Agilent Technologies AGILENT MODELS 6023A and 6028A Troubleshooting PWM & Clock, Relay Enable

Page 36

A2U18-13			cycle power	five 100ms pulses then hi
A2U18-12			cycle power	two 200ms pulses then hi
A2U18-15			cycle power	transition lo to hi at 800 msec
A2U17-8			cycle power	transition lo to hi at 1.0 sec
A2U17-11			cycle power	transition lo to hi at 1.1 sec
		A2Q5 (col)	cycle power	transistion 5.0 to 0.3Vdc at 1.0s
	DROPOUT
(RELAY ENABLE)

Troubleshooting PWM & Clock

The inputs to inhibit Gate A2U19A and PWM gate A2U19B are the keys to PWM troubleshooting. The 20KHz clock starts each PWM output pulse, and the pulse stops when any of the inputs to A2U19A or A2U19B goes low. The PWM is inhibited and prevented from initiating output pulses as long as any of the eight inputs is low.

Circuit Included. Pulse Width Modulator (PWM), Inhibit Gate A2U19A, Off-Pulse Oneshot, On-Pulse Oneshot, A2U17B, 20KHz Clock.

Setup. The Main Troubleshooting Setup, page 29. Apply the ac mains voltage to the bias transformer and switch on the LINE switch. Adjust the units current setting above 1.0Adc. Set the external supply (EXTERNAL) and adjust the unit's voltage setting (INTERNAL) as instructed below.

Inputs:

NODE ( - ) = A2J7-4

NODE ( + )	SETUP	MEASUREMENT	SOURCE
A2J3-1		5.0Vdc	A2Q3 (emitter)
A2U19-1		Hi	A2U17D-11
A2U19-2		Hi	remote inhibit
A2U19-4		Hi	A2U14-1,8
A2U19-5		Hi	A2U11B-6
A2U19-10		Hi	A2U16-7
A2U19-12	POWER LIMIT fully CCW	Lo	A2U14-2
A2U19-12	POWER LIMIT fully CW	Hi	A2U14-2

Outputs:
		SET VOLTAGE (Vdc)
NODE ( + )	EXTERNAL	INTERNAL	SETUP	MEASUREMENT
A2U21-7	0	0		TTL sq wave, 320KHz
A2U22-3	0	0		TTL sq wave, 160KHz
A2U22-6	0	0		TTL sq wave, 20KHz
A2U13-5	0	0		23.5∝s TTL pulses, 20KHz
A2U13-9	0	0		23.5∝s TTL pulses, 20KHz
A2U14-2	40	0	POWER LIMIT	lo
A2U19-5	40	0	fully CCW	lo
A2U19-5	40	0		lo
A2U13-9	40	0		lo
A2U17-6	40	0		lo
A2U15-13	40	0		lo
A2U15-5	40	0		lo
A2U17-6	40	0	POWER LIMIT	groups of 4 pulses 1.7∝s, TTL, 20KHz
A2U17-5	40	0	fully CW	1.7∝s, TTL, 20KHz
A2U17-5	40	0		1.7∝s, TTL, 20KHz

36

Image 36

Contents Autoranging Certification Safety Summary Safety Symbol Definitions Printing HistoryTable of Contents Replaceable Parts Troubleshooting Circuit DiagramsSafety Considerations ScopeManual Revisions Item DescriptionCalibration Procedure IntroductionTest Equipment Required Operation Verification TestsType Required Characteristics USE Recommended Model Test Equipment RequiredInitial Setup 1KVACalibration Procedure MONVout IoutPerformance Tests Measurement TechniquesCR7 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 ProceduresControl Board Test Connector, A2J7 PIN no Signal NameVdc WAVEFORM/CONDITIONS SourceRepair and Replacement Electrostatic ProtectionA2 Control Board Removal A4 Power Mesh Board Removal Overall Troubleshooting ProcedureA3 Front-Panel Board Removal A1 Main Board RemovalUsing the Tables SetupNode MeasurementMain Troubleshooting Setup Main Troubleshooting SetupModified Mains Cord Set For Troubleshooting Troubleshooting No-Output Failures Front-Panel TroubleshootingPWM-ON PWM-OFF Defective Check Functional Circuits A2J7-26 A2J7-25Board Troubleshooting Bias Supplies Symptoms Defective Circuit Check ComponentsSymptoms Defective Check Functional Circuits Board Node + Measurement SourceNode + Measurement SourceNode + N0DE Power Section Blocks Troubleshooting AC-Turn-on CircuitsSetup Measurement Source Setup MeasurementTroubleshooting PWM & Clock Relay EnablePower Limit Troubleshooting DC-To-DC Converter + OUTPWM-ON PWM-OFFTroubleshooting CV Circuit Troubleshooting CC CircuitTroubleshooting Down Programmer Troubleshooting OVP CircuitA4U4OUT 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 CircuitPower-Limit Comparator Constant-Current CC CircuitOvervoltage Protection OVP Circuit Control-Voltage ComparatorInitial-Ramp Circuit Pulse-Width Modulator PWMBias Voltage Detector AC-Surge Dropout DetectorSecond-Delay Circuit Display CircuitsPage Replaceable Parts Reference DesignatorsOrdering Information Description AbbreviationsElectrical Parts CR1CR2 CR3XA2P1 XA2P2Mechanical Parts Control Board Assembly CR3 Page Page Page VR3 VR4VR5 CR5 DS1DS5 IC A/D Cmos 3-1/2 DGT VR1VR2 NPN SI PfetTS1 Chassis ElectricalA1TB1 A2 Board Mechanical PartsA3 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 Specifications General InformationOption 002 Hardware Table A-1. Specifications, Option Remote Programming Input Compliance Voltage ± Current Programming EnableOutput Impedance 10.2 k ohm ± 5% Temperature Coefficient Status IndicatorsRemote Trip and Remote Reset Timing Power-on PresetMaximum Output Voltage logic high + On State logic lowTable A-1. Specifications, Option Pulse Timing Bias Supplies DC Output Ratings 25C ±Short Circuit Output Current 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 101Indicator and Qualifier Symbols OLD Symbol NEW SymbolLogic Symbols and Definitions 102 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 6023A Model 6028A107 From 108