Fluke 8842a - Manual

ix List of Figures Figure Title Page 1-1. External Dimensions .............................................................................................. 1-11 2-1. Line Voltage Selection Settings ............................................................................. 2-2 2-2. Adjusting the ...

1-1 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 .............................

Introduction and Specifications SPECIFICATIONS 1 1-3 1-4. SPECIFICATIONS Specifications for the 8842A are given in Table 1-1. External dimensions are shown inFigure 1-1. Table 1-1. Specifications DC VOLTAGEInput Characteristics RESOLUTION RANGE FULL SCALE 5 ñ DIGITS 5 ñ DIGITS 4 ñ DIGITS* INPUT RESI...

2-1 Chapter 2 Operating Instructions Title Page 2-1. INTRODUCTION ................................................................................ 2-2 2-2. INSTALLATION ................................................................................. 2-2 2-3. Installing the Power-Line Fuse ............

8842A Instruction Manual 2-2 2-1. INTRODUCTION This section provides instructions for installing and operating the 8842A. Refer toSection 4 for measurement considerations. 2-2. INSTALLATION 2-3. Installing the Power-Line Fuse WARNING FOR POWER-LINE VOLTAGES OF 198V TO 250V, THE POWER-LINE FUSE MUST ...

Operating Instructions INSTALLATION 2 2-3 2-5. Adjusting the Handle The handle provides two viewing angles for bench-top use. To adjust its position, pull theends out to a hard stop (about 1/4 inch on each side) and rotate it to one of the four stoppositions shown in Figure 2-2. To remove the handle...

8842A Instruction Manual 2-4 f2-04.wmf 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 theinstrument performs an internal self-test of its digital circuitry. The 8842A...

Operating Instructions OPERATING FEATURES 2 2-5 Note that the VAC and mA AC functions are available only with the True RMS ACoption. If this option is absent, pressing the VAC and mA AC function buttons causes the8842A to briefly display an error message (ERROR 30). ! ! M FUNCTION BUTTONS: RANGE BUT...

8842A Instruction Manual 2-8 2-10. Display Features The 8842A features a vacuum fluorescent display with a numeric field and annunciators.The annunciators are explained in Figure 2-5. 2-11. Error Messages If the 8842A detects an operator error or an internal failure, it displays an error messagefor ...

8842A Instruction Manual 2-10 2-12. Overrange Indication An input is overrange if it exceeds the full scale of the selected range. In most ranges, the8842A indicates an input is overrange by lighting the OVER annunciator and showing a"1" on the display. (See Figure 2-8.) The sign, the positi...

Operating Instructions OPERATING FEATURES 2 2-11 2-16. MANUAL RANGE In manual range, the 8842A remains fixed in the selected range until you select anotherrange or press AUTO. If you select a range which is not valid for the present function, orselect a function which is not valid for the present ra...

Operating Instructions MAKING MEASUREMENTS 2 2-13 2-24. MAKING MEASUREMENTS 2-25. Input Overload Protection Limits WARNING TO AVOID SHOCK HAZARD AND/OR INSTRUMENT DAMAGE,DO NOTAPPLY INPUT POTENTIALS THAT EXCEED THE INPUTOVERLOAD LIMITS SHOWN IN TABLE 2-2. The 8842A is protected against input overloa...

8842A Instruction Manual 2-14 To replace the front panel fuse, first remove the test leads. Then press in the lip of the 2Ainput terminal slightly and rotate it 1/4-turn counterclockwise. Spring tension will forcethe fuse and fuse holder out of the front panel. The internal 3A fuse should be replace...

Operating Instructions EXTERNAL CLEANING 2 2-15 f2-09.wmf Figure 2-9. Measuring Voltage and Resistance f2-10.wmf Figure 2-10. Measuring Current 2-30. EXTERNAL CLEANING WARNING TO AVOID ELECTRIC SHOCK OR INSTRUMENT DAMAGE,NEVER GET WATER INSIDE THE CASE. TO AVOIDINSTRUMENT DAMAGE, NEVER APPLY SOLVENT...

3-1 Chapter 3 Remote Programming Title Page 3-1. INTRODUCTION ................................................................................ 3-3 3-2. CAPABILITIES ................................................................................... 3-3 3-3. BUS SET-UP PROCEDURE ........................

