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

Test Equipment Required

Table 3-1. Test Equipment Required

Equipment Purpose Recommended Model

Logic Probe To check states of data lines. Agilent 545A Test Clips To gain access to IC pins. AP Products No. LTC Ammeter/Current Shunt To measure output current. Agilent 6680A & 6681A:

Burster 1280 Agilent 6682A, 6683A & 6684A:

Guildline 9230/300 Oscilloscope To check waveforms and signal levels. Agilent 54504A Signature Analyzer To troubleshoot most of the primary Agilent 5005A/B

and secondary interface circuits.

GPIB Controller To communicate with power supply via

the GPIB (for system units).

DC Voltmeter To measure output voltage and current,

bias and references.

Agilent BASIC series

Agilent 3458A

Troubleshooting Procedures

Power-On Selftest

Description

The procedures in the troubleshooting charts make use of the power-on selftest. The power-on selftest tests the front panel, GPIB interface (for GPIB system power supplies), and secondary interface circuits. If the power supply fails the selftest, the output remains disabled (turned off) and the front panel normally displays an error code or message (see Table 3-2). The message is displayed indefinitely and the power supply will not accept GPIB or front panel commands.

Disabling The Power-On Selftest

In order to perform troubleshooting procedures that require programming of the power supply, you must disable the power-on self test. Do this as follows:

1. Turn off the power supply.

2. Hold down the

3. Continue holding down the

4. The power supply is now on without executing power-on selftest.

Using the *TST? Query (GPIB Systems Supplies Only)

You can get the power supply to execute a partial selftest by sending it the GPIB *TST? query command. Table 3-2 shows the tests that are performed in response to this command. These tests do not interfere with normal operation or cause the output to change. The command returns a value of "0" if all tests pass. Otherwise, the command returns the error code of the first test that failed. No error codes are displayed on the front panel and the power supply will attempt to continue normal operation.

key and turn on the supply.

for 2 seconds and wait until the PWR ON INIT indicator goes off.

32 Troubleshooting

Table 3-2. Selftest Error Codes/Messages

Code and/or

Message

El FP RAM Front panel RAM test failed (power-on). Microprocessor AlU3

E2 FP ROM Front panel ROM test failed (power-on

and *TST?).

E3 EE CHKSM Front panel EEPROM checksum test failed

(power-on and *TST?).

E4 PRI XRAM Primary interface external RAM test failed

(power-on).

E5 PRI IRAM Primary interface internal RAM test failed

(power-on).

E6 PRI ROM Primary interface ROM test failed

(power-on and *TST?).

E7 GPIB GPIB interface test failed (power-on). Talker/listener A2U117

E8 SEC RAM Secondary interface RAM test failed

(power-on).

E9 SEC ROM Secondary interface ROM test failed

(power-on and *TST?).

E10 SEC 5V Secondary interface 5 volt readback test

failed (power-on and *TST?).

E11 TEMP Ambient temperature readback test failed

(power-on and *TST?).

E12 DACS CV or CC DAC tests failed (power-on). CV DAC Al0U510/U513 or CC DAC

Description Probable Cause Selftest Error

Codes/Messages

ROM AlU4 or address latches AlU8

Possibly due to power loss during a write operation. See Checksum Errors in Chapter 3 of Operating Manual. If power loss is not the problem, EEPROM A1U6 could be defective. (If you replace AlU6, the power supply must be reinitialized and calibrated.) RAM A2U108

Microprocessor A2U114

ROM A2U106

Microprocessor Al0U506

Comparators Al0U516, Al0U517 readback DAC A10U512/U515, or secondary bias supply (5Vs A4U304) Thermistor Al0RT500 or comparator Al0U517

A10U511/U514 (see Figure 3-7).

NOTE: The following error messages can appear due to a failure occurring either while the power supply is operating or during selftest.

SERIAL TIMOUT Serial data line failure on A2 board. See Figure 3-10 (system) or Figure 3-11 (bench).

SERIAL DOWN Serial data line failure on A2 board. See Figure 3-10 (system) or Figure 3-11 (bench).

UART PARITY UART failed. UART A2U112

UART FRAMING UART failed. UART A2U112

UART OVERRUN UART failed. UART A2U112

SBUF OVERRUN Serial buffer failure UART. UART A2U112 defective or GPIB board is in SA

mode

SBUF FULL Serial buffer failure. UART A2U112 defective or GPIB board is in SA

mode

EE WRITE ERR EEPROM write failure. EEPROM AlU6 defective or calibration error

SECONDARY DN Serial data line failure on Main board. See Figure 3-12.

Troubleshooting 33

Troubleshooting Charts

Figure 3-1 gives overall troubleshooting procedures to isolate the fault to a circuit board or particular circuit (see Figure 3-20 for the location of the circuit boards). These procedures include the use of power-on selftest (Table 3-2) and signature analysis techniques (Table 3-5 through Table 3-7). Some results of Figure 3-1 lead to more detailed troubleshooting charts that guide you to specific components. The troubleshooting charts are organized as follows:

Chart Trouble or Circuit

Figure 3-1 Overall procedure checks selftest errors, calibration errors, ac input circuit, fan, readback

circuits, A10 Control Board, GPIB cable, digital port, serial link, rotary controls, current amplifier.

Figure 3-2 No display (from Figure 3-1).

Figure 3-3 OV circuit not firing (from Figure 3-1). Figure 3-4 OV circuit is on at turn on (from Figure 3-1).

Figure 3-5 Output level is held low (from Figure 3-1).

Figure 3-6 Output level is held high (from Figure 3-1).

Figure 3-7 DAC circuits (from Figure 3-1). Figure 3-8 DAC test waveforms. Figure 3-9 CV and CC DAC and amplifiers (from Figure 3-1). Figure 3-10 Serial Down circuit (from Figure 3-1). Figure 3-11 Secondary interface circuit (from Figure 3-1). Figure 3-12 Slow downprogramming circuit (from Figure 3-1).

Troubleshooting Test Points

The troubleshooting charts reference test points listed in Table 6-3 of Chapter 6. Test points are identified by an encircled number (such as U in schematic diagrams and component location drawings, also in Chapter 6).

Bias and Reference Supplies

Many of the following troubleshooting procedures begin by checking the bias and/or reference voltages. Table 6-3 lists the test points for these voltages and gives the correct reading for each. The circuit board component location diagrams identify these points on each board.

34 Troubleshooting

Figure 3-1. Overall Troubleshooting (Sheet 1 of 4)

Troubleshooting 35

36 Troubleshooting

Figure 3-1. Overall Troubleshooting (Sheet 2 of 4)

Figure 3-1. Overall Troubleshooting (Sheet 3 of 4)

Troubleshooting 37

38 Troubleshooting

Figure 3-1. Overall Troubleshooting (Sheet 4 of 4)

Figure 3-2. No Display Troubleshooting

Troubleshooting 39

40 Troubleshooting

Figure 3-3. OV Will Not Fire Troubleshooting

Figure 3-4. OV At Turn-On Troubleshooting

Troubleshooting 41

42 Troubleshooting

Figure 3-5. Output Held Low Troubleshooting (Sheet 1 of 2)

Figure 3-5. Output Held Low Troubleshooting (Sheet 2 of 2)

Troubleshooting 43

44 Troubleshooting

Figure 3-6. Output Held High Troubleshooting

Figure 3-7. DAC Circuits Troubleshooting

Troubleshooting 45

46 Troubleshooting

Figure 3-8. DAC Test Waveforms

Figure 3-9. CV/CC DAC and Amplifier Circuit Troubleshooting

Troubleshooting 47

48 Troubleshooting

Figure 3-10. Serial Down Troubleshooting (Sheet 1 of 2) Figure 3-10. Serial Down Troubleshooting (Sheet 2 of 2)

Troubleshooting 49

50 Troubleshooting

Figure 3-11. Secondary Interface Down (Sheet 1 of 2) Figure 3-11. Secondary Interface Down (Sheet 2 of 2)

Troubleshooting 51

52 Troubleshooting

Figure 3-12. Slow Downprogramming Troubleshooting

CV/CC Status Annunciators Troubleshooting

When troubleshooting the CV/CC status annunciators or status readback circuits, first measure the voltage drop across the gating diodes, which are Al0D651 for the CC circuit and Al0D652 for the CV circuit (see A10, Sheet 2). A conducting diode indicates an active (ON) control circuit. This forward drop is applied to the input of the associated status comparator (A10U502) and drives the output low. The low signal indicates an active status which is sent to the secondary microprocessor A10U506 via Programmed GAL Al0U505 (see schematic Sheet 1). The front panel CV annunciator lights when the CV mode is active (CV is low) and the CC annunciator lights when the CC mode is active (CC is low). If neither is active, the UNREGULATED (Unr) annunciator comes on.

A3 FET Board Troubleshooting

Because test points on the FET board are not accessible when the board is installed, troubleshooting must be performed with the board removed from the power supply. Both static (power removed) and dynamic (power applied) troubleshooting procedures are provided. The location of different test points are shown by encircled numbers on the A3 FET Board schematic and component location diagrams (see Chapter 6). There are two isolated FET bridge assemblies (see schematic in Fig. 6-10 sheets 1 and 2). Test each FET bridge individually.

Note If any power FET (Q201-204, Q301-304, Q211, Q311, Q222, Q322, Q233, Q333, Q244, Q344) is

defective, you must replace all eight with a matched set.

Table 3-4. FET Troubleshooting Chart

Procedure Result

Static Troubleshooting

1. Turn the power supply off and remove the A3 FET board with its heatsink assembly

attached (see "Disassembly Procedures").

2. Measure the resistance between the + Rail (E202 & E302) and the - Rail ( E201 &

E301).

3. Measure the resistance between the gate of each FET (Q201-204, Q211, Q222, Q233, Q244, and Q301-304, Q311, Q322, Q333, and Q344) and

common (-Rail).

4. Measure the resistance across capacitor C201 & C301.

5. Measure the resistance across the 15V bias input (E206 to E207 and E306 to E307).

Continue with Dynamic Troubleshooting on the next page

≥ 20MΩ.

>15KΩ.

≈ 150Ω.

≈ 1KΩ in the forward direction and 490Ω in the reverse direction.

Troubleshooting 53

Table 3-4. FET Troubleshooting Chart (continued)

Procedure Result

Dynamic Troubleshooting

1. Turn off the power supply and remove the A3 FET Board with its heat sink

assembly.

2. Short the collectors of Q251 and Q253 or Q351 and Q353 by connecting the

collector (case) of each transistor to common ( E507) .

3. Connect waveform generator to J200-1 and J200-2.

4. Set generator to produce a 20 kHz, 20V p-p triangular waveform

5. Connect 15V from an external supply to E206 or E306 (positive) and E207 or

E307 (common).

: All of the following measurements are taken with respect to E207/E307 common,

test point

6. Check bias voltage at U203-1/U303-1 .

7. While adjusting the external 15V supply input, check the bias trip point at

U204-1/U304-1

8. Set external supply input to + 15V and check drive 1 waveform at

U201-10/U301-l0

9. Check that pulses are present at U201-1 , U201-7/U301-7 and

U302-1, U202-1

10. Pulses should be present on both sides of inductors L201-204 or L301-304 and

L213-216 or L313-316 as follows:

Check the pulses on the driver transistor side (Q251-Q254/Q351-Q354) of each

inductor.

Check the pulses on the FET regulator side (Q201-Q204, Q301-Q304, Q211, Q311,

Q222, Q322, Q233, Q333 and Q244, Q344) of each inductor.

If the waveforms do not have the fast step as shown in Figure 3-14, then the

associated FET gate input has an open circuit.

11. Measure the VREF voltage at U205-2 .

on A3 FET Board schematic diagram

and drive 2 waveform at U201-12/U301-12 .

, U202-7/U302-7 .

See "Disassembly Procedures"

See Figure 3-14A.

+5V

Voltage goes from low (0V) to high

(5V) at an input of approximately 12V; and from high to low at an input of approximately 13V.

See Figure 3-14B.

See Figure 3-14C.

See Figure 3-14D.

See Figure 3-14E.

≈ 1.7V

Check the peak current limit by connecting a 68KΩ resistor from +5V (U201-9) to

U205-3 or U304-5.

54 Troubleshooting

All pulses turn off.

