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Dual Display Multimeter

45

Service Manual
For IEC 1010 Meters Only

PN 609203 March 1999
1999 Fluke Corporation, All rights reserved. Printed in U.S.A. All product names are trademarks of their respective companies.

LIMITED WARRANTY & LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and workmanship under normal use and service. The warranty period is one year and begins on the date of shipment. Parts, product repairs and services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of a Fluke authorized reseller, and does not apply to fuses, disposable batteries or to any product which, in Fluke's opinion, has been misused, altered, neglected or damaged by accident or abnormal conditions of operation or handling. Fluke warrants that software will operate substantially in accordance with its functional specifications for 90 days and that it has been properly recorded on non-defective media. Fluke does not warrant that software will be error free or operate without interruption. Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is available if product is purchased through a Fluke authorized sales outlet or Buyer has paid the applicable international price. Fluke reserves the right to invoice Buyer for importation costs of repair/replacement parts when product purchased in one country is submitted for repair in another country. Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair, or replacement of a defective product which is returned to a Fluke authorized service center within the warranty period. To obtain warranty service, contact your nearest Fluke authorized service center or send the product, with a description of the difficulty, postage and insurance prepaid (FOB Destination), to the nearest Fluke authorized service center. Fluke assumes no risk for damage in transit. Following warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke determines that the failure was caused by misuse, alteration, accident or abnormal condition of operation or handling, Fluke will provide an estimate of repair costs and obtain authorization before commencing the work. Following repair, the product will be returned to the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges (FOB Shipping Point).
THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, WHETHER ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT, TORT, RELIANCE OR ANY OTHER THEORY.

Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court of competent jurisdiction, such holding will not affect the validity or enforceability of any other provision. To locate an authorized service center, visit us on the World Wide Web: www.fluke.com or call Fluke using the phone numbers listed below: USA and Canada: 1-888-99-FLUKE (1-888-993-5853) Europe: +31 402-678-200 Japan: +81-3-3434-0181 Singapore: +65-738-5655 Anywhere in the world: +1-425-356-5500 Fluke Corporation P.O. Box 9090 Everett, WA 98206-9090 U.S.A.
5/94

Fluke Europe B.V. P.O. Box 1186 5602 BD Eindhoven The Netherlands

Table of Contents

Chapter 1

Title

Page

Introduction and Specifications ........................................................... 1-1 1-1. 1-2. 1-3. 1-4. 1-5. 1-6. Introduction ............................................................................................ Operating Instructions............................................................................. Options and Accessories ......................................................................... Organization of the Service Manual ....................................................... Conventions ............................................................................................ Specifications.......................................................................................... 1-3 1-3 1-3 1-4 1-5 1-6

2

Theory of Operation .............................................................................. 2-1 2-1. 2-2. 2-3. 2-4. 2-5. 2-6. 2-7. 2-8. 2-9. 2-10. 2-11. 2-12. 2-13. 2-14. 2-15. 2-16. 2-17. 2-18. 2-19. 2-20. 2-21. 2-22. 2-23. 2-24. 2-25. Introduction ............................................................................................ Functional Block Description ................................................................. Power Supply ..................................................................................... Analog Measurement Processor ......................................................... Input Protection Circuit ...................................................................... Input Signal Conditioning .................................................................. Analog-to-Digital (A/D) Converter .................................................... Serial Communication (Guard Crossing) ........................................... Digital Kernel ..................................................................................... Display Assembly............................................................................... IEEE-488 Interface Option (-05)........................................................ Battery Pack Option (-01) .................................................................. Detailed Circuit Description ................................................................... Power Supply Circuit Description ...................................................... Raw DC Supply ............................................................................. 5-Volt Switching Supply................................................................ Inverter........................................................................................... Analog Measurement Processor ......................................................... Input Protection .................................................................................. Input Signal Conditioning .................................................................. Relays............................................................................................. DC Volts ........................................................................................ Ohms .............................................................................................. 100 M and 300 M Ranges ........................................................ AC Volts ........................................................................................
i

