Agilent Technologies AGILENT MODELS 6023A and 6028A service manual A2 Control Board Removal

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To avoid the possibility of personal injury, remove the power supply from operation before opening the cabinet. Turn off ac power and disconnect the line cord, load, and remote sense leads before attempting any repair or replacement.

When replacing any heatsink-mounted components except thermostat, smear a thin coating of heatsink compound between the component and heatsink. If a mica insulator is used, smear a thin coating of heatsink compound on both sides of the mica insulator.

Do not use any heatsink compound containing silicone, which can migrate and foul electrical contacts elsewhere in the system. An organic zinc oxide cream, such as American Oil and Supply Company Heatsink Compound #100, is recommended.

Most of thc attaching hardware in this unit is metric. The only non-metric (sometimes called English or inch) fittings are listed below. Be careful when both types of screws are removed not to get them mixed up.

a.Lock-link/shelf-mounting blocks (4 on rear panel, one at each corner).

b.Rear-panel fuse holder.

c.Rear-panel ground binding post.

d.Strap-handle screws (2).

e.Screws that secure side chassis to front-frame casting (8, 4 on each side).

f.Screws that secure front-panel to front-frame casting (4, 2 on top and 2 on bottom).

Top Outside Cover Removal. Remove three screws, the rear handle screw (Phillips, 10x32) and two top-rear corner screws (Pozidriv, M4x.7) using a Size 1, Pozidriv screwdriver. A Phillips head screwdriver does not fully seat into Pozidriv screws and risks stripping the heads. Do not remove the front handle screw, as the retaining nut will fall into the unit. Remove the top cover by sliding it to the rear and lifting at the front.

Bottom Cover Removal. Remove only for repair of main board. Remove two bottom-rear corner screws. (Pozidriv, M4x.7) and remove the bottom cover by sliding it to the rear. You do not need to remove the unit's feet.

Inside Top Cover Removal. The unit includes an inside cover which secures the vertical board assemblies. Remove the inside cover for repair but not for calibration. Remove the six mounting screws (Pozidriv, M4x.7) – three on each side and five board fastening screws (Pozidriv, M4x.7) all on top. Remove the inside cover by lifting at the front edge.

When installing the inside cover, insert it first at the right side. While holding it tilted up at the left, reach through the cutouts in the cover and fit the top tabs of the A2 control board into the mating slots in the cover. With the top cover in place reach through the cutout above the A4 power mesh board, align the board-fastening screw holes, and replace the rear- most screw to secure the A4 board. Press the inside cover down firmly while tightening screws that secure cover to chassis. Complete the installation by replacing the remaining ten screws. Be careful when replacing printed-circuit assemblies and covers not to bend any boards or components.

A2 Control Board Removal

After removing the inside cover, remove the A2 board by lifting first at the front edge and than pulling it up and out of the unit. Two connectors hold the A2 board at its bottom edge.

When installing the A2 board, insert it first at the rear of the unit. While holding it tilted up at the front, fit the A2TB1 terminal strip into the mating cutout in the rear panel. Then lower the A2 board's bottom connectors into the mating connectors on the main board. Press the A2 board into the connectors.

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Contents Autoranging Certification Safety Summary Safety Symbol Definitions Printing HistoryTable of Contents Replaceable Parts Safety Considerations TroubleshootingCircuit Diagrams ScopeManual Revisions Item DescriptionTest Equipment Required Calibration ProcedureIntroduction 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 ProceduresVdc Control Board Test Connector, A2J7PIN no Signal Name WAVEFORM/CONDITIONS SourceRepair and Replacement Electrostatic ProtectionA2 Control Board Removal A3 Front-Panel Board Removal A4 Power Mesh Board RemovalOverall Troubleshooting Procedure A1 Main Board RemovalNode Using the TablesSetup 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 Symptoms Defective Check Functional Circuits Board Troubleshooting Bias SuppliesSymptoms Defective Circuit Check Components Node + Measurement SourceNode + N0DE Node +Measurement Source Setup Measurement Source Power Section BlocksTroubleshooting AC-Turn-on Circuits Setup MeasurementPower Limit Troubleshooting PWM & ClockRelay Enable PWM-ON Troubleshooting DC-To-DC Converter+ OUT 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 CircuitOvervoltage Protection OVP Circuit Power-Limit ComparatorConstant-Current CC Circuit Control-Voltage ComparatorBias Voltage Detector Initial-Ramp CircuitPulse-Width Modulator PWM AC-Surge Dropout DetectorSecond-Delay Circuit Display CircuitsPage Replaceable Parts Reference DesignatorsOrdering Information Description AbbreviationsCR2 Electrical PartsCR1 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 ElectricalA3 Board Mechanical Parts A1TB1A2 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 Output Impedance 10.2 k ohm ± 5% Temperature Coefficient Table A-1. Specifications, Option Remote ProgrammingInput Compliance Voltage ± Current Programming Enable Status IndicatorsMaximum Output Voltage logic high + Remote Trip and Remote Reset TimingPower-on Preset On State logic lowShort Circuit Output Current Table A-1. Specifications, Option Pulse TimingBias Supplies DC Output Ratings 25C ± 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 101Logic Symbols and Definitions 102 Indicator and Qualifier SymbolsOLD Symbol NEW Symbol 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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