Fluke 8842a User Manual
8842A
®
Digital Multimeter
Instruction Manual
PN 879309
Date December 1991
Rev.3 7/96
© 1999 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.
Table of Contents
Chapter Title Page
1 Introduction and Specifications ........................................................ 1-1
1-1. INTRODUCTION................................................................................ 1-2
1-2. THE 8842A DIGITAL MULTIMETER.............................................. 1-2
1-3. OPTIONS AND ACCESSORIES........................................................ 1-2
1-4. SPECIFICATIONS .............................................................................. 1-3
2 Operating Instructions....................................................................... 2-1
2-1. INTRODUCTION................................................................................ 2-2
2-2. INSTALLATION................................................................................. 2-2
2-3. Installing the Power-Line Fuse ........................................................ 2-2
2-4. Connecting to Line Power................................................................ 2-2
2-5. Adjusting the Handle........................................................................ 2-3
2-6. Rack Mounting Kits......................................................................... 2-3
2-7. OPERATING FEATURES .................................................................. 2-4
2-8. Power-Up Features........................................................................... 2-4
2-9. Front and Rear Panel Features......................................................... 2-4
2-10. Display Features............................................................................... 2-8
2-11. Error Messages................................................................................. 2-8
2-12. Overrange Indication........................................................................ 2-10
2-13. Diagnostic Self-Tests....................................................................... 2-10
2-14. Ranging............................................................................................ 2-10
2-15. AUTORANGE............................................................................. 2-10
2-16. MANUAL RANGE..................................................................... 2-11
2-17. Triggering......................................................................................... 2-11
2-18. CONTINUOUS TRIGGER MODE ............................................ 2-11
2-19. EXTERNAL TRIGGER MODE ................................................. 2-11
2-20. Reading Rates and Noise Rejection................................................. 2-11
2-21. Automatic Settling Time Delay........................................................ 2-12
2-22. External Trigger Input (Option -05 Only)........................................ 2-12
2-23. Sample Complete Output (Option -05 Only)................................... 2-12
2-24. MAKING MEASUREMENTS............................................................ 2-13
2-25. Input Overload Protection Limits..................................................... 2-13
2-26. Measuring Voltage and Resistance.................................................. 2-13
2-27. Measuring Current ........................................................................... 2-13
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2-28. Current Fuse Protection.................................................................... 2-13
2-29. Offset Measurements....................................................................... 2-14
2-30. EXTERNAL CLEANING.................................................................... 2-15
3 Remote Programming........................................................................ 3-1
3-1. INTRODUCTION................................................................................ 3-3
3-2. CAPABILITIES................................................................................... 3-3
3-3. BUS SET-UP PROCEDURE............................................................... 3-3
3-4. AN OVERVIEW OF REMOTE OPERATION................................... 3-4
3-5. A NOTE ABOUT EXAMPLES........................................................... 3-6
3-6. DEVICE-DEPENDENT COMMAND SET ........................................ 3-6
3-7. Bn (Offset Commands).................................................................... 3-9
3-8. Cn (Calibration Commands)............................................................ 3-9
3-9. Dn (Display Commands).................................................................. 3-9
3-10. Fn (Function Commands) ................................................................ 3-10
3-11. Get Commands................................................................................. 3-10
3-12. G0 (Get Instrument Configuration).................................................. 3-12
3-13. G1 (Get SRQ Mask)......................................................................... 3-12
3-14. G2 (Get Calibration Prompt)............................................................ 3-12
3-15. G3 (Get User-Defined Message)...................................................... 3-13
3-16. G4 (Get Calibration Status).............................................................. 3-13
3-17. G5 (Get IAB Status)......................................................................... 3-14
3-18. G6 (Get YW Status)......................................................................... 3-14
3-19. G7 (Get Error Status)....................................................................... 3-14
3-20. G8 (Get Instrument Identification)................................................... 3-14
3-21. N (Numeric Entry Command).......................................................... 3-15
3-22. Put Commands................................................................................. 3-15
3-23. P0 (Put Instrument Configuration)................................................... 3-15
3-24. P1 (Put SRQ Mask).......................................................................... 3-16
3-25. P2 (Put Calibration Value).............................................................. 3-16
3-26. P3 (Put User-Defined Message)...................................................... 3-17
3-27. Rn (Range Commands).................................................................... 3-17
3-28. Sn (Reading Rate Commands)......................................................... 3-17
3-29. Tn (Trigger Mode Commands)........................................................ 3-17
3-30. Wn (Terminator Commands)........................................................... 3-19
3-31. X0 (Clear Error Register Command)............................................... 3-19
3-32. Yn (Suffix Commands).................................................................... 3-19
3-33. Z0 (Self-Test Command)................................................................. 3-19
3-34. (Device-Clear Command)................................................................ 3-20
3-35. ? (Single-Trigger Command)........................................................... 3-20
3-36. INPUT SYNTAX................................................................................. 3-20
3-37. Definitions........................................................................................ 3-20
3-38. Input Processing............................................................................... 3-21
3-39. Syntax Rules .................................................................................... 3-23
3-40. OUTPUT DATA.................................................................................. 3-24
3-41. Loading Output Data........................................................................ 3-24
3-42. Types of Output Data....................................................................... 3-25
3-43. Numeric Data and Error Messages................................................... 3-25
3-44. MEASUREMENT DATA........................................................... 3-25
3-45. OVERRANGE INDICATION .................................................... 3-26
3-46. ERROR MESSAGES.................................................................. 3-26
3-47. Status Data ....................................................................................... 3-26
3-48. Output Priority ................................................................................. 3-26
3-49. SERVICE REQUESTS........................................................................ 3-27
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Contents
3-50. The Serial Poll Register ................................................................... 3-27
3-51. The SRQ Mask................................................................................. 3-28
3-52. INTERFACE MESSAGES.................................................................. 3-29
3-53. Address Messages............................................................................ 3-29
3-54. Universal Commands....................................................................... 3-29
3-55. Addressed Commands...................................................................... 3-30
3-56. TALK-ONLY MODE.......................................................................... 3-30
3-57. REMOTE CALIBRATION.................................................................. 3-31
3-58. TIMING CONSIDERATIONS............................................................ 3-31
3-59. IMMEDIATE MODE COMMANDS.................................................. 3-31
3-60. EXAMPLE PROGRAMS.................................................................... 3-32
4 Measurement Tutorial........................................................................ 4-1
4-1. INTRODUCTION................................................................................ 4-2
4-2. DC VOLTAGE MEASUREMENT ..................................................... 4-2
4-3. Circuit Loading Error....................................................................... 4-2
4-4. Input Bias Current Error................................................................... 4-3
4-5. RESISTANCE MEASUREMENT ...................................................... 4-4
4-6. 2-Wire Ohms.................................................................................... 4-4
4-7. Correcting for Test Lead Resistance in 2-Wire Ohms..................... 4-5
4-8. 4-Wire Ohms.................................................................................... 4-5
4-9. Applications of the Ohms Functions................................................ 4-7
4-10. TESTING DIODES..................................................................... 4-7