Remote Programming INTRODUCTION 3 3-3 NOTE This section contains programming instructions for use with the IEEE-488Interface (Option -05). For installation instructions, refer to the Optionsand Accessories section. 3-1. INTRODUCTION The IEEE-488 Interface turns the 8842A into a fully programmable in...

Remote Programming AN OVERVIEW OF REMOTE OPERATION 3 3-5 f3-02.wmf Figure 3-2. Remote Operation Block Diagram

8842A Instruction Manual 3-6 Information is transferred between blocks by device-dependent commands. Eachcommand is shown next to an arrowhead which indicates the resulting informationtransfer. For example, Put command P0 takes a number from the input buffer and stores itin the primary status regist...

Remote Programming DEVICE-DEPENDENT COMMAND SET 3 3-7 RANGE COMMANDS R0 Autorange OnR1 200 mV, 200 Ω R2 2V, 2 k Ω R3 20V, 20 k Ω R4 200V, 200 k Ω , 200 mA R5 1000V dc, 700V ac, 2 M Ω , 2000 mA R6 20 M Ω R7 Autorange OffR8 20 mV, 20 Ω FUNCTION COMMANDS F1 VDCF2 VACF3 2 Wire k Ω F4 4 Wire k Ω F5 mA DC...

8842A Instruction Manual 3-10 3-10. Fn (Function Commands) The function commands duplicate the front panel function buttons. The 8842A defaults toF1 on power-up and on any device-clear command (*, DCL, or SDC). If F0 is sent to the8842A, it is internally converted to F1. The function setting can be ...

8842A Instruction Manual 3-12 3-12. G0 (Get Instrument Configuration) The G0 command copies the 8842A function, range, reading rate, and trigger mode intothe output buffer in the format shown in Figure 3-6. The four digits returned represent thearguments for the equivalent F, R, S, and T commands, a...

8842A Instruction Manual 3-14 3-17. G5 (Get IAB Status) The G5 command loads the output buffer with the IAB status in the format shown inFigure 3-6. As Table 3-1 explains, the IAB status is a four-character string whichindicates the status of the FRONT/REAR switch (front or rear analog inputs select...

Remote Programming DEVICE-DEPENDENT COMMAND SET 3 3-15 3-20. G8 (Get Instrument Identification) The G8 command copies the 8842A instrument identification into the output buffer in theformat shown in Figure 3-6. The identification is represented by four comma separatedfields that are interpreted in T...

8842A Instruction Manual 3-16 "N3120 P0" Identical to F3 R1 S2 T0. Selects 2 WIRE k Ω function, 200 Ω range, fast sample rate, continuous trigger. The P0 command allows broadside loading of the Function, Range, Reading Rate, andTrigger Mode commands (F, R, S, and T). The codes for these comm...

Remote Programming DEVICE-DEPENDENT COMMAND SET 3 3-17 etc. All of these strings result in the same value being used for the next calibration step.For complete information about remote calibration, refer to the Maintenance section. Numeric values exceeding full scale and negative values for ohms and...

8842A Instruction Manual 3-20 Error messages are indicated by an exponent of +21. For more about error messages, seeparagraph 3-40. Since the 8842A is reset at the end of the self-tests, the Z0 command should be the lastcommand in a given command string. The 8842A will ignore any subsequent commands...

Remote Programming INPUT SYNTAX 3 3-21 3-37. Definitions • Output commands: Commands which load data into the output buffer. The outputcommands are: the Get commands (G0 through G8); the Single-Trigger Command(?); the Continuous Trigger command (T0); and Group Execute Trigger (GET), not tobe confuse...

Remote Programming INPUT SYNTAX 3 3-23 Illegal commands (e.g., F9) generate an error message, but are otherwise ignored, and donot affect the instrument’s configuration. Example Explanation "* F9" This would load the output buffer with an error message and select F1(established by the * comm...

8842A Instruction Manual 3-24 In this incorrect example, the INPUT statement is located incorrectly for reading themeasurement data from line 100. The new input command string "F4" disallows thereading of data from the output buffer. Correct example 100 PRINT @3, "T1 ?" 200 INPUT @3,...

Remote Programming OUTPUT DATA 3 3-25 Because the 8842A gives priority to input processing, it completely processes allcharacters in the input buffer before it loads the output buffer. When the output buffer isloaded, the Data Available bit in the serial poll register is set true. Data from the outp...

