HP 6690A OPERATING AND SERVICE MANUAL

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SERVICE MANUAL

GPIB DC Power Supplies

Agilent Series 669xA

For instruments with Serial Numbers:

Agilent 6690A: MY41000131

Agilent 6691A: MY41000119

Agilent 6692A: MY41000133

For manual updates, a change page may be included.

For a history of manual updates, see Appendix A.

Agilent Part No. 5969-2907 Printed in Malaysia

November, 2002

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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.

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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.

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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 is 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. Significant changes to the manual occurring between revisions are covered by change sheets shipped with the manual. Note that not all changes made to the power supply affect the content of the manual. Refer to appendix A for a history of manual updates.

Edition 1 November, 2002

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.

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Table of Contents

Introduction ............................................................................................................................................................................ 7

Scope and Organization ...................................................................................................................................................... 7

Instrument Identification..................................................................................................................................................... 7

Related Documents .......................................................................................................................................................... 8

Manual Revisions............................................................................................................................................................. 7

Firmware Revisions .........................................................................................................................................................8

Safety Considerations .........................................................................................................................................................8

Electrostatic Discharge .......................................................................................................................................................8

Verification.............................................................................................................................................................................. 9

Introduction......................................................................................................................................................................... 9

Tests.................................................................................................................................................................................... 9

Test Equipment Required.................................................................................................................................................... 9

Equipment List................................................................................................................................................................. 9

Current-Monitoring Resistor............................................................................................................................................ 9

Electronic Load................................................................................................................................................................ 9

Programming the Tests ..................................................................................................................................................... 10

General Considerations .................................................................................................................................................. 10

General Measurement Techniques.................................................................................................................................... 11

Performance Test Record Sheets ......................................................................................................................................11

Operation Verification Tests............................................................................................................................................. 11

Performance Tests............................................................................................................................................................. 11

Constant Voltage (CV) Tests ......................................................................................................................................... 12

Constant Current (CC) Tests.......................................................................................................................................... 15

Averaging the CC Measurements................................................................................................................................... 19

Troubleshooting .................................................................................................................................................................... 25

Introduction....................................................................................................................................................................... 25

Test Equipment Required .............................................................................................................................................25

Power-On Selftest ............................................................................................................................................................. 26

Troubleshooting Charts.................................................................................................................................................. 26

Firmware Revisions .......................................................................................................................................................42

Test Headers................................................................................................................................................................... 42

Post-Repair Calibration..................................................................................................................................................... 43

When Required .............................................................................................................................................................. 43

Inhibit Calibration Jumper ............................................................................................................................................. 43

Calibration Password ..................................................................................................................................................... 43

Restoring Factory Calibration Constants .......................................................................................................................44

EEPROM Initialization..................................................................................................................................................... 44

Transferring Calibration Constants to Factory Preset Locations.......................................................................................44

Disassembly Procedures ...................................................................................................................................................48

Tools Required............................................................................................................................................................... 49

Top Cover ......................................................................................................................................................................49

Removing Protective RFI Shield (Galvanized Sheet Metal).......................................................................................... 49

GPIB Board.................................................................................................................................................................... 49

A4 AC Input Assembly.................................................................................................................................................. 50

A5 DC RAIL Assembly ................................................................................................................................................. 50

A6 BIAS Assembly........................................................................................................................................................ 50

A3 FET Board................................................................................................................................................................ 50

A10 Control Assembly................................................................................................................................................... 50

Front Panel Assembly .................................................................................................................................................... 51

S1 Line Switch............................................................................................................................................................... 51

A1 Front Panel Board..................................................................................................................................................... 51

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A1DSP1 LCD Display ................................................................................................................................................... 51

A1G1 and A1G2 Rotary Controls.................................................................................................................................. 51

A1KPD Keypad ............................................................................................................................................................. 51

Output Bus Boards A7, A81 and A9 & Chassis Components........................................................................................ 52

Principles of Operation ........................................................................................................................................................59

Introduction....................................................................................................................................................................... 59

A2 GPIB Board................................................................................................................................................................. 59

A1 Front Panel Assembly ................................................................................................................................................. 60

A10 Control Board.......................................................................................................................................................... 60

A4 AC Input Board........................................................................................................................................................... 62

A5 DC Rail Board............................................................................................................................................................. 63

A3 FET Board................................................................................................................................................................... 63

Output Circuits.................................................................................................................................................................. 64

Replaceable Parts .............................................................................................................................................................. 65

Introduction...................................................................................................................................................................... 65

How to Order Parts ...........................................................................................................................................................65

Diagrams................................................................................................................................................................................ 69

Introduction....................................................................................................................................................................... 69

Backdating............................................................................................................................................................................. 99

Index .................................................................................................................................................................................... 101

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Introduction

Scope and Organization

This manual contains information for troubleshooting and repairing Agilent Series 669xA, 6.6-kilowatt power supplies to the assembly level. The supplied schematics at the back of the manual are not intended for component level repair, only to provide additional information for isolating a problem to a specific assembly. The 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 assembly

and, if required, post-repair calibration and EEPROM initialization procedures.

Chapter 4 Principles of power supply operation on a block-diagram level. Chapter 5 Assembly-level replaceable parts, including parts ordering information. Chapter 6 Diagrams, including schematics, component location drawings, and troubleshooting test points.

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 MY The first two letters indicates the country of manufacture, where US = USA; MY = Malaysia. 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.

Manual Revisions

The edition and current revision of this manual is indicated on page 4. 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. Significant changes to the manual occurring between revisions are covered by change sheets shipped with the manual. Note that not all changes made to the power supply affect the content of the manual. Refer to appendix A for a history of manual updates.

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) A revised edition incorporates all new or corrected material since the previous printing date.

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. These changes will also be incorporated at future updates of the manual.

3) A history of changes to this manual that affect previously manufactured units is provided in Appendix A

- Manual Backdating.

Introduction

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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.

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.

Electrostatic Discharge Precautions

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

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Verification

Introduction

This chapter provides test procedures for checking the operation of Agilent Series 669xA power supplies. The required test equipment is specified and sample performance test record sheets are included. Instructions are given for performing the tests either from the front panel or from a controller over the GPIB.

Tests

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

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

supply is performing properly.

Performance

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.

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

Test Equipment Required

Equipment List

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. Connect the current monitor directly to these current-monitoring terminals.

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.

'' is needed for the Operation Verification test.

Verification 9

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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 6691A, 6692A: Guildline 9230/300

0.001Ω ± 0.04%, 300A, 100W Agilent 6690: Burster Type 1280

0.0001Ω ± 0.05%, 1000A, 100W 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: 7kW minimum

6.6 Kilowatt minimum Agilent 6690A = 34.1 milliohms 6600W

Agilent 6691A = 136 milliohms 6600W Agilent 6692A = 545 milliohms. 6600W

Oscilloscope

Sensitivity: 1mV Agilent Infinium Bandwidth Limit: 20MHz or equivalent Probe: 1:1 with RF tip

RMS Voltmeter

True RMS Bandwidth: 20MHz Rhode & Schwartz 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 669xA models.

Recommended Model

Agilent 6680A

4 each Agilent N3300A, with/3

each Agilent N3306A per mainframe for all units

Model URE3 RMS-P-P voltmeter

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

24.2 KVA or equivalent .

HP Series 200/300

Programming the Tests

General Considerations

Procedures are given for programming these tests either from the front panel keypad or from a GPIB controller. The

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

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

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

10 Verification

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Programming Parameters Table 2-2 lists the programming voltage and current values for each model. You can enter these values either from the front

panel or from a controller over the GPIB.

Table 2-2. Programming Voltage and Current Values

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

Voltage Voltage Current Current Overvoltage Agilent 6690A 15V 15.375V 440A 450A 18V Agilent 6691A Agilent 6692A

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 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.

30V 30.75V 220A 225A 36V 60V 61.5V 110A 112A 69V

Operation Verification Tests

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

Table 2-3. Operation Verification Tests

Test Refer To

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

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

Performance Tests

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

Verification 11

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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.

DVM

Electronic Load

a) CV Test Setup with 6.6kW Electronic Load

DVM

6.6kW Load Resistor

b) CV Test Setup with 6.6kW Load Resistor

Note: Start with switch closed, take full load reading,

open switch and take no load reading.

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

12 Verification

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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.

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).

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

Verification 13

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

Action

CV Source Effect (cont)

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.

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).

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

14 Verification

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

Action

Transient Recovery (cont)

3 Program the Electronic Load as follows:

• Operating mode to constant current.

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

• Transient current level to the supply's full rated output current.

• Transient generator frequency = 100Hz.

• 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 .

Normal Result

See Fig. 2-2.

Specified voltage level is reached within

900µs.

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 Figure 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.

Verification 15

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DVM

Electronic Load

Power Supply

6.6kW Load

Resistor

Current Monitor

Resistor

a) CC Test Setup with 6.6kW Electronic Load

* Note: Series power source required for CC Load Regulation Test, allows UUT to operate at 0 volts and electronic load to operate at its minimum input voltage specification. Voltage source must always be in CV mode. UUT must be in CC mode for all CC tests.

DVM

Current Monitor

Resistor

16 Verification

b) CC Test Setup with 6.6kW Load Resistor

Note: Start with switch closed, take reading at 0 output voltage. Open switch and take full load reading. UUT must be in CC mode for all CC tests.

Figure 2-3. CC Load Effect Test Setup

Page 17

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 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).

Value within specified Low Current limits.

High Current and readback limits.

Note: Refer to Figure 2-3. If you are using Agilent N3306A electronic loads, a series DC power source is required to

supply the minimum 3 volt input required by the Agilent N3306A electronic loads. The series DC source must be capable of 3VDC at a current level that is greater than the output current of the supply being tested. A switch can be used in place of the series supply if the electronic loads are used in place of a load resistor as shown in Fig. 2-3(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

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).

Verification 17

Page 18

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.

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

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.

18 Verification

Page 19

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 .

Verification 19

Page 20

Table 2-6. Performance Test Record Form

Test Facility:

__________________________________________ Report No._________________________________________ __________________________________________ Date______________________________________________

__________________________________________ Customer__________________________________________ Model_____________________________________ Tested By__________________________________________ Serial No __________________________________ Ambient Temperature (°C)_____________________________ Options ____________________________________ Relative Humidity (%)________________________________ Firmware Revision ___________________________ Nominal Line Frequency (Hz)__________________________

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

20 Verification

Page 21

Table 2-7. Performance Test Record for Agilent Model 6690A

MODEL Agilent_____________

Report No.________ Date___________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (15V) 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

Constant Voltage Tests

-15mV

- 22.5mV

out

14.979V

-30mV

out

- 0.95mV _______mV V

out

- 0.95mV _______mV V

out

0 0

0 _______mV 150mV

________mV ________mV

_________V

_______mV

_______mV _______mV

Maximum Spec.