4-11. TESTING ELECTROLYTIC CAPACITORS............................ 4-7
4-12. A PRECISION CURRENT SOURCE......................................... 4-8
4-13. DC CURRENT MEASUREMENT ..................................................... 4-8
4-14. REDUCING THERMAL VOLTAGES............................................... 4-9
4-15. AC VOLTAGE AND CURRENT MEASUREMENT........................ 4-10
4-16. True RMS Measurement.................................................................. 4-10
4-17. Waveform Comparison.................................................................... 4-10
4-18. Crest Factor...................................................................................... 4-12
4-19. AC-Coupled AC Measurements ...................................................... 4-12
4-20. Combined AC and DC Measurements............................................. 4-13
4-21. Bandwidth........................................................................................ 4-13
4-22. Zero-Input VAC Error...................................................................... 4-13
4-23. MAKING ACCURATE MEASUREMENTS ON THE 20 mV
AND 20Ω RANGES ............................................................................ 4-14
4-24. MAKING ACCURATE HIGH-RESISTANCE MEASUREMENTS . 4-15
(continued)
5 Theory of Operation........................................................................... 5-1
5-1. INTRODUCTION................................................................................ 5-3
5-2. OVERALL FUNCTIONAL DESCRIPTION...................................... 5-3
5-3. DETAILED CIRCUIT DESCRIPTION .............................................. 5-4
5-4. DC SCALING...................................................................................... 5-4
5-5. VDC Scaling.................................................................................... 5-6
5-6. VDC Protection................................................................................ 5-7
5-7. mA DC Scaling................................................................................ 5-7
5-8. Analog Filter.................................................................................... 5-7
5-9. TRACK/HOLD CIRCUIT ................................................................... 5-8
5-10. Track Configuration......................................................................... 5-10
5-11. Settling Configuration...................................................................... 5-11
5-12. Hold Configuration.......................................................................... 5-11
5-13. Pre-Charge Configuration................................................................ 5-11
5-14. PRECISION VOLTAGE REFERENCE.............................................. 5-11
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5-15. OHMS CURRENT SOURCE.............................................................. 5-12
5-16. OHMS PROTECTION......................................................................... 5-13
5-17. OHMS FUNCTIONS........................................................................... 5-13
5-18. 2-Wire Ohms.................................................................................... 5-13
5-19. 4-Wire Ohms.................................................................................... 5-15
5-20. A/D CONVERTER.............................................................................. 5-15
5-21. Timing/Data Control........................................................................ 5-17
5-22. Precision DAC ................................................................................. 5-18
5-23. A/D Amplifier.................................................................................. 5-18
5-24. Bootstrap Supplies ........................................................................... 5-18
5-25. DISPLAY............................................................................................. 5-19
5-26. KEYBOARD........................................................................................ 5-19
5-27. DIGITAL CONTROLLER................................................................... 5-19
5-28. In-Guard Microcomputer................................................................. 5-21
5-29. Function and Range Control............................................................ 5-23
5-30. A/D Control and Computation......................................................... 5-23
5-31. Calibration Correction...................................................................... 5-23
5-32. Keyboard/Display Control............................................................... 5-24
5-33. Troubleshooting Modes ................................................................... 5-24
5-34. Guard-Crossing Communication..................................................... 5-24
5-35. GUARD CROSSING........................................................................... 5-24
5-36. POWER SUPPLY................................................................................ 5-25
5-37. IEEE-488 INTERFACE (OPTION -05)............................................... 5-26
5-38. Out-Guard Microcomputer............................................................... 5-26
5-39. Guard Crossing................................................................................. 5-26
5-40. Bus Interface Circuitry..................................................................... 5-26
5-41. Signal Conditioning ......................................................................... 5-27
5-42. IEEE-488 Interface Power Supply................................................... 5-27
5-43. TRUE RMS AC (OPTION -09)........................................................... 5-27
5-44. VAC Scaling.................................................................................... 5-27
5-45. mA AC Scaling................................................................................ 5-28
5-46. Frequency Response Trimming ....................................................... 5-28
5-47. True RMS AC-to-DC Conversion ................................................... 5-28
6 Maintenance....................................................................................... 6-1
6-1. INTRODUCTION................................................................................ 6-3
6-2. PERFORMANCE TEST...................................................................... 6-4
6-3. Diagnostic Self-Tests....................................................................... 6-4
6-4. DC Voltage Test............................................................................... 6-5
6-5. AC Voltage Test (Option -09 Only)................................................. 6-7
6-6. Resistance Test................................................................................. 6-8
6-7. DC Current Test............................................................................... 6-9
6-8. AC Current Test (Option -09 Only)................................................. 6-10
6-9. CALIBRATION................................................................................... 6-10
6-10. Basic Calibration Procedure............................................................. 6-11
6-11. INITIAL PROCEDURE.............................................................. 6-11
6-12. A/D CALIBRATION .................................................................. 6-12
6-13. OFFSET AND GAIN CALIBRATION ...................................... 6-14
6-14. HIGH-FREQUENCY AC CALIBRATION................................ 6-15
6-15. Advanced Features and Special Considerations............................... 6-16
6-16. STORING VARIABLE INPUTS................................................ 6-16
6-17. CALIBRATING INDIVIDUAL RANGES................................. 6-17
6-18. VERIFYING CALIBRATION.................................................... 6-17
6-19. ERASING CALIBRATION MEMORY..................................... 6-18
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6-20. TOLERANCE CHECK............................................................... 6-18
6-21. AC CALIBRATION AT OTHER FREQUENCIES ................... 6-19
6-22. OPTIMIZING USE OF THE 5450A........................................... 6-19
6-23. Remote Calibration.......................................................................... 6-20
6-24. TIMING CONSIDERATIONS ................................................... 6-23
6-25. REMOTE ERASURE.................................................................. 6-24
6-26. EXAMPLE CALIBRATION PROGRAM.................................. 6-24
6-27. DISASSEMBLY PROCEDURE.......................................................... 6-25
6-28. Case Removal................................................................................... 6-26
6-29. True RMS AC PCA Removal (Option -09 Only)............................ 6-30
6-30. IEEE-488 Interface PCA Removal (Option -05 Only) .................... 6-30
6-31. Main PCA Removal......................................................................... 6-30
6-32. Front Panel Disassembly.................................................................. 6-32
6-33. REASSEMBLY PROCEDURE........................................................... 6-32
6-34. INTERNAL FUSE REPLACEMENT ................................................. 6-36
6-35. EXTERNAL TRIGGER POLARITY SELECTION (Option -05 Only)6-36
6-36. TROUBLESHOOTING....................................................................... 6-36
6-37. Initial Troubleshooting Procedur e.................................................... 6-36
6-38. Diagnostic Self-Tests....................................................................... 6-41
6-39. Self-Test Descriptions...................................................................... 6-42
6-40. Digital Controller Troubleshooting.................................................. 6-45
6-41. IN-GUARD MICROCOMPUTER SYSTEM............................. 6-45
6-48. DISPLAY SYSTEM.................................................................... 6-49
6-59. ANALOG CONTROL SIGNALS............................................... 6-51
6-62. DC Scaling Troubleshooting............................................................ 6-54
6-63. Track/Hold Troubleshooting............................................................ 6-56
6-64. Ohms Current Source Troubleshooting............................................ 6-56
6-65. Precision Voltage Reference Troubleshoo ting................................. 6-58
6-66. A/D Converter Troubleshooting....................................................... 6-59
6-67. Power Supply Troubleshooting........................................................ 6-61