Figure 3-13. A3 FET Board Test Waveforms

Troubleshooting 55

Signature Analysis

Introduction

The easiest and most efficient method of troubleshooting microprocessor-based instruments is with signature analysis (SA). This technique is similar to signal tracing with an oscilloscope in linear circuits. Part of the microprocessor memory is dedicated to SA, and a known bit stream is generated to stimulate as many nodes as possible within a circuit. Because it is virtually impossible to analyze a bit stream with an oscilloscope, a signature analyzer is used to compress the bit stream into a four-character signature. By comparing the signatures of the IC under test to the correct signature for each node, you can isolate faults to one or two components .

The following general rules apply to signature analysis testing:

1. Be sure to use the correct test setup connections for the specific test.

2. When examining an IC, note the correct signatures for Vcc (+5V) and for common. If an incorrect signature matches

either one, it probably indicates a short to that part of the circuit.

3. If two IC pins have identical signatures, they are probably shorted.

4. If two IC signatures are similar, it is only a coincidence.

5. If an input pin of an IC has an incorrect signal but the signal source (output of the previous IC) is correct, then look for

an open printed circuit track or soldering problems.

6. If the output signature of an IC is incorrect, it could be caused by that IC. However, it could also be caused by a short

at another component that is connected to that output.

Firmware Revisions

Each signature analysis table in this chapter shows the power supply firmware revision for which the table is valid. If needed, for a Bench Supply you can confirm the firmware revision of your power supply by checking the label on the Front panel ROM, AlU3, and on the Secondary microprocessor, A5U504. You can obtain the revisions on a Systems Supply with the GPIB *IDN? query command. The following sample Agilent BASIC program does this:

10 ALLOCATE L$[52] 20 OUTPUT 705;"*IDN?" 30 ENTER 705;L$ 40 DISP L$ 50 END

For a typical Model 6681A, the controller will return a string with four comma-separated fields, as follows:

"Agilent Technologies ,6681A,O,fA.01.05sA.01.04pA.0l.02"

The first three fields in the string are the manufacturer, model number and 0. The last field gives the firmware information as follows:

f= front panel firmware revision (A.01.05). s= secondary interface firmware revision (A.01.04). p= primary interface firmware revision (A.01.02).

Note The firmware revisions numbers shown here may not match the firmware revision of your instrument.

Firmware revision numbers are subject to change whenever the firmware is updated.

56 Troubleshooting

Test Headers

The power supply has two test headers as shown in Figure 3-15, each with a jumper that can be moved to different positions for SA testing and for other functions. To gain access to the headers, remove the power supply top cover.

Pins Description

Primary Interface Test Connector A2J106 (Systems Supplies Only)

7 and 8 (FLT/INH) Normal operating (and storage) position. DIG CNTL port** is configured for

fault indicator (FLT) output and remote inhibit (RI) input .

1 and 2 (SA Mode) Install jumper here for SA mode.

3 and 4 (DIG I/O) Install jumper here to configure DIG CNTL port** for digital I/O operation .

5 and 6 (RELAY LINK) Install jumper here to configure DIG CNTL port** for control of external relay

accessories. ** See Appendix D in power supply Operating Manual for information about the digital control port.

Front Panel Test Connector A1J3

7 and 8 (NORM) Normal operating (and storage) position of jumper.

1 and 2 (SA Mode) Install jumper here for SA mode.

3 and 4 (INHIBIT CAL) Install jumper here to disable calibration commands and prohibit calibration.

5 and 6 (FACTORY PRESET CAL) Install jumper here to restore original factory calibration constants.

Figure 3-14. Test Header Jumper Positions

Troubleshooting 57

Table 3-5. Primary Interface SA Test

Description: These signatures check some primary interface circuits on the Systems Supply A2 GPIB Board. Valid A2U106 ROM Firmware Revision: A.01.06 Test Setup: See Figure 3-17.

1. Turn off the power supply and remove the top cover.

2. Connect SA jumper of connector J106 on A2 GPIB Board (see Figure 3-15).

3. Connect signature analyzer CLOCK, START, STOP, and GROUND inputs as show in Figure 3-16 .

4. Turn on the power supply and use the signature analyzer probe to take the following signatures:

Power: 5V = 9FFP Serial Link: A2U109-3 = 0104 Microprocessor: A2U114-24 = 9FFP A2U114-25 = UF39 Digital Control Interface: A2U118-1 = 9AF1 A2U118-9 = 40A5 A2U118-10 = 1029 A2U118-15 = 0010 A2U118-16 = 040A Gated Array Logic: A2U119-2 = 0A55 A2U119-5 = 0040 A2U119-15 = 0040

5. After completing the tests, be sure to return the J106 jumper to its original position.

58 Troubleshooting

Figure 3-15. Signature Analysis Signal Inputs

Figure 3-16. Signature Analysis Connections, (Sheet 1 of 2)

Troubleshooting 59

Figure 3-16. Signature Analysis Connections, (Sheet 2 of 2)

Table 3-6. Front Panel SA Test

Description: These signatures check front panel microprocessor AlU3. Valid A1U4 ROM Firmware Revision: A.01.07 Test Setup: See Figure 3-17.

1 .Turn off the power supply and remove the top cover.

2. To gain access to A1 Front Panel Board, perform steps 1 and 2 of the disassembly procedure for A1 Front Panel

Assembly (see "Disassembly Procedures").

3. Connect SA jumper of connector J3 on A1 Front Panel Board (see Figure 3-15).

4. Connect signature analyzer CLOCK, START, STOP, and GROUND inputs and setup as shown in Figure 3-16.

5. Turn on the power supply and use the signature analyzer probe to take the following signatures:

Power: 5V = 3395

Microprocessor: AlU3-15 = 3395 A1U3-29 = 1029

AlU3-19 = 552U AlU3-30 = 0295 AlU3-20 = 954C AlU3-31 = 0000 AlU3-21 = A552 AlU3-32= 3395 AlU3-22 = 2954 AlU3-33 = 0008 AlU3-23 = 0A55 AlU3-34 = 040A AlU3-24 = 3395 AlU3-35 = 0102 AlU3-25 = 3395 AlU3-38 = 0002 AlU3-26 = 0000 AlU3-39 = 0020 AlU3-27 = 0000 AlU3-42 = 3395 AlU3-28 = 40A5

6. After completing the tests, be sure to return the J3 jumper to its original position.

60 Troubleshooting

Table 3-7. Secondary Interface SA Test

Description: These signatures check the secondary microprocessor A5U504. Valid A5U504 ROM Firmware Revision: A.01.04 Test Setup: See Figure 3-17.

1. Turn off the power supply and remove the top cover.

2. To obtain a setup that allows access to components and test points on the A5 Control Board, follow the procedure

given in Table 3-3 under "A5 Control Board Setup".

3. Connect signature analyzer CLOCK, START, STOP, and GROUND inputs and setup as shown in Figure 3-15.

4. To place the secondary interface in the SA mode, turn on the power supply while momentarily (for 2 seconds) shorting

A5U504-1 to A5U504-20 (common).

5. Use the signature analyzer probe to take the following signatures:

Power: 5V = lC4C

Microprocessor: A5U504-1 = F77H A5U504-21 = 0C98

A5U504-2 = C98P A5U504-22 = 5PC7 A5U504-3 = 1573 A5U504-23 = 0000 A5U504-4 = P42A A5U504-24 = 6CAP A5U504-5 = UHF8 A5U504-25 = A339 A5U504-6 = F5UC A5U504-26 = A319 A5U504-7 = UH8C A5U504-27 = A339 A5U504-8 = 23UC A5U504-28 = 0C98 A5U504-9 = 0000 A5U504-29 = lC4C A5U504-10 = IC4C A5U504-30 = 0000 A5U504-11 = lC4C A5U504-31 = lC4C A5U504-12 = C76F A5U504-32 = 0000 A5U504-13 = U042 A5U504-33 = 0000 A5U504-14 = 2189 A5U504-34 = lC47 A5U504-15 = lC4C A5U504-35 = 0000 A5U504-16 = lC45 A5U504-36 = 0UPU A5U504-17 = 0010 A5U504-37 = UF7P A5U504-18 = IC4C A5U504-38 = 347F A5U504-19 = lC4C A5U504-39 = CP47 A5U504-20 = 0000 A5U504-40 = lC4C

6. After completing the tests, be sure to return the J3 jumper to its original position.

Note After completing this test, you can exit the SA mode only by performing a power-on reset.

Troubleshooting 61

Post-Repair Calibration

When Required

Calibration is required annually and also whenever certain components are replaced. If components in any of the circuits listed below are replaced, the supply must be recalibrated.

Note For calibration procedures, see Appendix A of the Operating Manual.

Location Component

A10 Control Board CV/CC DACs/operational amplifiers, CV/CC control circuit amplifiers, readback

DAC/operational amplifier, readback comparators.

A1 Front Panel Assy A1 Front Panel Board or EEPROM AlU6.

Note: If either of these front panel components is replaced, the power supply must first be reinitialized before calibration (see "EEPROM Initialization" ) .

Inhibit Calibration Jumper

If CAL DENIED appears on the display when front panel calibration is attempted (or error code 1 occurs when GPIB calibration is attempted on a Systems Supply), the INHIBIT CAL jumper (see Figure 3-15) is installed. This prevents the power supply calibration from being changed. To calibrate the power supply first move this jumper from the INHIBIT CAL position to the NORM position.

Calibration Password

In order to enter the calibration mode, you must use the correct password as described in Appendix A of the Operating Manual. As shipped from the factory, the supply's model number (e.g., "6681") is the password. If you use an incorrect password, PASSWD ERROR appears on the display during front panel calibration, or error code 2 occurs during GPIB calibration, and the calibration mode is disabled. If you do not know the password, you can recover the calibration function by restoring the preset factory calibration constants as described below.

Restoring Factory Calibration Constants

This procedure allows you to recover the factory calibration constants. The ability to do this allows you to operate the power supply for troubleshooting and/or to recalibrate it as required. To restore the original factory calibration constants, proceed as follows:

1. Turn off the supply and remove the top cover.

Move the jumper in test header J3 on the A1 Front Panel Board from the NORM to the FACTORY PRESET CAL position (see Figure 3-15).

3. Turn on the power supply and note that ADDR 5 and then PWR ON INIT appear briefly on the front panel display.

4. When PWR ON INIT no longer appears, the supply's factory calibration constants have been restored and the password

has been changed to 0. There is no longer any password protection. You can now turn off the supply and restore the calibration jumper to the NORM position (see Figure 3-15).

5. Turn on the supply. You may now set a new password (if desired) and recalibrate the power supply.

62 Troubleshooting

EEPROM Initialization

EEPROM AlU6 on the A1 Front Panel Board stores the supply's GPIB address, model number, and constants required to program and calibrate the power supply. If either the front panel board or the EEPROM is replaced, the power supply must be reinitialized with the proper constants by running the program listed in Figure 3-18.

When the program pauses and asks you to make a selection, respond as follows:

Initialization (I) or Factory Preset Replacement (F)? I

After the power supply has been initialized, it must be calibrated as described in Appendix A of the Operating Manual. After calibration, transfer the new calibration constants to the EEPROM's "Factory Cal" locations as described next.

Transferring Calibration Constants To Factory Preset Locations

A newly initialized and calibrated power supply has calibration constants in operating locations but does not have the new factory calibration constants stored in EEPROM. This procedure transfers the calibration constants into the EEPROM FACTORY PRESET CAL locations by running the program listed in Figure 3-18.

When the initialization program pauses and asks you to make a selection, respond as follows:

Initialization (I) or Factory Preset Replacement (F)? F

The new calibration constants will then be stored. Pre-initialized and tested A1 Front Panel boards are available for Analog Programmable "bench" series supplies. (See Chapter 5, Table 5-4 for part numbers.)

A Bench Series Supply can be initialized and the new Factory Preset calibration constants loaded by temporarily replacing the A2 Isolator board with an A2 GPIB board. Then follow the instructions above for "EEPROM INITIALIZATION" and also "TRANSFERRING CALIBRATION CONSTANTS TO THE FACTORY PRESET LOCATIONS" described above.

After the supply has been Initialized, Calibrated, and the new Factory Presets stored, remove the GPIB board and reinstall the original Isolator board.