8842A Instruction Manual 3-26 NOTE In the fast (F) reading rate, the least significant digit is always zero, andshould be disregarded when interpreting accuracy specifications. 3-45. OVERRANGE INDICATION If a reading is overrange ( ≥ 200,000 counts), the measurement data has the following format: ±9...

Remote Programming SERVICE REQUESTS 3 3-27 1. Status data (from G0, G1, G3, G4, G5, G6, G7 and G8) 2. Error messages (if an error exists) 3. Numeric data (from G2 or a trigger) This means that an error message always overrides numeric data, but status data is senteven in the presence of an error. Ho...

Remote Programming INTERFACE MESSAGES 3 3-29 The SRQ mask can enable any combination of serial poll register bits 1 through 6. Its six-bit binary representation is ANDed bit-for-bit with serial poll register bits 1 through 6whenever the output buffer is loaded. If any mask-enabled bit in the serial ...

Remote Programming REMOTE CALIBRATION 3 3-31 6. Configure the 8842A with the front panel controls. The 8842A reads the TALK ONLY bit switch on power-up and when it receives theinterface command IFC. You can therefore set the TALK ONLY switch to 1 after power-up as long as you then send the 8842A the...

Remote Programming EXAMPLE PROGRAMS 3 3-33 f3-10.wmf Figure 3-9. Example Program

4-1 Chapter 4 Measurement Tutorial Title Page 4-1. INTRODUCTION ................................................................................ 4-2 4-2. DC VOLTAGE MEASUREMENT ..................................................... 4-2 4-3. Circuit Loading Error .........................................

8842A Instruction Manual 4-2 4-1. INTRODUCTION This section discusses considerations and techniques to help you use the 8842Aeffectively. Among other things, this section discusses sources of error which are aninherent part of the measurement process and which occur for all multimeters. Byunderstand...

Measurement Tutorial DC VOLTAGE MEASUREMENT 4 4-3 The input impedance of the 8842A is 10 M Ω in the 200V and 1000V dc ranges, and is greater than 10,000 M Ω in the 20 mV, 200 mV, 2V, and 20V ranges. Therefore, for the 8842A, circuit loading error is less than 0.01% as long as the source impedance is...

Measurement Tutorial RESISTANCE MEASUREMENT 4 4-5 The test current and full-scale voltage for each resistance range are shown in Table 4-1.Since the HI INPUT test lead is positive with respect to the LO INPUT lead, these testleads are not interchangeable when a semiconductor device is being measured...

Measurement Tutorial RESISTANCE MEASUREMENT 4 4-7 NOTE In the 2 M Ω and 20 M Ω ranges of 4-wire ohms, the voltage across the unknown resistance is sensed between the HI SENSE and LO INPUTterminals. Accuracy is not affected as long as the resistance of the LOINPUT lead is less than 10 Ω in the 2 M Ω ...

8842A Instruction Manual 4-8 4-12. A PRECISION CURRENT SOURCE The ohms current source (the internal current source used in the ohms functions) makes auseful troubleshooting tool in itself. It has excellent linearity and temperature stability. Itscompliance voltage is typically 5V in the lower five o...

Measurement Tutorial REDUCING THERMAL VOLTAGES 4 4-9 f4-05.wmf Figure 4-5. Burden Voltage Error Calculation 4-14. REDUCING THERMAL VOLTAGES When making very low-level dc measurements, thermal voltages can present anadditional source of error. Thermal voltages are the thermovoltaic potentials generat...

8842A Instruction Manual 4-10 4. Use caution when handling the circuit under test. 5. Wait for the circuit to reach thermal equilibrium. (Thermal voltages are generatedonly where there is a temperature gradient.) 4-15. AC VOLTAGE AND CURRENT MEASUREMENT When making precise measurements of ac voltage...

Measurement Tutorial AC VOLTAGE AND CURRENT MEASUREMENT 4 4-11 f4-06.wmf Figure 4-6. Waveform Comparison Chart Since average-responding meters have been in use for so long, you may haveaccumulated test or reference data based on them. The conversion factors in Figure 4-6should help you convert betwe...

