DC Scaling | Fluke 8842a specification

Theory of Operation 5

DC SCALING

f5-01.wmf

Figure 5-1. Overall Functional Block Diagram

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Image 112

Fluke 8842a instruction manual DC Scaling

Contents

8842A Page Table of Contents 8842A Remote Programming Measurement Tutorial Maintenance List of Replaceable Parts Schematic Diagrams List of Tables 805-7 List of Figures 805-8 IEEE-488 Interface PCA, Option True RMS AC PCA, Option Xii Introduction and Specifications Introduction Options and Accessories8842A Digital Multimeter Specifications Peak NM Signal RateFilter True RMS AC Voltage Option 8842A-09 Frequency Fundamental FrequencyCrest Factor For Inputs Full Scale 5½ Digits Current½ Digits Range Full Scale Resolution Current ½ Digits Through Unknown Hours 23±1C Rate Power Line FREQUECNCY1 Automatic Settling Time DelayAutoranging Function External Trigger Timing Characteristics Conversion Time ms 50 Hz 60 Hz 400 Hz Power General Operating Instructions Installing the Power-Line Fuse InstallationConnecting to Line Power Adjusting the Handle Rack Mounting Kits Power-Up Features Operating FeaturesFront and Rear Panel Features Operating Features Local button causes the 8842A to display its Rear Panel Features Display Features Error Messages Error Code Meaning Error Code Diagnostic Self-Tests Overrange IndicationRanging Autorange Continuous Trigger Mode External Trigger ModeManual Range Triggering External Trigger Input Option -05 Only Automatic Settling Time DelaySample Complete Output Option -05 Only Making Measurements Input Overload Protection LimitsMeasuring Voltage and Resistance Measuring Current Offset Measurements External Cleaning Measuring Voltage and Resistance 8842A Remote Programming Measurement Data Overrange Indication Error Messages BUS SET-UP Procedure Capabilities AN Overview of Remote Operation IEEE-488 Address Selection AN Overview of Remote Operation DEVICE-DEPENDENT Command SET ExampleExplanation DEVICE-DEPENDENT Command SET Device-Dependent Command Set Cn Calibration Commands Bn Offset CommandsDn Display Commands Fn Function Commands Get Commands Command Output String Meaning 13. G1 Get SRQ Mask 12. G0 Get Instrument Configuration14. G2 Get Calibration Prompt 15. G3 Get User-Defined Message 16. G4 Get Calibration Status 17. G5 Get IAB Status 19. G7 Get Error Status18. G6 Get YW Status Numeric Entry Command Put Commands23. P0 Put Instrument Configuration 20. G8 Get Instrument Identification 24. P1 Put SRQ Mask 25. P2 Put Calibration Value Sn Reading Rate Commands Rn Range Commands26. P3 Put User-Defined Message Tn Trigger Mode Commands Trigger Selection Logic Diagram Wn Terminator Commands 31. X0 Clear Error Register CommandYn Suffix Commands 33. Z0 Self-Test Command 35. ? Single-Trigger Command Device-Clear CommandInput Syntax Definitions Input Processing DEVICE-DEPENDENT Messages ERROR-PRODUCING CharactersInterface Messages Syntax Rules Incorrect example Output Data Loading Output Data Numeric Data and Error Messages Overrange Indication Error MessagesTypes of Output Data Measurement Data Error Messages Overrange IndicationStatus Data Output Priority Service Requests Serial Poll Register SRQ Mask Set Interface Messages Universal CommandsAddress Messages TALK-ONLY Mode Addressed Commands Remote Calibration Immediate Mode CommandsTiming Considerations Immediate-Mode Commands for Various Controllers Example Programs Example Programs 10. Example Program Taking Readings with Local Control 11. Example Program Using the Serial Poll Register 12. Example Program Record Errors During Selftest 13. Example Programs Using the IBM PC 14. Example Programs Using the IBM PC F3-1402.wmf F3-1403.wmf F3-1404.wmf F3-1405.wmf F3-1406.wmf F3-1407.wmf F3-1408.wmf F3-1409.wmf F3-1410.wmf F3-1411.wmf ASCII/IEEE Std 488-1978 Bus Codes 8842A Measurement Tutorial Circuit Loading Error DC Voltage Measurement Input Bias Current Error Measuring Input Bias Current Error Wire Ohms Resistance Measurement Correcting for Test Lead Resistance in 2-Wire Ohms Test Current Full Scale Voltage Testing Electrolytic Capacitors Testing DiodesApplications of the Ohms Functions DC Current Measurement Precision Current Source Burden Voltage Error Calculation Reducing Thermal Voltages True RMS Measurement AC Voltage and Current MeasurementWaveform Comparison AC Voltage and Current Measurement Crest Factor AC-Coupled AC Measurements Combined AC and DC Measurements Zero-Input VAC ErrorBandwidth Reduction of Zero-Input Error 20Ω Ranges Making Accurate HIGH-RESISTANCE Measurements 10. Shielding for Low Voltage Measurements 12. Leakage Resistance in High Resistance Measurement Theory of Operation True RMS AC Option VAC Scaling MA AC Scaling Overall Functional Description Detailed Circuit Description DC Scaling DC Scaling VDC Scaling DC Scaling VDC and mA DC MA DC Scaling VDC ProtectionAnalog Filter TRACK/HOLD Circuit Track/Hold Amplifier TRACK/HOLD Circuit Track Configuration Timing Diagram for One A/D Cycle Settling Configuration Hold ConfigurationPre-Charge