6-68. IEEE-488 Interface Troubleshooting (Option -05).......................... 6-64
6-69. SERVICE POSITION.................................................................. 6-64
6-70. DIAGNOSTIC PROGRAM ........................................................ 6-64
6-71. True RMS AC Troubleshooting (Option -09).................................. 6-66
6-72. SERVICE POSITION.................................................................. 6-66
6-73. MAJOR PROBLEMS.................................................................. 6-67
6-74. MORE OBSCURE PROBLEMS ................................................ 6-69
6-75. Guard Crossing Troubleshooting..................................................... 6-70
6-76. INTERNAL CLEANING..................................................................... 6-70
6-77. Cleaning Printed Circuit Assemblies............................................... 6-70
6-78. Cleaning After Soldering................................................................. 6-71
(continued)
7 List of Replaceable Parts................................................................... 7-1
7-1. INTRODUCTION................................................................................ 7-3
7-2. HOW TO OBTAIN PARTS................................................................. 7-3
7-3. MANUAL STATUS INFORMATION................................................ 7-3
7-4. NEWER INSTRUMENTS................................................................... 7-4
7-5. SERVICE CENTERS........................................................................... 7-4
8 Options and Accessories.................................................................. 8-1
8-1. INTRODUCTION................................................................................ 8-3
8-2. ACCESSORIES ................................................................................... 8-4
8-3. Rack-Mount Kits (Y8834, Y8835 and Y8836)................................ 8-4
8-4. Shielded IEEE-488 Interface Cables (Y8021, Y8022, and Y8023). 8-4
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8-5. Replacement Test Leads (TL70A)................................................... 8-4
8-6. Deluxe Test Lead Kits (Y8134)....................................................... 8-4
8-7. Slim-Flex Test Leads (Y8140)......................................................... 8-4
8-8. Temperature Probes (80T-150U, and 80TK.).................................. 8-4
8-9. RF Probes (85RF and 83RF)............................................................ 8-4
8-10. Current Shunt (80J-10)..................................................................... 8-5
8-11. Current Probes (Y8100, Y8101, 80i-400 and 80i-600).................... 8-5
8-12. High Voltage Probes (80K-6 and 80K-40) ...................................... 8-5
805 Option –05 IEEE-488 Interface........................................................... 805-1
805-1. INTRODUCTION................................................................................ 805-3
805-2. CAPABILITIES ................................................................................... 805-3
805-3. EXTERNAL CONTROLS................................................................... 805-3
805-4. INSTALLATION................................................................................. 805-3
805-5. PROGRAMMING INSTRUCTIONS.................................................. 805-4
805-6. MAINTENANCE................................................................................. 805-4
805-7. LIST OF REPLACEABLE PARTS..................................................... 805-4
809 Option –09 True RMS AC................................................................... 809-1
809-1. INTRODUCTION................................................................................ 809-3
809-2. INSTALLATION................................................................................. 809-3
809-3. OPERATING INSTRUCTIONS .......................................................... 809-4
809-4. MAINTENANCE................................................................................. 809-4
809-5. LIST OF REPLACEABLE PARTS..................................................... 809-4
9 Schematic Diagrams.......................................................................... 9-1
vi
List of Tables
Table Title Page
2-1. Error Codes............................................................................................................ 2-9
2-2. Input Overload Limits............................................................................................ 2-13
3-1. Status Data............................................................................................................. 3-11
3-2. Numeric Output Data Format................................................................................ 3-25
3-8. Serial Poll Register ................................................................................................ 3-28
3-3. Immediate-Mode Commands for Various Controllers.......................................... 3-32
3-4. ASCII/IEEE Std 488-1978 Bus Codes .................................................................. 3-49
4-1. Ohms Test Current................................................................................................. 4-6
5-1. Sample Rates and Reading Rates........................................................................... 5-23
6-1. Recommended Test Equipment............................................................................. 6-3
6-2. DC Voltage Test .................................................................................................... 6-6
6-3. Low- and Mid-Frequency AC Voltage Test.......................................................... 6-7
6-4. High-Frequency AC Voltage Test......................................................................... 6-8
6-5. Resistance Test...................................................................................................... 6-9
6-6. DC Current Test..................................................................................................... 6-9
6-7. AC Current Test..................................................................................................... 6-10
6-8. A/D Calibration Steps............................................................................................ 6-13
6-9. A/D Calibration Verification Test......................................................................... 6-13
6-10. Offset and Gain Calibration Steps ......................................................................... 6-14
6-11. High-Frequency AC Calibration Steps.................................................................. 6-16
6-12. Prompts When Calibrating Individual Ranges....................................................... 6-17
6-13. Tolerance Limits.................................................................................................... 6-19
6-14. Commands Used During remote Calibration......................................................... 6-21
6-15. Error Numbers Which Are Displayed When Commands Are Not Valid.............. 6-23
6-16. Overall State Table................................................................................................ 6-38
6-17. Circuitry Tested by the Analog Self-Tests............................................................. 6-40
6-18. Self-Test Voltages.................................................................................................. 6-42
6-19. Keyboard Wiring ................................................................................................... 6-51
6-20. Analog Control Devices......................................................................................... 6-52
6-21. Analog Control Logic States.................................................................................. 6-53
6-22. DC Scaling and Track/Hold Supply Voltages ....................................................... 6-55
6-23. Power Supply Voltages.......................................................................................... 6-63
6-24. Diagnostic Modes.................................................................................................. 6-65
6-25. I/O Port Configurations ......................................................................................... 6-66
6-26. Isolating a Defective AC Stage.............................................................................. 6-67
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6-27. AC Signal Tracing................................................................................................. 6-68
6-28. Truth Table for U804 and K2................................................................................ 6-69
7-1. 8842A Digital Multimeter...................................................................................... 7-5
7-2. A1 Main PCA........................................................................................................ 7-10
7-3. A2 Display PCA.................................................................................................... 7-14
8-1. Accessories ............................................................................................................ 8-3
8-2. Options................................................................................................................... 8-3
805-1.Option -05A IEEE-488 Interface PCA.................................................................. 805-7
809-1.Option -09 True RMS AC PCA............................................................................. 809-6
viii
List of Figures
Figure Title Page
1-1. External Dimensions.............................................................................................. 1-11
2-1. Line Voltage Selection Settings............................................................................. 2-2
2-2. Adjusting the Handle............................................................................................. 2-3
2-3. Rack-Mount Kits.................................................................................................... 2-3
2-4. Installing the Single Rack Mount Kit .................................................................... 2-4
2-5. Front Panel Features .............................................................................................. 2-5
2-6. Rear Panel Features ............................................................................................... 2-7
2-7. Typical Error Messages......................................................................................... 2-8
2-8. Overrange Indication ............................................................................................. 2-12
2-9. Measuring Voltage and Resistance........................................................................ 2-15