2-3 2-3 2-3 2-3 2-3 2-3 2-3 2-3 2-5 2-5 2-5 2-5 2-5 2-5 2-6 2-6 2-7 2-7 2-10 2-10 2-11 2-12 2-12 2-14 2-14

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2-26. 2-27. 2-28. 2-29. 2-30. 2-31. 2-32. 2-33. 2-34. 2-35. 2-36. 2-37. 2-38. 2-39. 2-40. 2-41. 2-42. 2-43. 2-44. 2-45. 2-46. 2-47. 3

DCmA ............................................................................................ ACmA ............................................................................................ Amps .............................................................................................. Diode/Continuity Test.................................................................... Frequency....................................................................................... Active Filter........................................................................................ A/D Converter .................................................................................... Serial Communication (Guard Crossing) ........................................... Digital Kernel ..................................................................................... RS-232 Interface ............................................................................ Microprocessor............................................................................... EEROM.......................................................................................... RAM .............................................................................................. ROM .............................................................................................. IEEE-488 Option Connections....................................................... Display Assembly............................................................................... Main Assembly Connector............................................................. Front Panel Switches...................................................................... Display ........................................................................................... Beeper Drive Circuit ...................................................................... Watchdog Timer and Reset Circuit ................................................ Display Controller with FIP ...........................................................

2-15 2-15 2-15 2-15 2-15 2-16 2-17 2-18 2-18 2-19 2-19 2-19 2-20 2-20 2-20 2-20 2-20 2-20 2-21 2-21 2-21 2-22

General Maintenance............................................................................. 3-1 3-1. 3-2. 3-3. 3-4. 3-5. 3-6. 3-7. 3-8. 3-9. 3-10. 3-11. 3-12. 3-13. 3-14. 3-15. 3-16. 3-17. 3-18. 3-19. 3-20. 3-21. 3-22. 3-23. 3-24. 3-25. 3-26. 3-27. 3-28. 3-29. 3-30. Introduction ............................................................................................ Warranty Repairs and Shipping Information .......................................... General Maintenance Information .......................................................... Required Equipment........................................................................... Power Requirements........................................................................... Static Safe Handling ........................................................................... Cleaning.................................................................................................. Fuse Test and Replacement .................................................................... Line Fuse ............................................................................................ Current Input Fuses ............................................................................ Testing Current Input Fuses ........................................................... Replacing the 500 mA and 440 mA Input Fuses (F1 and F5) ........ Replacing the 10 A Input Jack Fuse (F2) ....................................... Disassembly Procedures ......................................................................... Remove the Meter Case...................................................................... Remove Handle and Mounting Brackets ............................................ Remove the Front Panel Assembly..................................................... Remove the Display PCA................................................................... Remove the IEEE-488 Option............................................................ Remove the Main PCA....................................................................... Remove the Analog Measurement Processor Shields ........................ Remove the Rms PCA........................................................................ Remove the Battery Option ................................................................ Disconnect Miscellaneous Chassis Components ................................ Assembly Procedures.............................................................................. Install Miscellaneous Chassis Components ........................................ Install the Battery Option ................................................................... Install the Rms PCA ........................................................................... Install the Analog Measurement Processor Shields............................ Install the Main PCA ..........................................................................
ii

3-3 3-3 3-3 3-3 3-3 3-3 3-4 3-4 3-4 3-4 3-4 3-5 3-6 3-7 3-7 3-7 3-8 3-8 3-9 3-9 3-9 3-10 3-10 3-10 3-10 3-10 3-11 3-11 3-11 3-11

Contents (continued)

3-31. 3-32. 3-33. 3-34. 3-35. 4

Install the IEEE-488 Option ............................................................... Assemble the Front Panel Assembly .................................................. Install the Front Panel Assembly........................................................ Install the Handle and Mounting Brackets ......................................... Install the Meter Case.........................................................................