Troubleshooting 63

10 ! Program to initialize EPROM or move factory preset data in 668xA 20 ! power supplies. 30 ! RE-STORE " INIT_668X" 40 ! Rev A.00.00 dated 09 Nov 1993 50 ! 60 DIM Init_data(1:49),Model$[5],Idn$[21],Cal_data$[40] 70 INTEGER Addr(1:49),Length(1:49) 80 ASSIGN @Ps TO 705 ! Supply must be at address 705 90 CLEAR SCREEN 100 ! 110 Eprom_data_addr: ! Data address 120 DATA 2,6,10,14,18,19,20,24,28,32 130 DATA 36,37,38,42,46,50,54,55,56,57 140 DATA 64,68,72,76,80,116,l52,153,154,155 150 DATA l56,158,160,162,163,164,165,166,167,168 160 DATA 169,170,171,172,174,176,180,184,188 170 ! 180 Eprom_data_len: ! Data for word length 190 DATA 4,4,4,4,1,1,4,4,4,4 200 DATA 1,1,4,4,4,4,1,1,1,1 210 DATA 4,4,4,4,4,1,1,1,1,1 220 DATA 2,2,2,1,1,1,1,1,1,1 230 DATA 1,1,1,2,1,4,4,4,4 240 ! 250 Eprom_data_6680: ! ! EEPROM data for 6680A 260 DATA 729,71,5.125,0,83,0,4.235,72,895,0 270 DATA 98,3,36,17,6.25,0,83,255,20,10 280 DATA 6680,708,94,4.13,92,128,5,255,0,0 290 DATA 1296,6680,0,20,180,20,180,175,33,98 300 DATA 115,30,20,1,58,.002701,.2,.0017346,10.2286 310 ! 320 Eprom_data_6681: ! ! EEPROM data for 6681A 330 DATA 463,75,8.19,0,83,0,6.333,70,592,0 340 DATA 98,3,22.16,17.75,10.0,0,,83,255,20,10 350 DATA 6681,430,95,6.3645,92,128,5,255,0,0 360 DATA 1296,6681,0,20,180,20,180,175,33,98 370 DATA 115,30,20,1,58,.002701,.2,.0017346,10.2286 380 ! 390 Eprom_data_6682: ! ! EEPROM data for 6682A 400 DATA 175,74,21.5,0,83,0,15,73,246,0 410 DATA 98,21,8.7,10,26.3,0,83,255,20,10 420 DATA 6682,162,96,15,96,128,5,255,0,0 430 DATA 1296,6682,0,20,180,20,180,175,33,98 440 DATA 115,30,20,1,127,.002701,.2,.000307,10.25 450 ! 460 Eprom_data_6683: ! ! EPROM data for 6683A 470 DATA 116,74,32.8,0,83,0,23,75,164,0 480 DATA 98,21,5.5,10,40.0,0,83,255,20,10 490 DATA 6683,108,96,23,97,128,5,255,0,0 500 DATA 1296,6683,0,20,180,20,180,175,33,98

Figure 3-17. Initialization and Factory Preset Replacement Program Listing (Sheet 1 of 5)

64 Troubleshooting

510 DATA 115,30,20,1,127,.002701,.2,.00042,10.25 520 ! 530 Eprom_data_6684: ! ! EEPROM data for 6684A 540 DATA 93,74,41,0,83,0,29,70,131,0 550 DATA 98,21,4.6,10,50,0,83,255,20,10 560 DATA 6684,87,97,28,93,128,5,255,0,0 570 DATA 1296,6684,0,20,180,20,180,175,33,98 580 DATA 115,30,20,1,127,.002701,.2,.000333,10.234375 590 ! 600 ! 610 INPUT “Input Power Supply model number. Example:""6681A""",Model$ 620 CLEAR SCREEN 630 ! 640 RESTORE Eprom_data_addr 650 ! 660 FOR I=l T0 49 670 READ Addr(I) 680 NEXT I 690 ! 700 RESTORE Eprom_data_len 710 ! 720 FOR I=l T0 49 730 READ Length(I) 740 NEXT I 750 ! 760 SELECT TRIM$(UPC$(Model$)) ! Delete leading/trailing zeros and set to uppercase 770 CASE "6680A" 780 RESTORE Eprom_data_6680 790 CASE "6681A" 800 RESTORE Eprom_data_6681 810 CASE "6682A" 820 RESTORE Eprom_data_6682 830 CASE "6683A" 840 RESTORE Eprom_data_6683 850 CASE "6684A" 860 RESTORE Eprom_data_6684 870 ! 880 CASE ELSE 890 PRINT "Model number not found. Program is for models" 900 PRINT "Agilent 6680A, 6681A, 6682A, 6683A and 6684A only" 910 STOP 920 END SELECT 930 ! 940 FOR I=l T0 49 ! Read model dependent data 950 READ Init_data(I) 960 NEXT I 970 ! 980 OUTPUT @Ps;"*CLS" ! Clears power supply registers 990 ! 1000 OUTPUT @Ps;"CAL;STATE ON," ! Turn on cal mode, "0" passcode 1010 !

Figure 3-17. Initialization and Factory Preset Replacement Program Listing (Sheet 2 of 5)

Troubleshooting 65

1020 GOSUB Ps_error ! Error if passcode is not "0"! 1030 IF Err THEN 1040 OUTPUT @Ps;"*IDN?" ! Get data from model # location 1050 ENTER @Ps;Idn$ 1060 Model=VAL(Idn$[POS(Idn$,”,”)+1] ) 1070 ELSE 1080 GOTO Start 1090 END IF 1100 ! 1110 OUTPUT @Ps;"CAL:STATE ON,";Model ! Turn on cal mode, passcode = 1120 ! data at model number location 1130 ! 1140 GOSUB Ps_error ! Error if passcode is not same as 1150 ! data at model # location 1160 IF Err THEN 1170 OUTPUT @Ps;"CAL:STATE ON,";Model$[l,4] ! Turn on cal mode, passcode = 1180 ! model # 1190 GOSUB Ps_error 1200 IF Err THEN 1210 PRINT "Change pass code to the power supply model # or zero then restart the program." 1220 STOP 1230 ELSE 1240 GOTO Start 1250 END IF 1260 END IF 1270 ! 1280 Start: ! 1290 ! 1300 ! 1310 INPUT “Select Initialization (I) or Factory preset replacement (F).”,Sel$ 1320 CLEAR SCREEN 1330 SELECT (UPC$(Sel$)) 1340 CASE "I" ! Select Initialization 1350 GOTO Init_eeprom 1360 CASE "F" ! Select install new factory data 1370 GOTO Fact_preset 1380 CASE ELSE 1390 BEEP 1400 GOTO Start 1410 END SELECT 1420 ! 1430 Init_eeprom: ! 1440 PRINT “Initializing EEPROM” 1450 ! 1460 FOR I=1 TO 49 1470 OUTPUT @Ps;"DIAG:EEPR '';Addr(I);'','';Length(I);'','';Init_data(I) 1480 NEXT I 1490 GOTO Cal_off 1500 ! 1510 ! 1520 Fact_preset: !

Figure 3-17. Initialization and Factory Preset Replacement Program Listing (Sheet 3 of 5)

66 Troubleshooting

1530 CLEAR SCREEN 1540 PRINT "This program should ONLY be completed if your power supply” 1550 PRINT "EEPROM has been replaced or a component that will effect" 1560 PRINT "the calibration AND the alignment of voltage, overvoltage" 1570 PRINT "and current is complete AND unit has passed the performance" 1580 PRINT "test. Enter C to continue, any other key to abort.” 1590 INPUT Cont_prog$ 1600 IF (UPC$(Cont_prog$))< >"C" THEN GOTO Cal_off 1610 ! 1620 CLEAR SCREEN 1630 PRINT "Transferring calibration data to factory preset locations." 1640 ! 1650 Fact_cal_sour: ! Address of factory calibration data source 1660 DATA 2,6,68,72,20,24,76,80,150 1670 ! 1680 Fact_cal_dest : ! Address of factory calibration data destination 1690 DATA 84,88,92,96,100,104,108,112,116 1700 ! 1710 Fact_cal_len: ! Length of factory calibration data 1720 DATA 4,4,4,4,4,4,4,4,1 1730 ! 1740 RESTORE Fact_cal_sour 1750 FOR I=1 TO 9 1760 READ Cal_sour_addr(I) 1770 NEXT I 1780 ! 1790 RESTORE Fact_cal_dest 1800 FOR I=1 T0 9 1810 READ Cal_dest_addr(I) 1820 NEXT I 1830 ! 1840 RESTORE Fact_cal_len 1850 FOR I=1 T0 9 1860 READ Cal_length(I) 1870 NEXT I 1880 ! 1890 FOR I=1 T0 9 ! Locations of good data 1900 OUTPUT @Ps;"DIAG:EEPR? ";Cal_sour_addr(I);",";Cal_length(I) ! Read good data 1910 ENTER @Ps;Cal_data$ ! Enter good data 1920 OUTPUT @Ps;"DIAG:EEPR";Cal_dest_addr(I);",";Cal_length(I);”,”;Cal_data$ ! Write good data to factory preset locations 1930 NEXT I 1940 ! 1950 ! 1960 Cal_off 1970 CLEAR SCREEN 1980 OUTPUT @Ps;"CaL:STATE OFF" ! Turn off cal mode 1990 ! 2000 GOSUB Ps_error ! Check for errors

Figure 3-17. Initialization and Factory Preset Replacement Program Listing (Sheet 4 of 5)

Troubleshooting 67

2010 IF Err THEN 2020 PRINT "An error occurred during the EEPROM read/write, Check for" 2030 PRINT "programming errors. Initialization data may be incorrect." 2040 STOP 2050 END IF 2060 ! 2070 PRINT "Operation complete. Program stopped." 2080 STOP 2090 ! 2100 Ps_error: ! Error handling subroutine 2110 OUTPUT @Ps;"SYST:ERR?" ! Check for errors 2120 ENTER @Ps;Err 2130 RETURN 2140 ! 2150 END

Figure 3-17. Initialization and Factory Preset Replacement Program Listing (Sheet 5 of 5)

Disassembly Procedures

Shock Hazard: To avoid the possibility of personal injury, remove the power supply from service before removing the top cover. Turn off the ac power and disconnect the line cord, GPIB cable, load leads, and

remote sense leads before attempting any disassembly. Any disassembly work must only be performed by a qualified support technician.

Observe that the DC RAIL assembly LEDs (DS420 & DS421) are fully extinguished (no live voltages present) before attempting any disassembly work. Any disassembly work must only be performed by a qualified support technician.

Cable connections are shown in Figure 6-2 of Chapter 6 and component part numbers are given in Chapter 5. Reassembly procedures are essentially the reverse of the corresponding disassembly procedures.

Tools Required

þ TORX screwdriver size T-15 (for most all retaining screws).

þ TORX screwdriver size T-20 (for power supply carry straps).

þ Seven (7) mm metric hex driver (to remove GPIB read connector).

þ Pencil, paper, and labels to make notes to aid in the reinstallation of components.

þ Work 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 where necessary, such as, Agilent P/N 9300-0969 or 9300-0970.

68 Troubleshooting

Top Cover

1. Remove the four screws that secure the carrying straps (two TORX 20 screws on each side). These same screws secure

the cover to the chassis.

2. Spread the bottom rear of the cover, and then pull the cover backwards towards the rear of the power supply to

disengage it from the front panel.

Shock Hazard: Hazardous voltage can exist inside the power supply even after it has been turned off.

Check the INPUT RAIL LED (A4CR402) under the RFI shield (see Figure 3-18 end of this section for LED location). If the LED is on, there is still hazardous voltage inside the supply. Wait until the LED goes off (approximately 7 minutes after power is removed) before proceeding.

Removing Protective RFI Shield (Galvanized Sheet Metal)

Once you remove the top cover of the power supply, you will see the RFI galvanized sheet metal cover preventing the power supply from emanating RFI fields. The RFI shield covers most components and circuit boards, as well as, many of the chassis-mounted components. You must remove this shield in order to gain access to the inside of the power supply. Remove the shield as follows:

1. There are approximately 21 screws holding the cover to the frame.

2. There are two screws at the top of the shield that secure a retaining clip for the GPIB board. You do not need to remove

these screws, simply loosen the screws and slide the GPIB retaining clip backwards free of the GPIB board.