Configuration Precision Voltage Reference Ohms Current Source Ohms Current Source Ohms Protection Ohms Functions Ohms Scaling 20. A/D Converter Analog-to-Digital Converter Timing/Data Control Precision DAC Display Bootstrap Supplies23. A/D Amplifier Keyboard Digital Controller 13. Digital Controller Block Diagram In-Guard Microcomputer 14. Read/Write Timing Diagrams for Internal Bus Slow Medium Fast Power Line Frequency Function and Range Control30. A/D Control and Computation Calibration Correction Troubleshooting Modes Guard CrossingKeyboard/Display Control Guard-Crossing Communication Power Supply IEEE-488 Interface Option Out-Guard MicrocomputerGuard Crossing Bus Interface Circuitry IEEE-488 Interface Power Supply Signal ConditioningVAC Scaling Frequency Response Trimming MA AC ScalingTrue RMS AC-to-DC Conversion Static awareness Dow Chemical Maintenance External Trigger Polarity Selection Option -05 Only Minimum Specifications Recommended Model Instrument Type Performance Test Frequency Range Minimum Required Accuracy All Ranges DC Voltage Test Step Range Input Slow Medium Fast MIN MAX AC Voltage Test Option -09 Only Voltage Frequency Resistance Test New Offset must be stored for each new range selected DC Current Test Displayed ReadingSlow Medium MIN MAX Fast MIN MAX Calibration AC Current Test Option -09 OnlyStep Number Range Input Current Frequency Basic Calibration Procedure Initial Procedure 12. A/D Calibration Calibration Functions Step Displayed Prompt L O W a B L E ErrorStep Input Step Offset and Gain CalibrationDisplayed Prompt VDC VAC1 HIGH-FREQUENCY AC Calibration Storing Variable Inputs Advanced Features and Special ConsiderationsStep Displayed PROMPT1,2 Calibrating Individual Ranges Procedure Function LOW Prompt High PromptVerifying Calibration Erasing Calibration Memory Tolerance Check AC Calibration AT Other Frequencies Optimizing USE of the 5450ACalibration Tolerance Remote Calibration Optimizing Use of the 5450A Corresponding Command Front Panel FeatureComments 8842A Timing Considerations Remote Erasure Example Calibration Program Disassembly Procedure Example A/D Calibration Program A Disassembly Case Removal F6-062.wmf F6-063.wmf F6-064.wmf IEEE-488 Interface PCA Removal Option -05 Only True RMS AC PCA Removal Option -09 OnlyMain PCA Removal Maintenance Reassembly Procedure Front Panel Disassembly Reassembly Procedure Front Panel Disassembly Removing the Display Window Troubleshooting Internal Fuse ReplacementInitial Troubleshooting Procedure Troubleshooting 16. Overall State Table T6-162.wmf 17. Circuitry Tested by the Analog Self-Tests Diagnostic Self-Tests Test Number Self-Test DescriptionsTest Point Voltage Maintenance 8842A Digital Controller Troubleshooting IN-GUARD Microcomputer System In-Guard Microcomputer Address Latch U219 Calibration Memory U220 Display System Display Control U212 To-8 Strobe Decoder U213 Analog Control Signals Evaluating Static Signals Device REF. DES 21. Analog Control Logic States Evaluating Dynamic Signals DC Scaling Troubleshooting PIN or Device Supply Voltage Track/Hold Troubleshooting Ohms Current Source Troubleshooting 13. Typical Output Waveforms for Track/Hold Circuit TP103 Precision Voltage Reference Troubleshooting 66. A/D Converter Troubleshooting 14. Output of A/D Amplifier TP101 15. Waveforms at U101-24 and U101-25 Power Supply Troubleshooting For fire protection, use exact fuse replacement only 17. Waveforms at TP102 for Several Inputs on 2V DV Range Test Point Minimum Maximum Service Position IEEE-488 Interface Troubleshooting OptionDiagnostic Program Troubleshooting Switches Configuration True RMS AC Troubleshooting Option Port BIT Defective Ranges Major ProblemsDefective Stage Voltage AT TP801 Input VoltageVoltage AT TP802 More Obscure Problems Guard Crossing Troubleshooting Internal CleaningCleaning Printed Circuit Assemblies Cleaning After Soldering 21. Guard Crossing Test Waveforms 8842A List of Replaceable Parts 8842A HOW to Obtain Parts Manual Status Information Service Centers Newer Instruments REF of Option no Assembly Fluke Part noRevision Level F7-011.wmf F7-012.wmf F7-013.wmf F7-014.wmf A1 Main PCA CABLE, Display HEADER,1 ROW,.156CTR,6 PIN 8842A F7-03.wmf A2 Display PCA F7-03.wmf Supply Codes for Manufacturers Supply2.wmf Service Centers Service2.wmf 8842A Options and Accessories 8842A Description ModelNumber Option Accessories Current Probes Y8100, Y8101, 80i-400 Current Shunt 80J-10High Voltage Probes 80K-6 and 80K-40 8842A Option -05 IEEE-488 Interface 805-2 External Controls Programming Instructions MaintenanceList of Replaceable Parts List of Replaceable Parts 805-6 805-7 805-8 Option -09 True RMS AC 809-2 Option -09 True RMS AC Operating Instructions 809-5 Option -09 True RMS AC PCA 809-7 809-8 Schematic Diagrams 8842A Schematic Diagrams F9-012.wmf Main PCA, A/D Converter F9-022.wmf Main PCA, Ohms Current Source F9-032.wmf Main PCA, Digital F9-042.wmf Main PCA, Power Supply F9-052.wmf Display PCA F9-062.wmf F9-071.wmf F9-072.wmf IEEE-488 Interface PCA, Option IEEE-488 Interface PCA, Option -08