Agilent Technologies AGILENT MODELS 6023A and 6028A service manual A2J7-26 A2J7-25, Board

Page 32

Table 3-2. No-Output Failures

(Bias supplies and AC turn-on circuit functioning)

Status of PFET on/off-Pulses

PWM-ON

PWM-OFF

DEFECTIVE

CHECK FUNCTIONAL CIRCUITS

A2J7-26

A2J7-25

BOARD

 

lo

lo

A2

Control ckts: CV & CC thru on- & off-Pulse Oneshots *

lo

hi

A2 & A4

PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

hi

lo

A2 & A4

PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

hi

hi

A2 & A4

PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed

lo

N

A2

A2U17B,on-Pulse Oneshot and A2Q6A

N

lo

A2 & A4

Off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

hi

N

A2 & A4

A2U17A, on-Pulse Oneshot & DC-to-DC: A4Q3, and A4Q4 probably

 

 

 

failed

N

hi

A2 & A4

off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed

N

N

A2 & A4

Power-Limit Comparator and DC-to-DC: A4Q3 and A4Q4 probably

 

 

 

failed

lo= TTL low

hi= TTL high

N = normal 20KHz pulse train, TTL levels

*Decide which to troubleshoot -- the CV Circuit, the CC Circuit, or the PWM and Off-Pulse & On-Pulse Oneshots -- by measuring the CV CONTROL (A2CR24, cathode) and the CC CONTROL (A2CR19 cathode) voltages. Troubleshoot whichever is negative, and if neither is negative, troubleshoot the PWM. Make these voltage measurements after you have implemented the Main Troubleshooting Setup.

Table 3-3. Front-Panel Board Tests

.

Pin

Signal Name

Measureme

Description

Source

No

 

nt

 

 

1

+7.5V

7.5V

Derived from + 15V bias.

A3VR2, A3R3

2

-1V

-1.0V

Derived from –15V bias.

A3R86, A3R85, A3C17

*3

CV VOLTAGE

0-5V

For 0 to full scale output voltage.

A3U2-2, A3R1, A3R87.

*4

CC VOLTAGE

0-5V

For 0 to full scale output current.

A3U3A-1, A3R67

5

VOLTS test

-1888 on

Jumper to + 5V on A3 board.

A3U4-37

 

 

volts display

 

 

6

AMPS test

-1888 on

Jumper to + 5V on A3 board.

A3U5-37

 

 

amps display

 

 

*7

VOLTS input

0-1V

For 0 to full scale output voltage.

A3R8,A3U7-2,3,10

8

VOLTS low range

TTL high

If VOLTS display is below 20 volts

A3U9C-13, A3U6B

 

 

 

(press DISPLAY SETTINGS).

 

9

DISPLAY

TTL high

If DISPLAY SETTINGS switch on

A3S1,A3R80

 

SETTINGS

 

front-panel is depressed.

 

10

DISPLAY OVP

TTL high

If DISPLAY OVP switch on front-

A3S2,A3R82, A3U6C-8

 

 

 

panel is depressed.

 

*11

AMPS input

0-150mV

For 0 to full scale output current.

A3R65,A3R66,A3R67

12

-5 V

-5.0V

Derived from -15 V bias.

A3VR1, A3R2

13

buffered OVP

0-2.2V

1/10 of OVP voltage setting when

A3U3B-6,A3CR5,A3R72

 

 

 

DISPLAY OVP switch is

 

 

 

 

depressed. Varies with OVP

 

 

 

 

ADJUST pot.

 

* Switch A1S4 should be in the NORM position for these tests.