+15mV

+ 22.5mV

out

15.021V

+ 30mV

out

+ 0.95mV

out

+ 0.95mV

out

15mV

2.5 mV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (440A) I

out

Front Panel Display Readback

Load Effect

Source Effect

Constant Current Tests

-230mA

- 300mA

out

439.33A

- 740mA

out

- 62mA ________mA I

out

- 62.5mA ________mA I

out

*Enter your test results in this column.

_______mA _______mA

_________A

_______mA

+230mA

+ 300mA

out

440.67A

+ 740mA

out

+ 62mA

out

+ 62.5mA

out

Verification 21

Page 22

Table 2-8. Performance Test Record for Agilent Model 6691A

MODEL Agilent_____________

Report No.________ Date___________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (30V) 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

Constant Voltage Tests

-30mV

- 45mV

out

29.958V

- 60mV

out

- 1.7mV _______mV V

out

- 1.25mV _______mV V

out

0 0

0 _______mV 150mV

________mV ________mV

_________V

_______mV

_______mV _______mV

Maximum Spec.

+30mV

+ 45mV

out

30.042V

+ 60mV

out

+ 1.7mV

out

+ 1.25mV

out

25mV

2.5mV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (220A) I

out

Front Panel Display Readback

Load Effect

Source Effect

Constant Current Tests

-125mA

- 165mA

out

219.655A

- 385mA

out

- 28mA ________mA I

out

- 28mA ________mA I

out

*Enter your test results in this column.

_______mA _______mA

_________A

_______mA

+125mA

+ 165mA

out

220.345A

+ 385mA

out

+ 28mA

out

+ 28mA

out

22 Verification

Page 23

Table 2-9. Performance Test Record for Agilent Model 6692A

MODEL Agilent_____________

Report No.________ Date___________

Test Description

Voltage Programming and Readback

Low Voltage (0V) V

out

Front Panel Display Readback

High Voltage (60V) 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

Constant Voltage Tests

-60mV

- 90mV

out

59.916V

- 120mV

out

- 3.4mV _______mV V

out

-1.85mV _______mV V

out

0 0

0 _______mV 150mV

________mV ________mV

_________V

_______mV

_______mV _______mV

Maximum Spec.

+60mV

+ 90mV

out

60.084V

+ 120mV

out

+ 3.4mV

out

+ 1.85mV

out

25mV

2.5mV

Current Programming and Readback

Low Current (0A) I

out

Front Panel Display Readback

High Current (110A) I

out

Front Panel Display Readback

Load Effect

Source Effect

Constant Current Tests

-65mA

- 80mA

out

109.825A

- 190mA

out

- 14.5mA ________mA I

out

- 14.5mA ________mA I

out

*Enter your test results in this column.

_______mA _______mA

_________A

_______mA

+65mA

+ 80mA

out

+110.175A

+ 190mA

out

+ 14.5mA

out

+ 14.5mA

out

Verification 23

Page 24

Page 25

Troubleshooting

Introduction

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).

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.

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 An explanation of the error codes and messages generated during the power-on selftest.

A series of flow charts for systematic location of defective boards, circuits, and components.

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.

Test Equipment Required

Table 3-1. Test Equipment Required

Equipment Purpose Recommended Model

Test Clips To gain access to IC pins. AP Products No. LTC

Ammeter/Current Shunt To measure output current. Agilent 6690A: Burster 1280

Agilent 6691A, 6692A: Guildline 9230/300

Oscilloscope To check waveforms and signal levels. Agilent 54504A

GPIB Controller To communicate with power supply

via the GPIB (for system units).

Agilent BASIC series

DC Voltmeter To measure output voltage and

current, bias and references.

Agilent 3458A

Troubleshooting 25

Page 26

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

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.

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). Some results of Figure 3-1 lead to more detailed troubleshooting charts that guide you to specific components.

Many of the following troubleshooting procedures begin by checking the bias and/or reference voltages. Table 6-3 of chapter 6 lists the test points for these voltages and gives the correct reading for each. Test points are identified by an encircled number such as U in schematic diagrams and component location drawings. The circuit board component location diagrams identify these points on each board.

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 Serial Down circuit (from Figure 3-1).

Figure 3-9 Secondary interface circuit (from Figure 3-1).

Figure 3-10 Slow downprogramming circuit (from Figure 3-1).

Figure 3-11 FET troubleshooting (from table 3-2).

26 Troubleshooting

Page 27

Table 3-2. Selftest Error Codes/Messages

Code and/or

Message

El FP RAM Front panel RAM test failed (power-on). A1 board probably defective.*

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

and *TST?).

Description Probable Cause Selftest Error

Codes/Messages

A1 board probably defective.*

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). A2 board probably defective.

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). A10 board probably defective,* or A6 bias board

NOTE: The following error messages can appear because of a failure while the unit is operating or during selftest.

EEPROM U6 on the A1 board probably defective.*

A2 board probably defective.

A10 board probably defective.*

A10 board probably defective,* or A6 bias board defective

A10 board probably defective.*

defective (see Figure 3-7).

SERIAL TIMOUT Serial data line failure on A2 board. See Figure 3-8.

SERIAL DOWN Serial data line failure on A2 board. See Figure 3-8.

UART PARITY UART failed. A2 board probably defective.

UART FRAMING UART failed. A2 board probably defective.

UART OVERRUN UART failed. A2 board probably defective.

SBUF OVERRUN Serial buffer failure UART. A2 board probably defective or A2 board is in SA

mode (see Figure 3-12).

SBUF FULL Serial buffer failure. A2 board probably defective or A2 board is in SA

mode (see Figure 3-12).

EE WRITE ERR EEPROM write failure. EEPROM U6 on the A1 board probably defective

or calibration error.*

SECONDARY DN Serial data line failure on Main board. See Figure 3-9.

* If you replace either the Al or A10 board, the power supply must be reinitialized and calibrated.

Troubleshooting 27

Page 28

"OVERALL TROUBLESHOOTING"

START

YES

DID YOU DO

TROUBLE SHOOTING IN

PAGE 3-5 IN OPERATING

MANUAL ?

YES

TURN OFF SUPPLY AND REMOVE THE TOP COVER

AND RFI SHIELD. DISCONNECT LOAD. CONNECT

SENSE TERMINALS FOR LOCAL SENSING.

TURN ON SUPPLY AND CHECK FOR INDICATION

(FAN RUNNING, DISPLAY ON, DC RAIL LED DS420,

DS421 ON) THAT AC POWER IS ON.

YES

FAN RUNNING ?

YES

DISPLAY

ON?

YES

CHECK FOR AC POWER ON A4 BOARD. CHECK

F800 AND CHECK FOR 24 V BIAS ON A6 BOARD.

CHECK AC LINE SWITCH A1S1.

GO TO NO DISPLAY TROUBLESHOOTING FIG. 3-2

PERFORM CHECKS IN OPERATING MANUALS,

ERROR

MESSAGE

DISPLAYED?

WITH FRONT PANEL KEYS, PROGRAM FULL SCALE

VOLTAGE AND CURRENT (SEE TABLE 2-2). USE DVM

TO MEASURE VOLTAGE AT OUTPUT TERMINALS.

OUTPUT

VOLTAGE WITHIN

SPEC?

YES

GO TO SHEET 2

YES

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

28 Troubleshooting

SEE SELF TEST ERROR CODES, TABLE 3-2

VOLTAGE

RIGHT BUT OUT-

OF SPEC?

GO TO SHEET 4

YES

CALIBRATE THE SUPPLY

Page 29

A FROM SHEET 1

VOLTAGE

DISPLAY WITH-

IN SPECS?

YES

IS CV

ANNUNCIATOR

ON?

TURN OFF SUPPLY AND CONNECT A SHUNT

(SEE TABLE 3-1) ACROSS THE OUTPUT

TERMINALS. TURN ON SUPPLY AND PROGRAM

FULL-SCALE VOLTAGE AND CURRENT.

OUTPUT

CURRENT WITHIN

SPECS?

YES

READS

OK BUT OUTSIDE

SPECS?

YES

CALIBRATE SUPPLY.

PROBABLE DEFECTIVE A10 BOARD

CURRENT

OK BUT OUTSIDE

SPECS?

YES

PROBABLE DEFECTIVE A10 BOARD

CALIBRATE SUPPLY.

GO TO SHEET 4

CURRENT

DISPLAY WITH-

IN SPECS?

YES

IS CC

ANNUNCIATOR

ON?

YES

TURN OFF SUPPLY AND REMOVE SHUNT. TURN ON SUPPLY AND PROGRAM VOLTAGE AND CURRENT TO FULL SCALE. PROGRAM OV TO 1/2 FS

VOLTAGE. CHECK THAT SUPPLY GOES INTO AN

OV CONDITION (PROT ON AND OUTPUT=0).

CONDITION

OCCURRED?

YES

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

READS

OK BUT OUTSIDE

SPECS?

YES

CALIBRATE SUPPLY.

PROBABLE DEFECTIVE A10 BOARD

GO TO "OV WILL NOT FIRE"

TROUBLESHOOTING FIG 3-3.

PROBABLE DEFECTIVE A10 BOARD

D GO TO SHEET 3

Troubleshooting 29

Page 30

FROM SHEET 2

PROGRAM OV TO MAXIMUM AND PRESS PROT CLEAR KEY. OUTPUT SHOULD GO TO FULL

SCALE VOLTAGE.

PRESS OUTPUT ON/OFF REPEATEDLY WHILE

WATCHING VOLTAGE DISPLAY. DOWN-

PROGRAMMING SHOULD TAKE < 1 SECOND.

LESS THAN

1 SECOND?

YES

TURN OFF SUPPLY AND CONNECT A GPIB

CONTROLLER TO SUPPLY. CHECK IF SUPPLY

ACCEPTS GPIB COMMANDS.

ACCEPTS

COMMANDS?

YES

CHECK OPERATION OF DIGITAL CONTROL PORT, SERIAL LINK AND THE FRONT PANEL

V/I ROTARY CONTROLS.

DIGITAL

CONTROL PORT

OK?

YES

SERIAL

LINK OK?

GO TO 'SLOW DOWN PROGRAMMING'

TROUBLESHOOTING (SEE FIG. 3-12).

PROBABLE DEFECTIVE A2 BOARD

FRONT PANEL

CONTROLS OK?

NO PROBLEMS FOUND. PERFORM VERIFICATION

TESTS IN CHAPTER 2 TO ISOLATE PROBLEM.

30 Troubleshooting

YES

CHECK VOLTAGE RPG (A1G1) AND/OR

CURRENT RPG (A1G2) CONTROLS AND

CABLE CONNECTIONS.

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

Page 31

FROM SHEET 1

FROM SHEET 2

PROT

ANNUNCIATOR

ON?

YES

PRESS PROTECT KEY

"OT"

DISPLAYED?

"OV"

DISPLAYED?

"OC"

DISPLAYED?

RI (REMOTE INHIBIT) DISPLAYED.

CHECK FOR SHORT BETWEEN

A2TB101-3 AND GROUND.