8842A Instruction Manual 4-12 4-18. Crest Factor Crest factors are useful for expressing the ability of an instrument to measure a variety ofwaveforms accurately. The crest factor of a waveform is the ratio of its peak voltage to itsrms voltage. (For waveforms where the positive and negative half-cy...

Measurement Tutorial AC VOLTAGE AND CURRENT MEASUREMENT 4 4-13 measurements, for instance, cannot be made with dc coupling. Remember, however, thatwhen the 8842A measures signals with the ac functions, the reading on the display doesnot include the dc component (if one exists). For example, consider...

8842A Instruction Manual 4-14 The zero-input error is quickly reduced when the input is increased. The rms convertererror (a dc error) and the internally generated noise (a random ac error) are bothuncorrelated with the input signal. Therefore, when a signal is applied, the resultingreading is not t...

Measurement Tutorial MAKING ACCURATE HIGH-RESISTANCE MEASUREMENTS 4 4-15 f4-10.wmf Figure 4-10. Shielding for Low Voltage Measurements For low-level resistance measurements, connect the test lead shielding as shown in Figure4-11. Use the 4-wire ohms function to minimize the error caused by the resis...

5-1 Chapter 5 Theory of Operation Title Page 5-1. INTRODUCTION ................................................................................ 5-3 5-2. OVERALL FUNCTIONAL DESCRIPTION ...................................... 5-3 5-3. DETAILED CIRCUIT DESCRIPTION ..........................................

Theory of Operation DC SCALING 5 5-5 f5-01.wmf Figure 5-1. Overall Functional Block Diagram

8842A Instruction Manual 5-6 5-5. VDC Scaling Scaling is performed in the VDC function by two precision resistors networks (Z301 andZ302). These components are configured by relay K301, switching transistor Q311, andquad analog switches U302A and U301B to provide the correct scaling for each range.V...

Theory of Operation DC SCALING 5 5-7 In the 20 mV, 200 mV and and 2V ranges, the input voltage is applied directly to the T/HAmplifier via Q310, Q311, and U301B. In the 20 mV range, the T/H Amplifier has a gainof 100; in the 200 mV range, the T/H Amplifier has a gain of 10; in all other dc voltagera...

8842A Instruction Manual 5-8 5-9. TRACK/HOLD CIRCUIT The Track/Hold (T/H) circuit presents a stable voltage to the A/D Converter during theinput period of the A/D conversion cycle. The circuit also provides a gain of 100 in the20 mV, 20 Ω and 200 mA ranges, and a gain of 10 in the 200 mV dc, 200 Ω ,...

8842A Instruction Manual 5-10 f5-05.wmf Figure 5-5. Timing Diagram for One A/D Cycle 5-10. Track Configuration In the track configuration (Figure 5-4A), the T/H circuit functions as a non-invertingbuffer. The voltage on C308 tracks the scaled dc input voltage.

Theory of Operation PRECISION VOLTAGE REFERENCE 5 5-11 5-11. Settling Configuration The circuit assumes a settling configuration between the track and hold configurations.The circuit assumes the configuration in Figure 5-4B for unity gain and the configurationin Figure 5-4C for gain of 10. During th...

8842A Instruction Manual 5-12 Resistor R701, precision resistor network Z701, and transistor/zener diode combinationU701 are produced as a matched set so that the output of U702A is precisely -7.00000V.This output is remotely sensed at the pins of the custom A/D IC (U101). Diode CR701prevents the ou...

Theory of Operation OHMS PROTECTION 5 5-13 The second stage (U404, precision resistor network Z401, and analog switches U402 andU403) is a current amplifier whose gain is controlled by the In-Guard µ C. The In-Guard µ C sets the output current for each range by controlling U402 and U403. (See switch...

Theory of Operation A/D CONVERTER 5 5-15 The voltage sensed at the INPUT terminals is scaled as shown by the simplified switchtable in Figure 5-8. (Refer to the track period of the track/hold cycle, during which thescaled input voltage is sampled.) In the lower five ranges, the full scale input volt...

Theory of Operation A/D CONVERTER 5 5-17 f5-10.wmf Figure 5-10. First Remainder-Store Period This five-interval process thus generates five nibbles which are processed by the In-Guard µ C to produce one A/D sample. After the fifth nibble is generated, U101 interrupts the In-Guard µ C over line INT. ...