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Contents Autoranging Certification Safety Summary Safety Symbol Definitions Printing HistoryTable of Contents Replaceable Parts Troubleshooting Circuit DiagramsSafety Considerations ScopeManual Revisions Item DescriptionCalibration Procedure IntroductionTest Equipment Required Operation Verification TestsType Required Characteristics USE Recommended Model Test Equipment RequiredInitial Setup 1KVACalibration Procedure MONVout IoutCR7 Performance TestsMeasurement Techniques Current-Monitoring Resistor Setup Constant Voltage CV TestsBasic Test Setup RMS Measurement Test Setup, CV Pard Test Peak-To-Peak Measurement Test Setup, CV Pard Test 6023A 6028A KHz Noise, CV Peak-to-Peak PardLoad Transient Recovery Waveform Constant Current CC Tests CC Pard Test Setup Troubleshooting Initial Troubleshooting ProceduresControl Board Test Connector, A2J7 PIN no Signal NameVdc WAVEFORM/CONDITIONS SourceRepair and Replacement Electrostatic ProtectionA2 Control Board Removal A4 Power Mesh Board Removal Overall Troubleshooting ProcedureA3 Front-Panel Board Removal A1 Main Board RemovalUsing the Tables SetupNode MeasurementMain Troubleshooting Setup Main Troubleshooting SetupModified Mains Cord Set For Troubleshooting Troubleshooting No-Output Failures Front-Panel TroubleshootingBoard PWM-ON PWM-OFF Defective Check Functional CircuitsA2J7-26 A2J7-25 Troubleshooting Bias Supplies Symptoms Defective Circuit Check ComponentsSymptoms Defective Check Functional Circuits Board Node + Measurement SourceNode + N0DE Node +Measurement Source Power Section Blocks Troubleshooting AC-Turn-on CircuitsSetup Measurement Source Setup MeasurementPower Limit Troubleshooting PWM & ClockRelay Enable Troubleshooting DC-To-DC Converter + OUTPWM-ON PWM-OFFTroubleshooting CV Circuit Troubleshooting CC CircuitA4U4OUT Troubleshooting Down ProgrammerTroubleshooting OVP Circuit Waveforms SET Voltage Vdc Node + Page Autoranging Power Block Diagram OverviewBlock Diagram Simplified Schematic Simplified Schematic DC-to-DC Converter Down ProgrammerPfet Control Signals Timing Diagram Constant-Voltage CV CircuitPower-Limit Comparator Constant-Current CC CircuitOvervoltage Protection OVP Circuit Control-Voltage ComparatorInitial-Ramp Circuit Pulse-Width Modulator PWMBias Voltage Detector AC-Surge Dropout DetectorSecond-Delay Circuit Display CircuitsPage Replaceable Parts Reference DesignatorsOrdering Information Description AbbreviationsElectrical Parts CR1CR2 CR3Mechanical Parts XA2P1XA2P2 Control Board Assembly CR3 Page Page Page VR5 VR3VR4 DS5 CR5DS1 VR2 IC A/D Cmos 3-1/2 DGTVR1 NPN SI PfetTS1 Chassis ElectricalA1TB1 A2 Board Mechanical PartsA3 Board Mechanical Parts A4 Board Mechanical PartsOption 220 220V Operation Option 240 240V OperationComponent Location and Circuit Diagrams Schematic Diagram Notes Pin locations for other semi-conductors are shown below Top View, Top Covers Removed Main Board A1 Component Location Control Board A2 Component Location Front-Panel Board A3 Component Location Power Mesh Board A4 Component Location Page Page Option 002 Hardware SpecificationsGeneral Information Table A-1. Specifications, Option Remote Programming Input Compliance Voltage ± Current Programming EnableOutput Impedance 10.2 k ohm ± 5% Temperature Coefficient Status IndicatorsRemote Trip and Remote Reset Timing Power-on PresetMaximum Output Voltage logic high + On State logic lowTable A-1. Specifications, Option Pulse Timing Bias Supplies DC Output Ratings 25C ±Short Circuit Output Current Pard TypicalInstallation Connector Assembly ProcedureFigure A-1. Mating Connector Assembly OperationLocal/Remote Programming Resistance Voltage or Current Remote Resistance Programming Figure A-4. Calculating Value of Series Dropping ResistorFigure A-5. Remote Resistance Programming Remote Monitoring Status Indicators Remote ControlRemote Reset OvervoltagePower-On Preset Figure A-8. Remote ControlAC Dropout Buffer Circuit Multiple Supply System ShutdownMaintenance Bias SuppliesTroubleshooting Resistance and Voltage Programming Troubleshooting Current ProgrammingFigure A-11. Troubleshooting Current Programming of CV Mode Figure A-13. Troubleshooting Status Indicators Page Table A-3. Replacement Parts REF. Desig Model no Description100 VR9 101Indicator and Qualifier Symbols OLD Symbol NEW SymbolLogic Symbols and Definitions 102 DefinitionsSchematic Notes Schematic Diagram Notes 103Schematic Notes Figure A-15. Option 002 Board, Component Location 104Figure A-16. Option 002 Board, Schematic Diagram 105 Page 107 Model 6023AModel 6028A From 108
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