Fluke 8842A User Manual

8842A
Instruction Manual
x
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 Voltage 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

Fluke 8842A Specifications

General

Maximum Voltage	1000 V
Maximum Current	2 A
Operating Temperature	0°C to 50°C
Weight	2.5 kg
DC Voltage Range	100mV to 1000V
DC Current Range	0 to 2 A
AC Current Range	0 to 2 A
Frequency Range	20 Hz to 20kHz
Basic Resistance Accuracy	0.01%
Dimensions	216mm x 88mm x 280mm
Resistance Range	200 Ω to 20 MΩ