YES

OUTPUT

VOLTAGE NEAR

OV?

YES

GO TO "OUTPUT HELD HIGH"

TROUBLESHOOTING FIG. 3-6.

PROBABLE DEFECTIVE A10 BOARD

GO TO "OV AT TURN-ON"

TROUBLESHOOTING FIG 3-4.

CHECK IF OCP IS ENABLED AT

TURN-ON AND CURRENT IS

PROGRAMMED TO ZERO,

OR OUTPUT SHORTED

GO TO "OUTPUT HELD LOW"

TROUBLESHOOTING FIG. 3-5

YES

PROBABLE DEFECTIVE A10 BOARD

VOLT-

AGE RIGHT BUT

OUTSIDE SPEC?

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

Troubleshooting 31

Page 32

START

"NO DISPLAY"

TURN OFF SUPPLY, REMOVE TOP COVER AND RFI SHIELD. UNPLUG CABLE W5 FROM J108 ON A2 GPIB BOARD AND UNPLUG CABLE W4 FROM J507 ON A10 CONTROL BOARD. PLUG CABLE W5 INTO J507 ON A10 BOARD. THIS REMOVES GPIB BOARD FROM THE DATA PATH AND CONNECTS THE FRONT PANEL

DIRECTLY TO THE CONTROL BOARD, SEE WARNING.

TURN ON THE SUPPLY AND TRY TO PROGRAM THE SUPPLY FROM THE FRONT PANEL.

WARNING:

THS CONFIGURATION IS FOR THE TEST ONLY. DO NOT

FLOAT THE OUTPUT OR ATTEMPT TO OPERATE THE SUPPLY.

SUPPLY

OPERATES

PROPERLY?

TURN OFF THE SUPPLY IN ORDER TO ACCESS

A1 FRONT PANEL BOARD. REMOVE A1 FRONT

TURN ON SUPPLY. CHECK +5V BIAS AT R1-6

CONNECT METER COMMON TO R1-3.

CHECK THE FOLLOWING DISPLAY VOLTAGES:

1.1V AT R1-14; 2.2V AT R1-2.

CHECK 12 MHz CLOCK SIGNAL AT A1U3-66.

PANEL ASSEMBLY.

12MHz

SIGNAL OK?

YES

CHECK TEST POINTS 1 - 4 . (SEE TABLE 6-3).

CHECK CABLE W4.

PROBABLE DEFECTIVE A6 BOARD.

DISPLAY

& BIAS VOLTAGES

OK?

YES

CHECK

PCLR (RESET*)

A2U2-16 = 5V?

PROBABLE DEFECTIVE A1 BOARD

OR A2 BOARD

CONNECT EXTERNAL VOLTMETER TO OUTPUT TERMINALS. PROGRAM VOLTAGE AND CURRENT AT THE FRONT PANEL. MEASURE VOLTAGE AT OUTPUT TERMINALS. (IF OUTPUT IS DISABLED, PRESS OUTPUT KEY).

LCD DSP1 OR CABLE W2 IS DEFECTIVE.

32 Troubleshooting

YES

OUTPUT VOLTAGE

PRESENT?

YES

PROBABLE DEFECTIVE A1 BOARD

Figure 3-2. No Display Troubleshooting)

Page 33

START

"OV WILL NOT FIRE"

TURN OFF SUPPLY, REMOVE TOP COVER AND RFI SHIELD. TURN ON SUPPLY

AND CHECK BIAS AND REFERENCE VOLTAGES (TEST POINTS 15

THROUGH 22 . SEE TABLE 6-3).

VOLTAGES OK?

YES

TURN SUPPLY ON AND PROGRAM THE OUTPUT

VOLTAGE AND CURRENT TO 1/2 SCALE. PROGRAM THE OV TO ZERO.

INSURE THAT OUTPUT VOLTAGE IS AS PROGRAMMED AND THE OVER-

VOLTAGE CONDITION IS NOT DETECTED (OV ANNUNCIATOR IS OFF).

CHECK VOLTAGES AT A10U502-12 70 AND A10U502-14

63 WITH RESPECT TO COMMON 36 (See TABLE 6-3)

NOTE: U502-14 PULSES ARE LOW WHEN "OV" FIRES.

5 V

0 V

APPROXIMATELY 1 MILLISEC.LOW WHEN "OV" FIRES.

PROBABLE DEFECTIVE A6 BOARD

A10U502-12 NEGATIVE?

YES

A10U502-14

LOW?

YES

PROBABLE DEFECTIVE A10 BOARD OR A9 DOWNPROGRAMMER BOARD

Figure 3-3. OV Will Not Fire Troubleshooting)

PROBABLE DEFECTIVE A10 BOARD

Troubleshooting 33

Page 34

START

"OV AT TURN-ON"

CHECK THAT THE OUTPUT VOLTAGE SETTING

IS NOT HIGHER THAN THE OV SETTING IN THE

MEMORY REGISTER. PROGRAM 0 VOLTS AND

MAXIMUM OV. THEN SAVE IN REGISTER 0

(PRESS THE SHIFT, SAVE, 0, ENTER KEYS).

TURN OFF SUPPLY.

DURING THESE TESTS THE OUTPUT MAY BE AT

WARNING:

HAZARDOUS LEVELS.

CONNECT A DC SCOPE ACROSS THE OUTPUT TERMINALS. TURN ON SUPPLY AND CHECK

THAT OUTPUT DOES NOT MOMENTARILY GO

HIGHER THAN THE VOLTAGE SETTINGS.

MOMENTARILY

GOES HIGHER?

TURN OFF SUPPLY. REMOVE TOP COVER AND

RFI SHIELD. DISABLE THE OV INPUT BY LIFTING

A10R536. TURN ON SUPPLY AND CHECK

OUTPUT VOLTAGE.

OUTPUT

HIGH?

OV STILL

OCCURS?

CHECK VOLTGES AT A10U521-7 84 ,

A10U502-12 70 , AND A10U502-14 63

WITH RESPECT TO COMMON 30

DOES

A10U521-7

= +5.4 +/- 0.5 V?

YES

GO TO "OUTPUT HELD HIGH"

TROUBLESHOOTING FIG. 3-6.

GO TO "OUTPUT HELD HIGH"

TROUBLESHOOTING FIG. 3-6.

PROBABLE DEFECTIVE A10 BOARD

CHECK THAT A10U521-7 GOES FROM 0 V

TO APPROX. 5.4 V AS OVERVOLTAGE

IS PROGRAMMED FROM 0 TO MAXIMUM.

IF NOT, PROBABLE DEFECTIVE A10 BOARD

PROBABLE DEFECTIVE A10 BOARD OR A9 DOWNPROGRAMMER BOARD

34 Troubleshooting

A10U502-12

> +0.5V?

YES

A10U502-14

HIGH?

YES

PROBABLE DEFECTIVE A10 BOARD

Figure 3-4. OV At Turn-On Troubleshooting)

Page 35

START

"OUTPUT HELD LOW"

THE OUTPUT IS HELD LOW AND PROT IS NOT ON. TURN OFF SUPPLY, DISCONNECT THE LOAD, REMOVE TOP COVER AND RFI SHIELD. TURN ON SUPPLY AND CHECK BIAS

VOLTAGES (TEST POINTS 9 THROUGH 22 , SEE TABLE 6-3).

TURN OFF SUPPLY AND GO TO "A5 CONTROL BOARD TROUBLESHOOTING SETUP" (TABLE 6-3). TURN ON SUPPLY AND PROGRAM OUTPUT TO 1/2 FULL SCALE VOLTAGE AND CURRENT. PROGRAM

OV TO MAXIMUM, OCP OFF, AND ENABLE THE OUTPUT.

CHECK CURRENT READING

ON FRONT PANEL DISPLAY

DISPLAY

READS 1/2 F.S.

CURRENT?

CHECK CC PROGRAM LEVEL

AT A10U514-6 40

40 = -5V ?

YES

ARE

VOLTAGES

OK?

YES

IS CC

ANNUNCIATOR

ON?

CHECK FOR SHORT

CIRCUIT IN OUTPUT

CHECK CURRRENT CALIBRATION

USE DIFFERENTIAL INPUT OSCILLOSCOPE

TO CHECK FOR PULSES AT A10J511 62 ,

A10U602-9 52 , A10U600-10 56 , A10U607-1 51,

A10U604-8 59 AND A10U605-7 55 .

SEE CORRECT WAVEFORMS IN FIG 6-1.

PROBABLE DEFECTIVE A6 BOARD

IS UNR

ANNUNCIATOR

ON?

YES

IS TP 62

OK?

15V, 40KHz YES

SEE "FET TROUBLE-

SHOOTING" FIG 3-11

CHECK CV PROGRAMMING

LEVEL AT A10U513-6 39

DOES

TP 56

= -5V?

CHECK VOLTAGE CALIBRATION.

SEE APPENDIX A IN OPERATING

MANUAL.

PROBABLE DEFECTIVE A10 BOARD

YES

PROBABLE DEFECTIVE A10 BOARD

Figure 3-5. Output Held Low Troubleshooting)

Troubleshooting 35

Page 36

START

"OUTPUT HELD HIGH"

TURN OFF THE SUPPLY AND REMOVE THE

COVER AND RFI SHIELD. DISCONNECT LOAD.

TURN SUPPLY ON AND CHECK THE BIAS AND

REFERENCE VOLTAGES (TEST POINTS 9

THROUGH 22 . SEE TABLE 6-3.

ARE

VOLTAGES

OK?

YES

DISABLE THE OV CIRCUIT BY LIFTING

A10R536. TURN ON SUPPLY AND PROGRAM

OUTPUT VOLTAGE AND CURRENT TO ZERO.

CHECK IF CV "OR" GATE DIODE

A10D652 IS CONDUCTING

A10D652

CONDUCTING?

YES

CHECK VOLTAGE LEVEL AT FAST SENSE

DIFF AMP A10U608-7 49 .

PROBABLE DEFECTIVE A6 BOARD

PROBABLE DEFECTIVE A10 BOARD

36 Troubleshooting

DOES

TP 49

= -10V?

YES

PROBABLE DEFECTIVE A10 BOARD

OR A8 FAST SENSE BOARD

Figure 3-6. Output Held High Troubleshooting)

Page 37

START

"DAC DEFECTIVE"

TURN OFF SUPPLY AND REMOVE TOP COVER. TURN ON SUPPLY AND CHECK BIAS AND REFERENCE VOLTAGES (TEST POINTS 9

THOUGH 22 . (SEE TABLE 6-3*).

ARE

VOLTAGES

OK?

YES

SHORT A10U506-1 (SA MODE) TO A10U506-20 (COM), SEE FIG. 3-15. TURN ON SUPPLY AND WAIT TWO SECONDS THEN REMOVE SHORT. WAIT FOR "POWER ON INIT" TO COMPLETE. USE A SCOPE TO CHECK THE CV DAC (A10U513-6), CC DAC (A10U514-6) AND READBACK DAC (A10U515-6) OUTPUTS. COMPARE THE WAVEFORMS TAKEN AT THESE POINTS WITH THE WAVEFORMS GIVEN IN FIG 6-1.