2-10. Measuring Current................................................................................................. 2-15
3-1. IEEE-488 Address Selection.................................................................................. 3-4
3-2. Remote Operation Block Diagram......................................................................... 3-5
3-3. Typical Command String....................................................................................... 3-6
3-4. Commands Which Correspond to the Front Panel................................................. 3-7
3-5. Device-Dependent Command Set.......................................................................... 3-8
3-6. Output Data Format............................................................................................... 3-10
3-6. Trigger Selection Logic Diagram.......................................................................... 3-18
3-7. Interpretation of Messages..................................................................................... 3-22
3-9. Example Program................................................................................................... 3-33
3-10. Example Program: Taking Readings with Local Control...................................... 3-34
3-11. Example Program: Using the Serial Poll Register................................................. 3-35
3-12. Example Program: Record Errors During Selftest................................................. 3-36
3-13. Example Programs: Using the IBM PC................................................................. 3-37
4-1. Circuit Loading Error Calculation......................................................................... 4-2
4-2. Measuring Input Bias Current Error...................................................................... 4-3
4-3. Wire Ohms Measurement...................................................................................... 4-4
4-4. Wire Ohms Measurement...................................................................................... 4-6
4-5. Burden Voltage Error Calculation......................................................................... 4-9
4-6. Waveform Comparison Chart................................................................................ 4-11
4-7. Typical Crest Factors for Various Waveforms...................................................... 4-12
4-8. Combined AC and DC Measurement.................................................................... 4-13
4-9. Reduction of Zero-Input Error............................................................................... 4-14
4-10. Shielding for Low Voltage Measurements............................................................ 4-15
4-11. Shielding for Low Resistance Measurements........................................................ 4-15
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4-12. Leakage Resistance in High Resistance Measurement.......................................... 4-16
5-1. Overall Functional Block Diagram........................................................................ 5-5
5-2. DC Scaling (VDC and mA DC)............................................................................. 5-6
5-3. Track/Hold Amplifier............................................................................................ 5-8
5-4. Track/Hold Circuit Configurations........................................................................ 5-9
5-5. Timing Diagram for One A/D Cycle..................................................................... 5-10
5-6. Precision Voltag e Reference.................................................................................. 5-11
5-7. Ohms Current Source............................................................................................. 5-12
5-8. Ohms Scaling......................................................................................................... 5-14
5-9. Analog-to-Digital Converter.................................................................................. 5-16
5-10. First Remainder-Store Period ................................................................................ 5-17
5-11. Autozero Period..................................................................................................... 5-18
5-12. Vacuum Fluorescent Display................................................................................. 5-19
5-13. Digital Controller Block Diagram.......................................................................... 5-20
5-14. Read/Write Timing Diagrams for Internal Bus...................................................... 5-22
5-15. Guard Crossing Circuit.......................................................................................... 5-24
5-16. IEEE-488 Interface Block Diagram....................................................................... 5-26
5-17. True RMS AC Option Block Diagram.................................................................. 5-27
5-18. True RMS AC-to-DC Converter............................................................................ 5-28
6-1. DC Calibration Connections.................................................................................. 6-6
6-2. First A/D Calibration Prompt................................................................................. 6-11
6-3. Calibration Functions............................................................................................. 6-12
6-4. Optimizing Use of the 5450A................................................................................ 6-20
6-5. Example A/D Calibration Program........................................................................ 6-25
6-6. 8842A Disassembly............................................................................................... 6-26
6-7. Front Panel Disassembly........................................................................................ 6-34
6-8. Removing the Display Window............................................................................. 6-35
6-9. U202 Pin Diagram................................................................................................. 6-46
6-10. Waveforms for In-Guard Troubleshooting Mode.................................................. 6-47
6-11. Waveforms for Display Logic ............................................................................... 6-49
6-12. Typical Dynamic Control Signals.......................................................................... 6-54
6-13. Typical Output Waveforms for Track/Hold Circuit (TP103)................................ 6-57
6-14. Output of A/D Amplifier (TP101)......................................................................... 6-59
6-15. Waveforms at U101-24 and U101-25.................................................................... 6-60
6-16. Typical Bus Data Line Waveform......................................................................... 6-60
6-17. Waveforms at TP102 for Several Inputs on 2V DV Range................................... 6-62
6-18. Calculating the A/D Reading From TP102 Waveform.......................................... 6-63
6-19. Option -05 Service Position................................................................................... 6-65
6-20. Option -09 Service Position................................................................................... 6-68
6-21. Guard Crossing Test Waveforms........................................................................... 6-71
7-1. 8842A Digital Multimeter...................................................................................... 7-6
7-2. A1 Main PCA........................................................................................................ 7-13
7-3. A2 Display PCA.................................................................................................... 7-15
7-4. Service Centers...................................................................................................... 7-18
7-4. Service Centers (cont)............................................................................................ 7-19
805-1.Installing Option -05.............................................................................................. 805-5
805-2.IEEE-488 Interface PCA........................................................................................ 805-8
809-1.Installing Option -09.............................................................................................. 809-5
809-2.True RMS AC PCA ............................................................................................... 809-7
9-1. Main PCA, DC Scaling and F/R Switch................................................................ 9-3
9-2. Main PCA, A/D Converter .................................................................................... 9-5
9-3. Main PCA, Ohms Current Source ......................................................................... 9-7
9-4. Main PCA, Digital................................................................................................. 9-9
9-5. Main PCA, Power Supply...................................................................................... 9-11
9-6. Display PCA.......................................................................................................... 9-13
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9-7. IEEE-488 Interface PCA, Option -05.................................................................... 9-15
9-8. True RMS AC PCA, Option -09............................................................................ 9-17
(continued)
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Chapter 1
Introduction and Specifications
Title Page
1-1. INTRODUCTION................................................................................1-2
1-2. THE 8842A DIGITAL MULTIMETER..............................................1-2
1-3. OPTIONS AND ACCESSORIES........................................................1-2
1-4. SPECIFICATIONS ..............................................................................1-3
1-1
8842A
Instruction Manual
1-1. INTRODUCTION
1-2. THE 8842A DIGITAL MULTIMETER
This manual provides complete operating instructions and service information for the
8842A. If you want to get started using your 8842A right away, proceed to the operating
instructions in Section 2. If you intend to use the 8842A with the IEEE-488 Interface
(Option -05), read Sections 2 and 3. This meter has been designed and tested according to
IEC publication 348, Safety Requirements for Electronic Measuring Apparatus. This
manual contains information and warnings which must be followed to ensure safe
operation and retain the meter in safe condition.