3-12 3-12 3-15 3-15 3-15

Performance Testing and Calibration.................................................. 4-1 4-1. 4-2. 4-3. 4-4. 4-5. 4-6. 4-7. 4-8. 4-9. 4-10. 4-11. 4-12. 4-13. 4-14. 4-15. 4-16. 4-17. 4-18. 4-19. 4-20. 4-21. 4-22. 4-23. 4-24. 4-25. 4-26. 4-27. 4-28. 4-29. 4-30. Introduction ............................................................................................ Required Equipment ............................................................................... Performance Tests .................................................................................. Front Panel Calibration........................................................................... Introduction ........................................................................................ Entering Calibration Mode ................................................................. Exiting Calibration Mode ................................................................... DC Volts Calibration (Front Panel).................................................... AC Volts Calibration (Front Panel).................................................... DC and AC Milliamp Calibration (Front Panel) ................................ DC and AC Amps Calibration (Front Panel)...................................... Ohms Calibration (Front Panel) ......................................................... Alternate Ohms Calibration (Front Panel).......................................... Continuity/Hysteresis Threshold Calibration (Front Panel) ............... Frequency Calibration (Front Panel) .................................................. Editing the Prompt for Different Calibration Points........................... Calibration Using the Computer Interface .............................................. Setup................................................................................................... RS-232 Interface ............................................................................ IEEE-488 Interface ........................................................................ The Calibration Procedure.................................................................. DC Volts Calibration (Computer Interface) ....................................... AC Volts Calibration (Computer Interface) ....................................... DC and AC Milliamps Calibration (Computer Interface) .................. DC and AC Amps Calibration (Computer Interface) ......................... Ohms Calibration (Computer Interface) ............................................. Continuity/Hysteresis Threshold Calibration (Computer Interface)... Frequency Calibration (Computer Interface)...................................... Concluding Calibration Using the Computer Interface ...................... Alternate Ohms Calibration (Computer Interface) ............................. 4-3 4-3 4-4 4-7 4-7 4-8 4-9 4-9 4-9 4-9 4-11 4-11 4-13 4-13 4-13 4-13 4-14 4-14 4-14 4-15 4-17 4-18 4-18 4-18 4-18 4-18 4-19 4-19 4-19 4-19

5

Diagnostic Testing and Troubleshooting............................................ 5-1 5-1. 5-2. 5-3. 5-4. 5-5. 5-6. 5-7. 5-8. 5-9. 5-10. 5-11. 5-12. 5-13. 5-14. Introduction ............................................................................................ Servicing Surface-Mount Assemblies..................................................... Error Codes............................................................................................. General Troubleshooting Procedures...................................................... Power Supply Troubleshooting .......................................................... Raw DC Supply ............................................................................. 5-Volt Switching Supply................................................................ Inverter........................................................................................... Analog Troubleshooting..................................................................... Uart Test......................................................................................... DC Volts Troubleshooting ............................................................. AC Volts Troubleshooting ............................................................. Ohms Troubleshooting................................................................... Digital Troubleshooting..........................................................................
iii

5-3 5-3 5-4 5-10 5-10 5-10 5-11 5-12 5-13 5-13 5-14 5-14 5-14 5-15

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5-15. 5-16. 5-17. 5-18. 5-19. 5-20. 5-21. 6

Display Assembly Troubleshooting........................................................ Calibration Failures ................................................................................ Introduction ........................................................................................ Calibration-Related Components........................................................ Calibration Interrelationships ............................................................. Retrieving Calibration Constants........................................................ Replacing the EEROM A1U5 ............................................................

5-17 5-19 5-19 5-20 5-21 5-21 5-21

List of Replaceable Parts ...................................................................... 6-1 6-1. 6-2. 6-3. 6-4. 6-5. 6-6. Introduction ............................................................................................ How to Obtain Parts................................................................................ How to Contact Fluke ............................................................................. Manual Status Information ..................................................................... Newer Instruments.................................................................................. Parts ........................................................................................................ 6-3 6-3 6-4 6-4 6-4 6-4