IS ONE

DAC MISSING

STEPS?

YES

* IF THE SUPPLY FAILS SELF TEST, TURN OFF

THE SUPPLY, DEPRESS THE 7 KEY AND THEN

TURN IT ON WHILE HOLDING THE KEY DOWN

SO AS TO SKIP SELF TEST.

PROBABLE DEFECTIVE A6 BOARD

PROBABLE DEFECTIVE A10 BOARD

ARE ALL

DACS MISSING

STEPS?

CV OR CC DAC

DEFECTIVE?

PROBABLE DEFECTIVE A10 BOARD

YES

Figure 3-7. DAC Circuits Troubleshooting)

PROBABLE DEFECTIVE A10 BOARD

CHECK REF VOLTAGE FOR CV/CC DACS AT

A10U504-6 37 WITH RESPECT TO 36 .

DOES A10U504-6

= 10V?

PROBABLE DEFECTIVE A10 BOARD

YES

PROBABLE DEFECTIVE A10 BOARD

Troubleshooting 37

Page 38

START

"SERIAL DOWN"

TURN OFF SUPPLY, REMOVE TOP COVER AND RFI SHIELD.

UNPLUG CABLE W5 FROM J108 ON A2 GPIB BOARD AND

UNPLUG CABLE W4 FROM J507 ON A10 CONTROL BOARD. PLUG CABLE W5 INTO J507 ON A10 BOARD (SEE WARNING).

TURN ON THE SUPPLY AND TRY TO PROGRAM IT FROM THE

FRONT PANEL.

THIS REMOVES THE GPIB BOARD

WARNING:

FROM THE DATA PATH AND CONNECTS THE FRONT PANEL DIRECTLY TO THE CONTROL BOARD. THIS CONFIGURATION IS FOR TEST ONLY. DO NOT FLOAT THE OUTPUT OR ATTEMPT TO OPERATE

OPERATE THE SUPPLY IN THIS CONFIGURATION.

SUPPLY OPERATES PROPERLY?

TURN OFF SUPPLY. REMOVE FRONT PANEL

ASSEMBLY TO ACCESS THE A1 FRONT PANEL BOARD. TURN ON SUPPLY AND CHECK FOR

PULSES AT A1U3-17 AND A1U3-18 .

PULSES

AT A1U3-17? CHECK CABLE W5.

YES

PROBABLE DEFECTIVE A1 BOARD

Figure 3-8. Serial Down Troubleshooting)

PROBABLE DEFECTIVE A2 BOARD

YES

PULSES

AT A1U3-18?

38 Troubleshooting

Page 39

START

"SECONDARY DOWN"

DISPLAY READS "SECONDARY DN". TURN OFF SUPPLY

AND REMOVE TOP COVER. TURN ON SUPPLY AND CHECK FOR

SERIAL DATA PULSES AT A2U110-8 TEST POINT 5

WITH RESPECT TO PRIMARY GROUND 1 . (SEE TABLE 6-3).

PULSES

AT A2U110-8?

YES

CHECK FOR 5V AT A2U110-8 WITH RESPECT TO SECONDARY

COMMON (A2U110-5) 12

5V AT

A2U110-8

YES

CHECK FOR SERIAL DATA PULSES AT THE A10 CONTROL BOARD

CIRCUIT POINTS AS INDICATED BELOW WITH RESPECT TO

SECONDARY COMMON 12 .

PULSES

AT A10U506-10?

SECONDARY BIAS CIRCUIT TEST POINTS 20 21

PROBABLE DEFECTIVE A2 BOARD

CHECK CABLE W4. CHECK

AND 22 . (SEE TABLE 6-3).

PROBABLE DEFECTIVE A2 BOARD

CHECK FOR CABLE W4 OPEN.

YES

PULSES

AT A10U504-11 AND

A10U505-14 ?

YES

PROBABLE DEFECTIVE A2 BOARD

Figure 3-9. Secondary Interface Down)

PROBABLE DEFECTIVE A10 BOARD

Troubleshooting 39

Page 40

START

"SLOW DOWN PROGRAMMING"

TURN ON SUPPLY

AND PROGRAM OUTPUT VOLTAGE AND

CURRENT TO 1/2 FULL SCALE.

CHECK VOLTAGE LEVELS AT A10U609-1 AND

A10U610-1 WITH RESPECT TO SECONDARY

COMMON 36 . SEE TABLE 6-3.

CHECK FUSES A9F980, F981 BY

MEASURING CONTINUITY

A10U610-1

= +2.5V?

YES

A10U609-1

< 10V?

YES

PROBABLE DEFECTIVE A9 BOARD

Figure 3-10. Slow Downprogramming Troubleshooting)

PROBABLE DEFECTIVE A10 BOARD

NOTE: SHOULD TOGGLE BETWEEN <1 V WITH OUTPUT

OFF AND APPROX. 11 V WITH OUTPUT ON

40 Troubleshooting

Page 41

Note 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 (refer to the disassembly procedures at the back of this chapter

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.

NOTE:

BECAUSE TEST POINTS ON THE A3 FET BOARD ARE NOT

TURN OFF SUPPLY AND REMOVE A3 FET BOARD WITH HEATSINK ASSEMBLY ATTACHED. (SEE DISASSEMBLY PROCEDURES)

MEASURE RESISTANCE BETWEEN

+RAIL AND -RAIL (E201 AND E301)

ACCESSIBLE WHEN THE BOARD IS INSTALLED, TROUBLESHOOTING MUST BE PERFORMED WITH THE BOARD REMOVED FROM THE SUPPLY.

>=20 Mohm?

MEASURE RESISTANCE BETWEEN THE GATE OF EACH FET AND COMMON (-RAIL)

>15 Kohms?

MEASURE RESISTANCE ACROSS

CAPACITOR C201 AND C301.

approx.

150 ohms?

MEASURE RESISTANCE ACROSS 15V BIAS INPUT. (E206 TO E207 AND E306 TO E307)

1k ohm forward?

490 ohm reverse?

YES

PROBABLE DEFECTIVE A3 BOARD

CONTINUE WITH DYNAMIC

TROUBLESHOOTING IN TABLE 6-3.

Figure 3-11. FET Troubleshooting Chart)

Troubleshooting 41

Page 42

Firmware Revisions

Firmware revision labels are located on the Front panel ROM, AlU3, and on the Secondary microprocessor, A5U504. You can obtain the revisions 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 6691A, the controller will return a string with four comma-separated fields, as follows:

"Hewlett-Packard ,6691A,O,fA.01.05sA.01.04pA.0l.02"

The first three fields 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.

Test Headers

The power supply has two test headers as shown in Figure 3-12, each with a jumper that can be moved to different positions for various functions. To gain access to the headers, remove the power supply top cover.

Pins Description

Primary Interface Test Connector A2J106

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) NOT AVAILABLE

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) NOT AVAILABLE

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.

42 Troubleshooting

Page 43

Figure 3-12. Test Header Jumper Positions

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.

Troubleshooting 43

Page 44

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.

2. 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.

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 3-13.

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.

44 Troubleshooting

Page 45

10 ! Program to initialize EPROM or move factory preset data in 669xA 20 ! power supplies. 30 ! RE-STORE "INIT_669X" 40 ! Rev A.00.00 dated Feb 2002 50 ! 60 DIM Init_data(1:49),Model$[5],Idn$[21],Cal_data$[40] 70 INTEGER Addr(1:49),Length(1:49) 80 ASSIGN @Ps TO 705 ! Supply must be at address 705 90 CLEAR SCREEN 100 ! 110 Eprom_data_addr: ! Data address 120 DATA 2,6,10,14,18,19,20,24,28,32 130 DATA 36,37,38,42,46,50,54,55,56,57 140 DATA 64,68,72,76,80,116,152,153,154,155 150 DATA 156,158,160,162,163,164,165,166,167,168 160 DATA 169,170,171,172,174,176,180,184,188 170 ! 180 Eprom_data_len: ! Data for word length 190 DATA 4,4,4,4,1,1,4,4,4,4 200 DATA 1,1,4,4,4,4,1,1,1,1 210 DATA 4,4,4,4,4,1,1,1,1,1 220 DATA 2,2,2,1,1,1,1,1,1,1 230 DATA 1,1,1,2,1,4,4,4,4 240 ! 250 Eprom_data_6690: ! ! EEPROM data for 6690A 260 DATA 175,74,15.375,0,83,0,15,73,450,0 270 DATA 98,21,8.7,10,18.0,0,83,255,20,10 280 DATA 6690,162,96,15,96,128,5,255,0,0 290 DATA 1296,6690,0,20,180,20,180,175,33,98 300 DATA 115,30,20,1,127,.002701,.2,.000307,10.25 310 ! 320 Eprom_data_6691: ! ! EPROM data for 6691A 330 DATA 116,74,30.75,0,83,0,23,75,225,0 340 DATA 98,21,5.5,10,36.0,0,83,255,20,10 350 DATA 6691,108,96,23,97,128,5,255,0,0 360 DATA 1296,6691,0,20,180,20,180,175,33,98 370 DATA 115,30,20,1,127,.002701,.2,.00042,10.25 380 ! 390 Eprom_data_6692: ! ! EEPROM data for 6692A 400 DATA 93,74,61.5,0,83,0,29,70,112,0 410 DATA 98,21,4.6,10,69,0,83,255,20,10 420 DATA 6692,87,97,28,93,128,5,255,0,0 430 DATA 1296,6692,0,20,180,20,180,175,33,98 440 DATA 115,30,20,1,127,.002701,.2,.000333,10.234375 450 ! 460 INPUT "Input Power Supply model number. Example:""6691A""",Model$ 470 CLEAR SCREEN 480 ! 490 RESTORE Eprom_data_addr 500 ! 510 FOR I=1 T0 49 520 READ Addr(I) 530 NEXT I 540 !

