Manuals / Agilent Technologies / Home Audio / Stereo System

Agilent Technologies 66332A, 6634B, 6633B, 6632B service manual Principles of Operation

Models: 6632B 6633B 66332A 6634B

1 82

Download 82 pages 25.5 Kb

Page 53

Principles of Operation - 4

The output is programmed off.

An overvoltage condition is detected (OV_Detect* signal is received).

The line voltage falls below 90 volts (approximately).

Current readback is provided by three separate circuits. The previously discussed high range current signal (Imon_H) returns the high range current measurement. When the unit is operating in the low current readback mode, a separate low range current shunt and amplifier provides low-current readback via the Imon_L signal. The Range_Select signal drives shunt clamps Q304 and Q305, which clamp the voltage across RmLo to approximately 1.8 V. A third current readback circuit is available on the Agilent 66332A unit. It consists of a high bandwidth current amplifier that returns dynamic current measurements from the output filter capacitor via the Imon_P signal. Note that the Imon_H and the Imon_P signal are combined to return the actual output current measurement.

An overvoltage detect circuit compares the output voltage to the programmed overvoltage setting. When the output exceeds the programmed setting, the OV_Detect* signal goes low, which informs the logic array that an OV condition has occurred. The crowbar control circuit is enabled when the OV_SCR* signal is received. When an overvoltage condition occurs, the SCR control circuit generates the OV signal, which causes the following actions to occur:

1.The SCR fires, shorting the supply's output.

2.The microprocessor circuits are notified of the OV condition (OV_Detect* is low) in order to program the output off, turn off the gain stage bias, and update the status of the unit.

3.When a output protection clear command is executed, the microprocessor circuits resets the OV circuits, turns on the gain stage bias, and programs the output to its previous level.

The fan driver control circuit provides the DC voltage to operate the cooling fan. The Fan_Prog signal from the secondary interface circuit varies this voltage according to the ambient and heatsink temperature as well as the output voltage and current of the supply.

53

Image 53

Agilent Technologies 66332A, 6634B, 6633B, 6632B service manual Principles of Operation

Contents

Agilent Model 66332A System DC Power SupplyDynamic Measurement DC Source and Agilent Model 6632B, 6633B, 6634BWARRANTY Warranty InformationLIMITATION OF WARRANTY CERTIFICATIONBEFORE APPLYING POWER Safety SummaryDO NOT SERVICE OR ADJUST ALONE SAFETY SYMBOLSDescription Safety Symbol DefinitionsSymbol Instrument Identification Printing HistoryTROUBLESHOOTING Table of ContentsINTRODUCTION VERIFICATION AND PERFORMANCE TESTSDIAGRAMS REPLACEABLE PARTS LISTPRINCIPLES OF OPERATION INDEXPage Introduction Safety ConsiderationsOrganization Related DocumentsElectrostatic Discharge RevisionsManual Revisions Firmware RevisionsTest Equipment Required Verification and Performance TestsIntroduction Figure 2-1.Test Setup Test SetupMeasurement Techniques 2 - Verification and Performance TestsPerformance Tests Operation Verification TestsElectronic Load Current-MonitoringResistorConstant Voltage CV Tests CV SetupVoltage Programming and Readback Accuracy CV Load EffectVerification and Performance Tests CV Source EffectCV Noise PARD CC Setup Transient Recovery TimeConstant Current CC Tests Current Programming and Readback AccuracyLow Range Current Readback Accuracy Current Sink -CCOperationCC Load and Line Regulation Verification and Performance Tests2 - Verification and Performance Tests CC Load EffectCC Source Effect Verification and Performance Tests Performance Test Equipment FormCC Noise PARD 2 - Verification and Performance Tests Performance Test Record FormsVerification and Performance Tests 2 - Verification and Performance Tests Introduction TroubleshootingFlow Charts Overall Troubleshooting3 - Troubleshooting Test Equipment RequiredFigure 3-1Sheet 1. Main Flowchart Troubleshooting3 - Troubleshooting Figure 3-1Sheet 2. Main Flowchart continuedTroubleshooting Figure 3-1Sheet 3. Main Flowchart continued3 - Troubleshooting Figure 3-1Sheet 4. OV at Turn-OnTroubleshooting Figure 3-1Sheet 5. OV at Turn-Oncontinued3 - Troubleshooting Figure 3-1Sheet 6. FS Indicated but Fuse OKTroubleshooting Figure 3-1Sheet 7. No Output Voltage3 - Troubleshooting Figure 3-1Sheet 8. No Output Voltage continuedTroubleshooting Figure 3-1Sheet 9 No Output Voltage continued3 - Troubleshooting Figure 3-1Sheet 10. No Current LimitTroubleshooting Figure 3-1Sheet 11. Unit Does Not OV3 - Troubleshooting Figure 3-1Sheet 12. High Output VoltagePower-on Self-testFailures Specific Troubleshooting ProceduresTable 3-2. Self-TestError Codes/Messages TroubleshootingBias and Rail Voltages CV/CC Status Annunciators TroubleshootingTable 3-3.Bias and Reference Voltages 3 - TroubleshootingTroubleshooting J307 Voltage Measurements3 - Troubleshooting Disabling Protection FeaturesManual Fan Speed Control Calibration Password Inhibit Calibration SwitchPost-repairCalibration TroubleshootingUpgrade Procedure ROM UpgradeInitialization Identifying the FirmwareList of Required Tools Disassembly ProceduresFigure 3-2.Component Location TroubleshootingA2 Interface Board, Removal and Replacement Cover, Removal and ReplacementFront Panel Assembly, Removal and Replacement 3 - TroubleshootingA3 Front Panel Board, Removal and Replacement S1 Line Switch, Removal and ReplacementT1 Power Transformer, Removal and Replacement A1 Main Control Board3 - Troubleshooting Line Voltage WiringFigure 3-3.Transformer Wiring Table 4-1.Power Supply Interface signals I/O Interface SignalsPrinciples of Operation IntroductionA2 Interface Circuits A3 Front Panel CircuitsPrimary Interface Secondary InterfacePrinciples of Operation Figure 4-1.A2/A3 Block Diagram4 - Principles of Operation Power CircuitsA1 Main Board Circuits Principles of Operation Figure 4-2.A1 Block Diagram4 - Principles of Operation Control CircuitsPrinciples of Operation Page Introduction Replaceable Parts ListTable 5-1.Chassis, Electrical Table 5-2.Chassis, Mechanical 5 - Replaceable PartsFigure 5-1.Mechanical Parts ldentification Replaceable Parts5 - Replaceable Parts Table 5-3.A1 Control Board PC Board AssemblyReplaceable Parts - 5 - Replaceable Parts Replaceable Parts 5 - Replaceable Parts Replaceable Parts 5 - Replaceable Parts Replaceable Parts 5 - Replaceable Parts Replaceable Parts 5 - Replaceable Parts Replaceable Parts Table 5-5.A5 AC input/RFI Board Table 5-4.Binding Post Option #020Table 5-6.Relay Option #760 5 - Replaceable PartsGeneral Schematic Notes DiagramsTable 6-1. Model-dependentComponents IntroductionTable 6-1. Model-dependentComponents continued 6 - DiagramsTable 6-2.A1 Board Component Locations Diagrams6 - Diagrams Table 6-2continuedFigure 6-1.A1 Board Component Locations Figure 6-2.A4 and A6 Board Component Locations Figure 6-3.A1 Board schematic sheet A1 Board schematic sheet A1 Board schematic sheet Figure 6-4.A6 Relay Option Board schematic Index