8842A Instruction Manual 5-18 The bit-switches determine the output voltage of U102B by controlling the binary laddernetwork. The gain of U102B is set by the ratio of a precision feedback resistor (Z101-7, -8) and the equivalent output resistance of the ladder network. 5-23. A/D Amplifier The A/D Am...

Theory of Operation KEYBOARD 5 5-19 f5-12.wmf Figure 5-12. Vacuum Fluorescent Display The Digital Controller sequentially enables the G lines by applying +30V dc (nominal).When a G line is enabled, electrons flow from the filament to the enabled grid. If a P lineis enabled (i.e., raised to a nominal...

Theory of Operation DIGITAL CONTROLLER 5 5-21 5-28. In-Guard Microcomputer The In-Guard Microcomputer ( µ C) is a single-chip Z8 microcomputer containing 4K bytes of ROM, 144 bytes of RAM, a UART, and four 8-bit I/O ports. It communicateswith the rest of the instrument via the internal bus and dedic...

Theory of Operation POWER SUPPLY 5 5-25 The circuit in Figure 5-15 has two stable states, corresponding to output high (+5V) andoutput low (0V). If the output is high, the voltage present at the non-inverting input of opamp A is approximately +140 mV. Since the inputs to op amps A and B are inverted...

8842A Instruction Manual 5-26 5-37. IEEE-488 INTERFACE (OPTION -05) The IEEE-488 Interface has five major parts, as shown in the block diagram in Figure 5-16. All components are contained in a single printed circuit assembly (PCA). Referencedesignations are numbered in the 900 series. f5-16.wmf Figu...

Theory of Operation TRUE RMS AC (OPTION -09) 5 5-27 5-41. Signal Conditioning The SAMPLE COMPLETE and EXT TRIG signals (J903 and J904) are conditioned byU909. Diodes CR903, CR904, CR905, and CR906 and resistors R917 and R918 provideprotection from excessive voltages. Jumpers E902 and E903 allow sele...

8842A Instruction Manual 5-28 U806A, U806B, and a voltage divider (R804 and R805) provide gain which is selectedfor each range by the analog switches in U804. The configuration for each range is shownin Figure 5-17. (In this figure, the CMOS analog switches are represented by mechanicalswitches.) Wh...

Some semiconductors and custom IC's can bedamaged by electrostatic discharge duringhandling. This notice explains how you canminimize the chances of destroying such devicesby: 1. Knowing that there is a problem.2. Leaning the guidelines for handling them.3. Using the procedures, packaging, and bench...

6-1 Chapter 6 Maintenance Title Page 6-1. INTRODUCTION .................................................................................. 6-3 6-2. PERFORMANCE TEST ........................................................................ 6-4 6-3. Diagnostic Self-Tests ...................................

Maintenance PERFORMANCE TEST 6 6-5 To initiate the self-tests, press the SRQ button for 3 seconds. The TEST annunciator willthen light up, and the 8842A will run through the analog tests in sequence. Each testnumber is displayed for about 1 second. The instrument can be stopped in any of the testcon...

Maintenance PERFORMANCE TEST 6 6-7 6-5. AC Voltage Test (Option -09 Only) The following procedure may be used to verify the accuracy of the VAC function: 1. Ensure the 8842A is on and warmed up for at least 1 hour. 2. Select the VAC function and the slow (S) reading rate. 3. Connect the AC Calibrato...

8842A Instruction Manual 6-8 Table 6-4. High-Frequency AC Voltage Test INPUT TEST LIMITS (IN VOLTS) STEP NUMBER RANGE VOLTAGE FREQUENCY ERROR IN COUNTS MIN MAX 1 200 mV 0.010000V 50 kHz 169 09.831 mVAC 10.169 mVAC 2 * 200 mV 0.010000V 100 kHz 350 09.650 mVAC 10.350 mVAC 3 * 2V 0.10000V 100 kHz 350 0...

Maintenance PERFORMANCE TEST 6 6-9 Table 6-5. Resistance Test Error From Input 1 (in counts) Step Range Input (Nominal) Slow Medium Fast 2 1 20 Ω 3 0 Ω (short) ±40 ±60 ±20 2 20 Ω 3 10 Ω ±49 ±69 ±21 3 200 Ω 3 0 Ω (short) ±4 ±6 ±3 4 200 Ω 3 100 Ω ±11 ±13 ±4 5 2 k Ω 0 Ω (short) ±3 ±5 ±2 6 2 k Ω 1 k Ω ±...

