233 Serial Communication Guard Crossing

The Microprocessor communicates with the Analog Measurement Processor using this isolated two-wire, full-duplex asynchronous interface circuit. When the Microprocessor is transmitting to the Analog Measurement Processor, the transmit data bits appear at A1U6-11, which drives the combination of AQ19, A1R33 and A1U3-1. The optocoupler A1U3 then optically transfers this information to its output circuit, comprised of A1U3-7, A1R30, A1R28 and A1R27. The transmitted data is then presented to A1TP4...

46 Entering Calibration Mode

Always begin the calibration procedure as follows 1. Allow the Fluke 45 to stabilize in an environment with ambient temperature of 18 to 28 C and relative humidity of less than 70 . Then turn the Fluke 45 on, and allow it to warm up for at least 1 hour. 2. The Cal Enable button is located on the right side of the display and is recessed beneath a calibration seal. Enable the calibration mode by pressing the Cal Enable button for about three seconds (CAL appears in secondary display.) Use a...

21 Introduction

This chapter presents a layered description of Fluke 45 circuitry. First, the multimeter is described in general terms with a Functional Block Description. Then, each block is detailed further (often to the component level) with Detailed Circuit Descriptions. Refer to Chapter 9 of this manual for full schematic diagrams. Signal names followed by a '*' are active (asserted) low. Signal names not so marked are active high. Refer to Figure 2-1, Overall Functional Block Diagram, during the...

518 Calibration Related Components

Measurement function calibration depends on various combinations of components in and around the Analog Measurement Processor. The major components are Divider Network (DC Ohms) A1Z1 Integrate Resistors, Reference Divider A1Z3 Calibration of the Fluke 45 utilizes a building block approach individual components are calibrated separately and the appropriate calibration building blocks are assembled later for correction of any particular measurement function, range, and rate. Calibration steps are...

218 Analog Measurement Processor

Refer to Figure 2-2 for an overall picture of the Analog Measurement Processor chip and its peripheral circuits. Table 2-1 describes Analog Measurement Processor chip signal names. The Analog Measurement Processor (A1U1) is a 68-pin CMOS device that, under control of the Main Processor (A1U6), performs the following functions Active filtering of dc-type measurements. The active filter is disabled for fast reading rate measurements. Support for direct volts, direct current, true rms alternating...

13 Options and Accessories

These options can be installed either at the factory or in the field. The following discussions pertain to the field-installable option kits The Battery Kit (Option -01K) consists of a rechargeable, 8 V, lead-acid battery, with battery bracket and charger assembly. The battery has a typical operating time of eight hours and is fully operable at ambient temperatures between 0 and 50 C. The IEEE-488 Interface Kit (Option -05K) consists of a printed circuit assembly,...

241 Display Assembly

Display Assembly operation classified into six functional circuit blocks the Main Assembly Connector, the Front Panel Switches, the Display, the Beeper Drive Circuit, the Watchdog Timer Reset Circuit, and the Display Controller. These blocks are described in the following paragraphs. The Main Assembly Connector is a 20-pin connector (A2J1) that provides the interface between the Main Assembly and the other functional blocks on the Display Assembly. Seven of the connector pins provide the...

220 Input Signal Conditioning

The input signal (voltage, current, or resistance) must be scaled or conditioned to a form that can be measured by the a d converter. High dc voltage levels must be attenuated. Resistances, currents, and ac voltages must be converted to a representative dc voltage. DC-type measurements (dc volts, dc current, ohms, and diode test) are then filtered by the active filter. AC measurements (ac volts and ac current) are passively filtered after being converted to a dc voltage. In the medium and fast...

321 Remove the Analog Measurement Processor Shields

The Analog Measurement Processor resides within a plastic shield on the top of the Main PCA. Although having the appearance of a dark gray piece of plastic, this shield is electrically conductive treat it as you would any other conducting surface. On the bottom of the Main PCA, the Analog Measurement Processor is protected with a metallic shield. Access the Analog Measurement Processor with the following procedure Working from the bottom of the Main PCA, remove the single Phillips head screw (J...

14 Organization of the Service Manual

This manual focuses on component-level repair of the Fluke 45 Dual Display Multimeter. To that end, manual chapters are often interdependent effective troubleshooting may require not only reference to the troubleshooting procedures in Chapter 5, but also some understanding of the detailed Theory of Operation in Chapter 2 and some tracing of circuit operation in the Schematic Diagrams presented in Chapter 9. Often, scanning the table of contents will yield an appropriate place to start using the...