Figure 3-13. Initialization and Factory Preset Replacement Program Listing (Sheet 1 of 4)

Troubleshooting 45

Page 46

550 RESTORE Eprom_data_len 560 ! 570 FOR I=1 T0 49 580 READ Length(I) 590 NEXT I 600 ! 610 SELECT TRIM$(UPC$(Model$)) ! Delete leading/trailing zeros and set to uppercase 620 CASE "6690A" 630 RESTORE Eprom_data_6690 640 CASE "66 91A" 650 RESTORE Eprom_data_6691 660 CASE "66 92A" 670 RESTORE Eprom_data_6692 680 ! 690 CASE ELSE 700 PRINT "Model number not found. Program is for models" 710 PRINT "Agilent 6690A, 6691A, and 6692A only" 720 STOP 730 END SELECT 740 ! 750 FOR I=1 T0 49 ! Read model dependent data 760 READ Init_data(I) 770 NEXT I 780 ! 790 OUTPUT @Ps;"*CLS" ! Clears power supply registers 800 ! 810 OUTPUT @Ps;"CAL;STATE ON," ! Turn on cal mode, "0" passcode 820 ! 830 GOSUB Ps_error ! Error if passcode is not "0"! 840 IF Err THEN 850 OUTPUT @Ps;"*IDN?" ! Get data from model # location 860 ENTER @Ps;Idn$ 870 Model=VAL(Idn$[POS(Idn$,",")+1] ) 880 ELSE 890 GOTO Start 900 END IF 910 ! 920 OU TPUT @Ps;"CAL:STATE ON,";Model ! Turn on cal mode, passcode = 930 ! data at model number location 940 ! 950 GOSUB Ps_error ! Error if passcode is not same as 960 ! data at model # location 970 IF Err THEN 980 OUTPUT @Ps;"CAL:STATE ON,";Model$[1,4] ! Turn on cal mode, passcode = 990 ! model # 1000 GOSUB Ps_error 1010 IF Err THEN 1020 PRINT "Change pass code to the power supply model # or zero then restart the program." 1030 STOP 1040 ELSE 1050 GOTO Start 1060 END IF 1070 END IF 1080 !

Figure 3-13. Initialization and Factory Preset Replacement Program Listing (Sheet 2 of 4)

46 Troubleshooting

Page 47

1090 Start: ! 1100 ! 1110 INPUT "Select Initialization (I) or Factory preset replacement (F).",Sel$ 1120 CLEAR SCREEN 1130 SELECT (UPC$(Sel$)) 1140 CASE "I" ! Select Initialization 1150 GOTO Init_eeprom 1160 CASE "F" ! Select install new factory data 1170 GOTO Fact_preset 1180 CASE ELSE 1190 BEEP 1200 GOTO Start 1210 END SELECT 1220 ! 1230 Init_eeprom: ! 1240 PRINT "Initializing EEPROM" 1250 ! 1260 FOR I=1 TO 49 1270 OUTPUT @Ps;"DIAG:EEPR '';Addr(I);'','';Length(I);'','';Init_da ta(I) 1280 NEXT I 1290 GOTO Cal_off 1300 ! 1310 Fact_preset: ! 1320 CLEAR SCREEN 1330 PRINT "This program should ONLY be completed if your power supply" 1340 PRINT "EEPROM has been replaced or a component that will effect" 1350 PRINT "the calibration AND the alignment of voltage, overvoltage" 1360 PRINT "and current is complete AND unit has passed the performance" 1370 PRINT "test. Enter C to continue, any other key to abort." 1380 INPUT Cont_prog$ 1390 IF (UPC$(Cont_prog$))< >"C" THEN GOTO Cal_off 1400 ! 1410 CLEAR SCREEN 1420 PRINT "Transferring calibration data to factory preset locations." 1430 ! 1440 Fact_cal_sour: ! Address of factory calibration data source 1450 DATA 2,6,68,72,20,24,76,80,150 1460 ! 1470 Fact_cal_dest: ! Address of factory calibration data destination 1480 DATA 84,88,92,96,100,104,108,112,116 1490 ! 1500 Fact_cal_len: ! Length of factory calibration data 1510 DATA 4,4,4,4,4,4,4,4,1 1520 ! 1530 RESTORE Fact_cal_sour 1540 FOR I=1 TO 9 1550 READ Cal_sour_addr(I) 1560 NEXT I 1570 ! 1580 RESTORE Fact_cal_dest 1590 FOR I=1 T0 9 1600 READ Cal_dest_addr(I) 1610 NEXT I 1620 !

Figure 3-13. Initialization and Factory Preset Replacement Program Listing (Sheet 3 of 4)

Troubleshooting 47

Page 48

1630 RESTORE Fact_cal_len 1640 FOR I=1 T0 9 1650 READ Cal_length(I) 1660 NEXT I 1670 ! 1680 FOR I=1 T0 9 ! Locations of good data 1690 OUTPUT @Ps;"DIAG:EEPR? ";Cal_sour_addr(I);",";Cal_length(I) ! Read good data 1700 ENTER @Ps;Cal_data$ ! Enter good data 1710 OUTPUT @Ps;"DIAG:EEPR";Cal_dest_addr(I);",";Cal_length(I);",";Cal_data$ 1720 ! Write good data to factory preset locations 1730 NEXT I 1740 ! 1750 ! 1760 Cal_off 1770 CLEAR SCREEN 1780 OUTPUT @Ps;"CAL:STATE OFF" ! Turn off cal mode 1790 ! 1800 GOSUB Ps_error ! Check for errors 1810 IF Err THEN 1820 PRINT "An error occurred during the EEPROM read/write, Check for" 1830 PRINT "programming errors. Initialization data may be incorrect." 1840 STOP 1850 END IF 1860 ! 1870 PRINT "Operation complete. Program stopped." 1880 STOP 1890 ! 1900 Ps_error: ! Error handling subroutine 1910 OUTPUT @Ps;"SYST:ERR?" ! Check for errors 1920 ENTER @Ps;Err 1930 RETURN 1940 ! 1950 END

Figure 3-13. Initialization and Factory Preset Replacement Program Listing (Sheet 4 of 4)

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.

48 Troubleshooting

Page 49

Tools Required

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

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

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

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

• 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.

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 49

Page 50

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

4. Disconnect phone cable going to J108.

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

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

3. 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 to their correct locations later. If you 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.

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.

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.

50 Troubleshooting

Page 51

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.

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.

Troubleshooting 51

Page 52

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 3-14 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.

A9 DownProgrammer

Slow Sense Assy

Output Bus

A10 Control Assy

(on top tray)

Fan

Fuses

Heat sink

A8 Fast Sense Assy

A7 Snubber Assy

L900 (top), L901 (bottom)

D900 (top), D901 (bottom)

T900 (top), T901 (bottom)

Keypad

A1 Front Panel PC Assy

A6 Bias Assy

Display

A2 GPIB Assy (above A4)

RFI Filter (underneath A4)

Figure 3-14. Component Locations (Top Cover and RFI Shield Removed)

52 Troubleshooting

3O Line Choke

(underneath A5)

A4 AC Input Assy

A5 DC Rail Assy

24V Bias Xfmr (underneath A5)

A3 FET Assy

Page 53

Figure 3-15. 3-Inch Front Panel Frame Assembly

Troubleshooting 53

Page 54

54 Troubleshooting

Figure 3-16. Assembly A10, Exploded View

Page 55

Figure 3-17. Assembly A10, Exploded View (6690A)

Troubleshooting 55

Page 56

56 Troubleshooting

Figure 3-18. Assembly A10, Exploded View (6691A, 6692A)

Page 57

Figure 3-19. Three-Phase Line Choke Subchassis Wiring

Troubleshooting 57

Page 58

58 Troubleshooting

Figure 3-20. 24 Volt Fan Transformer

Page 59

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 circuits.

• A2 GPIB circuits.

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

circuits.

• Power circuits on the A4 AC Input Board.

• A3 FET Assembly circuits.

• A5 DC Rail Board circuits.

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

circuits.

• 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 59

Page 60

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. Signature analysis troubleshooting is not supported.

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).

60 Principles Of Operation

Page 61

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 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.

Principles Of Operation 61

Page 62

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.

A4 AC Input Board

The A4 Input Board contains the Inrush-Current Limit relay (K401), Main Power Relays (K402, K403), and current-limiting resistors (R407, R408). 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 relays (K402, K403) close, shorting out the current-limit resistor.

62 Principles Of Operation

Page 63

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.

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.

board. Be certain that the LEDs are completely extinguished.

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

Principles Of Operation 63

Page 64

Output Circuits

The output circuits include the following circuits:

• Chassis mounted components.

• Two power transformers, T900/T901.

• Two inductors, L900/L901.

• Two rectifiers, D900/D901.

• 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/D901, 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.

P/O SNUBBER

BOARD

FET

BOARD

T900

RFI

FILTER

AC INPUT

BOARD

DC RAIL

BOARD

+RAIL

-RAIL

FAST

SENSE

R900

SLOW SENSE

DOWN PROG

LOWER FRONT PANEL ASSY

UPPER FRONT PANEL ASSY

GPIB

CONTROLLER

SERIAL

LINK

DIGITAL

CONTROL

DISPLAY

ON\OFF

FRONT PANEL

BOARD

GPIB

BOARD

KEY PAD

+24V

AUX BIAS

TRANS.

FAN

BIAS

BOARD

T901

SECONDARY

INTERFACE

P/O SNUBBER

BOARD

CONTROL BOARD

CT/CC

CONTROL

CIRCUITS

SWITCHING

CONTROL

-S

MON

Figure 4-3. Agilent Series 669xA Power Supply, Block Diagram

64 Principles Of Operation

Page 65

Replaceable Parts

Introduction

This section lists the replaceable electrical and mechanical parts for the Agilent 669xA 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 (see Figure 3-20 for location of all assemblies) Table 5-1 A1 Front Panel Board Table 5-2 A2 GPIB Board Table 5-3 A3 FET Board Table 5-4 A4 AC Input Board Table 5-5 A5 DC Rail Board Table 5-6 A6 Bias Board Table 5-7 A7 Snubber Board Table 5-8 A9 Down Programming/Slow Sense Board Table 5-9

A8 and A10 assemblies contain no user- replaceable parts.

