface circuits. Specific
	paragraphs for:
	• Checking the bias and reference supplies.
	• Troubleshooting the CV/CC status annunciators.
	• Troubleshooting the A3 FET board.
Post-Repair Adjustments	Calibration and EEPROM initialization procedures required after the replacement of
	certain critical components.
Disassembly Procedures	Gaining access to and/or replacing components.

Troubleshooting 31