3. Remove all shield securing screws using a TORX T-15 screwdriver and save for later reinstallation .

4. Lift the RF shield out of the chassis.

5. When DC RAIL LEDs are extinguished, it is safe to work inside the power supply. (See Warning note above.)

Note The following procedures describe the removal of most of the circuit boards within the power supply.

Once the GPIB board is removed, you will have access to the A4 AC Input Assembly and the A5 DC Rail Assembly. Similarly, once the A10 control board is removed along with the Rectifier HS you will have access to other components and boards within the supply.

It is recommended that when you disconnect any wires and/or cable connectors you should immediately label them to simplify their reinstallation later.

GPIB Board

To remove the GPIB board, disconnect the cables from the following connectors at the GPIB board:

1. Disconnect the cable going to connector P101.

2. Disconnect phone cable going to J107.

3. Disconnect phone cable going to J107.

4. Disconnect phone cable going to J108.

5. Remove two (2) holding screws at read of chassis holding GPIB board in place.

6. Using a 7 mm driver, remove the two (2) screws holding the GPIB connector at rear of chassis.

7. The GPIB board can now be lifted out from the chassis.

Troubleshooting 69

A4 AC Input Assembly

To remove the A4 AC Input Board first remove the GPIB board then disconnect these cables from the following connectors at the GPIB board:

1. Disconnect the cables going to connector J417 and J420.

2. Disconnect the cable going to connector J419.

3. Remove the three (3) fuse assemblies inside rear of power supply to free the wires going to E400, E401, and E402 on

the AC Input Board.

4. Remove the holding screw at the center of board just to the left of the 3-phase choke.

5. Disconnect phone cable going to J108.

6. Slide the board to the right and lift out.

7. Other wires going to the board can now be removed/unsoldered.

A5 DC RAIL Assembly

Disconnect these cables from the following connectors at the A5 DC RAIL board:

1. Disconnect the cables going to four connectors: J430, J431, J432, and J433.

2. Disconnect the cable going to connector J440.

3. Remove the four (4) holding screws TORX T-15 holding the A5 DC RAIL board in place.

4. Lift the board out and remove/desolder any other wires preventing the board from being removed.

A6 BIAS Assembly

Disconnect the cables from the following connectors at the A6 BIAS Assembly board:

1. Disconnect cables from connectors J809, J821, J830, and J831 on the A6 BIAS Board.

2. Remove two (2) holding screws at top side of board.

3. Slide board upward until board is free of slotted standoffs. There is one of these standoffs at the top of the board and

two at the bottom. Wiggle the board slightly to clear all three standoffs then lift the board out.

4. Once the board is free from its restraining standoffs, you can proceed to remove/unsolder any other wires/cables as

necessary to remove the A6 BIAS Board entirely.

Note It is recommended that you label any connectors you disconnect from the A6 BIAS Board to facilitate the

reinstallation of these cables/wires back to their correct locations later. If you should have trouble later in determining which cable goes to which connector during reinstallation, refer to the cabling diagram in Chapter 6.

A3 FET Board

Follow this procedure to remove the A3 FET Board:

1. Remove the four (4) holding screws that secure the two black caps over the Rectifier HS assembly.

2. Once these caps are removed, you can remove the Rectifier HS which faces the A3 FET Board.

3. Disconnect two connectors, P430 and P431, at the A5 DC RAIL assembly.

4. Disconnect two connectors P/O cable assemblies P/N 5080-2283, at the A5 DC RAIL assembly.

5. You can now lift out the A3 FET board and remove/unsolder any other wires necessary to fully remove the A3 board.

70 Troubleshooting

A10 Control Assembly

Disconnect the cables from the following connectors at the A10 DC RAIL board:

1. Disconnect the ribbon cable going from to the A6 Bias board. This cable connects to J509 on the A10 board but it is

easier to disconnect it at the A6 Bias Board.

2. Disconnect cables from connector J507 (phone) and connectors J510, J511, J512, and J513 on the A10 Control Board.

3. At rear of power supply, remove holding screw directly above fan. This screw holds the frame and A10 control board

in place.

4. At rear of power supply unplug connector DIG CNTL from A10 Control Board.

5. Move board to the right and lift board and associated steel frame out of chassis.

Front Panel Assembly

1. Peel off vinyl trim (one strip on each side of front panel) to access the four screws that secure the front panel assembly

to the chassis.

2. Remove the four screws (two on each side) using a size T-10 TORX.

3. Disconnect phone cable W5 from J6 on the A1 Front Panel Board.

4. Record the color code and the location of each of the four wires connected to line switch S1.

5. Disconnect the wires from the switch assembly.

6. Remove the front panel assembly.

S1 Line Switch

1. Remove Front Panel Assembly and disconnect switch wires as described in that procedure.

2. Release the switch locking tabs by pressing them inward against the body of the switch and removing the switch.

A1 Front Panel Board

1. Remove the Front Panel Assembly and disconnect the switch as described under "Front Panel Assembly".

2. Disconnect LCD display ribbon cable W2 from J2 on the A1 Front Panel Board.

Note When reinstalling the LCD ribbon cable, be sure to line up the "stripe" of the ribbon cable with pin 1

on J2.

3. Use a small Allen wrench (0.050") to loosen the set screws that are inset in the knobs. (These are the AlG1 and AlG2

Voltage/Current control shafts that extend through the front panel.) Remove knobs and shaft bushings.

Note Be careful not to unscrew the knob set screws too far out as they can easily fall out of the knob and

become lost.

4. Remove screw (if installed) that secures board to the Front Panel Assembly. The screw is located near J4 on the Front

Panel Board.

5. Lift tab (near J6 on front panel board) and slide left to release board from the A1 Front Panel Assembly and remove

board.

Troubleshooting 71

A1DSP1 LCD Display

1. Remove the A1 Front Panel Board as described in that procedure.

2. Remove the nuts securing the LCD display to the front panel assembly and remove the LCD and attached ribbon cable

(see CAUTION below). (When reinstalling this cable, be sure to line up the cable stripe over the LCD connector pin marked with a square.)

The display connector is fragile. When removing the cable from the LCD display, carefully rock the cable connector back and forth while gently pulling it back.

A1G1 and A1G2 Rotary Controls

1. Remove the A1 Front Panel Board as described in that procedure.

2. Remove the AlG1 and AlG2 cables from connectors A1J4 and A1J5.

3. Remove nuts securing the AlG1 AlG2 controls to the board and remove controls.

A1KPD Keypad

1. Remove the A1 Front Panel Board as described in that procedure.

2. With board removed, keypad can easily be lifted out of the Front Panel Assembly.

Output Bus Boards A7, A81 and A9 & Chassis Components

Note To remove the A7 Snubber Board, A8 Fast Sense Assembly, A9 Downprogrammer and other chassis

mounted components, first remove the A10 Control Board frame assembly and the two Rectifier Heat Sinks described earlier. Once the heat sinks are removed you will have access to the A7, A8, and A9 boards as well as other chassis mounted components.

Should you have any difficulty in removing power supply components or boards, contact the Agilent Technologies Support Line for help.

Shock Hazard: Hazardous voltage can exist inside the power supply even after it has been turned off.

Check the INPUT RAIL LED (A4CR402) under the RFI shield (see Figure 3-18 end of this section for LED location). It the LED is on, there is still hazardous voltage inside the supply. Wait until the LED goes off (approximately 7 minutes after power is removed) before proceeding.

72 Troubleshooting

Figure 3-18. Component Locations (Top Cover and RFI Shield Removed)

Troubleshooting 73

74 Troubleshooting

Figure 3-19. 5-Inch Front Panel Frame Assembly

Figure 3-20. 3-Inch Front Panel Frame Assembly

Troubleshooting 75

76 Troubleshooting

Figure 3-21. Assembly A10, Exploded View

Figure 3-22. Assembly A10, Exploded View (6680A, 6681A)

Troubleshooting 77

78 Troubleshooting

Figure 3-23. Assembly A10, Exploded View (6682A, 6683A, 6684A)

Figure 3-24. Three-Phase Line Choke Subchassis Wiring

Troubleshooting 79

80 Troubleshooting

Figure 3-25. 24 Volt Fan Transformer

Principles Of Operation

Introduction

Figure 4-3 (at the end of this chapter) is a block diagram showing the major circuits within the power supply. The power supply consists of the following circuits:

• A1 Front Panel Board ckts.

• A2 GPIB ckts.

• A10 Control Board including the secondary interface ckts, CV/CC control ckts, switching/downprogramming control

ckts.

• Power circuits on the A4 AC Input Board.

• A3 FET Assembly ckts.

• A5 DC Rail Board ckts.

• Output bus circuits which include the A7 Snubber Board, A8 Slow Sense Board, and A9 Downprogrammer Board

ckts.

• Output rectifiers and filter capacitors.

• Ferrite cores mounted on the output bus form the output filter inductors.

• A6 Bias Board supply which supplies low-voltage, low-power, bias voltages where required.

Each block in Figure 4-3 identifies a schematic diagram in Chapter 6 where the circuits are shown in detail. You can refer to the component location diagrams in Chapter 6 to locate specific components mentioned in this description. Chapter 6 also has a cabling diagram showing the circuit board interconnections.

A2 GPIB Board

Circuits on the A2 GPIB board provide the interface between the GPIB controller and the power supply. All communications between the power supply and the GPIB controller are processed by the GPIB interface and primary microprocessor circuits on the A2 board.

The primary microprocessor circuits (microprocessor, U114, ROM U106, and RAM U108) decode and execute all instructions and control all data transfers between the GPIB controller and the Secondary Interface on the A10 Control Board. The primary microprocessor also processes measurement and status data received from the Secondary Interface.

A UART (universal asynchronous receive/transmit) IC (U112) on the A2 board converts data between the primary microprocessor's 8-bit, parallel bus and the serial I/O port. The serial data is transferred between the primary interface and the secondary interface via a programmed GAL (gated array logic) IC (U119) and optical isolator ICs (U110/U111). These ICs isolate the primary interface circuits (referenced to earth ground) from the secondary interface circuits (referenced to power supply common). The GAL IC also provides a serial I/O port to the A1 Front Panel Board to enable front panel control of the power supply.

A serial link interface IC (U109) on the A2 GPIB Board allows up to sixteen supplies to be connected together and programmed from one GPIB address. The first supply is the only supply connected directly to the GPIB controller and is set to the primary GPIB address. The remaining supplies are set to secondary addresses and are linked (daisy chained) together via the Jl/J2 phone jacks at the rear of each supply. The serial link configuration is described in the Power Supply Operating Manual.

Principles Of Operation 81

A digital control interface on the A2 GPIB Board provides the following power supply functions:

• Relay link.

• Digital 1/0.

• Remote inhibit (INH).

• Discrete fault indicator (FLT).

An optical isolator IC (U113) isolates the FLT output signal common from the external fault circuit common. The desired digital interface function is selected by placing a jumper in a header (J106) on the A2 GPIB Board. Appendix D in the Power Supply Operating Manual describes how to select one of these functions and how to make the appropriate external connections to the DIG CNTL connector on the supply's rear panel. Another jumper position on the header selects the SA (signature analysis) mode, which is used for troubleshooting (see Chapter 3).

The A2 Board has a bias supply regulator IC (U121) that provides +5V (with respect to earth ground) for the primary interface circuits and the bias voltage for the front panel board circuits, the LCD, and the keypad. The A2 Board also has a line or bias voltage detector IC (U101) that generates a power clear signal (PCLR). This signal initializes certain primary interface and front panel circuits when normal ac line voltage is applied, and also shuts these circuits down when the line voltage drops below the required minimum.

A1 Front Panel Assembly

The power supply A1 Front Panel Assembly contains a circuit board, keypad, liquid crystal display (LCD), and the power on/off switch.

The Front Panel Circuit Board A1 contains microprocessor circuits (microprocessor U3 and ROM U4) that decode and execute all front panel keypad commands. These are transferred to the power supply output via the serial I/O port to the A2 board GAL (gated-array logic) IC and isolators, and to the secondary interface circuits on the A10 Control Board. The front panel microprocessor circuits also process power supply measurement and status data received from the serial I/O port. This data is displayed on the LCD.

IC EEPROM, U6, (electrically-erasable, programmable, read-only memory) on the A1 Front Panel Board stores data and configuration information. This information includes calibration constants, GPIB address, the present programming language, and model-dependent data such as the minimum and maximum values of voltage and current.