8842A Instruction Manual 6-10 6-8. AC Current Test (Option -09 Only) The following procedure may be used to test the mA AC function: 1. Ensure the 8842A is on and warmed up for at least 1 hour. 2. Select the mA AC function. 3. Connect the AC Current Source to provide a current input to the 2A and LO...

Maintenance CALIBRATION 6 6-11 6-10. Basic Calibration Procedure The basic calibration procedure consists of the following four parts. These parts must beperformed in the order shown. 1. Initial Procedure. 2. A/D Calibration. 3. Offset and Gain Calibration for each function and range. 4. High-Freque...

8842A Instruction Manual 6-12 f6-03.wmf Figure 6-3. Calibration Functions The following functions are inappropriate during calibration, and are thereforeunavailable: • Offset • Autoranging • External Trigger • Front Panel Trigger • Front panel SRQ (Under local control) • Diagnostic self-tests 6-12. ...

8842A Instruction Manual 6-14 The A/D Calibration procedure is an iterative process. Each pass through the procedureuses the constants stored previously and improves them. Normally, one pass is adequate.However, if the calibration memory has been erased or replaced, or the A/D Converterhas undergone...

8842A Instruction Manual 6-16 5. The calibration procedure is now completed. Exit the calibration mode by pressingthe CAL ENABLE switch, and attach a calibration certification sticker over the CALENABLE switch. 6-15. Advanced Features and Special Considerations Table 6-11. High-Frequency AC Calibrat...

Maintenance CALIBRATION 6 6-17 6-17. CALIBRATING INDIVIDUAL RANGES During Offset and Gain and High-Frequency AC Calibration, it is possible to calibrateindividually selected ranges. This feature does not apply to the mA DC and mA ACfunctions and is not permitted during A/D Calibration. To calibrate ...

8842A Instruction Manual 6-18 1. If you just completed the Offset and Gain or High-Frequency AC Calibration for anentire function (not just one range), the range buttons can be used to change ranges inorder to verify all ranges were calibrated correctly. 2. If you just calibrated an individually sel...

Maintenance CALIBRATION 6 6-19 If ERROR 41 occurs, the most likely cause is that the reference input is incorrect (e.g.,has the wrong polarity). If the input is in fact correct, refer to the Troubleshootingheading in this section. Table 6-13. Tolerance Limits CALIBRATION TOLERANCE 1. A/D Calibration...

8842A Instruction Manual 6-24 The C0 command can take up to 22 seconds. If during this time the controller continuesto send the 8842A more commands, the commands may fill up the 8842A’s input buffer.If this happens, errors will probably occur. You can avoid this problem by knowing when these command...

Maintenance DISASSEMBLY PROCEDURE 6 6-25 f6-05.wmf Figure 6-5. Example A/D Calibration Program 6-27. DISASSEMBLY PROCEDURE WARNING TO AVOID ELECTRIC SHOCK, REMOVE THE POWER CORDAND TEST LEADS BEFORE DISASSEMBLING THEINSTRUMENT. OPENING COVERS MAY EXPOSE LIVE PARTS. CAUTION To avoid contaminating the...

8842A Instruction Manual 6-26 6-28. Case Removal 1. Remove the grounding screw from the bottom of the case. Remove two rear bezelmounting screws. (See Figure 6-6A.) 2. While holding the front panel, slide the case and rear bezel off the chassis (SeeFigure 6-6B). (At this point, the rear bezel is not...

8842A Instruction Manual 6-30 6-29. True RMS AC PCA Removal (Option -09 Only) The True RMS AC PCA should be removed by reversing the last three steps in Figure809-1 (see Section 8). 1. Release the True RMS AC PCA from the chassis by pulling the four plastic latchesupward (Figure 809-1E). 2. Raise th...

Maintenance REASSEMBLY PROCEDURE 6 6-33 NOTE When installing the Main PCA, guide the rear ribbon cable around theshield connected to the rear panel so that the cable is next to the side of thechassis. Make certain that the cable is not pinched between the shield andthe Main PCA. a. Slide the Main PC...

