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.

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.

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 (Intended for connection to external protective conductor.)

Frame or chassis terminal On (supply)

Terminal for Neutral conductor on permanently installed equipment

Terminal is at earth potential (Used for measurement and control circuits designed to be operated with one terminal at earth potential.)

Printing History

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

Edition 1 April 1994 Edition 2 September, 2000

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.

Out position of a bi-stable push control

Off (supply)

Standby (supply) Units with this symbol are not completely disconnected from ac mains when this switch is off. To completely disconnect the unit from ac mains, either disconnect the power cord or have a qualified electrician install an external switch.

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

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

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

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.

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

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.

observe standard, antistatic practices can result in serious degradation of performance, even when an

Introduction

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

Operation Verification These tests do not check all parameters, but comprise a short procedure to verify that the power

Performance

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.

Purpose

supply is performing properly.

These tests verify all the Specifications (not Supplementary Characteristics) listed in Table 1-1 of the Power Supply Operating Manual.

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 "

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.

'' is needed for the Operation Verification test.

Verification 11

Table 2-1. Test Equipment Required

Type Required Characteristics

Digital Voltmeter

Current Monitor Resistor

DC Power Supply

Resolution: 10 nV @ 1V Agilent 3458A Readout: 8 1/2 digits Accuracy: 20 ppm

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 Source with current capability

equal to UUT

Electronic Load

Resistor Load

Range: Voltage and current range must

exceed that of supply under test. Power:

5.4KW minimum

or 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 Variable-Voltage

Transformer (AC Source)

0.1Volt per ampere: 1Hz to 20MHz Pearson Model 411 Power: 3 Phase 24KVA; Range:

180-235V 47 - 63Hz; 360- 440V

47 - 63Hz

GPIB Controller

Full GPIB capabilities

1 Required for Operation Verification Tests.

Required for remote testing of 668xA models.

Recommended Model

Agilent 6680A

3 each Agilent 6050A, w/3 each

Agilent 60504B per Agilent 6050A for all units

Superior Powerstat 1156DT-3Y, 0-280V, 50A,

24.2 KVA or equivalent .

HP Series 200/300

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

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.

Agilent Model Full Scale Max. Prog. Full Scale Max. Prog. Max. Prog.

Agilent 6680A 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

other, severe arcing can occur resulting in burns, ignition or welding of parts. DO NOT ATTEMPT

Table 2-2. Programming Voltage and Current Values

Voltage Voltage Current Current Overvoltage

5V 5.125V 875A 895A 6.25V

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

2 Voltage Programming and Readback Accuracy

3 Current Programming and Readback Accuracy

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).

Power Supply Operating Manual

Table 2-4

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

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.

1 Turn off the power supply and connect a DVM across +S and -S

(see Fig. 2-1).

2 Turn on the power supply with no load and program the output for 0 volts

and maximum programmable current (see Table 2-2).

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

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

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

CV Load Effect

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

1 Turn off the power supply and connect a DVM across +S and -S

(see Fig. 2-1).

2 Turn 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).

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

the front panel display.

4 Record voltage reading of the DVM.

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

DVM.

6 Check test result.

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.

1 Turn off the power supply and connect the ac power input through a

variable-voltage transformer.

CV annunciator on. Output current near

Readings within specified Low Voltage limits.

Readings within specified High Voltage limits.

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.

Normal Result

16 Verification

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

Action

CV Source Effect (cont)

2 Set the transformer to the nominal ac line voltage. Connect the DVM

across +S and -S (see Fig. 2-1).

3 Turn 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).

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

the front panel display.

5 Adjust the transformer to decrease the ac input voltage to the low- line

condition (174Vac or 191Vac). Record the output voltage reading of the DVM.

6 Adjust the transformer to increase the ac input voltage to the high-line

condition (220Vac or 250Vac). Record the output voltage reading on the DVM.

7 Check test result.

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.

1 Turn 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.

2 Turn 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).

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

the front panel display.

4 Record the amplitude of the waveform.

5 Replace the oscilloscope connection with an ac rms voltmeter.

6 Record 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.

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

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.

Normal Result

Verification 17

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

Action

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).

1 Turn off the power supply and connect an oscilloscope across +S and -S

(see Fig. 2-1).

2 Turn 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).

3 Program the Electronic Load as follows:

þ Operating mode to constant current. þ Input load current to 1/2 the supply's full rated output current. þ Transient current level to the supply's full rated output current. þ Transient generator frequency = 100Hz. þ Transient generator duty cycle = 50%.

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

waveform.

5 Measure 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-µs interval .

See Fig. 2-2.

Specified voltage level is reached within

900µs.

Normal Result

18 Verification

Figure 2-2. Transient Response Waveform

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.