One of the EEPROM storage locations holds a checksum value used to verify the integrity of this EEPROM data. Access to the calibration data in the EEPROM is controlled by the combination of a password and jumper options on a header (J3) located on the A1 board (see Post-Repair Calibration in Chapter 3).

The power supply can be calibrated manually using the front panel keys, or via the GPIB bus with SCPI (Standard Commands for Programmable Instruments) commands. The calibration procedure is in Appendix A of the Power Supply Operating Manual).

A10 Control Board

The A10 Control Board contains the Secondary Interface, CV/CC Control Circuits, Readback Circuits, PWM Switching Circuits and OV/Downprogramming Circuits. These circuits are shown schematically in the A10 Control Board schematic.

Secondary Interface (P/O A10 Board)

These circuits are shown in detail on the A10 Control Board schematic and include the Secondary Microprocessor (U506), Programmed GAL (U505), three DAC/OpAmp circuits (U510-U515), Readback Comparator circuits (U516, U517) and OV/Shunt DAC OpAmp circuit, (U520, U521).

82 Principles Of Operation

The Secondary Microprocessor translates serial data received from the A2 board into parallel 12 bit data. The data bus is connected directly to the four DAC/OpAmp circuits. Under control of the lip the selected DAC converts the bus data into an analog signal. The DAC reference circuit (U503, U504) provides a +10V reference for the CV and CC DACs and a

-11.6V reference for the readback DAC. Zener VR501 provides a-6.2V reference for the OV Shunt DAC.

The CV DAC/OpAmp (U510, U513) converts the programmed voltage value from the bus or front panel into the CVPROG signal. CVPROG is sent to the CV Error Amp and compared with the VMON signal to control the magnitude of the output voltage in the CV mode. The range of CVPROG is 0 volts to -10 volts, which corresponds to the zero-to-full-scale output voltage range of the supply.

The CC DAC/OpAmp (U511, U514) converts the programmed current value from the bus or front panel into the CCPROG signal. CCPROG is sent to the CC Error Amp and is compared with the IMON signal to control the magnitude of the output current in the CC mode. The range of CCPROG is 0 volts to -10 volts, which corresponds to the zero-to-full-scale output current range of the supply.

The Readback Comparators (U516, U517) operate with the Readback DAC/OpAmp (U512, U515) to return the following signals to the µP:

• The monitored output voltage (VMON).

• The monitored output current (IMON).

• The ambient temperature (AMB_SENSE).

• The programmed voltage value (CVPROG).

• The programmed current value (CCPROG).

• The fan detector (FAN_DEW).

The readback DAC circuit is controlled by the µP to successively approximate (to 12-bit resolution) the value of each signal monitored. The CVPROG and CCPROG signals are used during selftest to check DAC/OpAmp operation. The µP monitors the fan speed and ambient temperature and generates the FAN_PWM control signal to adjust fan speed depending upon the ambient temperature measured internally in the power supply.

A dual DAC, Shunt-Trim/OV, Amplifier circuit (U520, U521) performs two functions. One is to convert the programmed overvoltage value from the bus or front panel into the OVREF signal. The OVREF signal is compared by U502 with the output voltage. Second, the Shunt Trim DAC calibrates the IMON signal by sampling the current flowing through current-sense resistor (R900) on the output power bus together with the TRIM input signal.

Figure 4-1. AC Calibration of IMON

During power initiation, the secondary processor generates PWM DISABLE to the power supply's output off for 10

seconds. After 10 seconds PWM DISABLE is removed and the supply's output can be programmed.

CV/CC Control (P/O A10 Board) These circuits are shown in detail on the A10 Control Board schematic and include the CV (constant voltage) and CC (constant current) control loops. The power supply must act as either a CV or CC supply for

Principles Of Operation 83

any value of load impedance. Switching between CV and CC is done automatically by the CV/CC control circuits at a value of load impedance equal to the ratio of the programmed voltage value to the programmed current value.

A low-level CV or CC signal is generated by the applicable status comparator (P/O U502) and returned to the secondary processor to indicate that the corresponding mode, CV or CC, is in effect.

In CV mode, an OR gate diode (D652) conducts and the CV loop regulates the output voltage. A CV error amplifier (P/O U621) compares the programmed voltage signal CVPROG to VMON which is the output signal from the V_DIF amplifier(P/O U621). The range of VMON is 0 volts to +10 volts which corresponds to the zero-to-full-scale output voltage of the supply. If the output voltage exceeds the programmed voltage the OR GATE signal goes low causing the output voltage to decrease to the programmed value.

Conversely, if the output voltage is less than the programmed voltage, the OR GATE signal goes high causing the output voltage to increase to the programmed value. An externally applied dc signal, VPROG, can be used to program the output voltage. A 0 volt to -5 volt VP level produces a proportional zero-to-full-scale output voltage.

In CC mode, an OR gate diode (D651) conducts and the CC loop regulates the output voltage. A CC error amplifier (P/O U620) compares the programmed voltage signal CCPROG to IMON which is the output signal of 2nd I_AMP (P/O U620). The range of IMON is 0 volts to +10 volts which corresponds to the zero-to-full-scale output voltage of the supply. If the output current exceeds the programmed current, the OR GATE signal goes low causing the output current to decrease to the programmed value.

Conversely, if the output current is less than the programmed current, the OR GATE signal goes high causing the output current to increase to the programmed value. An externally applied dc signal, IPROG, can be used to program the output current. A 0 volt to -5 volt IP level produces a proportional zero-to-full-scale output current.

Switching/Downprogramming Control (P/O A10) These circuits include a Ramp Generator, Divider /Deadtime Latch, Fast Sense Differential Amplifier, Pulse Width Modulator, Summing Comparator, Down-Programmer Control and OV Comparator circuits.

The Divider/Deadtime Latch (U600, U601, U602) divides the 2-MHz ALE_CK signal from the Secondary µP and supplies 40 KHz pulses to the Ramp Generator (U607) and ON Latch ( U604).

The OR-GATE signal (CV or CC control signal as previously described) is summed with the 40 KHz triangular waveform produced by the Ramp Generator. An input from the Fast Sense Differential Amplifier is also summed to compensate for a sudden transient in the rectified output.

The width of the output pulses from the Summing Amplifier vary as the OR-GATE control signal increases or decreases. These pulses are applied to the Pulse-Width Modulator (U603) via the On Latch. The PWM generates the square wave pulses that are applied to the A3 FET assembly to turn the FET switches on and off. The Deadtime Latch resets the ON Latch to provide a minimum off time for the FET switches.

The OV circuit compares the output voltage level with the OVREF signal which represents the programmed overvoltage level. When the output voltage exceeds the programmed OV value, the downprogrammer circuits are activated and the FET switches are turned off

The Downprogrammer control circuit generates control signal DP CONTROL whenever an OV or disable condition has been detected, or when the output voltage exceeds the programmed value. DP CONTROL causes the downprogrammer FETs (Q980, Q981) on the A9 Downprogrammer/Fast Sense board to conduct and conduct current away from the load.

84 Principles Of Operation

A4 AC Input Board

The A4 Input Board contains the Inrush-Current Limit relay (K401), Main Power Relay (K402), current-limiting resistors (R407, R408) and open-fuse-detect resistor circuit (R400-R405). On power-on, the current-limit relay (K401) closes allowing the dc rail capacitors to charge under a controlled condition. This applies ac voltage to the A6 Bias Board. After the turn-on initialization period (approximately 10 seconds), the main relay (K402) closes, shorting out the current-limit resistor.

The open-fuse resistors supply partial ac voltage to the front panel LED board. An open-fuse causes an unbalanced voltage to be supplied to the open-fuse detect circuit causing the front panel Check Fuses LED to flash. If all three fuses are good, or if all three are open, the Check Fuse does not flash. The three-phase line inductor is connected to the A4 Input board via J417 (Range 1, 180-235Vac) or J418 (Range 2, 360-440Vac).

A5 DC Rail Board

The A5 DC Rail board contains the full-wave, three-phase, rectifiers and the input filter circuits. The ac mains are full-wave rectified by D420-D425 and converted to two, 300-volt dc rails by filter capacitors, C423-C426, and by two range select connectors. In range 1 (180-235Vac), J438 connects the two DC rails, called Rail #1 and Rail #2, in parallel. Each rail supplies 300Vdc to the A3 FET board via J430 and J431. In Range 2 (360-440Vac), J439 connects the two DC rails in series. Each rail still supplies 300 Vdc to the A3 FET board via J430 and J431.

The A5 DC Rail board also contains the bias transformer and primary range select connectors J436 (Range 1) and J437 (Range 2). There are two LEDS (DS420, DS421) which light when more than 40Vdc is present on the dc rails.

As a precaution always disconnect power supply from ac mains and wait 7 minutes before handling dc rail

The +24 auxiliary bias fuse, F420, and the standard bias fuse, F421, are located on the dc rail board.

board. Be certain that the LEDs are completely extinguished.

A3 FET Board

The A3 FET board consists of two power FET stages connected between the +rail and -rail voltages, and connected across the FET stages is a chassis mounted power transformer. The entire circuit represents an H-bridge configuration. A complete stage consists of eight, power FETs and two, bridge-driver ICs. The power FETs are mounted on but isolated from the heat sink assembly. The two power FET stages are isolated from each other.

The DRIVElA, lB and DRIVE2A, 2B pulses, received from the A10 Control board, are used by the bridge drivers (U201, U202, U301, U302) to derive control pulses for the FET switches. The width of the pulses determines the ON time of the FET switches, thereby determining the magnitude of the output voltage or current. DRIVElA pulses turn on one set of +RAIL (Q301, Q311) and -RAIL (Q303, Q333) FETs, causing current to flow through power transformer, T900, in one direction. DRIVE2A pulses turn on the other set of +RAIL (Q304, Q344) and -RAIL (Q302, Q322) FETs causing current to flow through T900 in the opposite direction. The FET on/off periods are controlled by the duty-cycle detect and the peak-current detection circuits. If the output attempts to change, regulation is accomplished by the CV/CC control circuits on the A10 Control board. These circuits vary the width of the drive pulses and the duration of the FET on/off periods.

Principles Of Operation 85

Figure 4-2. 1ST Stage of the FET H-Bridge Configuration

Output Circuits

The output circuits include the following circuits:

• Chassis mounted components.

• Two power transformers, T900/T901.

• Two inductors, L900/L901.

• Four rectifiers, D900 through D903.

• Output capacitors.

• A7 Snubber board mounted to the heat sink.

• A8 Fast Sense board.

• A9 Slow/Downprogrammer board and output bus bars.

Each combination of power transformers, T900/T901, and rectifiers, D900/D903, couples the output pulses from the A3 FET board. The output of each transformer/rectifier combination is connected in parallel before being applied to the output filter. The output filter assembly consists of bus bars with the filter capacitors bolted to them. The filter chokes, L902 through L906, consist of ferrite cores enclosing the bus bar. The current-sense resistor, R900, is part of the positive-output bus bar.

86 Principles Of Operation

Figure 4-3. Agilent Series 668xA Power Supply, Block Diagram

Principles Of Operation 87

Replaceable Parts

INTRODUCTION

Chapter Organization

This section lists the replaceable electrical and mechanical parts for the Agilent 668xA series power supplies. (Component location diagrams are located in Chapter 6.) The lists consist of tables organized by assemblies as follows:

Assembly See

Main chassis * Table 5-3 A1 Front Panel EBoard Table 5-4 LED Board Table 5-5 A2 GPIB Board Table 5-6 A3 FET Board Table 5-7 A4 AC Input Board Table 5-8 A5 DC Rail Board Table 5-9 A6 Bias Board Table 5-9 A7 Snubber Board Table 5-11 A8 Fast Sense Board Table 5-9 A9 Down Programming/Slow Sense Board Table 5-9 A10 Control Board Table 5-10 * The locations of circuit board assemblies and chassis-mounted components are shown in Fig 3-20.

Reading the Tables

Each table lists electrical components alphabetically by reference designator and provides the Agilent part number followed by the part description. Mechanical parts are placed after the electrical parts and listed alphabetically by part description. Unless otherwise specified, a listed part is used in all models of the series. Model-specific parts are tabulated by model number under the reference designator. The reference designators are defined in Table 5-1. Abbreviations used in parts descriptions are explained in Table 5-2.

