Agilent Technologies AGILENT MODELS 6023A and 6028A service manual A4 Power Mesh Board Removal

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A4 Power Mesh Board Removal

After removing the inside cover, remove the A4 power mesh board by lifting, using the large aluminum heatsink as a handle. Two connectors hold the A4 board at its bottom edge.

When installing the A4 power mesh board, lower it vertically into its connectors and press in place.

A3 Front-Panel Board Removal

Remove the A3 front-panel board by first removing the entire front-panel assembly. You do not need to remove the top cover. Follow this procedure:

a.Remove the top plastic insert by prying up with a flat-blade screwdriver, and remove the front feet by lifting the tabs and sliding toward the front of the unit.

b.Remove the four front-panel assembly mounting screws (Phillips 8-32) on the top and bottom at the corners using a Pozidriv or Phillips head screwdriver (Phillips head screwdriver may be used only with these four screws).

c.Gently pull the front-panel assembly away from the unit as far as permitted by the connecting cables.

d.Remove the ground-wire screw (Pozidriv, M4x.7) holding the green-yellow ground wire.

e.Note the locations of the four power-wire connections to the power switch and then unplug the quick-connect plugs.

f.Unplug the W3 3-wire cable from connector A1J3 on the A1 main board.

g.Remove the A3 board from the front-panel assembly by removing the five mounting screws (Pozidriv, M4x.7)

Install the A3 Board by reversing the steps above. The power wires are correctly connected to the power switch wires if they do not cross each other.

A1 Main Board Removal

Removing the A1 main board requires removing the rear panel, all boards except the A3 front-panel board, and 17 A1 board mounting screws. Component-access cutouts in the bottom inside cover allow unsoldering most A1-board components for repair without removing the A1 board.

To remove the A1 board, proceed as follows:

a.Remove the A2 and A4 boards according to the above instructions.

b.Detach the rear panel by removing the four mounting screws (Pozidriv, M4x.7) two on each side. Gently pull the rear panel away from the unit as far as permitted by the four wires connected to the A1 board.

c.Unplug the W1 ribbon cable from connector A1J1.

d.Remove the A1 board by removing the 17 mounting screws (Pozdriv, M4x.7).

e.Note locations and the unplug the two ac power wires and the two fan wires to the A1 board.

Overall Troubleshooting Procedure

Perform the troubleshooting and repair procedures which follow only if you are trained in equipment service and are aware of the danger from fire and electrical-shock hazards. Some of the procedures include removing the unit's protective covers which may expose you to potentially lethal electrical shock. Whenever possible, make test connections and perform service with the power removed.

After performing the Initial Troubleshooting Procedures, focus on developing a logical approach to locating the source of the trouble. The underlying strategy for the troubleshooting procedures here is to guide you to the faulty circuit nodes which have improper signals or voltages. It relies on you to identify the particular functional circuit to troubleshoot from symptom tables and by understanding how the unit works. It then relies on you to discover the defective component or components which cause the faulty circuit nodes. So, read the BLOCK DIAGRAM overview in Chapter 4 and read the functional circuit descriptions for the circuits that you suspect may be defective. Then return to this section for help finding the faulty circuit nodes.