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 6692A)

Table 5-1. Main Chassis, Replaceable Parts

Ref. Desig. Agilent Part No. Description

ASSEMBLIES & SUBASSEMBLIES

5060-3553 TESTED FRONT FRAME ASSEMBLY A1 5060-3542 TESTED KEYBOARD PC ASSEMBLY A2 5063-4851 TESTED GPIB PC ASSEMBLY A3 5065-0642 TESTED FET PC ASSEMBLY A4 5065-0644 TESTED AC INPUT PC ASSEMBLY A5 5065-0645 TESTED DC RAIL PC ASSEMBLY A6 5065-0643 TESTED BIAS PC ASSEMBLY A7

6690A 06682-60021 SNUBBER PC BOARD 6691A 06683-60021 SNUBBER PC BOARD

6692A 06692-60021 SNUBBER PC BOARD A8 06681-60023 FAST SENSE PC BOARD A9

6690A 06690-60024 DOWN PROGRAMMER / SLOW SENSE BOARD

6691A 06691-60022 DOWN PROGRAMMER / SLOW SENSE BOARD

6692A 06692-60022 DOWN PROGRAMMER / SLOW SENSE BOARD A10

6690A 06690-61020 TESTED CONTROL PC BOARD

6691A 06691-61020 TESTED CONTROL PC BOARD

6692A 06692-61020 TESTED CONTROL PC BOARD

Replaceable Parts 65

Page 66

Table 5-1. Main Chassis, Replaceable Parts (continued)

ELECTRICAL PARTS

C900-905

6690A 0180-4615 CAP 18000uF 28V

6691A 0180-4596 CAP 13000uF 45V

6692A 0181-0028 CAP 4700uF 80V C906

6690A 0180-4615 CAP 18000uF 28V C907

6690A 0180-4615 CAP 18000uF 28V

6691A 0180-4596 CAP 13000uF 45V

6692A 0181-0028 CAP 4700uF 80V C920-925 0160-4183 CAP 1000pF 250V D900A,B

6690A 1906-0722 RECTIFIER 400A, 100V

6691A 1906-0397 RECTIFIER 20020

6692A 1906-0398 RECTIFIER 20040/20140 D90lA,B

6690A 1906-0722 RECTIFIER 400A, 100V

6691A 1906-0397 RECTIFIER 20020

6692A 1906-0398 RECTIFIER 20040/20140 L900, 901

6690A 06690-80001 CHOKE - OUTPUT

6691A 06691-80001 CHOKE - OUTPUT

6692A 06692-80001 CHOKE - OUTPUT L902, 903 5080-2257 CORE L904 - 906 9170-1571 CORE R900

6690A 5080-2297 SHUNT-CURRENT

6691A 06682-80002 SHUNT-CURRENT

6692A 5080-2324 SHUNT-CURRENT T900, 901

6690A 9100-6062 POWER TRANSFORMER

6691A 9100-6063 POWER TRANSFORMER

6692A 9100-6064 POWER TRANSFORMER

66 Replaceable Parts

9100-6065 24V BIAS TRANSFORMER 3160-4116 FAN-TUBEAXIAL 2110-1077 FUSE 20A 690V (3 required for 400VAC) 2110-1078 FUSE 40A 690V (3 required for 208VAC) 5065-6934 FUSE KIT FOR 208VAC (contains 3 fuses ) 5065-6935 FUSE KIT FOR 400VAC (contains 3 fuses ) 5080-2148 CABLE - CHAINING (2 meters) 5080-2168 CABLE - A2 GPIB/A1 FRONT PANEL 5080-2280 CABLE - A6 BIAS/A10 CONTROL 5080-2287 CABLE - A10 CONTROL/A8 FAST SENSE 5080-2316 CABLE - A10 CONTROL/A9 SLOW SENSE

MECHANICAL PARTS

5040-1694 BUSS BAR, PLUS, output end (large) 5040-1696 BUSS BAR, PLUS, internal end (small) 5060-3489 BUSS BAR, MINUS (WITH L902/L903 CORE) 5040-1688 BUSS BAR BEZEL (ON REAR PANEL) 5040-1689 SUPPORT-PLASTIC (BUSS BAR PLUS TO CHASSIS) 5040-1701 BRACE-PLASTIC (ACROSS BUSS BARS)

Page 67

Table 5-1. Main Chassis, Replaceable Parts (continued)

06652-00005 GROUND BRACKET (A9 BOARD TO CHASSIS)

1252-1488 TERM-BLOCK-4 POSITION GPIB) 1252-3698 TERM-BLOCK-7 POSITION CONTROL) 3160-4117 FAN FINGER GUARD 5001-0538 TRIM-SIDES 5001-0539 TRIM SIDES,FRENCH GRAY 5001-6776 CHASSIS, BASE 5002-1591 REAR PANEL 5182-9192 LABEL - REAR PANEL 5001-6779 COVER-GREY 5040-1697 SPACER BLOCK - 2 (COVER TO REAR PANEL) 5001-6793 GPIB-BRACKET (A2 BOARD TO CHASSIS TOP) 5020-2783 HEATSINK-DIODE 5020-2785 HEATSINK-FET 5020-2797 SHIELD-PLASTIC - 2 (FET/DIODE HEATSINK) 5040-1691 PLENUM (FAN TO FET/DIODE HEATSINK) 5002-1592 AC INPUT COVER 9310-6711 CLAMP- POWER CORD 5065-6933 KIT (AC INPUT COVER WITH CLAMP) 2110-1312 FUSEHOLDER 3-PHASE 5041-8801 FOOT - 4 5041-8819 CAP-STRAP HANDLE 5041-8820 CAP-STRAP HANDLE 5062-3705 STRAP HANDLE 5080-2545 CARTON ( shipping container ) 5080-2418 TRAY ( shipping container ) 5080-2414 SKID ( shipping container ) 5080-2415 FOAM PAD ( shipping container ) 5964-8269 MANUAL-OPERATING

Table 5-2. Front Panel Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

A1 5060-3542 A1 KEYPAD PC BOARD (tested)

0370-3238 KNOB Ref: G1, G2 0515-2535 SCREW - Ref: keypad PCB to front frame 1000-0842 WINDOW (3 inch front frame) 5001-6794 BLINDER (5 inch front frame) 5040-1735 KEYPAD 5040-1687 FRONT FRAME - 88.1mm ( 3.5 inch ) 5040-1698 FRONT FRAME - 132.6mm ( 5.25 inch )

5185-1342 LABEL (3.5 inch & 5.25 inch front frame) 06690-80002 NAMEPLATE front panel model description 06691-80002 NAMEPLATE front panel model description 06692-80002 NAMEPLATE front panel model description

Table 5-3. A2 GPIB Board, Replaceable Parts

Ref. Desig. Agilent Part No. Description

1205-0758 HEATSINK (U121)

0515-0642 SCREW (U121)

0515-0911 SCREW M3x0 5 (J101)

Replaceable Parts 67

Page 68

Table 5-4. A3 FET Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

Q201-204, 211, 222, 233, 244 Q301-304, 311, 322, 333, 344 5080-2279 CABLE FET CTRL (E208-E209 to CONTROL J511) 5080-2283 CABLE +15V BIAS (E206-E207 to BIAS J831)

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

Ref. Desig. Agilent Part No. Description

J419 1251-6832 CONNECTOR K401 0490-1908 RELAY 24V COIL 5080-2284 CABLE RELAY CTRL (E411-E413 to BIAS J827)

Table 5-6. A5 DC Rail Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

F420 2110-1066 FUSE 1AM, 500V F421 2110-0934 FUSE .5AM, 500V J430, 431 1251-7616 CONNECTOR J432 1251-6832 CONNECTOR J436, 437, 438, 439 1251-3837 CONNECTOR J440 1252-0055 CONNECTOR J441 1252-0056 CONNECTOR 5080-2286 CABLE BIAS 24V (E440-E443 to BIAS J816) 5080-2289 CABLE AC BIAS (E430-E434 to AC INPUT J419) 5080-2293 CABLE LINE SELECT (E444-E447 to J436/J437) 5080-2294 CABLE LINE SELECT (E448-E451 to J438/J439)

Table 5-7. A6 Bias Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

F800 2110-0712 FUSE-SUBMIN 4A F803, 804, 805, 806 2110-0679 FUSE 1.5AM, 125V J801 1252-1670 CONNECTOR J816 1252-0056 CONNECTOR J827 1251-7070 CONNECTOR J830, 831 1252-0055 CONNECTOR 5080-2292 CABLE BIAS (E800-E804 to DC RAIL J432)

Table 5-8. A8 Fast Sense Assembly, Replaceable Parts

Ref. Desig. Agilent Part No. Description

5080-2287 CABLE (El001 -El003 to CONTROL J512)

Table 5-9. A9 Down Programmer/Slow Sense, Replaceable Parts

Ref. Desig. Agilent Part No. Description

Q981, 982 1855-1003 POWER MOSFET 0340-1507 INSULATOR - 2 (Q981, 982 TO HEATSINK) 5080-2212 CABLE (J910 to CONTROL J510)

1855-1674 MOSFET 500V 20A (replace as matched set) 1855-1674 MOSFET 500V 20A (replace as matched set)

68 Replaceable Parts

Page 69

Diagrams

Introduction

This chapter contains drawings and diagrams for troubleshooting and maintaining Agilent Series 669xA Power Supplies. Unless otherwise specified, a drawing or diagram applies to all models of the series. Wiring connections to external equipment are shown in the Power Supply Operating Manual.

In the 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.

Table 6-1 summarizes the contents of this chapter.

Table 6-1. Summary of Chapter Contents

Function Description See

Signal names Table of signal name mnemonics Table 6-2

Test points Description of each test point. The location of each test point is shown on

the appropriate schematic and its associated parts location drawing.

Schematic notes A list of general notes that are applicable to all schematic diagrams.

Notes that apply to a specific schematics appear on the schematic sheet.

Waveforms Test point waveforms for Table 6-3. Figure 6-1

Interconnections Drawing identifying each circuit board, the cables between boards, and

schematic diagram for each board.

Schematics Al Front Panel Board.

A2 GPIB Board. A3 FET Board. A4 AC Input Power Board. A5 DC Rail Board. A6 Bias Board. A7 Snubber Board. A8 Fast Sense Board. A9 Down Programming/Slow Sense Board. A10 Control Board.

Assembly and component locations

A diagram that shows the location of components on a circuit board is included with each circuit board schematic.

A drawing showing location of each circuit board in the chassis is in Chapter 3.

Table 6-3

Table 6-4

Figure 6-2

Figure 3-15

Diagrams 69

Page 70

Table 6-2. Signal Name Mnemonics

Mnemonic Description Mnemonic Description

A(0)--A(15) AD (O)--AD(7) AMB_SENSE Ambient temperature sense NEG_IMON Negative current monitor ANA(0)--ANA(7) ATN BIAS_OK BOVPROG BSTX cc CCPROG Constant current programming OVSCR Overvoltage SCR (crowbar) cv CVPROG D(0)_D(7) D101--Dl08 DAV DFI Discrete fault indicator PTX Primary transmit serial data DFI-EN DPS DN_PGM DRIVE_A/B EOI End or identify (GPIB) REN Remote enable FAC_CAL FAN_PWM FPRX FPTX FS HSRQ GPIB service request SA Signature analysis IFC IMON INH_CAL IP IPROG ISEN Current sense VMON Voltage monitor ISRQ KO(0)-KO(5) KI(0)--KI(5)

Address lines Address bus

Analog Signal readback bus Attention (GPIB) ±15V bias supplies have stabilized BuFfered OV programming BuFfered secondary transmit Constant current status

Constant voltage status Constant voltage programming Data lines Data lines (GPIB) Data valid (GPIB)

Discrete fault indicator enable Downprogramming shunt Down programming FET drive signals

Factory calibration Fan pulse width modulation Front panel receive serial data Front panel transmit serial data Fast sense

Interface clear (GPIB) Current monitor Inhibit calibration External current programming Current programming

Interface service request Keypad output data bus Keypad input data bus

MSRQ NDAC

NRFD OV OV_CLR OVCMP OVP_BIAS OVPROG

PCLR PREF PREF_2 PREN PRX

PWM_EN RAM RDY REF_PWM

RI ROM SPCLR RX RxD

SRQ SRX STX TxD UART

VPROG WR

Microprocessor service request Not data accepted (GPIB)

Not ready or data (GPIB) Overvoltage Overvoltage clear Overvoltage comparator Overvoltage protection bias Overvoltage programming

Primary power clear Primary reference voltage (2.53V) Primary reference voltage (1.0V) Primary remote enable Primary receive serial data

Pulse width modulator enable Random access memory Ready Reference pulse width modulator

Remote inhibit Read only memory Secondary power clear Receive serial data Receive Serial Data

Service request (GPIB) Secondary receive serial data Secondary transmit serial data Transmit Serial Data Universal asynchronous receive/transmit

Voltage programming Write

Table 6-3. Test Points

TEST POINT No. & Loc. Signal Tested Measurement and Conditions

A2 GPIB BOARD

J106-4

U101- 1 U101-6

U101-8

U110-3 U111-6 U119-4 U119-18

70 Diagrams

Primary/chassis ground Connect meter or scope common here. Make

measurements at test points 2 through 8.