Table 5-1. Part Reference Designators

A assembly J jack SW switch B blower (fan) K relay T transformer C capacitor L inductor TB terminal block CR thyristor/SCR P plug U integrated circuit D diode Q transistor VR voltage regulator DSP display (LCD) R resistor W cable or jumper F fuse RT thermal resistor Y crystal oscillator

Table 5-2. Part Description Abbreviations

assy assembly M metric sq square w/o without bd board mch machine submin subminiature xfmr transformer blvl belleville mm millimeter thk thick xtal crystal gnd ground mtg mounting thrd thread lg long PCB pc board w/ with

Replaceable Parts 89

How to Order Parts

You can order parts from your local Agilent Technologies, Inc. Sales and Support Office (see the list of offices in the back of this manual). When ordering a part, please include the following information:

• the Agilent part number • the part description

• the desired quantity • the model number of the power supply (for example, Agilent 6682A)

Table 5-3. Main Chassis, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ASSEMBLIES & SUBASSEMBLIES

5060-3553 TESTED FRONT PANEL/KEYPAD

5060-3542 TESTED KEYPAD PCB ASSY. A2 5060-3591 TESTED GPIB PC ASSY. A3 5060-3540 TESTED FET ASSY. A4 5060-3543 TESTED AC INPUT BOARD ASSY. A5 5060-3544 TESTED DC RAIL BOARD ASSY. A6 5060-3541 TESTED BIAS PC ASSY. A7

6680A 06680-60021 SNUBBER PCB ASSY. 6681A 06681-60021 SNUBBER PCB ASSY. 6682A 06682-60021 SNUBBER PCB ASSY. 6683A 06683-60021 SNUBBER PCB ASSY.

6684A 06684-60021 SNUBBER PCB ASSY. A8 FAST SENSE PCB A9

6680A 06680-60022 DOWN PROGRAMMER / SLOW SENSE PC

6681A 06681-60022 DOWN PROGRAMMER / SLOW SENSE PC

6682A 06682-60022 DOWN PROGRAMMER / SLOW SENSE PC

6683A 06683-60022 DOWN PROGRAMMER / SLOW SENSE PC

6684A 06684-60022 DOWN PROGRAMMER / SLOW SENSE PC A10

6680A 06681-61020 TESTED CONTROL PCB ASSY.

6681A 06681-61020 TESTED CONTROL PCB ASSY.

6682A 06682-61020 TESTED CONTROL PCB ASSY.

6683A 06683-61020 TESTED CONTROL PCB ASSY.

6684A 06684-61020 TESTED CONTROL PCB ASSY.

ELECTRICAL PARTS

C423, 424, 425, 426 0180-4369 C-F 1500uF 400V C900

6680A 0180-4516 CAP 33000uF 7.5V

6681A 0180-4532 CAP 22000uF 16V

6682A 0180-4615 CAP 18000uF 28V C901, 902, 903, 904, 905

6680A 0180-4516 CAP 33000uF 7.5V

6681A 0180-4532 CAP 22000uF 16V

6682A 0180-4615 CAP 18000uF 28V

6683A 0180-4596 CAP 13000uF 45V

6684A 0180-4597 CAP 7.200uF 55V C906

6680A 0180-4516 CAP 33000uF 7.5V

6681A 0180-4532 CAP 22000uF 16V

90 Replaceable Parts

Table 5-3. Main Chassis, Replaceable Parts

Ref. Desig. Agilent Part No. Description

C907

6680A 0180-4516 CAP 33000uF 7.5V

6681A 0180-4532 CAP 22000uF 16V

6682A 0180-4615 CAP 18000uF 28V

6683A 0180-4596 CAP 13000uF 45V

6684A 0180-4597 CAP 7.200uF 55V C920, 921,922,923,924,925

6682A, 6683A, 6684A 0160-4183 CAP 1000pF 250V D900

6680A, 6681A 1906-0396 SHOTTY RECTIFIER D900A,B

6682A 1906-0397 SHOTTY RECTIFIER

6683A, 6684A 1906-0398 SHOTTY RECTIFIER D901

6680A, 6681A 1906-0396 SHOTTY RECTIFIER D90lA,B

6682A 1906-0397 SHOTTY RECTIFIER

6683A, 6684A 1906-0398 SHOTTY RECTIFIER D902, 903

6680A, 6681A 1906-0396 SHOTTY RECTIFIER L900, 901

6680A, 6681A 06681-80001 CHOKE - OUTPUT

6682A 06681-80004 CHOKE - OUTPUT

6683A 06681-80005 CHOKE - OUTPUT

6684A 06681-80006 CHOKE - OUTPUT L902, 903 5080-2257 CORE L904, 905, 906 9170-1571 CORE Q981, 982 1855-0834 POWER MOSFET R900

6680A 5080-2296 SHUNT-CURRENT

6681A 5080-2297 SHUNT-CURRENT

6682A 06682-80002 SHUNT-CURRENT

6683A 5080-2324 SHUNT-CURRENT

6684A 5080-2324 SHUNT-CURRENT T900, 901

6680A 9100-5042 POWER TRANSFORMER

6681A 9100-5043 POWER TRANSFORMER

6682A 9100-5086 POWER TRANSFORMER

6683A 9100-5085 POWER TRANSFORMER

6684A 9100-5076 POWER TRANSFORMER

MECHANICAL PARTS

06652-00005 BUS BAR 06680-20001 BUSS BAR BLOCK 06680-20002 BUSS/FET BLOCK 06680-80003 NAMEPLATE front panel model description 06681-80003 NAMEPLATE front panel model description 06682-80001 NAMEPLATE front panel model description 06683-80001 NAMEPLATE front panel model description 06684-80001 NAMEPLATE front panel model description

0960-0882 SENSOR-MOISTURE 1252-1488 TERM-BLK-4 POS 1252-3698 CONNECTOR

Replaceable Parts 91

Table 5-3. Main Chassis, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

2110-0910 FUSE (see 5060-3513 ) 2110-0911 FUSE (see 5060-3512 ) 3160-0419 FAN FINGER GUARD 3160-0571 FAN-TUBEAXIAL 5001-0538 TRIM-SIDES 5001-0539 TRIM SIDES,FRENCH GRAY 5001-6776 CHASSIS, BASE 5001-6778 PANEL, REAR 5001-6779 COVER-OUTSIDE 5001-6780 INPUT SUB-CHASSIS (see 5060-3490 ) 5001-6781 OUTPUT SUB-CHASSIS 5001-6782 CHASSIS-TOP (inside cover ) 5001-6783 INPUT DECK 5001-6784 OUTPUT DECK 5001-6791 TRAY (control board ) 5001-6792 SHIELD 5001-6793 GPIB-BRACKET (chassis top ) 5020-2783 HEATSINK-DIODE 5020-2785 HEATSINK-FET 5020-2797 SHIELD-ISOLATION 5020-2808 INSULATOR 5040-1688 BUSS-BEZEL 5040-1689 BUSS BAR SUPPORT 5040-1690 BRACKET-HS 5040-1691 HS-PLEN 5040-1694 BUSS BAR, PLUS, output end (large) 5040-1696 BUSS BAR, PLUS, internal end (small) 5040-1697 BLOCK-TOP COVER 5040-1700 COLLAR-MOLDED 5040-1701 BUSS BAR BRACE

5041-880 1 FOOT

5041-8819 CAP-STRAP HANDLE 5041-8820 CAP-STRAP HANDLE 5060-3237 AC INPUT COVER ASSY. 5060-3490 AC SUB-CHASSIS ASSY. 5060-3489 NEGATIVE OUTPUT BUSS BAR ASSY.

with L902/L903 CORE 5001-6780 SUB-CHASSIS 5080-2262 3 PHASE LINE CHOKE 5080-2298 CABLE - 3 phase line choke/AC input assy 9100-5044 FAN TRANSFORMER 5060-3492 WIRE KIT (+/- sense leads) 5060-3512 400VAC/16A FUSE KIT 2110-0911 3 ea. FUSE 16AM 400VAC 5060-3513 208VAC/30A FUSE KIT 2110-0910 3 ea. FUSE 30AM 500V 5062-3705 STRAP HANDLE 5080-2038 LABEL-WARNING (no operator serviceable) 5080-2148 CABLE (chaining- 2 meters) 5080-2168 CABLE-ASSY. 5080-2277 SUL-THERMAL 5080-2280 CABLE- BIAS/CONTROL 5080-2282 CABLE - AC/RFI FILTER 5080-2285 CABLE- GPIB/FAN

92 Replaceable Parts

Table 5-3. Main Chassis, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

1400-0611 CABLE CLAMP (GPIB/FAN) 5080-2299 LABEL REAR PANEL 5080-2413 CRATE ( shipping container ) 5080-2414 SKID ( shipping container ) 5080-2415 FOAM PAD ( shipping container ) 5080-2314 EDGE PROTECTOR 12 inches ( shipping container ) 5080-2315 EDGE PROTECTOR 2.5 inches ( shipping container ) 5080-2316 CABLE ASSY. 5960-5588 MANUAL-OPERATING

668lA#400 400V OPERATION 6681A#601 BUS BAR COVER 6681A#602 BUS BAR SPACER

5060-3514 BB SPCR KIT #602

6681A#861 CABLE-UL/CSA

8120-6203 L CORD 10AWG300V

6681A#862 CABLE-HARMONIZED

8120-6204 L CORD 2.5mm450V

6681A#908 RACK MOUNT KIT

5062-3974 RACK MTG KIT 5062-3977 RACK MOUNT KIT

6681A#909 RACK MOUNT KIT W/HANDLES

5062-3974 RACK MTG KIT 5062-3983 RACK MOUNT KIT 7120-6153 LABEL-WARNG 9135-0493 FILTER-RFI

Table 5-4. A1 Front Panel Board, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

C1 0160-5422 C2 0160-4808 Capacitor 470pF 5% C4 0160-4787 Capacitor 22pF 5% 100V C5 0180-0155 C6,7 0160-5422 C8 0160-4835 C10-12, C14-16 0160-5422 C17 0180-0155 D1,2 1906-0229 Diode array 50V L1 9140-0158 COIL lUH 10% J2 1251-4927 Receptacle LCD display J3 1251-4926 Receptacle test header J4,5 1252-0718 Receptacle (A3G1, A3G2) J6 1251-8184 Receptacle phone (GPIB board) L1 9140-0158 R1 1810-0560 Resistor network DIP R2 0698-3359 Resistor 12.7K 1% R23-25,27-30 0698-3155 Resistor 4.64K l% R37 1810-0371 Resistor network SIP R38 0698-3441 R39,40 0698-3155 Resistor 4.64K 1% RT1 0837-0412 Thermistor

Capacitor 0.047µF 20%

Capacitor 2.2µF 20V

Capacitor 0.047µF 20%

Capacitor 0.1µF 10% 50V

Capacitor 0.047µF 20%

Capacitor 2.2µF 20V

Inductor 1µH 10%

Resistor 215 Ω 1% 0.125W

Replaceable Parts 93

Table 5-4. A1 Front Panel Board, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

S1 3101-3088 Line switch VR16 1902-0950 Diode Zener 4.7V 5 U3 1820-6721 IC MPU U4 5080-2466 ROM programmed front panel U6 1818-4792 IC memory U8 1820-2724 IC SN74ALS573BN W3 1258-0209 Jumper (J3) W5 0811-3590 Jumper Y1 0410-2159 Crystal 10 MHz Z16 1902-0950 Diode Zener 4.7V 5%

MECHANICAL PARTS

-- 1200-1274 Socket IC (U3)

-- 1200-1417 Socket IC (U4)

-- 0340-1277 Insulator (Y1)

-- 0370-3238 KNOB Ref: RPG

-- 0515-1455 SCREW - Ref: keypad PCB to front frame

-- 0590-0534 NUT - SELFTREAD Ref: Display & LED board to front panel

-- 0960-0912 RPG - OPTICAL ENCODER

5063-3408 PCA (KEYPAD)

-- 1000-0842 WINDOW Ref: 3 inches front frame

-- 5001-6794 BLINDER Ref: 5 inches front frame

-- 5040-1665 KEYPAD

-- 5040-1687 FRONT FRAME - 88.1mm ( 3.5 inches )

