Agilent Technologies AGILENT MODELS 6023A and 6028A service manual

Page 98

c.Turn on power supply.

d.DVM should read approximately 5Vdc.

e.Set voltage and current controls of power supply to maximum.

f.Decrease resistance of electronic load until "UNREGULATED" LED on front-panel lights.

a.DVM should now read between 0 and 0.4Vdc.

To check LOW BIAS or AC Dropout proceed as follows:

a.Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-19.

b.Substitute an oscilloscope in place of DVM. Set vertical deflection for 1 volt/div on the DC input.

c.Turn power on and observe oscilloscope trace. Voltage should increase to 5V at power-on and drop to between 0 and 0.4Vac approximately 3 sec.

d.Turn power off. Voltage should go to about 5Vdc before decaying back to 0V.

Note

In this test, the Low BIAS or AC Dropout signal decays to 0V only because of loss of power to the + 5V

 

REG Bias Supply used in the test set-up. If in doubt, use an external + 5V supply for this test.

To check OVERTEMPERATURE proceed as follows:

a.Turn off power supply and disconnect line cord.

b.Wait at least two minutes for input capacitors to discharge .

c.Remove top cover and inside cover.

d.Using test set-up, Figure A-13, connect top end of 2KΩ resistor to J3-16.

e.Turn on power supply.

f.DVM should read approximately 5VAC.

g.Turn off power and wait two minutes.

h.Remove the A4 FET Assembly from the unit.

i.Turn on power supply. DVM should read between 0 to 0.4Vdc.

Note

The FET heatsinks are connected to the primary circuit and hazardous voltage (up to between 300 to

 

400V) exists between the heatsinks and the heatsink and the chassis. These potentials remain for up to 2

 

minutes if the power supply is turned off. Do not touch the heatsinks or any components on the heatsink

 

assemblies while the power supply is turned on or for at least two minutes after primary power is

 

removed. Do not place any of the heatsink assemblies on extender boards.

Troubleshooting Remote Shutdown. The following procedures check the Remote Shutdown features of 002 Option. Troubleshooting can be accomplished by using a logic probe and referring to the schematic and the circuit description on page 93. Before attempting to troubleshoot the Remote Shutdown section of the option, check for + 5Vdc internal bias. This voltage must be present for proper operation of these circuits

To check the REMOTE TRIP and REMOTE RESET proceed as follows:

a.Connect +5V (J3-23) to Control Isolator bias (J3-l0).

b.Turn unit on and short REMOTE TRIP (J3-30) to + 5V common (J3-7) momentarily. Output should go into unregulated condition with output off.

c.Short REMOTE RESET (J3-29) to + 5V common (J3-7) momentarily and OUTPUT should return to its initial state.

To check REMOTE INHIBIT proceed as follows:

a.Table A-3. Replacement Connect +5V (J3-23) to control isolator bias (J3-10).

b.Turn unit on and short REMOTE INHIBIT (J3-31 ) to + 5V common (J3-7). Output should go to an unregulated output off condition.

c.Remove short between REMOTE INHIBIT (J3-31 ) and + 5V common (J3-7) and output should return to its initial state.

98

Page 97 Page 99
Image 98
Page 97 Page 99
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
Top Page Image Contents