+ 5V primary bias + 5V + 0.2V

PCLR

PCLR*

STX SRX FPRX Toggles between 0 and +5V. FPTX

Goes high for approximately 40 ms at power on, then goes low. Held low for approximately 40 ms at power on, then goes high. Toggles between 0 and +5V.

Toggles between 0 and +5V.

Page 71

Table 6-3. Test Points (continued)

TEST POINT No. & Loc. Signal Tested Measurement and Conditions

A4 AC Input Board

Connect meter between TP 9 and 10, or 9 and 11, or 10 and 11, and measure approximately 220VAC or 440VAC.

J418-1/J417-7 J418-2/J417-8 J418-3/J417-9 K402 coil

J430-1 (+) to J430-2 (-) J431-1 (+) to J431-2 (-)

J801-4 to J801-5

J801-1 (+) to J801-2 (-) J827-1 (+) to J827-2 (-)

J827-1 (+) to J827-3 (-) J816-3 to J816-4

R813 R806

R812

AC Mains Voltage

AC Mains Voltage AC Mains Voltage 24VDC Coil Voltage Turns on PS, and after power-on initialization

test, reads approximately 24VDC.

A5 DC Rail Board

Rail #1 Voltage Measure approximately 290VDC Rail #2 Voltage Measure approximately 290VDC

A6 Bias Board

GPIB 5V Bias

Fan voltage Measure 24Vdc Inrush relay coil Measure 24Vdc

Rail relay coil Measure 24Vdc after power-on initialization test.

24V Primary Measure approximately 34VAC

-15V bias -15V

+ 5V bias +5V +15V bias +15V

+15 ± 0.9V measure approx. 11VAC

A3 FET Board

NOTE: 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 (refer to the disassembly procedures at the back of chapter 3).

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).

E207/E307

U203-1/U303-1 U204-1/U304-1

U201-1/U301-1 U201-12/U301-12 U201-10/U301-10 U201-7/U301-7 U202-1/U302-1 U202-7/U302-7 U205-2

Secondary common (Sheet 1,2) Connect meter or scope common here. Make

measurements at test points 27 through 35.

Bias voltage (Sheet 1, 2) +5V Bias trip point (Sheet 1, 2) Voltage goes from low (0V) to high (5V) at an

input of ≈ 12V; and from high to low at ≈ 13V.

Drive 1 waveform (Sheet 1) See Figure 6-1 Drive 2 waveform (Sheet 2) See Figure 6-1 Drive pulses (Sheet 1, 2) See Figure 6-1 Drive pulses (Sheet 1, 2) See Figure 6-1 Drive pulses (Sheet 1, 2) See Figure 6-1 Drive pulses (Sheet 1, 2) See Figure 6-1 VREF voltage (Sheet 1)

≈ 1.7V

Diagrams 71

Page 72

Table 6-3. Test Points (continued)

TEST POINT No. & Loc. Signal Tested Measurement and Conditions

A10 Control Board

+C500

U504-6

U503-7 U513-6 U514-6

U621-1 U621-7 U502-2 U624-1 U622-6 U620-7 U620-1 U502-3

U608-7 U607-7

U607-1

U602-9 U605-3

U602-6 U605-7

U600-10

U601-6 U601-3

U604-3 U603-3

U603-13

J511-1,2

U502-14 U521-7

Q610, collector

U609-7

Secondary common (Sheet 1) Connect meter or scope common here. Make

measurements at test points 37 - 61, and 62 - 70.

CC/CC DACs reference (Sheet 1) Readback DAC reference (Sheet 1)

CVPROG (Sheets 2,4) See Figure 6-1 CCPROG (Sheets 2,4)

NOTE: Measurement and Conditions for test points 41 through 70 are as follows:

1. Voltage = ½ scale

2. Current = ½ scale

3. OV = full scale

VMON (Sheet 4) CV CONTROL (Sheet 4) CV mode =+2.4V CC mode = +10V CV* (Sheet 4) CV mode =0V CC mode = 5V

CC CLAMP AMP output (Sheet 4) CV mode =+2.2V CC mode = +2.2V 1ST I AMP output (Sheet 4) CV mode =0V CC mode = -0.4V 2ND I AMP output (Sheet 4) CV mode =0V CC mode = +4.5V

CC CONTROL (Sheet 4) CV mode =+10V CC mode = +0.4V CC* (Sheet 4) CV mode =+5V CC mode = 0V

FAST SENSE AMP (Sheet 3) CV mode = -4V CC mode = 0V

RAMP GEN (Sheet 3) See Figure 6-1 RAMP GEN (Sheet 3) See Figure 6-1

DIVIDER output (Sheet 3) See Figure 6-1 SUMMING POINT (Sheet 3) See Figure 6-1

DEADTIME LATCH (Sheet 3) See Figure 6-1

SUM COMPARATOR (Sheet 3) See Figure 6-1 DIVIDER CLOCK (Sheet 3) See Figure 6-1

DIVIDER RESET (Sheet 3) See Figure 6-1 ON LATCH CLOCK (Sheet 3) See Figure 6-1

ON LATCH (Sheet 3) See Figure 6-1

PWM_EN (Sheet 3) Held high for approximately 12 seconds at

REF_PWM (Sheet 3)

NOTE: Temporarily move both scope leads to J511 for TP DRV A, DRV B (Sheet 3) See Figure 6-1

OV COMPARATOR (Sheet 1) +5V

OVREF (Sheet 2) +5.4V DP CONTROL (Sheet 3) CV Mode = N/A CC Mode = -0.14V DP CONTROL (Sheet 3) CV Mode = +13V CC Mode = 0V

+10V ± 0.05V

-11.6V ± 0.1V

See Figure 6-1

a. CV mode measurement is with no load b. CC mode measurement is with output

shorted.

CV mode =+4.6V CC mode = 0V

power-on, then goes low. +5 ± 0.2V

72 Diagrams

Page 73

Table 6-4. General Schematic Notes

1. Schematic sheets are not intended for component-level troubleshooting. Component values and ratings do

not match the values used on all models.

2. All resistors are in ohms ±1%, 1/8W, unless otherwise specified.

3. All capacitors are in microfarads unless otherwise specified.

4. Signal lines that are terminated by flags continue on other sheets, and may also go to other locations on the same sheet. Example: CVPROG (SH.2 8C); "SH.2 8C" indicates the sheet number and the coordinates on that sheet where the CVPROG signal line goes.

5. Unterminated signal lines go to a least one other location on the same sheet.

6. Unless otherwise noted, bias connections to integrated-circuit packages are as follows:

Common + 5V

14-pin packages pin 7 pin 14 16-pin packages pin 8 pin 16 20-pin packages pin 10 pin 20

5.00 V /div 10 us/div

TEST SIGNAL FROM SIGNAL GENERATOR

5.00 V /div 10 us/div

TEST POINT 29 30

1.00 V /div 0.2 ms/div

TEST POINT 39 40

5.00 V /div 10 us/div

TEST POINT 31 THRU 34

1.00 V /div 0.2 ms/div

READBACK DAC (U515 pin 6)

Figure 6-1. Test Point Waveforms for Table 6-3 (sheet 1 of 2)

Diagrams 73

Page 74

74 Diagrams

Figure 6-1. Test Point Waveforms for Table 6-3 (sheet 2 of 2)

Page 75

FAN

FUSES

F1, F2, F3

BLACK

WHITE

RED

3 O

LINE

CHOKE

RFI

FILTER

GRA

WHT/BRN/GRA

WHT/RED/GRA

5182-9200

5182-9190

180-235 VAC RANGE 1 J417

OR T418

RANGE 2

360-440 VAC

A4 AC INPUT

ASSEMBLY

E400

E401

E402

E411

E412 E413

J419

J420

5080-2284

5080-2289

5065-0637

J821

A6 BIAS

ASSEMBLY

J827

5080 2292

J432

E430

E434

E420

E425

E800

E803

RAIL

ASSEMBLY

J816

5080 2286

E440

E443

J801

J809

J830

J831

J430

J431

5182-9185

5080-2280

5080-2283

5080

2283

5065-0635

5065-0636

P101

J509

E306

E307

E206 E207

E201

E202

E301

E302

A2 GPIB

J107

5080

2168

J507

A10

CONTROL

ASSEMBLY

J511

5080 2279

E208 E209

ASSEMBLY

(W4)

FET

J108

J510

J512

5080-2168

(W5)

5080-2316

5080-2287

FRONT PANEL

ASSEMBLY

SLOW SENSE

J910

DOWNPROGRAM

E1000 E1001

FAST SENSE

E1002

J440 J441

5185 1343

FRONT PANEL

J433

5080 2290

24V

BIAS

XFMR

J223 J224 J226

POWER

XFMR

RECT

5060-3327

J225

POWER

XFMR

RECT

5060-3327

A7 SNUBBER

RECT

Figure 6-2. Circuit Board Cabling Diagram

Page 76

Figure 6-3. A1 Front Panel Board, Assembly Diagram

Page 77

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-4. A1 Front Panel Board, Schematic Diagram

Page 78

Figure 6-5. A2 GPIB Board, Component Location

Page 79

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-6. A2 GPIB Board, Schematic Diagram

Page 80

Figure 6-7. A3 FET Board, Component and Test Point Location

Page 81

Schematic sheets are not intended for component-level troubleshooting.

Component values and ratings may not match the values used on all models.