7

Option -01 Battery Pack ........................................................................ 7-1 7-1. 7-2. 7-3. 7-4. 7-5. 7-6. 7-7. 7-8. 7-9. 7-10. 7-11. 7-12. 7-13. 7-14. 7-15. 7-16. 7-17. 7-18. 7-19. 7-20. 7-21. 7-22. Introduction ............................................................................................ Specifications.......................................................................................... Theory of Operation ............................................................................... Functional Block Description............................................................. Switching Power Supply ................................................................ Cycle/Float Charge Rate Switch .................................................... Low Battery Indicator Detector...................................................... Low Battery Disconnect................................................................. Constant Voltage Trickle Charger.................................................. Other Circuits................................................................................. General Maintenance .............................................................................. Removal ............................................................................................. Installation .......................................................................................... Performance Testing ............................................................................... General Operability ............................................................................ Low Battery Indicator Detector and Low Battery Disconnect Test.... Cycle/Float Charge Rate Switch Test................................................. Calibration .............................................................................................. Troubleshooting...................................................................................... Additional Tests...................................................................................... Schematic Diagram................................................................................. List of Replaceable Parts ........................................................................ 7-3 7-3 7-3 7-3 7-5 7-5 7-5 7-5 7-6 7-6 7-6 7-6 7-7 7-9 7-9 7-10 7-10 7-12 7-13 7-14 7-14 7-14

8

Option -05 IEEE-488 Interface............................................................... 8-1 8-1. 8-2. 8-3. 8-4. 8-5. 8-6. 8-7. 8-8. 8-9. 8-10. 8-11. 8-12. Introduction ............................................................................................ Theory of Operation ............................................................................... Functional Block Description............................................................. Detailed Circuit Description............................................................... Main Assembly Connectors ........................................................... Address Decoding Circuit .............................................................. Isolation Circuits ............................................................................ IEEE-488 Controller ...................................................................... IEEE-488 Transceivers/Connector................................................. General Maintenance .............................................................................. Removing the IEEE-488 Interface Option ......................................... Installing the IEEE-488 Interface Option ...........................................
iv

8-3 8-3 8-3 8-3 8-3 8-3 8-4 8-4 8-5 8-8 8-8 8-9

Contents (continued)

8-13. 8-14. 8-15. 8-16. 8-17. 8-18. 8-19. 8-20. 8-21. 8-22. 8-23. 8-24. 8-25. 9

Performance Testing ............................................................................... Troubleshooting...................................................................................... Power-up Problems ............................................................................ Communication Problems .................................................................. Failure to Select IEEE-488 Interface Option ................................. Failure to Handshake on IEEE-488 Bus......................................... Failure to Enter Remote ................................................................. Failure to Receive Multiple Character Commands ........................ Failure to Transmit Query Responses ............................................ Failure to Generate an End or Identify (EOI)................................. Failure to Generate a Service Request (SRQ) ................................ Schematic Diagram................................................................................. List of Replaceable Parts ........................................................................

8-9 8-10 8-10 8-10 8-10 8-11 8-11 8-12 8-12 8-12 8-12 8-12 8-12

Schematic Diagrams ............................................................................. 9-1 Index

v

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vi

List of Tables

Table 1-1. 2-1. 2-2. 2-3. 2-4. 2-5. 2-6. 3-1. 4-1. 4-2. 4-3. 4-4. 4-5. 4-6. 4-7. 4-8. 4-9. 5-1. 5-2. 5-3. 5-4. 5-5. 5-6. 5-7. 5-8. 5-9. 6-1. 6-2. 6-3. 6-4. 6-5. 7-1. 7-2. 8-1. 8-2.

