Agilent Technologies AGILENT MODELS 6023A and 6028A service manual Bias Supplies, Maintenance

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If it is necessary to have all the supplies come up simultaneously after a system shutdown, follow this procedure:

a.First bring the REMOTE INHIBIT line low.

b.Provide a negative-going pulse to the REMOTE RESET .

c.After at least one second, return REMOTE INHIBIT to a high level.

Figure A-10. System Shutdown Using Bias Supply Output

Figure A-10 shows a second method of system shutdown. This method is appropriate in systems which are not controller-operated and in which more than four supplies must be shutdown simultaneously. Because each supply derives its CONTROL ISOLATOR BIAS from the previous supply's + 5V REG, there is no limit to the number of supplies that can be shutdown. Each supply must be reset individually.

Using either method of system shutdown, PCLR inhibits the OVERVOLTAGE indicator from going low and shutting

down succeeding supplies upon initial sum-on. After the supplies have stabilized, PCLR returns to a high state.

Bias Supplies

The outputs of three current-limited bias supplies are available for user-supplied circuitry. These are + 15V @ 75mA at J3-4, -15V @ 75mA at J3-20, and +5 V @ 100mA at J3-23; all with respect to J3-7, L Common.

It may be desirable to install noise-suppression capacitors on the bias supply outputs near the load circuits. The capacitors should be ceramic or tantalum type, approximately 0.1∝F to 10∝F.

Maintenance

The following paragraphs provide procedures and setups to aid in checking and troubleshooting the 002 Option Board. This information, used in conjunction with the schematic drawing and the Operation section of this Appendix, will help in the isolation and repair of faulty circuits.

When testing the option, use of the test connector on page 83 will allow easier access to the J3 contacts.

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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 IoutMeasurement Techniques Performance TestsCR7 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 TroubleshootingA2J7-26 A2J7-25 PWM-ON PWM-OFF Defective Check Functional CircuitsBoard Symptoms Defective Check Functional Circuits Board Troubleshooting Bias SuppliesSymptoms Defective Circuit Check Components Node + Measurement SourceMeasurement Source Node +Node + N0DE Setup Measurement Source Power Section BlocksTroubleshooting AC-Turn-on Circuits Setup MeasurementRelay Enable Troubleshooting PWM & ClockPower Limit PWM-ON Troubleshooting DC-To-DC Converter+ OUT PWM-OFFTroubleshooting CV Circuit Troubleshooting CC CircuitTroubleshooting OVP Circuit Troubleshooting Down ProgrammerA4U4OUT 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 CR3XA2P2 XA2P1Mechanical Parts Control Board Assembly CR3 Page Page Page VR4 VR3VR5 DS1 CR5DS5 VR1 IC A/D Cmos 3-1/2 DGTVR2 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 General Information SpecificationsOption 002 Hardware 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 Model 6028A Model 6023A107 From 108