The Fluke 8842A Digital Multimeter is a high-performance 5-1/2 digit instrument
designed for general-purpose bench or systems applications. The 8842A is the top-of-theline DMM in the 8840A family. Using proprietary thin film resistor networks, a stable
reference amplifier and stable active components, the 8842A offers superior
measurement performance and stability. It also offers additional 20 mV, 20 ohm, and
200 mA dc ranges. Features of the 8842A include:
• Highly legible vacuum fluorescent display
• Intuitively easy front panel operation
• Basic dc accuracy of 0.003% for 1 year
• 2-wire and 4-wire resistance measurement
• DC current measurement
• Up to 100 readings per second
• Closed-case calibration (no internal adjustments)
• Built-in self-tests
1-3. OPTIONS AND ACCESSORIES
A number of options and accessories are available for the 8842A which can be easily
installed at any time. The options include:
• IEEE-488 Interface (Option -05), featuring:
• Full programmability
• Simple and predictable command set
• Fast measurement throughput
• External Trigger input connector
• Sample Complete output connector
1-2
• Automated calibration
• Low cost
• True RMS AC (Option -09), featuring:
• AC voltage measurement
• AC current measurement
Accessories include a variety of rack mounting kits, probes, test leads, and cables. Full
information about options and accessories can be found in Section 8.
1-4. SPECIFICATIONS
Specifications for the 8842A are given in Table 1-1. External dimensions are shown in
Figure 1-1.
DC VOLTAGE
Input Characteristics
Table 1-1. Specifications
Introduction and Specifications
SPECIFICATIONS
1
FULL SCALE 5ñ
RANGE
20 mV 19.9999 mV 0.1µV1 µV ≥10,000 MΩ
200 mV 199.999 mV 1µV 10 µV ≥10,000 MΩ
2V 1.99999V 10 µV 100 µV ≥10,000 MΩ
20V 19.9999V 100 µV1 mV≥10,000 MΩ
200V 199.999V 1 mV 10 mV 10 MΩ
1000V 1000.00V 10 mV 100 mV 10 MΩ
*4ñ digits at the fastest reading rate.
Accuracy
NORMAL (S) READING RATE ............. ±(% of Reading + Number of Counts)
RANGE 24 HOURî 23±1°C 90 DAY 23±5°C 1 YEAR 23±5°C 2 YEAR 23±5°C
2
20 mV
200 mV
2
2V 0.0015 + 2 0.0025 + 2 0.0030 + 2 0.0050 + 3
20V 0.0015 + 2 0.0030 + 2 0.0035 + 2 0.0060 + 3
DIGITS
0.0050 + 20
0.0030 + 2 0.0045 + 3 0.0070 + 3 0.0100 + 4
3
5ñ DIGITS 4ñ DIGITS*
0.0070 + 30
RESOLUTION
3
0.0100 + 30
INPUT
RESISTANCE
3
0.0120 + 40
3
200V 0.0015 + 2 0.0030 + 2 0.0035 + 2 0.0060 + 3
1000V 0.0020 + 2 0.0035 + 2 0.0045 + 2 0.0070 + 3
1. Relative to calibration standards.
2. Within one hour of dc zero, using offset control.
3. When offset control is not used the number of counts are 50, 70, 90 and 90 for 24 hours, 90 day, 1
year, and 2 year respectively.
4. When offset control is not used the number of counts are 5, 7, 9 for 24 hours, 90 day, 1 year, and 2
year respectively.
MEDIUM AND FAST RATES: ................In medium rate, add 3 counts (20 counts on 20 mV Range) to
number of counts. In fast rate, use 2 (4½ digit mode) counts
(30 counts on 20 mV range) for the number of counts
1-3
8842A
Instruction Manual
Operating Characteristics
TEMPERATURE COEFFICIENT ...........<(0.0006% of reading + 0.3 Count) per °C from 0°C to 18°C
and 28°C to 50°C.
MAXIMUM INPUT...................................1000V dc or peak ac on any range.
NOISE REJECTION................................Automatically optimized at power-up for 50, 60, or 400 Hz.
RATE READINGS/
SECONDî
S
M
2.5 Analog & Digital >98 dB 20V or 2x FS >140 dB
20 Digital >45 dB 1x FS >100 dB
FILTER NMRRï PEAK NM
SIGNAL
F 100 None _ 1x FS >60 dB
1. Reading rate with internal trigger and 60 Hz power line frequency. See “reading rates” for more detail.
2. Normal Mode Rejection Ratio, at 50 or 60 Hz ±0.1%. The NMRR for 400 Hz ±0.1% is 85 dB in S rate
and 35 dB in M rate.
3. Common Mode Rejection Ratio at 50 or 60 Hz ±0.1%, with 1 kΩ in series with either lead. The CMRR
is >140 dB at dc for all reading rates.
4. 20 volts or 2 times full scale whichever is greater, not to exceed 1000V.
5. Reading rate-1/3 rdg / sec. in the 20 mV, 20Ω, 200 mA dc ranges
6. Reading rate-1.25 rdg / sec. in the 20 mV, 20Ω, 200 mA dc ranges
TRUE RMS AC VOLTAGE (OPTION 8842A-09)
Input Characteristics
RESOLUTIONRANGE FULL SCALE 5ñ
DIGITS
5ñ DIGITS 4ñ DIGITS*
IMPENDANCE
CMRRð
INPUT
1-4
200 mV 199.999 mV 1 µV 10 µV1 MΩ
2V 1.99999V 10 µV 100 µV Shunted
20V 19.9999V 100 µV1 mV By
200V 199.999V 1 mV 10 mV <100 pF
700V 700.00V 10 mV 100 mV
*4ñ digits at the fastest reading rate
Introduction and Specifications
Accuracy
NORMAL (s) READING RATE .............. ±(% of Reading + Number of Counts).
For sinewave inputs ≥10,000 counts1.