Maintenance REASSEMBLY PROCEDURE 6 6-35 f6-08.wmf Figure 6-8. Removing the Display Window CAUTION Make certain that the CAL ENABLE switch shaft is in the out(disabled) position after the CAL ENABLE push rod is installed.If the 8842A is switched on with the CAL ENABLE switch in theenabled position, t...

Maintenance TROUBLESHOOTING 6 6-37 If the display lights up, perform the self-test by pressing the SRQ button for 3 seconds.(Remember, the input terminals must be disconnected from the test leads during the self-tests. Otherwise, the 8842A may indicate errors are present.) The test numbers willappea...

Maintenance TROUBLESHOOTING 6 6-41 A failure in the instrument may cause the 8842A to display random patterns or nothing atall. Usually, analog circuit failures do not cause the display to go blank or display randompatterns. The best place to start troubleshooting a "dead" instrument or an i...

8842A Instruction Manual 6-42 6-39. Self-Test Descriptions Table 6-18. Self-Test Voltages TEST NUMBER TEST POINT VOLTAGE 1 TP803 ±5 mV dc 2 TP803 ±5 mV dc 3 TP803 ±5 mV dc 4 TP103 T/H output waveform for zero input (Figure 6-14) 5 TP302 ±5 mV dc 6 TP302 ±5 mV dc 7 TP302 +50 mV dc typical 8 TP302 +11...

8842A Instruction Manual 6-44 These tests put the 8842A in the respective range of the 2-wire ohms function. Theycheck that each range of the Ohms Current Source has enough compliance voltage tooverload the dc front end. • TEST 15: 1000 VDC + X10 T/H + 20 M Ω Puts the Ohms Current Source in the 500 ...

Maintenance TROUBLESHOOTING 6 6-45 • TEST 28: External Program Memory (U222) A two-byte check sum is calculated over the entire 4K External Program Memory andcompared with the checksum bytes at the end of that memory. A special add and shiftalgorithm minimizes the possibility of double errors cancel...

Maintenance TROUBLESHOOTING 6 6-47 1. Power supplies: +5V dc at U202-1; 0V dc U202-11. 2. µ C clock output: 8 MHz at U202-2,-3. 3. Trigger line U202-40 (TP201): Square wave, 50% duty, low 0V, high 3.8V(nominal). The period of the trigger signal should be 12.500 ms for 60 Hz line. 4. Interrupt from A...

8842A Instruction Manual 6-48 16, -18, -21, -25 are the same as Waveform B. The waveforms should be interruptedevery 1.5 sec for 0.2 sec due to interrupts from the watchdog timer. (Note: XU222 pinsrefer to a 28-pin socket.) 6-45. Calibration Memory (U220) Sync on U219-3. Verify that U220-1, -3, -5, ...

8842A Instruction Manual 6-50 Check for the same waveforms at outputs U215-11 through U215-18. (However, the highlevel should be approximately 30V.) If these waveforms are OK, then strobe decoderU213 and display control U212 are OK in this regard. 6-51. 3-to-8 Strobe Decoder (U213) Check for strobe ...

8842A Instruction Manual 6-52 Table 6-20. Analog Control Devices DEVICE REF. DES. Relay Buffer U201 Quad Comparator U305 Quad Analog Switch U301 Quad Analog Switch U302 Quad Analog Switch U303 Quad Analog Switch U402 Quad Analog Switch U403 8-Bit Latch U803 * Quad Analog Switch U804 * Quad Analog Sw...

8842A Instruction Manual 6-56 6-63. Track/Hold Troubleshooting If a problem is suspected in the Track/Hold (T/H) circuit, first check the power supplyvoltages of all active components. (See Table 6-22.) Next, check the T/H output waveform at TP103 with an oscilloscope. Set the 8842A tothe VDC functi...

Maintenance TROUBLESHOOTING 6 6-57 f6-13.wmf Figure 6-13. Typical Output Waveforms for Track/Hold Circuit (TP103) To test whether the Ohms Current Source is actually being sourced out the HI and LOOUTPUT terminals, select the 20 k Ω range and the 2-wire ohms function, connect a 10 k Ω resistor acros...