-- 5040-1698 FRONT FRAME - 132.6mm ( 5.25 inches )

-- 5063-3473 LCD DISPLAY

-- 5080-2245 LABEL Ref: 3.5 inches & 5 inches front frame

-- 5080-2261 CABLE Ref: Keypad PCB to LCD display

Table 5-5. Front Panel Board LED Assy, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

C450 0180-4132 CAP 6.8uF 35V C451 0160-4808 CAP 470pF 5% D450, 451, 452, 453 1901-1098 DIO-1N4150 R450 0698-3444 RES 316 1% .125W R451 0757-0401 RES 100 1% .125W R452 0698-3156 RES 14.7K 1% R453 0698-8827 RES lM 1% .125W R454 0698-3156 RES 14 7K 1% R455 0757-0280 RES lK 1% .125W U450 1858-0076 XSTR ARY 14P-DIP U451 1858-0077 XSTR ARY 14P DIP Z450 1902-0562 DIO-ZNR 22.1V 5%

MECHANICAL PARTS

5080-2281 CABLE LINE SWITCH Ref: E456=E457 to S1 5080-2283 CABLE LED AC INPUT

Ref: E450-E451 to DC RAIL J440

5080-2286 CABLE DEW/S1 CONNECTION

Ref: E452-E455 to DC RAIL J441

94 Replaceable Parts

Table 5-6. A2 GPIB Board, Replaceable Parts (see Note)

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

C122 0180-4606 C128 0160-4281 Capacitor 2,200pF F101 2110-0699 Fuse Subminature 5AM J101 1252-2320 Connector Receptacle (GPIB) J106 1251-4926 Connector Receptacle (Test Header) J107, 108, 114, 115 1251-7330 Connector Receptacle P101 1251-4245 Connector Plug 2-pin (AC Bias) U110, U111 1990-0444 IC Optoisolator U113 1990-0543 IC Optoisolator U117 1820-2549 IC Optoisolator U118 1820-4185 IC Optoisolator U121 1820-0430 IC Voltage regulator TB101 0360-2312 Terminal Block (Digital Control)

MECHANICAL PARTS

-- 1205-0758 Heatsink (U121)

-- 0535-0031 Nut hex w/lockwasher (J101)

-- 0515-0642 Screw (U121)

-- 0515-0911 Screw M3x0 5 (J101)

Note: All other parts are surface mounted and are not field repairable

Table 5-7. A3 FET Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

Capacitor 10,000µF

C201 0160-7505 7uF+ - 5% 200V C202 0180-4132 CAP 6.8uF 35V C203 0160-4835 CAP .luF 10% 50V C204, 205 0160-5098 CAP .22uF 10% C206 0180-4132 CAP 6.8uF 35V C207, 208, 209 0160-2006 CAP 100pF 10% C210, 211, 213, 214, 0160-6838 CAP 2200pF lKV C215, 216 0160-2006 CAP 100pF 10% C217 0160-5098 CAP .22uF 10% C218 0160-4835 CAP .luF 10% 50V C219 0160-2006 CAP 100pF 10% C220 0180-4132 CAP 6.8uF 35V C221 0160-5098 CAP .22uF 10% C222 0180-4132 CAP 6.8uF 35V C226 0160-4791 CAP 10pF 5% 100V C227 0160-4835 CAP .luF 10% 50V C228 0160-2301 CAP 2000pF 100V C229 0160-4918 CAP .022uF 50V C230 0160-4831 CAP 4700pF 10% C231 0160-2301 CAP 2000pF 100V C235, 236, 237, 238 0160-4832 CAP .0luF 10% C239 0160-4791 CAP 10pF 5% 100V C240 0160-4832 CAP .0luF 10% C242, 243 0160-5098 CAP .22uF 10%

Replaceable Parts 95

Table 5-7. A3 FET Assembly, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

C244, 245 0160-6806 CAP .luF 400V C248 0160-4832 CAP .0luF 10% C258 0180-4132 CAP 6.8uF 35V C301 0160-7505 7uF+ - 5% 200V C302 0180-4132 CAP 6.8uF 35V C303 0160-4835 CAP .luF 10% 50V C304, 305 0160-5098 CAP .22uF 10% C306 0180-4132 CAP 6.8uF 35V C307, 308, 309 0160-2006 CAP 100pF 10% C310, 311, 313, 314 0160-6838 CAP 2200pF lKV C315, 316 0160-2006 CAP 100pF 10% C317 0160-5098 CAP .22uF 10% C318 0160-4835 CAP .luF 10% 50V C319 0160-2006 CAP 100pF 10% C320 0180-4132 CAP 6.8uF 35V C321 0160-5098 CAP .22uF 10% C322 0180-4132 CAP 6.8uF 35V C326 0160-4791 CAP 10pF 5% 100V C329 0160-5098 CAP .22uF 10% C330 0160-4832 CAP .01uF 10% C331 0160-4835 CAP .luF 10% 50V C335, 336, 337, 338 0160-4832 CAP .0luF 10% C339 0160-4791 CAP 10pF 5% 100V C340 0160-4832 CAP .01uF 10% C342, 343 0160-5098 CAP .22uF 10% C344, 345 0160-6806 CAP .luF 400V C346 0160-4800 CAP 120pF 5% D201, 202 1901-0050 DIO-SWITCHING D202 1901-1065 DIO-lN4936 PWR D203, 204 1901-0050 DIO-SWITCHING D205 1901-1065 DIO-lN4936 PWR D206, 207, 208, 209, 210 1901-0050 DIO-SWITCHING D213, 214, 215, 216, 217 1901-0050 DIO-SWITCHING D220, 221, 222, 223 1901-0050 DIO-SWITCHING D224 1901-0731 DIO-PWR RECT D301, 302 1901-0050 DIO-SWITCHING D302 1901-1065 DIO-lN4936 PWR D303, 304 1901-0050 DIO-SWITCHING D305 1901-1065 DIO-lN4936 PWR D306, 307, 308, 309, 310 1901-0050 DIO-SWITCHING D313, 314, 315, 316, 317 1901-0050 DIO-SWITCHING D320, 321, 322, 323 1901-0050 DIO-SWITCHING D324 1901-0731 DIO-PWR RECT L201, 202, 203, 204 9170-1454 CORE-SHLD-BEAD L205, 206, 207, 208, 209 9170-1510 CORE-MAGNETIC L210, 211, 212 9170-1510 CORE-MAGNETIC L213, 214, 215, 216 9170-1454 CORE-SHLD-BEAD L301, 302, 303, 304 9170-1454 CORE-SHLD-BEAD L305, 306, 307, 308, 309 9170-1510 CORE-MAGNETIC L310, 311, 312 9170-1510 CORE-MAGNETIC L313, 314, 315, 316 9170-1454 CORE-SHLD-BEAD Q201, 202, 203, 204 1855-0859 MOSFET 500V 20A Q211, 222, 233, 244 1855-0859 MOSFET 500V 20A Q251, 252, 253, 254 1853-0363 D45H5/D45H8/363

96 Replaceable Parts

Table 5-7. A3 FET Assembly, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

Q301, 302, 303, 304 1855-0859 MOSFET 500V 20A Q311, 322, 333, 344 1855-0859 MOSFET 500V 20A Q351, 352, 353, 354 1853-0363 D45H5/D45H8/363 R201 0811-3903 RES 150 Ohm 5W NI R202 0699-0208 RES 1 5% .25W CF R203 0683-5615 RES 560 5% .25W R205 0683-0625 RES 6.2 5% .25W R206 0683-7505 RES 75 5% .25W R207 0683-0335 RES 3.3 5% .25W R208 0683-3305 RES 33 5% .25W R209 0683-0625 RES 6.2 5% .25W R210 0683-8205 RES 82 5% .25W R211, 212 0683-1535 RES 15K 5% .25W R213, 214, 216, 217 0811-3903 RES 150 Ohm 5W NI R220, 221 0811-3903 RES 150 Ohm 5W NI R222 0811-2556 RES 1.25 1% 4W R224, 225 0811-3903 RES 150 Ohm 5W NI R226 0683-1535 RES 15K 5% .25W R227 0698-3159 RES 26.1K 1% R228 0683-8205 RES 82 5% .25W R229 0683-0625 RES 6.2 5% .25W R230 0683-3305 RES 33 5% .25W R231 0683-7505 RES 75 5% 25W R232 0683-0335 RES 3.3 5% 25W R233 0683-0625 RES 6.2 5% 25W R237 0757-0437 RES 4.75K 1% R238 0757-0280 RES lK 1% .125W R239 0757-0437 RES 4.75K 1% R240 0757-0280 RES lK 1% .125W R241, 242 0757-0437 RES 4.75K 1% R243 0683-1535 RES 15K 5% .25W R244 0698-4457 RES 576 1% .125W R245 0683-1015 RES 100 5% .25W R246 0683-1555 RES 1.5M 5% .25W R247 0757-0462 RES 75K 1% R248 0698-3159 RES 26.1K 1% R249 0757-0444 RES 13.1K 1% R250 0698-3572 RES 60.4K 1% R251 0757-0288 RES 9.09K 1% R252 0698-3225 RES 1.43K 1% R253 0698-6533 RES 12.5K 1% R254 0698-3279 RES 4.99K 1% R255 0683-1015 RES 100 5% .25W R256 0698-3432 RES 26.1 1% R257 0698-3430 RES 21.5 1% R258 0683-1035 RES l0K 5% .25W R260, 261 0683-8205 RES 82 5% .25W R262 0683-1215 RES 120 5% .25W R263, 264, 265 0683-8205 RES 82 5% .25W R266 0683-1215 RES 120 5% .25W R267 0683-8205 RES 82 5% .25W R268 0698-3572 RES 60.4K 1% R269 0698-4121 RES 11.3K 1% R270 0757-0440 RES 7.5K 1%

Replaceable Parts 97

Table 5-7. A3 FET Assembly, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

R271 0757-0200 RES 5.62K 1% R272 0757-0442 RES l0K 1% .125W R273, 274, 275 0757-0437 RES 4.75K 1% R277 0698-3633 RES 3905% 2W MO R301 0811-3903 RES 150Ohm 5W NI R302 0699-0208 RES 1 5% .25W CF R303 0683-5615 RES 5605% .25W R304 0698-4435 RES 2.49K 1% R305 0683-0625 RES6.25% .25W R306 0683-7505 RES 75 5% .25W R307 0683-0335 RES 3.3 5% .25W R308 0683-3305 RES 33 5% .25W R309 0683-0625 RES 6.2 5% .25W R310 0683-8205 RES 82 5% .25W R311 0683-1535 RES 15K 5% .25W R312 0683-1535 RES 15K 5% .25W R313, 314, 316, 317 0811-3903 RES 150 Ohm 5W NI R320, 321 0811-3903 RES 150 Ohm 5W NI R322 0811-2556 RES 1.25 1% 4W R324, 325 0811-3903 RES 150 Ohm 5W NI R326 0683-1535 RES 15K 5% .25W R327 0683-1555 RES 1.5M 5% .25W R328 0683-8205 RES 82 5% .25W R329 0683-0625 RES 6.2 5% .25W R330 0683-3305 RES 33 5% .25W R331 0683-7505 RES 75 5% .25W R332 0683-0335 RES 3.3 5% .25W R333 0683-0625 RES 6.2 5% .25W R337 0757-0437 RES 4.75K 1% R338 C757-0280 RES lK 1% .125W R339 0757-0437 RES 4.75K 1% R340 0757-0280 RES lK 1% .125W R341, 342 0757-0437 RES 4.75K 1% R343 0683-1535 RES 15K 5% .25W R354 0757-0442 RES 10K 1% .125W R355 0698-3136 RES 17.8K 1% R356, 357 0757-0382 RES 16.21% R360, 361 0683-8205 RES 82 5% .25W R362 0683-1215 RES 120 5% .25W R363, 364, 365 0683-8205 RES 82 5% .25W R366 0683-1215 RES 120 5% .25W R367 0683-8205 RES 82 5% .25W R368 0698-3572 RES 60.4K 1% R369 0698-4121 RES 11.3K 1% R370 0757-0440 RES 7.5K 1% R371 0757-0200 RES 5.62K 1% R372 0757-0442 RES 10K 1% .125W R373, 374, 375 0757-0437 RES 4.75K 1% R377 0698-3633 RES 390 5% 2W MO R378 0757-0274 RES 1.21K 1% R379 0683-1005 RES 10 5% .25W R380 0757-0437 RES 4.75K 1% R381 0698-0085 RES 2.61K 1% R382 0683-1015 RES 100 5% .25W