Figure 6-8. A3 FET Board, Schematic Diagram (sheet 1 of 2)

Page 82

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-8. A3 FET Board, Schematic Diagram (sheet 2 of 2)

Page 83

PHASE 2

BLK

12_AWG_AMPIN

E1942

SINGLE PHASE INPUT

20%

1UF

275V PM

0160-7606

5 6

9140-2548

C7C8

CHASSIS

PHASE 1

20%

250V

0160-4355

.01UF

5%4.7M

20%

1UF

275V PM

0160-7606

900

0683-4755

1/4W

12_AWG_AMPIN

TO AC INPUT RAIL E401 (GRA)

E19411

WHT

RED

12_AWG_AMPIN

E19132

12_AWG_AMPIN

E19133

PHASE 1

PHASE 3

C2C3

20%

1UF

20%

1UF

275V PM

0160-7606

20%

1UF

20%

1UF

275V PM

0160-7606

5%4.7M

900

1/4W

5%4.7M

900

1/4W

0683-4755

CHASSIS

PHASE 2

20%

250V

0160-4355

.01UF

PHASE 3

20%

250V

0160-4355

.01UF

MP2

0590-2027

12_AWG_AMPIN

TO AC INPUT E402 (WHT/GRA/BRN)

E19413

12_AWG_AMPIN

TO AC INPUT E400 (WHT/GRA/RED)

E19415

Figure 6-9. RFI Board, Component and Test Point Location

CHASSIS

Figure 6-10. RFI Board, Schematic Diagram

Page 84

Figure 6-11. A4 AC Input Board, Component and Test Point Location

Page 85

TO J19133

TO J19132

TO J1942

WHT / RED / GRA

GRA

WHT / BRN / GRA

E400

E401

E402

J419

2 3

5 PIN

UTILITY

4 5

1251-6832

BIAS / FUSE LED

LUG

C400

20%

1UF

275V PM

C401

0160-7606

20%

1UF

275V PM

C402

0160-7606

20%

1UF

275V PM

0160-7606

K401

7 8

5 6 1 2

0490-1908

9 10

INRUSH+24.5V

R407

27 5%

20W

0699-3191

R408

27 5%

20W

0699-3191

C428R435

200

0698-3609

20%

.01 440V PM 0160-7898

CONNECTOR

J417

2 3 4 5 6

12 PIN

UTILITY

7 8

9 10 11 12

1253-0755

LINE CHOKE

CONNECTOR

TO BIAS PCB

RANGE 1

(SEE LINE CHOKE CONNECTION DETAIL)

C429R436

200

0698-3609

200

0698-3609

5 6 4 7

1 2

K402

0490-2010

20%

.01 440V PM 0160-7898

C430R437

20%

.01

440V PM 0160-7898

8 9

J418

2 3 4 5 6

12 PIN

UTILITY

7 8

9 10 11 12

1253-0755

LINE CHOKE

CONNECTOR

RANGE 2

PHASE X

LINE CHOKE CONNECTION DETAIL

PHASE Y PHASE Z

MAIN+24.5V

R438 C431

22 2W 0698-3609

200

440V PM 0160-7898

.01

R439 C432

22 2W 0698-3609

200

440V PM 0160-7898

.01

R440 C433

22 2W 0698-3609

440V PM

200

0160-7898

K403

5 4 6

0490-2010

1 2

+24.5V MAIN

.01

RANGE 1

1 2

J420

3 4

6 PIN

UTILITY

5 6

1253-0754

20%

+24.5V

20%

INRUSH

8 7 9

MAIN

DC RAIL

CONNECTOR

E411

0362-0807

E412

0362-0807

E413

0362-0807

BRN

RED

ORN

FROM BIAS PCB

RANGE 2

RANGE 1

NOTE:

IF RANGE 1 IS SELECTED BY CHOKE PLUG, PIN NUMBERS REFER TO J417 IF RANGE 2 IS SELECTED BY CHOKE PLUG, PIN NUMBERS REFER TO J418

RANGE 1

RANGE 2

RANGE 1

RANGE 2

RANGE 1

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-12. A4 AC Input Board, Schematic Diagram

Page 86

Figure 6-13. A5 DC Rail Board, Component and Test Point Location

Page 87

DC RAIL

CONNECTOR

J420

(AC INPUT PCB)

WHT / RED / GRA

GRA

WHT / BRN / GRA

AC INPUT

E420

1252-1346

E421

1252-1346

E422

1252-1346

E423

1252-1346

E424

1252-1346

E425

1252-1346

C420 R420

20%

1UF

275V PM

200

0698-3611

0160-7606

R421C421

20%

1UF

200

275V PM

R422C422

0698-3611

0160-7606

20%

1UF

200

275V PM

0698-3611

0160-7606

D420

1901-1717

ASSY: 5064-0070

D423

1901-1717

HS420

1 2

1205-0350

HS423

1 2

1205-0350

D424 D421

HS421

1 2

1205-0350

1901-1717

HS424

1 2

1205-0350

1901-1717

D425 D422

1901-1717

ASSY: 5064-0070ASSY: 5064-0070

1901-1717

ASSY: 5064-0070ASSY: 5064-0070ASSY: 5064-0070

HS422

1 2

1205-0350

HS425

1 2

1205-0350

R426R428 R425 R424 R423

R427

8.2K

200

0764-0044

200

0764-0044

200

0764-0044

200

0764-0044

200

0764-0044

200

0764-0044

C426C425

50-10% 1500

AL 400V

E448

E449

AL 400V

149674

1252-1346

149674

RED

GRA

L420

1 2

(COIL: 5080-2263 / SLUG: 9170-1575)

5080-2300

RANGE 1

1251-3837

UTILITY

4 PIN

J438

L421

(COIL: 5080-2263 / SLUG: 9170-1575)

5080-2300

4 3 2 1

RANGE 2

1251-3837

UTILITY

4 PIN

J439

BLK

WHT

E450

E451

1252-1346

C424C423

50-10% 1500

AL 400V

149674

R431

RED

R433 R429R430R434 R432

RED

8.2K

200

8.2K

DS420DS421

8.2K

200

0764-0044

200

0764-0044

1990-0517

200

0764-0044

200

0764-0044

200

0764-0044

1990-0517

J430

1 2

2 PIN

UTILITY

1253-4842

DC RAIL 1

J431

1 2

2 PIN

UTILITY

1253-4842

DC RAIL 2

AC INPUT PCB

J419 - 2

J419 - 4

J419 - 3

J419 - 5

J419 - 1

BLK / ORN

BLK / GRN

BLK / WHT

BLK / YEL

BLK / RED

BIAS INPUT

E430

0362-0807

E431

0362-0807

E432

0362-0807

E433

0362-0807

E434

0362-0807

MP8

SCREW_M4_P

F420

2110-1066

SEE NOTE

F421

.5A

2110-0934

(CLIP: 2110-0726)

NOTE: FOR F420

668X SERIES 2110-0921 (0.5A) 669X SERIES

20%

C418

250V PM

0160-4048

.022

2110-1066 (1A)

C419

20%

250V PM

.022

NL0160-4048

CLIPFUSE 2110-1107 2110-1072

RANGE 1

1251-3837

4 3 2 1

UTILITY

4 PIN

J436

RANGE 2

NOTE:

E448 CONNECTS TO J438-2 J439-2

RANGE 1

E449 CONNECTS TO J438-3 J439-3 E450 CONNECTS TO J438-1 J439-1 E451 CONNECTS TO J438-4 J439-4

E444 CONNECTS TO J436-3 J437-3 E445 CONNECTS TO J436-4 J437-4 E446 CONNECTS TO J436-1 J437-1 E447 CONNECTS TO J436-2 J437-2

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

E445

RANGE 2

1251-3837

4 3 2 1

UTILITY

4 PIN

J437

BLK / GRN

BLK / YEL

BLK / ORN

BLK / RED

0362-0807

E444

0362-0807

E447

0362-0807

E446

0362-0807

C427

20%

.047

440V PM

0160-7743

2 1

1 2 3 4

1 2 3 4 5 6

1 2 3 4 5

HEADER

1252-0055

J440

E441

0362-0807

E440

0362-0807

E442

0362-0807

E443

0362-0807

J441

4 PIN

POST

1252-0056

J433

6 PIN

UTILITY

1251-3819

J432

5 PIN

UTILITY

1251-6832

BLOWN

FUSE

DETECT

WHT / YEL

WHT / ORN

WHT / RED

WHT / BRN

TB01

TO LED PCB

TO J816 - 4

TO J816 - 3

TO J816 - 2

TO J816 - 1

DEW LED

SWITCH

SECONDARY TO / FROM 24V

PRIMARY

TB02

24V REGULATOR TO BIAS PCB FAN

RELAYS

TO LED PCB

(FP)

BIAS XFMR

TB03

MOUNTED ON

CHASSIS

TO BIAS PCB

PRIMARY

Figure 6-14. A5 DC Rail Board, Schematic Diagram

Page 88

17 18

Figure 6-15. A6 Bias Board, Component and Test Point Location

Page 89

668xA

669xA

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-16. A6 Bias Bo

ard, Schematic Diagram (Sheet 1of 2)

Page 90

Schematic sheets are not intended for component-level troubleshooting.

Component values and ratings may not match the values used on all models.

Figure 6-16. A6 Bias Board, Schematic Diagram (Sheet 2 of 2)

Page 91

Figure 6-17. Power Mesh, Schematic Diagram, All Models

Page 92

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-18. A7 Snubber Board, Component Location and Schematic Diagram

Figure 6-19. A8 Fast Sense Board, Component Location and Schematic Diagram

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Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-20. A9 Down Programming/Slow Sense, Component Location and Schematic Diagram

Page 94

Figure 6-21. A10 Control Board, Component and Test Point Location

Page 95

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-22. A10 Control Board, Schematic Diagram (Sheet 1 of 4)

Page 96

Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-22. A10 Control Board, Schematic Diagram (Sheet 2 of 4)

Page 97

Schematic sheets are not intended for component-level troubleshooting.

Component values and ratings may not match the values used on all models.

Figure 6-22. A10 Control Board, Schematic Diagram (Sheet 3 of 4)

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Schematic sheets are not intended for component-level troubleshooting. Component values and ratings may not match the values used on all models.

Figure 6-22. A10 Control Board, Schematic Diagram (Sheet 4 of 4)

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Backdating

Manual backdating describes changes that must be made to this manual for power supplies whose serial numbers predate the latest revision of this manual.

Look in the following table and locate your Agilent model. Then look at each serial number listed for this group. If the serial number of your power supply is prior to any of the serial number(s) listed, perform the change indicated in the Change column. Note that several changes can apply to your supply.

Serial Numbers Change

Model 6690A

MY41000131 1

Model 6691A

MY41000119 1

Model 6692A

MY41000133 1

Change 1

In Table 5-1 Main Chassis

DELETE

ADD

CHANGE

In Table 5-2 Front Panel,

CHANGE

CABLE, PN 5185-1343. LED BOARD, P/N 5060-3483. CABLE, P/N 5080-2281 CABLE, P/N 5080-2283 CABLE, P/N 5080-2286 BIAS BOARD, from P/N 5065-6937, to 5065-0643.

LABEL from PN 5185-1342, to P/N 5182-

9191.

Backdating 99

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HP 6690A OPERATING AND SERVICE MANUAL

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Scope and Organization

Instrument Identification

Manual Revisions

Firmware Revisions

Related Documents

Safety Considerations

Electrostatic Discharge Precautions

Verification

Introduction

Tests

Test Equipment Required

Equipment List

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

Test Equipment Required

Power-On Selftest

Troubleshooting Charts

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

How to Order Parts

Diagrams

Introduction

Backdating