FREQUENCY 24 HOURS2 23±1°C 90 DAY 23±5°C 1 YEAR 23±5°C 2 YEARS ±5°C
20-45 1.2 + 100 1.2 + 100 1.2 + 100 1.2 + 100
45-200 0.3 + 100 0.35 + 100 0.4 + 100 0.5 + 100
200-20k
(200 mV range) 0.06 + 100 0.08 + 100 0.10 + 100 0.20 + 100
(2V-200V range) 0.05 + 80 0.07 + 80 0.08 + 80 0.15 + 80
(700V range) 0.06 + 100 0.08 + 100 0.10 + 100 0.20 + 100
20k-50k 0.15 + 120 0.19 + 150 0.21 + 200 0.25 + 250
50k-100k 0.4 + 300 0.5 + 300 0.5 + 400 0.5 + 500
1. For sinewave inputs between 1,000 and 10,000 counts, add to number of counts 100 counts for
frequencies 20 Hz to 20 kHz, 200 counts for 20 kHz, and 500 counts for 50 kHz to 100 kHz.
SPECIFICATIONS
1
2. Relative to calibration standards.
MEDIUM AND FAST READING RATES........In medium rate, add 50 counts to number of counts. In the
fast rate the specifications apply for sinewave inputs
≥1000 (4½ digit PRGH FRXQWV and >100 Hz.
NONSINUSOIDAL INPUTS...........................For nonsinusoidal inputs ≥10,000 counts with frequency
components ≥100 kHz, add the following % of reading to
the accuracy specifications.
FUNDAMENTAL
FREQUENCY
45 Hz to 20 kHz 20 Hz 0.05 0.15 0.3
20 Hz to 45 Hz and 20
kHz to 50 kHz
Operating Characteristics
MAXIMUM INPUT...................................700V rms, 1000V peak or 2 x 107 Volts-Hertz product
TEMPERATURE COEFFICIENT............±(% of reading + Number of Counts) per °C, to 18°C and 28°C
FOR INPUTS
1.0 TO 1.5 1.5 TO 2.0 2.0 TO 3.0
0.2 0.7 1.5
(whichever is less) for any range.
to 50°C.
20-20k 20k-50k 50k-100k
CREST FACTOR
FREQUENCY IN HERTZ
≥10,000 counts 0.019 + 9 0.021 + 9 0.027 + 10
≥1,000 counts 0.019 + 12 0.021 + 15 0.027 + 21
COMMON MODE REJECTION..............>60 dB at 50 or 60 Hz with 1 kΩ in either lead.
1-5
8842A
Instruction Manual
CURRENT
Input Characteristics
DC Accuracy
RESOLUTIONRANGE FULL SCALE 5½
DIGITS
5½ DIGITS 4½ DIGITS
200 mA
2
199.999 mA 1 µA 10 µA
2000 mA 1999.99 mA 10 µA 100 µA
1. 4½ digits at the fastest reading rate.
2. The 200mA range is available for dc current only.
NORMAL (S) READING RATE...............±(% of reading + number of counts).
RANGE 90 DAYS 23±5°C 1 YEAR 23±5°C 2 YEARS 23±5°C
200 mA 0.04 + 40 0.05 + 40 0.08 + 40
2000 mA
1
≤1A 0.04 + 4 0.05 + 4 0.08+4
>1A 0.1 + 4 0.1 + 4 0.15+4
MEDIUM AND FAST READING RATES In medium reading rate, add 2 counts (20 counts on 200 mA
range) to number of counts. In fast reading rate, use 2 (4½
digit mode) counts (20 counts on 200 mA range) for number
of counts.
AC Accuracy (Option –09)
NORMAL (S) READING RATE...............±(% of Reading + Number of Counts).
23±5°C, for sinewave inputs ≥10,000 counts
1
.
FREQUENCY IN HERTZ
20-45 45-100 100-5K*
ONE YEAR 2.0 + 200 0.5 + 200 0.4 + 200
TWO YEAR 3.0 + 300 0.7 + 300 0.6 + 300
*Typically 20 kHz
1. For sinewave inputs between 1,000 and 10,000 counts, add to number of counts 100 counts for
frequencies 20 Hz to 5 kHz (typically 20 kHz).
1-6
Introduction and Specifications
SPECIFICATIONS
MEDIUM AND FAST READING RATES........In medium rate, add 50 counts to number of counts. In fast
reading rate, for sinewave inputs ≥1000 (4½ digit mode)
counts and frequencies >100 Hz, the accuracy is ±(0.4%
of reading +30 (4½ digit mode) counts).
NONSINUSOIDAL INPUTS ...........................For nonsinusoidal inputs ≥10,000 counts with frequency
components ≤100 kHz, add the following % of reading to
the accuracy specifications
1
FUNDAMENTAL
FREQUENCY
45 HZ to 5 kHz
20 Hz to 45 Hz
Operating Characteristics
TEMPERATURE COEFFICIENT............Less than 0.1 x accuracy specification per °C to 18°C and
MAXIMUM INPUT...................................2A dc or rms ac. Protected with 2A, 250V fuse accessible at
BURDEN VOLTAGE...............................1V dc or rms ac typical at full scale.
RESISTANCE
Input Characteristics
RANGE FULL SCALE
5½ DIGITS
2
20Ω
200Ω 199.999Ω 1 mΩ 10 mΩ 1 mA
2 kΩ 1.99999 kΩ 10 mΩ 100 mΩ 1 mA
19.999Ω 0.1 mΩ 1 mΩ 1 mA
1.0 TO 1.5 1.5 TO 2.0 2.0 TO 3.0
0.05
0.2
28°C to 50°C.
front panel, and interval 3A, 600V fuse.
5½ DIGITS 4½ DIGITS
CREST FACTOR
0.15
0.7
RESOLUTION
CURRENT
1
THROUGH UNKNOWN
0.3
1.5
20 kΩ 19.9999 kΩ 100 mΩ 1Ω 100 µA
200 kΩ 199.999 kΩ 1Ω 10Ω 10 µA
2000 kΩ 1999.99 kΩ 10Ω 100Ω 5 µA
20 MΩ 19.9999 MΩ 100Ω 1 kΩ 0.5 µA
1. 4½ digits at the fastest reading rate.
2. Four-wire ohms only.
1-7
8842A
Instruction Manual
Accuracy
NORMAL (S) READING RATE...............±(% of Reading + Number of Counts)1.
RANGE 24 HOURS 23±1°C 90 DAY 23±5°C 1 YEAR 23±5°C 2 YEARS 23±1°C
20Ω
200Ω
3
3
0.007 + 30
0.0040 + 3
4
5
0.009 + 40
0.007 + 4
4
5
0.012 + 40
0.010 + 4
4
5
0.015 + 40
0.012 + 4
2 kΩ 0.0025 + 2 0.005 + 3 0.008 + 3 0.010 + 3
20 kΩ 0.0025 + 2 0.005 + 3 0.008 + 3 0.010 + 3
200 kΩ 0.0025 + 2 0.006 + 3 0.010 + 3 0.012 + 3
2000 kΩ 0.023 + 3 0.025 + 3 0.027 + 3 0.030 + 3
20 MΩ 0.023 + 3 0.040 + 4 0.042 + 4 0.050 + 4
1. Within one hour of ohms zero, using offset control.
2. Relative to calibration standards.
3. Applies to 4-wire ohms only.
4. When offset control is not used the number of counts are 50, 70, 90 and 90 for 24 hours,90 day, 1
year, and 2 year respectively.