1 Turn off the power supply and connect the current monitoring resistor as

shown in Fig. 2-3. Connect a DVM across the resistor .

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

amperes.

3 Short the load.

4 Observe the DVM voltage reading. Divide this by the resistance of the

current monitor resistor. Record the result as the Low Current value.

5 Record the front panel display readback. Value within specified readback limits.

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

7 Repeat Steps 4 and 5. Both current readings within specified

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.

1 Turn off the power supply and connect the current transformer, resistor,

capacitor and rms voltmeter (see Fig. 2-4).

Value within specified Low Current limits.

High Current and readback limits.

Verification 19

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

Action Normal Result

CC Noise (PARD) (cont)

2 Measure 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.

3 Turn 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).

4 Adjust the load in the CV mode for full-scale voltage (see Table 2-2) as

shown on the front panel display.

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

obtain the rms noise current.

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).

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).

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).

1 Turn off the power supply and connect a DVM across the current

monitoring resistor (see Fig. 2-3).

2 Turn 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).

3 Set 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.

4 Observe the DVM reading. Divide this by the resistance of the current

monitoring resistor to obtain the output current. Record the result.

5 Program the Electronic Load input to 3 volts or short the Electronic Load

input and repeat Step 5.

6 Check the result. The difference between the current

20 Verification

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.

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

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) .

1 Turn off the power supply and connect the ac power input through a

variable-voltage transformer.

2 Set the transformer to the nominal ac line voltage. Connect the DVM

across the current monitoring resistor (see Fig. 2-3).

3 Turn 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).

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

5 Adjust the transformer to decrease the ac input voltage to the low-line

condition (180Vac or 360Vac).

6 Observe the DVM reading. Divide this voltage by the resistance of the

current monitoring resistor to obtain the output current. Record the result.

7 Adjust the transformer to increase the ac input voltage to the high-line

condition (235Vac or 440Vac).

8 Observe the DVM reading. Divide this voltage by the resistance of the

current monitoring resistor to obtain the output current. Record the result.

9 Check the test result. The difference between the current

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

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

Verification 21

22 Verification

Figure 2-3. CC Load Effect Test Setup

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

c. Press

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

b. Press

c. 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.

. until MATH function is selected, then press .

until STAT function is selected, then press .

until RMATH function is selected, then press .

until MEAN function is selected, then press .

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

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (5V) V

out

Front Panel Display Readback

Load Effect

Source Effect

PARD (Ripple and Noise)

Peak-to-Peak RMS

Transient Response Time (at 900 µµµµs)

Minimum

Spec.

Results

Maximum

Spec.

Constant Voltage Tests

-5mV

- 7.5mV

out

4.993V

- 10mV

out

- 0.3mV _______mV V

out

- 0.3mV _______mV V

out

0 0

________mV ________mV

_________V

_______mV

_______mV _______mV

+5mV

+ 7.5mV

out

5.007V

+ 10mV

out

+ 0.3mV 750 nV

out

+ 0.3mV 750 nV

out

10mV

1.5mV

0 _______mV 150mV 23mV

Measurement

Uncertainty

1.6 µV

56 µV 56 µV

904 µV 150 µV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (875A) I

out

Front Panel Display Readback

PARD (Ripple and Noise)

RMS

Load Effect

Source Effect

Constant Current Tests

-450mA

- 600mA

out

873.675A

- 1.475mA

out

_______mA _______mA

_________A

_______mA

0 ________mA 290mA 3.8mA

- 108mA ________mA I

out

- 108mA ________mA I

out

*Enter your test results in this column.

+450mA

+ 600mA

out

+876.325A

+ 1.475mA

out

+ 108mA 937 µA

out

+ 108mA 937 µA

out

15 µA 15 µA

462mA 462mA

26 Verification

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

MODEL Agilent_____________

Report No.______________ Date_____________________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (8V) V

out

Front Panel Display Readback

Load Effect

Source Effect

PARD (Ripple and Noise)

Peak-to-Peak RMS

Transient Response Time (at 900 µµµµs)

Minimum

Spec.

Results

Maximum

Spec.

Constant Voltage Tests

-8mV

- 12mV

out

7.988V

- 16mV

out

- 0.5mV _______mV V

out

- 0.5mV _______mV V

out

0 0

________mV ________mV

_________V

_______mV

_______mV _______mV

+8mV

+ 12mV

out

8.011V

+ 16mV

out

+ 0.5mV 900 nV

out

+ 0.5mV 900 nV

out

10mV

1.5 mV

0 _______mV 150mV 23mV

Measurement

Uncertainty

1.6 µV

88 µV 88 µV

904 µV 150 µV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (580A) I

out

Front Panel Display Readback

PARD (Ripple and Noise)

RMS

Load Effect

Source Effect

Constant Current Tests

-300mA

-400mA

out

579.120A

-980mA

out

_______mA _______mA

_________A

________A

0 ________mA 190mA 3.8mA

- 69mA ________mA I

out

- 69mA ________mA I

out

*Enter your test results in this column.