8842A Instruction Manual 6-58 If the ohms functions do not work in any range, check the supplies at U401 (+/-15V),U404 (+30V and -5V), U402 (+15V, +5V, and 0V), and U403 (+15V, +5V, and 0V), andcheck the -7V reference at R416. Also, test the Ohms Protection circuitry as follows:Select the 20 k Ω ran...

Maintenance TROUBLESHOOTING 6 6-61 problem between the A/D Converter and the In-Guard µ C can cause erroneous or noisy readings or offsets. Similar problems may be caused by a failure of the CalibrationMemory (U220) or by bad A/D calibration constants. (To check for bad A/D calibrationconstants, cle...

8842A Instruction Manual 6-64 The True RMS AC PCA, if installed, uses +5V and +/-15V. If there is a problem withone of those supplies, first disconnect the True RMS AC PCA. If the problem goes away,troubleshoot the True RMS AC PCA using the procedure given later in this section. With most power supp...

8842A Instruction Manual 6-70 It is safe to force one control line at a time high (+5V) or low (0V) to test the individualswitches in U808. (The on resistance of switches in U808 should be less than 500 Ω ; the off resistance should be greater than 10 M Ω .) Forcing the control lines high or low sho...

Maintenance INTERNAL CLEANING 6 6-71 6-78. Cleaning After Soldering CAUTION T.M.C. Cleaner and similar products can can attack the nylonlatches and other plastic pieces. f6-21.wmf Figure 6-21. Guard Crossing Test Waveforms If a PCA has been soldered, it should first be cleaned with SPRAYON T.M.C Cle...

7-1 Chapter 7 List of Replaceable Parts Title Page 7-1. INTRODUCTION ................................................................................ 7-3 7-2. HOW TO OBTAIN PARTS................................................................. 7-3 7-3. MANUAL STATUS INFORMATION.........................

8842A Instruction Manual 7-4 7-4. NEWER INSTRUMENTS Changes and improvements made to the instrument are identified by incrementing therevision letter marked on the affected pca. These changes are documented on asupplemental change/errata sheet which, when applicable, is included with the manual. 7-5...

List of Replaceable Parts SERVICE CENTERS 7 7-5 Manual Status Information REF OF OPTION NO. ASSEMBLY FLUKE PART NO. REVISION LEVEL A1A2 0509 Main PCADisplay PCAIEEE-488 Interface PCATrue RMS AC PCA 759365728873879267759266 BE __ DN Table 7-1. 8842A Digital Multimeter

8-1 Chapter 8 Options and Accessories Title Page 8-1. INTRODUCTION .................................................................................. 8-3 8-2. ACCESSORIES ..................................................................................... 8-4 8-3. Rack-Mount Kits (Y8834, Y8835 and ...

8842A Instruction Manual 8-4 8-2. ACCESSORIES Accessories include a variety of rack-mounting kits, cables, test leads, and probes. Theaccessories include installation and/or operating instructions. 8-3. Rack-Mount Kits (Y8834, Y8835 and Y8836) The rack-mount kits allow the 8842A to be mounted in sta...

Options and Accessories ACCESSORIES 8 8-5 8-10. Current Shunt (80J-10) The 80J-10 current shunt extends ac or dc current measurement up to 10A continuous, orto 20A for one minute without overheating. 8-11. Current Probes (Y8100, Y8101, 80i-400 and 80i-600) The current probes extend the ac and dc cur...

8842A Instruction Manual 805-4 3. Disconnect the ribbon cable from the plastic rear panel insert by pulling the tabson either side of the ribbon cable connector outward. Pull the ribbon cabledirectly toward the front panel (Figure 805-1C). 4. Remove the rear panel insert by releasing the two snap ta...

Option –05 IEEE-488 Interface LIST OF REPLACEABLE PARTS 805-5 f805-1_1.wmf Figure 805-1. Installing Option -05

809-1 Chapter 809 Option –09 True RMS AC Title Page 809-1. INTRODUCTION .................................................................................. 809-3809-2. INSTALLATION ................................................................................... 809-3809-3. OPERATING INSTRUCTIONS.....

Option –09 True RMS AC INTRODUCTION 809-3 809-1. INTRODUCTION The True RMS AC option gives the 8842A the ability to make ac voltage and currentmeasurements. The ac functions are selected with the front panel VAC and mA ACbuttons, or by remote commands if the IEEE-488 Interface option is installed.Sp...