4
5
5. When offset control is not used the number of counts are 5, 7, 9 and 9 for 24 hours, 90 day, 1 year,
and 2 year respectively.
MEDIUM AND FAST READING RATES........In medium rate, add 2 counts to the number of counts for
the 200Ω through 200 kΩ ranges, 3 counts for the 2000
kΩ and 20 MΩ ranges, and 20 counts for the 20Ω range.
In fast reading rate, use 3 (4½ digit mode) counts for the
number of counts for the 200Ω range, 20 (4½ digit mode)
counts for the 20Ω range and 2 (4½ digit mode) counts for
all other ranges.
Operating Characteristics
TEMPERATURE COEFFICIENT............Less than 0.1 x accuracy specification per °C from 0°C to 18°C
and 28°C to 50°C.
MEASUREMENT CONFIGURATION.....2-wire or 4-wire in all ranges accept 20Ω range. Only 4-wire
configuration is allowed in the 20Ω range.
OPEN CIRCUIT VOLTAGE ....................Less than 6.5V on the 20Ω through the 200 kΩ ranges. Les s
than 13V on the 2000 kΩ and 20 MΩ ranges.
INPUT PROTECTION.............................To 300V rms.
1-8
Introduction and Specifications
SPECIFICATIONS
Reading Rates
READING RATES WITH INTERNAL TRIGGER (readings per second)
RATE
POWER LINE FREQUECNCY
50 Hz 60 Hz 400 Hz
S 2.08 (.26)
M 16.7 (1.04)
2
2
2.5 (.31)
20 (1.25)
2
2
F 100 100 100
1. Sensed automatically at power-up.
2. In 20 mV, 20 ohm, and 200 mA DC ranges.
AUTORANGING
The 8842A autoranges up to the highest ranges in all funtions, down to the 200 mV range in the VDC
and VAC funtions, and down to the 200 Ω ranges in the ohms funtions. To select the 20 mV dc, 20Ω, or
200 mA dc range, press the respective range button (or send the respective range command, if using
the IEEE-488 option).
1
2.38 (.30)
19.0 (1.19)
1
2
2
AUTOMATIC SETTLING TIME DELAY
Time in milliseconds from single trigger to start of A/D conversion, Autorange off.
FUNCTION RANGE
READING RATE
SMF
VDC 20 mV 342 342 9 30
200 mV 342 61 9 5
2V-1000V 342 17 9 9
VAC All 551 551 551 30 (Note 2)
MA DC 200 mA 342 342 9 9
2000 mA 342 17 9 5
MA AC 2000 mA 551 551 551 30 (Note 2)
Ohms 20Ω 395 395 17 40
200Ω 395 106 17 5
2 kΩ 322 17 13 5
20 kΩ 342 17 13 5
200 kΩ 141 121 21 5
NUMBER OF COUNTS
FROM FINAL VALUE
1
2000 kΩ 141 101 81 10
20 MΩ 1020 964 723 10
1. Difference between first reading and final value for an in-range step change coincident with trigger.
For slow reading rate. 50 counts for medium rate; 10 counts for fast rate.
1-9
8842A
Instruction Manual
EXTERNAL TRIGGER TIMING CHARACTERISTICS
The following diagram shows the nominal timing for the various processes which take place between an
external trigger and data sent out on the IEEE-488 interface. Delays will vary if a second trigger comes
before the data handshake is complete.
t1-1.wmf
NOTES: 1. Time for single trigger to start of A/D conversion.(See “Automatic Settling Time
Delay” on previous page.) If the delay is disabled by using the T3 or T4 command,
then the delay is 1 ms±150 µs. When the 8842A is triggered with an IEEE-488
command (GET or ?), the automatic settling time delay begins after the trigger
command has been processed and recognized.
2. A/D conversion time is dependent on the reading rate and power-line frequency:
RATE
50 Hz 60 Hz 400 Hz
S 472 (3800)* 395 (3195)* 414 (3300)*
M 52 (960)* 45 (795)* 47 (840)*
F777
*In 20 mV DC, 20Ω and 200 mA DC ranges.
3. Sample complete is a 2.5 µs pulse which indicates that the analog input may be
changed for the next reading.
4. When talking to a fast controller.
A/D CONVERSION TIME (ms)
1-10
Introduction and Specifications
SPECIFICATIONS
GENERAL
COMMON MODE VOLTAGE..................1000V dc or peak ac, or 700V rms ac from any input to earth.
TEMPREATURE RANGE.......................0 to 50°C operating, -40 to 70°C storage.
HUMIDITY RANGE.................................80% RH from 0 to 35°C, 70% to 50°C.
WARMUP TIME......................................1 hour to rated specifications.
POWER ..................................................100, 120, 220, or 240V ac ±10% (250V ac maximum), switch
selectable at rear panel. 50, 60, or 400 Hz, automatically
sensed at power-up. 20 VA maximum.
VIBRATION.............................................Meets requirements of MIL-T- 28800C for Type III, Class 3,
Style E equipment.
PROTECTION ........................................ANSI C39.5 AND IEC 348, Class I.
SIZE ........................................................8.9 cm high, 21.6 cm wide, 37.1 cm deep(3.47 in high, 8.5 in
wide, 14.6 in deep).
WEIGHT..................................................Net, 3.4 kg (7.5 lb); shipping, 5.0 kg (11 lb).
INCLUDED..............................................Line cord, test leads, Instruction/Service Manual, IEEE-488
Quick Reference Guide, (Option –05 only), and instrument
performance record.
1
IEEE-488 INTERFACE FUNTION ..........Option allows complete control and data output capability, and
supports the following interface funtion subsets: SH1,AH1, T5,
L4, SR1, RL1, DC1, DT1, E1, PP0, AND C0.
ELECTROMAGNETIC COMPATIBILITYSpecifications apply when used in an environment with fields
strengths ≤ 1 V/m, (0.8 V/m for DC Current.) For fields
strengths up to 3 V/m, multiply floor adder by 12 for VDC and
Resistance and 200 for DC current. VAC and AC Current have
no adders up to 3 V/m.
