Agilent Technologies AGILENT MODELS 6023A and 6028A service manual Main Troubleshooting Setup

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Main Troubleshooting Setup

Figure 3-1 shows the troubleshooting setup for troubleshooting all of the unit except the front-panel and initial no output failures (See page 31). The external power supply provides the unit's internal bus voltage. The ac mains cord connects to the unit's A1T3 bias transformer via an isolation transformer, thereby energizing the bias supplies, but it does not connect to the input rectifier and filter because that would create the bus voltage. With the external supply the unit operates as a dc-to-dc converter. The supply biases the A4Q3 and A4Q4 PFETs with a low voltage rather than the 320Vdc bus voltage. This protects the PFETs from failure from excess power dissipation if the power-limit comparator or the off-pulse circuitry are defective. It also reduces the possibility of electrical shock to the troubleshooter.

Figure 3-1. Main Troubleshooting Setup

The troubleshooting setup of Figure 3-1 connects high ac mains voltage to the A1F2 fuse, the A1S2 Mains- Voltage Select Switch, the fan and printed-circuit traces at the left edge of the A1 main board. Be extremely careful when working on the unit with the protective inside cover removed to avoid touching the ac mains voltage.

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Contents Autoranging Certification Safety Summary Printing History Safety Symbol DefinitionsTable of Contents Replaceable Parts Circuit Diagrams TroubleshootingSafety Considerations ScopeItem Description Manual RevisionsIntroduction Calibration ProcedureTest Equipment Required Operation Verification TestsTest Equipment Required Type Required Characteristics USE Recommended Model1KVA Initial SetupMON Calibration ProcedureIout VoutCR7 Performance TestsMeasurement Techniques 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 TroubleshootingPIN no Signal Name Control Board Test Connector, A2J7Vdc WAVEFORM/CONDITIONS SourceElectrostatic Protection Repair and ReplacementA2 Control Board Removal Overall Troubleshooting Procedure A4 Power Mesh Board RemovalA3 Front-Panel Board Removal A1 Main Board RemovalSetup Using the TablesNode MeasurementMain Troubleshooting Setup Main Troubleshooting SetupModified Mains Cord Set For Troubleshooting Front-Panel Troubleshooting Troubleshooting No-Output FailuresBoard PWM-ON PWM-OFF Defective Check Functional CircuitsA2J7-26 A2J7-25 Symptoms Defective Circuit Check Components Troubleshooting Bias SuppliesSymptoms Defective Check Functional Circuits Board Node + Measurement SourceNode + N0DE Node +Measurement Source Troubleshooting AC-Turn-on Circuits Power Section BlocksSetup Measurement Source Setup MeasurementPower Limit Troubleshooting PWM & ClockRelay Enable + OUT Troubleshooting DC-To-DC ConverterPWM-ON PWM-OFFTroubleshooting CC Circuit Troubleshooting CV CircuitA4U4OUT Troubleshooting Down ProgrammerTroubleshooting OVP Circuit 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 DiagramConstant-Current CC Circuit Power-Limit ComparatorOvervoltage Protection OVP Circuit Control-Voltage ComparatorPulse-Width Modulator PWM Initial-Ramp CircuitBias Voltage Detector AC-Surge Dropout DetectorDisplay Circuits Second-Delay CircuitPage Reference Designators Replaceable PartsDescription Abbreviations Ordering InformationCR1 Electrical PartsCR2 CR3Mechanical Parts XA2P1XA2P2 Control Board Assembly CR3 Page Page Page VR5 VR3VR4 DS5 CR5DS1 VR2 IC A/D Cmos 3-1/2 DGTVR1 Pfet NPN SIChassis Electrical TS1A2 Board Mechanical Parts A1TB1A3 Board Mechanical Parts A4 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 Option 002 Hardware SpecificationsGeneral Information Input Compliance Voltage ± Current Programming Enable Table A-1. Specifications, Option Remote ProgrammingOutput Impedance 10.2 k ohm ± 5% Temperature Coefficient Status IndicatorsPower-on Preset Remote Trip and Remote Reset TimingMaximum Output Voltage logic high + On State logic lowBias Supplies DC Output Ratings 25C ± Table A-1. Specifications, Option Pulse TimingShort Circuit Output Current Pard TypicalConnector 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 VR9OLD Symbol NEW Symbol Indicator and Qualifier SymbolsLogic Symbols and Definitions 102 DefinitionsSchematic Diagram Notes 103 Schematic NotesFigure A-15. Option 002 Board, Component Location 104 Schematic NotesFigure A-16. Option 002 Board, Schematic Diagram 105 Page 107 Model 6023AModel 6028A 108 From