+300mA

+400mA

out

+580.880A

+ 980mA

out

+69mA 790 µA

out

+ 69mA 790 µA

out

15mA 15mA

311mA 311mA

Verification 27

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

MODEL Agilent_____________

Report No.______________ Date_____________________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (21V) V

out

Front Panel Display Readback

Load Effect

Source Effect

PARD (Ripple and Noise)

Peak-to-Peak RMS

Transient Response Time (at 900 µµµµs)

Minimum

Spec.

Results

Maximum

Spec.

Constant Voltage Tests

-21mV

- 32mV

out

20.970V

-42mV

out

- 1mV _______mV V

out

- 1mV _______mV V

out

0 0

________mV ________mV

_________V

_______mV

_______mV _______mV

+21mV

+ 32mV

out

21.029V

+ 42mV

out

+ 1mV 20 µV

out

+1mV 20 µV

out

10mV

1.75 mV

0 _______mV 150mV 23 µV

Measurement

Uncertainty

1.7 µV

347 µV 347 µV

904 µV 150 µV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (240A) I

out

Front Panel Display Readback

PARD (Ripple and Noise)

RMS

Load Effect

Source Effect

Constant Current Tests

-125mA

- 165mA

out

239.635A

- 405mA

out

_______mA _______mA

_________A

_______mA

0 ________mA 80mA 0.8mA

- 24mA ________mA I

out

- 24mA ________mA I

out

*Enter your test results in this column.

+125mA

+ 165mA

out

+240.365A

+ 405mA

out

+ 24mA 172 µA

out

+ 24mA 172 µA

out

1.5mA

84mA 84mA

28 Verification

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

MODEL Agilent_____________

Report No.______________ Date_____________________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (32V) V

out

Front Panel Display Readback

Load Effect

Source Effect

PARD (Ripple and Noise)

Peak-to-Peak RMS

Transient Response Time (at 900 µµµµs)

Minimum

Spec.

Results

Maximum

Spec.

Constant Voltage Tests

-32mV

- 48mV

out

31.995V

- 64mV

out

- 1.7mV _______mV V

out

- 1.7mV _______mV V

out

0 0

________mV ________mV

_________V

_______mV

_______mV _______mV

+32mV

+ 48mV

out

32.044V

+ 64mV

out

+ 1.7mV 26 µV

out

+ 1.7mV 26 µV

out

10mV

2.0mV

0 _______mV 150mV 23 µV

Measurement

Uncertainty

1.9 µV

488 µV 488 µV

904 µV 150 µV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (160A) I

out

Front Panel Display Readback

PARD (Ripple and Noise)

RMS

Load Effect

Source Effect

Constant Current Tests

-85mA

- 110mA

out

159.755A

- 270mA

out

_______mA _______mA

_________A

_______mA

0 ________mA 55mA 0.56mA

- 18mA ________mA I

out

- 18mA ________mA I

out

*Enter your test results in this column.

+85mA

+ 110mA

out

+160.245A

+ 270mA

out

+ 18mA 148 µA

out

+ 18mA 148 µA

out

1.5mA

36mA 36mA

Verification 29

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

MODEL Agilent_____________

Report No.______________ Date_____________________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (40V) V

out

Front Panel Display Readback

Load Effect

Source Effect

PARD (Ripple and Noise)

Peak-to-Peak RMS

Transient Response Time (at 900 µµµµs)

Minimum

Spec.

Results

Maximum

Spec.

Constant Voltage Tests

-40mV

- 60mV

out

39.944V

- 80mV

out

- 2.3mV _______mV V

out

-2.3mV _______mV V

out

0 0

________mV ________mV

_________V

_______mV

_______mV _______mV

+40mV

+ 60mV

out

40.056V

+ 80mV

out

+ 2.3mV 30 µV

out

+ 2.3mV 30 µV

out

10mV

2.5mV

0 _______mV 150mV 23 µV

Measurement

Uncertainty

2 µV 2 µV

590 µV 590 µV

904 µV 150 µV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (128A) I

out

Front Panel Display Readback

PARD (Ripple and Noise)

RMS

Load Effect

Source Effect

Constant Current Tests

-65mA

- 90mA

out

127.807A

- 218mA

out

_______mA _______mA

_________A

_______mA

0 ________mA 45mA 0.23mA

- 15mA ________mA I

out

- 15mA ________mA I

out

*Enter your test results in this column.

+65mA

+ 90mA

out

+128.193A

+ 218mA

out

+ 15mA 138mA

out

+ 15mA 138mA

out

1.5mA

24mA 24mA

30 Verification

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

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