Input Voltage, Voltage AT TP801, Voltage AT TP802 | Fluke 8842a

8842A

Instruction Manual

f6-20.wmf

Figure 6-20. Option -09 Service Position

If the signal at the input to U801A (pin 5) is incorrect, U804 may be defective, or the switch codes may be wrong. If the latter problem is suspected, refer to Table 6-28 and test the control lines to U804 (U804-1, 8, 9, 16). If a logic error is found, it may be due to excessive loading or a faulty data latch (U803), or other cabling or main-board digital problems. High-frequency oscillation problems are usually caused by switches being on when they should be off, resulting in positive feedback loops being closed around portions of the scaling circuitry.

Table 6-27. AC Signal Tracing

RANGE

200mV

2V

20V

200V

700V

INPUT VOLTAGE (1

kHz)

100mV

1V

10V

10V

100V

VOLTAGE AT TP801

20mV

200mV

2V

20mV

200mV

VOLTAGE AT TP802

1V

1V 1V

100mV

100mV

If the signal at TP802 is incorrect, but U801-5 is OK, the digitally controlled filter section (U801A and U808) is probably defective.

6-68

Image 205

Fluke 8842a instruction manual Input Voltage, Voltage AT TP801, Voltage AT TP802

Contents

8842A Page Table of Contents Remote Programming 8842A 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 Rate Peak NM SignalFilter True RMS AC Voltage Option 8842A-09 Fundamental Frequency FrequencyCrest Factor For Inputs Full Scale 5½ Digits Current½ Digits Through Unknown Range Full Scale Resolution Current ½ Digits Hours 23±1C Automatic Settling Time Delay Rate Power Line FREQUECNCY1Autoranging Function Conversion Time ms 50 Hz 60 Hz 400 Hz External Trigger Timing Characteristics General Power Operating Instructions Installing the Power-Line Fuse InstallationConnecting to Line Power Rack Mounting Kits Adjusting the Handle Power-Up Features Operating FeaturesFront and Rear Panel Features Operating Features Local button causes the 8842A to display its Rear Panel Features Error Messages Display Features Meaning Error Code Error Code Overrange Indication Diagnostic Self-TestsRanging Autorange External Trigger Mode Continuous Trigger ModeManual Range Triggering External Trigger Input Option -05 Only Automatic Settling Time DelaySample Complete Output Option -05 Only Input Overload Protection Limits Making MeasurementsMeasuring Voltage and Resistance Measuring Current Offset Measurements Measuring Voltage and Resistance External Cleaning 8842A Remote Programming Measurement Data Overrange Indication Error Messages Capabilities BUS SET-UP Procedure IEEE-488 Address Selection AN Overview of Remote Operation AN Overview of Remote Operation ExampleExplanation DEVICE-DEPENDENT Command SET DEVICE-DEPENDENT Command SET Device-Dependent Command Set Cn Calibration Commands Bn Offset CommandsDn Display Commands Get Commands Fn Function Commands Meaning Command Output String 13. G1 Get SRQ Mask 12. G0 Get Instrument Configuration14. G2 Get Calibration Prompt 16. G4 Get Calibration Status 15. G3 Get User-Defined Message 17. G5 Get IAB Status 19. G7 Get Error Status18. G6 Get YW Status Put Commands Numeric Entry Command23. P0 Put Instrument Configuration 20. G8 Get Instrument Identification 25. P2 Put Calibration Value 24. P1 Put SRQ Mask Sn Reading Rate Commands Rn Range Commands26. P3 Put User-Defined Message Trigger Selection Logic Diagram Tn Trigger Mode Commands 31. X0 Clear Error Register Command Wn Terminator CommandsYn Suffix Commands 33. Z0 Self-Test Command 35. ? Single-Trigger Command Device-Clear CommandInput Syntax Input Processing Definitions DEVICE-DEPENDENT Messages ERROR-PRODUCING CharactersInterface Messages Incorrect example Syntax Rules Loading Output Data Output Data Overrange Indication Error Messages Numeric Data and Error MessagesTypes of Output Data Measurement Data Overrange Indication Error MessagesStatus Data Output Priority Serial Poll Register Service Requests Set SRQ Mask Interface Messages Universal CommandsAddress Messages Addressed Commands TALK-ONLY Mode Remote Calibration Immediate Mode CommandsTiming Considerations Example Programs Immediate-Mode Commands for Various Controllers 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 DC Voltage Measurement Circuit Loading Error Measuring Input Bias Current Error Input Bias Current Error Resistance Measurement Wire