98 Replaceable Parts

Table 5-7. A3 FET Assembly, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

R383 0757-0442 RES 10K 1% .125W R384, 385 8159-0005 RES-ZERO OHMS T202 9100-4350 XFMR-CURRENT T204 06624-80091 XFMR-PULSE T205 5080-2238 XFMR-CUR SHARING T302 9100-4350 XFMR-CURRENT T304 06624-80091 XFMR-PULSE U201, 202 1820-8433 PWM I.C. IR2110 U203 1826-1343 IC-VOLTAGE REG TL431CP U204 1826-0138 IC COMPARATOR LM339N U205 1826-1475 VOLTAGE COMPTR LT101lCN8 U301, 302 1820-8433 PWM I.C. IR2110 U303 1826-1343 IC-VOLTAGE REG TL431CP U304 1826-0412 IC LM393N U305 1990-0996 OPTO-ISOLATOR HCPL-2200 Z201, 301 1902-1377 DIO-ZNR 6 19V

MECHANICAL PARTS

5080-2279 CABLE FET CONTROL

Ref: E208-E209 to CONTROL J511

5080-2283 CABLE +15V BIAS

Ref: E206-E207 to BIAS J831 Ref: E306-E307 to BIAS J830

5080-2291 CABLE FET RAIL A

Ref: E201-E202 to DCRAIL J430

5080-2295 CABLE FET RAIL B

Ref: E301-E302 to DCRAIL J431

Table 5-8. A4 AC Input Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

C420 0160-7606 CAP 1uF 275V C428, 429, 430 0160-7898 CAP 0.01uF 440V J417, 418 1251-5422 CONNECTOR J419 1251-6832 CONNECTOR J420 1251-3819 CONNECTOR K401 0490-1908 RELAY 24V COIL K402 5060-3593 CONTACTOR, 3 POLE R400, 401,402,403,404,405 0764-0027 RES 75K 5% 2W MO R407, 408 0699-3191 RES 27 OHM 5% 20W R435, 436, 437 0698-3609 RES 22 OHM 5% 2W

MECHANICAL PARTS

5060-3493 WIRE KIT (E403-E408 to Fl,F2,F3) 5080-2284 CABLE RELAY CNTRL (E411-E413 to BIAS J827)

Replaceable Parts 99

Table 5-9. A5 DC Rail Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

C418 0160-4048 CAP 0.022uF 20% C420, 421, 422 0160-7606 CAP luF 275V C427 0160-7743 C-F .047uF 380V D420, 421, 422, 424, 425 5060-3516 ASSY.-RECTIFIER DS420, 421 1990-0517 LED F420 2110-1107 FUSE CLIPS F420 2110-0934 FUSE .5AM, 500V F421 2110-1107 FUSE CLIPS F421 2110-0934 FUSE .5AM, 500V J430, 431 1251-7616 CONNECTOR J432 1251-6832 CONNECTOR J433 1251-3819 CONNECTOR J436, 437, 438, 439 1251-3837 CONNECTOR J440 1252-0055 CONNECTOR J441 1252-0056 CONNECTOR L420, 421 5080-2300 INDUCTOR-NM R420, 421, 422 0698-3611 RES 27 5% 2W MO R423, 424, 425,426,427,428 0764-0044 RES 8.2K 5% 2W R429, 430, 431,432,433,434 0764-0044 RES 8.2K 5% 2W

MECHANICAL PARTS

5080-2286 CABLE BIAS 24V SECONDARY

Ref: E440-E443 to BIAS J816

5080-2288 CABLE AC POWER

Ref: E420-E425 to ACINPUT J420

5080-2289 CABLE AC BIAS

Ref: E430-E434 to ACINPUT J419

5080-2293 CABLE BIAS LINE SELECT

Ref: E444-E447 to J436/J437

5080-2294 CABLE RAIL LINE SELECT

Ref: E448-451 to J438/J439

Table 5-10. A6 Bias Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ELECTRICAL PARTS

C800 0160-4834 CAP .047uF 10% C801 0180-4140 CAP 1800 uF 63V C803 0160-5422 CAP .047uF 20% C804 0180-4131 CAP 4.7uF 35V C805 0160-7743 C-F .047uF 380V C806 0160-4834 CAP .047uF 10% C807 0180-3587 CAP 1000uF 50V C808 0180-0230 C-F luF 50V C809, 810 0180-4129 CAP luF 35V C811, 812 0160-4834 CAP .047uF 10% C813 0180-2980 C-F 1000uF 50V C814, 815 0180-4129 CAP luF 35V C8 16, 817 0180-4405 CAP 470 uF 50V C818, 819 0180-0230 C-F luF 50V C820, 821, 822 0180-4129 CAP luF 35V

100 Replaceable Parts

Table 5-10. A6 Bias Assembly, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

C823 0180-4131 CAP 4.7uF 35V C824, 825 0180-3298 C-F 2200uF 50V C826 0160-4834 CAP .047uF 10% C827 0180-3587 CAP 1000uF 50V C828 0180-0230 C-F luF 50V C829, 830, 831 0180-4129 CAP luF 35V C841 0180-4397 C-F 100uF 63V C842 0180-4131 CAP 4.7uF 35V C843, 844, 845 0160-4835 CAP .luF 10% 50V C846 0180-4131 CAP 4.7uF 35V C847 0180-0228 C-F 22uF 15V D800, 801, 802,803,804,805 1901-0731 DIO-PWR RECT D806, 807, 808,809,810,811 1901-0731 DIO-PWR RECT D812, 813, 814,815,816,817 1901-0731 DIO-PWR RECT D818, 819 1901-0731 DIO-PWR RECT D820 1902-0018 DIO-ZNR lN941 D830 1901-1098 DIO-IN4150 D832 1902-3393 DIO-ZNR 75V 55'o F800 2110-0712 FU-SUBMIN 4A F803, 804, 805, 806 2110-0679 FUSE 1.5AM, 125V J801 1252-1670 CONNECTOR J809 1252-8837 CONNECTOR J816 1252-0056 CONNECTOR J821 1252-5230 CONNECTOR J827 1251-7070 CONNECTOR J830, 831 1252-0055 CONNECTOR Q818, 819 5060-3245 HEAT SINK-TRANSISTOR (1854-0828) ASSY. Q820, 821, 822 5060-3527 HEAT SINK-TRANSISTOR (1854-0828) ASSY. R800 0683-3025 RES 3K 5% .25W R801, 802 0683-0475 RES 4.7 5% .25W R803 0698-0084 RES 2.15K 1% R804 0698-3440 RES 196 1% .125W R805, 806 8159-0005 RES-ZERO OHMS R807, 808, 809 0698-0084 RES 2.15K 1% R810 0698-3440 RES 196 1% .125W R811 0699-0208 RES 1 5% .25W CF R812, 813, 814, 815, 816 8159-0005 RES-ZERO OHMS R817 0757-0442 RES 10K 1% .125W R818 0698-6392 RES 22K .1%.125W R819 0698-6631 RES 2.5K .1% R820 0699-0070 RES 3.16M 1% R821 0698-4493 RES 34K 1% .125W R822 0757-0290 RES 6.19K 1% R823 0757-0283 RES 2K 1% .125W R824 0699-0070 RES 3.16M 1% R825 0757-0444 RES 12.1K 1% R827 0757-0274 RES 1.21K 1% R828 0757-0444 RES 12.1K 1% R831 0757-0290 RES 6.19K 1% R833 0757-0280 RES lK 1% .125W R834 0757-0442 RES 10K 1% .125W R835 0698-0085 RES 2.61K 1% R836 0757-0442 RES 10K 1% .125W R841 0698-6363 RES 40K .1%

Replaceable Parts 101

Table 5-10. A6 Bias Assembly, Replaceable Parts (continued)

Ref. Desig. Agilent Part No. Description

R842 0698-6360 RES 10K .1% R843 0757-0472 RES 200K 1% R844 0698-6977 RES 30K .1% .125 R845, 847 0698-6360 RES 10K .1% R848 0698-6977 RES 30K .1% .125 R849 0683-3325 RES 3.3K 5% .25W R850 0698-6977 RES 30K .1% .125 R851 0698-4037 RES 46.4 1% R852 0683-3325 RES 3.3K 5% .25W R853, 854, 855 0683-1005 RES 10 5% .25W R856 0698-3152 RES 3.48K 1% R857 0698-4037 RES 46.4 1% R858, 859, 860 0683-1005 RES 10 5% .25W R861 0698-8234 RES 12.1K 1% R862 0699-0070 RES 3.16M 1% R863 0757-0469 RES 150K 1% R864 0699-0070 RES 3.16M 1% R865 0757-0464 RES 90.9K 1% R867 0757-0290 RES 6.19K 1% R868 0757-0199 RES 21.5K 1% R869 0757-0281 RES 2.74K 1% R870 8159-0005 RES-ZERO OHMS R871 0698-3440 RES 196 1% .125W R872 0698-0084 RES 2.15K 1% R873 8159-0005 RES-ZERO OHMS R874 0757-0274 RES 1.21K 1% R875 0698-4037 RES 46.4 1% R876, 877, 878 0683-1005 RES 10 5% .25W R879, 880 8159-0005 RES-ZERO OHMS T801 9100-5040 XFMR- GPIB T802 9100-5041 XFMR-BIAS U801 5060-2942 HEAT SINK-LM317T REGULATOR ASSY. U802 5060-2948 HEAT SINK-UA7805UC REGULATOR ASSY. U803 5060-2942 HEAT SINK-LM317T REGULATOR ASSY. U804 5060-2943 HEAT SINK-LM337T REGULATOR ASSY. U805 5060-2942 HEAT SINK-LM317T REGULATOR ASSY. U806 1826-0544 IC-V RGLTR 2.5V MC1403U U807 1826-0138 IC COMPARATOR LM339N U808 1858-0047 XSTR ARY 16P-DIP U809, 810, 811 1990-1074 OPTO-ISOLATOR 4N35 U812 1826-0161 IC LM324N U813 1990-1074 OPTO-ISOLATOR 4N35

102 Replaceable Parts

MECHANICAL PARTS

5080-2292 CABLE PRIMARY BIAS

Ref: E800-E804 to DCRAIL J432

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

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Scope

Organization

Instrument Identification

Related Documents

Manual Revisions

Firmware Revisions

Safety Considerations

Conventions

Electrostatic Discharge

Verification

Introduction

Tests

Test Equipment Required

List of Equipment

Electronic Load

Programming The Tests

General Considerations

General Measurement Techniques

Performance Test Record Sheets

Operation Verification Tests

Performance Tests

Constant Voltage (CV) Tests

Constant Current (CC) Tests

Averaging the CC Measurements

Troubleshooting

Introduction

Localizing the Problem

Chapter Organization

Test Equipment Required

Troubleshooting Procedures

Troubleshooting Charts

Troubleshooting Test Points

Bias and Reference Supplies

CV/CC Status Annunciators Troubleshooting

A3 FET Board Troubleshooting

Signature Analysis

Introduction

Firmware Revisions

Test Headers

When Required

Inhibit Calibration Jumper

Calibration Password

Restoring Factory Calibration Constants

EEPROM Initialization

Transferring Calibration Constants To Factory Preset Locations

Disassembly Procedures

Tools Required

Top Cover

Removing Protective RFI Shield (Galvanized Sheet Metal)

GPIB Board

A4 AC Input Assembly

A5 DC RAIL Assembly

A6 BIAS Assembly

A3 FET Board

A10 Control Assembly

Front Panel Assembly

S1 Line Switch

A1 Front Panel Board

A1DSP1 LCD Display

A1G1 and A1G2 Rotary Controls

A1KPD Keypad

Output Bus Boards A7, A81 and A9 & Chassis Components

Principles Of Operation

Introduction

A2 GPIB Board

A1 Front Panel Assembly

A10 Control Board

Secondary Interface (P/O A10 Board)

A4 AC Input Board

A5 DC Rail Board

A3 FET Board

Output Circuits

Replaceable Parts

INTRODUCTION

Chapter Organization