Figure 1-1. External Dimensions
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1-11
Chapter 2
Operating Instructions
Title Page
2-1. INTRODUCTION................................................................................2-2
2-2. INSTALLATION.................................................................................2-2
2-3. Installing the Power-Line Fuse ........................................................2-2
2-4. Connecting to Line Power................................................................2-2
2-5. Adjusting the Handle........................................................................2-3
2-6. Rack Mounting Kits.........................................................................2-3
2-7. OPERATING FEATURES ..................................................................2-4
2-8. Power-Up Features...........................................................................2-4
2-9. Front and Rear Panel Features.........................................................2-4
2-10. Display Features...............................................................................2-8
2-11. Error Messages.................................................................................2-8
2-12. Overrange Indication........................................................................2-10
2-13. Diagnostic Self-Tests.......................................................................2-10
2-14. Ranging............................................................................................2-10
2-15. AUTORANGE.............................................................................2-10
2-16. MANUAL RANGE.....................................................................2-11
2-17. Triggering.........................................................................................2-11
2-18. CONTINUOUS TRIGGER MODE ............................................2-11
2-19. EXTERNAL TRIGGER MODE .................................................2-11
2-20. Reading Rates and Noise Rejection.................................................2-11
2-21. Automatic Settling Time Delay........................................................2-12
2-22. External Trigger Input (Option -05 Only)........................................2-12
2-23. Sample Complete Output (Option -05 Only)...................................2-12
2-24. MAKING MEASUREMENTS............................................................2-13
2-25. Input Overload Protection Limits.....................................................2-13
2-26. Measuring Voltage and Resistance..................................................2-13
2-27. Measuring Current ...........................................................................2-13
2-28. Current Fuse Protection....................................................................2-13
2-29. Offset Measurements.......................................................................2-14
2-30. EXTERNAL CLEANING....................................................................2-15
2-1
8842A
Instruction Manual
2-1. INTRODUCTION
2-2. INSTALLATION
2-3. Installing the Power-Line Fuse
This section provides instructions for installing and operating the 8842A. Refer to
Section 4 for measurement considerations.
WARNING
FOR POWER-LINE VOLTAGES OF 198V TO 250V, THE POWERLINE FUSE MUST BE REPLACED WITH A 1/8A, 250V SLO-BLO
FUSE FOR FIRE PROTECTION. TO AVOID ELECTRIC SHOCK,
REMOVE THE POWER CORD BEFORE REPLACING THE
EXTERNAL LINE FUSE.
The 8842A has a rear-panel power-line fuse in series with the power supply. A 1/4A,
250V slow-blow fuse is installed in the factory for operation from 90V to 132V. For
operation with power-line voltages of 198V to 250V, the fuse must be replaced with a
1/8A, 250V slo-blow fuse.
To replace the power-line fuse, first remove the power cord. Then turn the rear-panel fuse
cover 1/4-turn counterclockwise with a screwdriver.
For power-line voltages of 198V to 250V, use only a 1/4 x 1 1/4 (6.3mm x 32mm) fuse
with at least a 100A breaking capacity.
2-4. Connecting to Line Power
TO AVOID SHOCK HAZARD, CONNECT THE INSTRUMENT
POWER CORD TO A POWER RECEPTACLE WITH EARTH
GROUND. TO AVOID INSTRUMENT DAMAGE, CHECK THAT
THE REAR PANEL LINE VOLTAGE SELECTION SWITCHES ARE
SET TO THE POWER-LINE VOLTAGE IN OUR AREA.
The 8842A can be configured to accept line power of 100, 120, 220, or 240V ac (+/-10%,
250V maximum) at 50, 60, or 400 Hz. The voltage must be selected by setting the rear
panel LINE SET switches as shown in Figure 2-1. The 8842A automatically senses the
power-line frequency at power-up, so that no adjustment for frequency is necessary.
WARNING
2-2
Figure 2-1. Line Voltage S election Settings
f2-01.wmf
2-5. Adjusting the Handle
The handle provides two viewing angles for bench-top use. To adjust its position, pull the
ends out to a hard stop (about 1/4 inch on each side) and rotate it to one of the four stop
positions shown in Figure 2-2. To remove the handle, adjust it to the vertical stop
position and pull the ends all the way out.
2-6. Rack Mounting Kits
You can mount the 8842A in a standard 19-inch rack panel using the accessory rack
mounting kits shown in Figure 2-3. To install the Single Rack Mount Kit, remove the
handle and handle mounting plates, and attach the rack ears with the screws provided
(Figure 2-4). The Dual Rack Mount Kit is installed similarly. (Both kits include mounting
instructions.)
The rear feet may be rotated 180 degrees to clear a narrow rack space.
Operating Instructions
INSTALLATION
2
Figure 2-2. Adjusting the Handle
Figure 2-3. Rack-Mount Kits
f2-02.wmf
f2-03.wmf
2-3
8842A
Instruction Manual
Figure 2-4. Installing the Single Rack Mount Kit
2-7. OPERATING FEATURES
2-8. Power-Up Features
When the 8842A is turned on, all display segments light up for about 2 seconds while the
instrument performs an internal self-test of its digital circuitry. The 8842A then assumes
the following configuration:
• VDC function
• Autorange, starting in the 1000V range
• Slow reading rate
• Continuous, internal trigg er
• OFFSET off
• Local (front panel) control
While all display segments are lit during the power-up self-test, you can freeze the
display by pressing the SRQ button. All display segments will then remain lit until you
press any button.
f2-04.wmf
2-4
2-9. Front and Rear Panel Features
Front panel features are explained in Figure 2-5. Rear panel features are explained in
Figure 2-6.
The alternate functions embossed below the front pane l range buttons and the spec ia l
feature buttons are enabled by the CAL ENABLE switch. These functions are for use
only when calibrating the instrument. See the Maintenance section for further
explanation.
CAUTION
To avoid accidentally uncalibrating the 8842A, do not press the
CAL ENABLE switch unless calibrating the instrument. Never
cycle power on or off while the CAL ENABLE switch is on.
Operating Instructions
OPERATING FEATURES
Note that the VAC and mA AC functions are available only with the True RMS AC
option. If this option is absent, pressing the VAC and mA AC function buttons causes the
8842A to briefly display an error message (ERROR 30).
FUNCTION BUTTONS:
Display
4-Wire Ohms
DC Current
AC Current*
CAL ENABLE switch
enables calibration
mode. (CAUTION! See text.)
HIGH and LO SENSE
Terminals for 4-Wire Ohms Only
DC Volts
AC Volts*
2-Wire Ohms
2
HI and LO
INPUT Terminals
2A INPUT Terminal
(Houses 2A fuse)
FRONT/REAR switch selects
either front or rear inputs.
Calibration Functions
(embossed)
*Available with 8842A-09 True RMS AC only.
Gives error message if option not installed.
!
!
RANGE BUTTON:
20 mV or 20
200 mV or 200
2V or 2 k
20V or 20 k
SPECIAL
FEATURES
M
200V, 200 k or
200 mA dc
1000V dc, 700V ac,
2 M or 2000 mA
20 M
Autorange On/Off **
** For a description of the autorange feature,
see paragraph 2-14.
POWER switch turns 8842A
on or off. Also initiates
power-up self-test and
resets instrument to:
VDC function
Autorange
Slow reading rate
Continuous trigger
OFFSET off
Local (front panel) control
Figure 2-5. Front Panel Features
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2-5
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