Ohms Correcting for Test Lead Resistance in 2-Wire Ohms Full Scale Voltage Test Current Testing Electrolytic Capacitors Testing DiodesApplications of the Ohms Functions Precision Current Source DC Current Measurement Reducing Thermal Voltages Burden Voltage Error Calculation True RMS Measurement AC Voltage and Current MeasurementWaveform Comparison AC Voltage and Current Measurement AC-Coupled AC Measurements Crest Factor Combined AC and DC Measurements Zero-Input VAC ErrorBandwidth 20Ω Ranges Reduction of Zero-Input Error 10. Shielding for Low Voltage Measurements Making Accurate HIGH-RESISTANCE Measurements 12. Leakage Resistance in High Resistance Measurement Theory of Operation True RMS AC Option VAC Scaling MA AC Scaling Overall Functional Description DC Scaling Detailed Circuit Description DC Scaling DC Scaling VDC and mA DC VDC Scaling MA DC Scaling VDC ProtectionAnalog Filter Track/Hold Amplifier TRACK/HOLD Circuit TRACK/HOLD Circuit Timing Diagram for One A/D Cycle Track Configuration Hold Configuration Settling ConfigurationPre-Charge Configuration Precision Voltage Reference Ohms Current Source Ohms Current Source Ohms Functions Ohms Protection Ohms Scaling 20. A/D Converter Analog-to-Digital Converter Precision DAC Timing/Data Control Display Bootstrap Supplies23. A/D Amplifier Digital Controller Keyboard 13. Digital Controller Block Diagram In-Guard Microcomputer 14. Read/Write Timing Diagrams for Internal Bus Function and Range Control Slow Medium Fast Power Line Frequency30. A/D Control and Computation Calibration Correction Guard Crossing Troubleshooting ModesKeyboard/Display Control Guard-Crossing Communication Power Supply Out-Guard Microcomputer IEEE-488 Interface OptionGuard 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 Instrument Type Minimum Specifications Recommended Model Frequency Range Minimum Required Accuracy All Ranges Performance Test DC Voltage Test Slow Medium Fast MIN MAX Step Range Input Voltage Frequency AC Voltage Test Option -09 Only New Offset must be stored for each new range selected Resistance Test Displayed Reading DC Current TestSlow Medium MIN MAX Fast MIN MAX AC Current Test Option -09 Only CalibrationStep Number Range Input Current Frequency Initial Procedure Basic Calibration Procedure Calibration Functions 12. A/D Calibration 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 Tolerance Check Erasing Calibration Memory Optimizing USE of the 5450A AC Calibration AT Other FrequenciesCalibration Tolerance Optimizing Use of the 5450A Remote Calibration Corresponding Command Front Panel FeatureComments 8842A Timing Considerations Example Calibration Program Remote Erasure Example A/D Calibration Program Disassembly Procedure Case Removal A Disassembly 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 Front Panel Disassembly Reassembly Procedure 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 IN-GUARD Microcomputer System Digital Controller Troubleshooting In-Guard Microcomputer Address Latch U219 Display System Calibration Memory U220 Display Control U212 To-8 Strobe Decoder U213 Analog Control Signals Device REF. DES Evaluating Static Signals 21. Analog Control Logic States DC Scaling Troubleshooting Evaluating Dynamic Signals Supply Voltage PIN or Device Ohms Current Source Troubleshooting Track/Hold Troubleshooting 13. Typical Output Waveforms for Track/Hold Circuit TP103 Precision Voltage Reference Troubleshooting 14. Output of A/D Amplifier TP101 66. A/D Converter Troubleshooting 15. Waveforms at U101-24 and U101-25 For fire protection, use exact fuse replacement only Power Supply Troubleshooting 17. Waveforms at TP102 for Several Inputs on 2V DV Range Minimum Maximum Test Point Service Position IEEE-488 Interface Troubleshooting OptionDiagnostic Program Switches Configuration Troubleshooting Port BIT True RMS AC Troubleshooting Option Defective Ranges Major ProblemsDefective Stage Voltage AT TP801 Input VoltageVoltage AT TP802 More Obscure Problems Guard Crossing Troubleshooting Internal CleaningCleaning Printed Circuit Assemblies 21. Guard Crossing Test Waveforms Cleaning After Soldering 8842A List of Replaceable Parts 8842A Manual Status Information HOW to Obtain Parts Newer Instruments Service Centers 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