54 General Troubleshooting Procedures

The Fluke 45 allows for some fault isolation using self-diagnostic routines and descriptive error codes. However, these features are somewhat limited and do not provide in-depth troubleshooting tools. The Fluke 45 incorporates a semi-modular design determining modules not related to a problem constitutes the first step in the troubleshooting process. Disconnect the Battery Option cable at the Main PCA. Disconnect the IEEE-488 Interface Option at P2 and P3 on the IEEE-488 Interface PCA. If...

44 Front Panel Calibration

The Fluke 45 features closed-case calibration using known reference sources. The multimeter automatically prompts you for the required reference sources, measures them, calculates correction factors, and stores the correction factors in the nonvolatile calibration memory. Closed-case calibration has many advantages. There are no parts to disassemble, no mechanical adjustments to make, and the Fluke 45 can be calibrated by an automated instrumentation system. The Fluke 45 should normally be...

43 Performance Tests

The following performance tests are provided to ensure that the meter is in proper operating condition. If the meter fails any of the performance tests, calibration adjustment and or repair is needed. To perform these tests, you will need a Fluke 5700A Multifunction Calibrator and a 5725A Amplifier or equipment meeting the minimum specifications given in Table 4-1. Each of the measurements listed in the following steps assumes the meter is being tested after a one-hour warmup in an environment...

418 Setup

Before performing this type of calibration, make sure that computer interface connections are made to the Fluke 45. Then verify the ac power connection to the Fluke 45, and turn the meter on. For RS-232 interface operation, use the following procedure from the front panel 2. Use ( B or to scroll to the desired baud rate. Then press (auto) to select the displayed rate. 3. Use ( B or to scroll to the desired parity (E for even, Odd for odd, or no for none.) Then press (auto) to select the...

410 DC and AC Milliamp Calibration Front Panel

Perform the dc and ac milliamps calibration as follows 1. If the meter is already in calibration mode, press the ( B or button to select mA DC calibration. Otherwise, select calibration mode first (press Cal Enable button for three seconds), then select mA DC calibration by pressing the ( button twice. 2. Connect the dc milliamps source to the 100 mA and COM inputs. 3. Apply the dc milliamp outputs indicated in Table 4-5 (steps 18 and 19), and calibrate the meter with the A button. 4. Press the...

214 Power Supply Circuit Description

The Power Supply consists of the following three functional sections The Raw DC Supply converts line voltage (90 V to 264 V ac) to a dc output of 7.5 V The 5 V Switching Supply converts the Raw DC Supply output to 5.1 V 0.25 V dc. Using the 5 V Switching Supply output, the Inverter generates the -30 V dc, -5 V dc, and 5 V ac supply levels needed for the vacuum-fluorescent display. Also, the Inverter provides isolated positive and negative 5.25 V outputs for the in-guard circuitry. The Raw DC...

Multimeter Gmt-19a - Schematic Diagram

Tektronix 465 Interface Circuit Board

ALL RESI STANCE I S I N OHMS. 2. ALL CAPACI TANCE IS IN M CRO FARADS. Z1 < Z1 s Z1 < Z1 5 Z1 5 Z1 > 10K> 10K> 10K> 10K> 10K> 10K 1. PILL RESISTANCES ARE IN OHMS,1 8 UIFITT ,+ -5* . 2. PILL CAPACITANCES ARE IN MICROFARADS. Figure 9-3. A1A1 True rms PCA (cont) Figure 9-5. A5 IEEE-488 Interface PCA 1. ALL RESISTANCES ORE IN OHMS, 1 8LIATT , + -5x . 2. ALL CAPACITANCES ARE IN MICROFARADS. DRU m5fp nrfp m3rc norc ifc ifc ren ren gnd ucc 75161...

Option 01 Battery Pack

Cycle Float Charge Rate 7-5 7-7. Low Battery Indicator 7-5 7-9. Constant Voltage Trickle 7-6 7-16. Low Battery Indicator Detector and Low Battery Disconnect Test 7-10 7-17. Cycle Float Charge Rate Switch 7-10 The Fluke 45-01K Battery Kit is a field installable option that may be installed in the meter. The installation of the Battery Kit facilitates portable operation of the meter for typically eight hours. The Battery Pack Option PCA consists of the five functional blocks illustrated in...