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Contents Autoranging Certification Safety Summary Printing History Safety Symbol DefinitionsTable of Contents Replaceable Parts Scope TroubleshootingCircuit Diagrams Safety ConsiderationsItem Description Manual RevisionsOperation Verification Tests Calibration ProcedureIntroduction Test Equipment RequiredTest Equipment Required Type Required Characteristics USE Recommended Model1KVA Initial SetupMON Calibration ProcedureIout VoutPerformance Tests Measurement TechniquesCR7 Constant Voltage CV Tests Current-Monitoring Resistor SetupBasic Test Setup RMS Measurement Test Setup, CV Pard Test Peak-To-Peak Measurement Test Setup, CV Pard Test KHz Noise, CV Peak-to-Peak Pard 6023A 6028ALoad Transient Recovery Waveform Constant Current CC Tests CC Pard Test Setup Initial Troubleshooting Procedures TroubleshootingWAVEFORM/CONDITIONS Source Control Board Test Connector, A2J7PIN no Signal Name VdcElectrostatic Protection Repair and ReplacementA2 Control Board Removal A1 Main Board Removal A4 Power Mesh Board RemovalOverall Troubleshooting Procedure A3 Front-Panel Board RemovalMeasurement Using the TablesSetup NodeMain Troubleshooting Setup Main Troubleshooting SetupModified Mains Cord Set For Troubleshooting Front-Panel Troubleshooting Troubleshooting No-Output FailuresPWM-ON PWM-OFF Defective Check Functional Circuits A2J7-26 A2J7-25Board Node + Measurement Source Troubleshooting Bias SuppliesSymptoms Defective Circuit Check Components Symptoms Defective Check Functional Circuits BoardNode + Measurement SourceNode + N0DE Setup Measurement Power Section BlocksTroubleshooting AC-Turn-on Circuits Setup Measurement SourceTroubleshooting PWM & Clock Relay EnablePower Limit PWM-OFF Troubleshooting DC-To-DC Converter+ OUT PWM-ONTroubleshooting CC Circuit Troubleshooting CV CircuitTroubleshooting Down Programmer Troubleshooting OVP CircuitA4U4OUT Waveforms SET Voltage Vdc Node + Page Block Diagram Overview Autoranging PowerBlock Diagram Simplified Schematic Simplified Schematic Down Programmer DC-to-DC ConverterConstant-Voltage CV Circuit Pfet Control Signals Timing DiagramControl-Voltage Comparator Power-Limit ComparatorConstant-Current CC Circuit Overvoltage Protection OVP CircuitAC-Surge Dropout Detector Initial-Ramp CircuitPulse-Width Modulator PWM Bias Voltage DetectorDisplay Circuits Second-Delay CircuitPage Reference Designators Replaceable PartsDescription Abbreviations Ordering InformationCR3 Electrical PartsCR1 CR2XA2P1 XA2P2Mechanical Parts Control Board Assembly CR3 Page Page Page VR3 VR4VR5 CR5 DS1DS5 IC A/D Cmos 3-1/2 DGT VR1VR2 Pfet NPN SIChassis Electrical TS1A4 Board Mechanical Parts A1TB1A2 Board Mechanical Parts A3 Board Mechanical PartsOption 240 240V Operation Option 220 220V 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 Specifications General InformationOption 002 Hardware Status Indicators Table A-1. Specifications, Option Remote ProgrammingInput Compliance Voltage ± Current Programming Enable Output Impedance 10.2 k ohm ± 5% Temperature CoefficientOn State logic low Remote Trip and Remote Reset TimingPower-on Preset Maximum Output Voltage logic high +Pard Typical Table A-1. Specifications, Option Pulse TimingBias Supplies DC Output Ratings 25C ± Short Circuit Output CurrentConnector Assembly Procedure InstallationOperation Figure A-1. Mating Connector AssemblyLocal/Remote Programming Resistance Voltage or Current Figure A-4. Calculating Value of Series Dropping Resistor Remote Resistance ProgrammingFigure A-5. Remote Resistance Programming Remote Monitoring Remote Control Status IndicatorsOvervoltage Remote ResetFigure A-8. Remote Control Power-On PresetMultiple Supply System Shutdown AC Dropout Buffer CircuitBias Supplies MaintenanceTroubleshooting Current Programming Troubleshooting Resistance and Voltage ProgrammingFigure A-11. Troubleshooting Current Programming of CV Mode Figure A-13. Troubleshooting Status Indicators Page REF. Desig Model no Description Table A-3. Replacement Parts100 101 VR9Definitions Indicator and Qualifier SymbolsOLD Symbol NEW Symbol Logic Symbols and Definitions 102Schematic Diagram Notes 103 Schematic NotesFigure A-15. Option 002 Board, Component Location 104 Schematic NotesFigure A-16. Option 002 Board, Schematic Diagram 105 Page Model 6023A Model 6028A107 108 From
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