Title Accessories ............................................................................................................. Analog Measurement Processor Pin Name Description.......................................... Relay Operation ...................................................................................................... Reference Resistance .............................................................................................. AC Volts Input Signal Dividers .............................................................................. Front Panel Switch Scanning .................................................................................. Display Initialization Modes ................................................................................... Fuses ....................................................................................................................... Recommended Test Equipment .............................................................................. Performance Tests for Volts, Diode Test, Ohms, and Frequency Functions........... Performance Tests for mA Current Functions ........................................................ Performance Tests for Current Functions ............................................................... Front Panel Calibration ........................................................................................... Specifications Increase with Different Calibration Points ...................................... Calibration Using the Computer Interface .............................................................. Calibration Mode Computer Interface Commands ................................................. EEROM Calibration Constants ............................................................................... Error Codes ............................................................................................................. Power Supplies........................................................................................................ DC Volts Troubleshooting ...................................................................................... AC Volts Troubleshooting ...................................................................................... Display Initialization............................................................................................... Calibration Steps and Related Components ............................................................ Components Unique to Calibration Steps ............................................................... Calibration Hierarchy.............................................................................................. Calibration Constants .............................................................................................. Manual Status Information...................................................................................... Final Assembly ....................................................................................................... A1 Main PCA ......................................................................................................... A1A1 True Rms PCA ............................................................................................. A2 Display PCA ..................................................................................................... Option -01 Battery Pack Final Assembly................................................................ A4 Battery Pack PCA ............................................................................................. IEEE-488 Transceiver Control................................................................................ Option -05 IEEE - 488 Interface Final Assembly ...................................................
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Page 1-4 2-9 2-11 2-13 2-14 2-21 2-23 3-6 4-3 4-5 4-7 4-7 4-10 4-14 4-16 4-20 4-21 5-5 5-11 5-14 5-15 5-18 5-22 5-23 5-24 5-24 6-4 6-5 6-8 6-12 6-13 7-15 7-16 8-6 8-13

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Service Manual

8-3.

A5 IEEE-488 Interface PCA................................................................................... 8-14

viii

List of Figures

Figure 2-1. 2-2. 2-3. 2-4. 2-5. 2-6. 2-7. 2-8. 2-9. 2-10. 2-11. 3-1. 3-2. 3-3. 3-4. 3-5. 4-1. 5-1. 5-2. 5-3. 5-4. 5-5. 5-6. 6-1. 6-2. 6-3. 6-4. 7-1. 7-2. 7-3. 7-4. 7-5. 7-6. 7-7. 7-8.

Title Overall Functional Block Diagram ......................................................................... Analog Simplified Schematic Diagram................................................................... DC Volts 300 V Range Simplified Schematic ........................................................ Ohms Simplified Schematic.................................................................................... AC Buffer Simplified Schematic ............................................................................ DC mA and Amps Simplified Schematic................................................................ Active Filter Simplified Schematic ......................................................................... A/D Converter Simplified Schematic ..................................................................... Command Byte Transfer Waveforms ..................................................................... Grid Control Signal Timing .................................................................................... Grid-Anode Timing Relationships .......................................................................... Replacing the Line Fuse (F3).................................................................................. Replacing the External 100 mA Input Fuse (F1) .................................................... Removing the Case ................................................................................................. Removing the Handle and Handle Mounting Brackets ........................................... Assembly Details .................................................................................................... Four Wire Configuration......................................................................................... Test Point Locator................................................................................................... Volt Switching Supply ............................................................................................ Main Processor Timing ........................................................................................... Display Controller to Microprocessor Signals ........................................................ Primary Display ...................................................................................................... Secondary Display .................................................................................................. Final Assembly ....................................................................................................... A1 Main PCA ......................................................................................................... A1A1 True Rms PCA ............................................................................................. A2 Display PCA ..................................................................................................... Battery Pack Option Functional Block Diagram..................................................... Removing the Case ................................................................................................. Installing the Battery Kit......................................................................................... Battery Pack Option Connecting Cable................................................................... Cycle/Float Charge Rate Switch Test ..................................................................... Unplugging the Battery Pack Connectors ............................................................... Test Points and Adjustments................................................................................... Option-01 Battery Pack Final Assembly.................................................................
ix

Page 2-4 2-8 2-12 2-13 2-14 2-16 2-17 2-18 2-23 2-24 2-24 3-5 3-6 3-7 3-8 3-13 4-12 5-6 5-12 5-16 5-17 5-18 5-18 6-6 6-11 6-12 6-14 7-4 7-7 7-8 7-9 7-11 7-13 7-14 7-15

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7-9. 8-1. 8-2. 8-3. 8-4. 8-5. 8-6. 9-1. 9-2. 9-3. 9-4. 9-5. 9-6.