421 The Calibration Procedure

Now select calibration mode on the Fluke 45. Using a thin, blunt-tipped object, press the recessed Cal Enable button for three seconds. Avoid using sharp objects that might damage this button. Refer to Table 4-8 for brief descriptions of calibration mode commands. The CALREF xxx.xx command tells the Fluke 45 to change the calibration prompt to the exact value of the input from the calibrator. Use of this command is equivalent to the act of editing the calibration prompt from the front panel...

515 Display Assembly Troubleshooting

Display A2ds1

The following discussion is helpful if it has been determined that the Display Assembly is faulty. This initial determination may not be arrived at easily, since an improperly operating display may be the result of a hardware or software problem that is not a direct functional part of the Display Assembly. Consult the General Troubleshooting Procedures found earlier in this chapter for procedures to isolate the fault to the Display Assembly. Use the following discussion of display software...

Theory of Operation

Functional Block Description 2-3 2-8. Serial Communication Guard Crossing 2-3 2-11. IEEE-488 Interface Option 2-5 2-7 2-11 2-12 2-15 2-15 2-15 2-15 2-33. Serial Communication Guard Crossing 2-18 2-19 2-19 2-20 2-21 2-46. Watchdog Timer and Reset 2-21 2-47. Display Controller with 2-22

7

Battery Pca 825885

Remove the two 6-32 x 1 4 panhead Phillips screws securing the Battery Pack Option see Figure 7-4 . 5. Carefully slide the Battery Pack Option out of the meter as shown in Figure 7-4 . Do not pinch the wires running from the circuit board to the battery terminals. To prevent damage to the meter when servicing the Main PCA, unplug the battery pack ribbon cable at the Main PCA or disconnect the wires to the battery pack. Use the following instructions to install the Battery Kit Option. Refer...

Option 05IEEE488 Interface

Removing the IEEE-488 Interface 8-8 8-12. Installing the IEEE-488 Interface 8-9 8-17. Failure to Select IEEE-488 Interface Option 8-10 8-18. Failure to Handshake on IEEE-488 8-11 8-20. Failure to Receive Multiple Character Commands 8-12 8-21. Failure to Transmit Query 8-12 8-22. Failure to Generate an End or Identify EOI 8-12 8-23. Failure to Generate a Service Request SRQ 8-12 The IEEE-488 Interface turns the Fluke 45 into a fully programmable instrument for use with the IEEE Standard...

53 Error Codes

Wiring Connection Fluke 2680a

At reset, the Fluke 45 software attempts power-up self-tests and initialization of ROM, RAM, Display, EEROM, and measurement hardware. Self-test failures are reported on the display with error in the secondary display and an error code 1-9 in the primary display. Several of these error codes might never be displayed. Certainly, errors 4 and 5, which signify a faulty or dead display, could not be reported in the normal displayed manner. Other errors might not appear on the display. Therefore,...

Fluke 45 848205

Fluke Service Manual

The following pages give detailed listings of Fluke 45 parts. This instrument may contain a Nickel-Cadmium battery. Do not mix with the solid waste stream. Spent batteries should be disposed of by a qualified recycler or hazardous materials handler. Contact your authorized Fluke service center for recycling information. CONN ACC,D-SUB,FEMALE SCREWLOCK,.250 CABLE ASSY,FLAT,20 COND,MICROMOD,2 IN CORD,LINE,5-15 IEC,3-18AWG,SVT,7.5 FT 1. For 250 V order part number 769422. SOCKET,IC,28 PIN,DUAL...

List of Figures

Analog Simplified Schematic 2-3. DC Volts 300 V Range Simplified 2-4. Ohms Simplified 2-5. AC Buffer Simplified 2-6. DC mA and Amps Simplified 2-7. Active Filter Simplified 2-8. A D Converter Simplified Schematic 2-9. Command Byte Transfer 2-10. Grid Control Signal 2-11. Grid-Anode Timing 3-1. Replacing the Line Fuse 3-2. Replacing the External 100 mA Input Fuse 3-3. Removing the Case 3-4. Removing the Handle and Handle Mounting 3-5. Assembly 4-1. Four Wire...