A4 Battery Pack PCA ............................................................................................. Disassembly ............................................................................................................ IEEE-488 Interface Connector................................................................................ IEEE-488 Module Assembly .................................................................................. IEEE-488 Interface Performance Test .................................................................... Option -05 IEEE-488 Interface Final Assembly ..................................................... A5 IEEE-488 Interface PCA................................................................................... A1 Main PCA ......................................................................................................... A1 Main PCA ......................................................................................................... A2 Display PCA ..................................................................................................... A1A1 True Rms PCA ............................................................................................. A4 Battery PCA ...................................................................................................... A5 IEEE-488 Interface PCA...................................................................................

7-18 8-6 8-7 8-8 8-10 8-13 8-15 9-2 9-2 9-8 9-10 9-12 9-14

x

Chapter 1

Introduction and Specifications

Title 1-1. 1-2. 1-3. 1-4. 1-5. 1-6. Introduction ............................................................................................ Operating Instructions............................................................................. Options and Accessories ......................................................................... Organization of the Service Manual ....................................................... Conventions ............................................................................................ Specifications..........................................................................................

Page 1-3 1-3 1-3 1-4 1-5 1-6

1-1

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Service Manual

1-2

Introduction and Specifications Introduction

1

1-1. Introduction
The Fluke 45 Dual Display Multimeter (also referred to as "the meter") is a 4-1/2-digit (30,000-count) meter with a 5-digit (100,000-count) high resolution mode designed for bench-top, field service, and system applications. The meter uses a dual vacuumfluorescent display, allowing for two types of readings from a single input. Primary and secondary displays show the user-defined readings side by side. Even though the readings are made sequentially, the displays show both readings at all times for ease of comparison. Some features provided by the meter are: Computer interface operation via the RS-232 interface (included) or the IEEE-488 interface (optional). The meter is fully programmable for use on the IEEE Standard 488.1 (1987). The meter is also designed in compliance with supplemental standard IEEE-488.2 (1987). True rms ac (AC + DC) rms, calculated Frequency measurements to greater than 1 MHz. 1 V sensitivity in volts dc Decibels with variable reference impedance and audio power measurement capability. A compare mode to determine if a measurement is within, above, or below a designated range. 100,000, 30,000, and 3,000 selectable count resolution, with reading speeds of 2.5, 5, and 20 readings per second (rps), respectively. Built-in self-tests with closed-case calibration (no internal adjustments).



1-2. Operating Instructions
Full operating instructions are provided in the Fluke 45 Users Manual. Reference to these instructions may be necessary during some of the maintenance and repair procedures presented in this Service Manual. For quick references, an operating instruction summary is presented on the inside of the front cover of the Service Manual. For more detailed information, refer to the Users Manual.

1-3. Options and Accessories
Three options are available. 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 50C. The IEEE-488 Interface Kit (Option -05K) consists of a printed circuit assembly, connecting cables, and mounting hardware. This option provides full programmability, external trigger input, and automated calibration. The IEEE-488 computer interface command set is identical to the RS-232 interface commands wherever possible. Option -15K combines Options -01K and -05K as a single kit.
1-3





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Service Manual

The Fluke 45 Dual Display Multimeter can be mounted in a standard 19-inch rack panel on either the right-hand or left-hand side using the Fluke M00-200-634 Rack Mount Kit. Accessories for the Fluke 45 are listed in Table 1-1.
Table 1-1. Accessories Model C40 M00-200634 RS40 Description Soft carrying case. Provides padded protection for the meter. Includes a pocket for the manual and pouch for the test leads and line cord. Rackmount Kit. Allows meter to be mounted on either the right or left side of a standard 19-inch rack. RS-232 terminal interface cable. Connects other Fluke 45 to any terminal or printer with properly configured DTE connector (DB-25, female pins), including an IBM PC, IBM PC/XT or IBM PS/2 (models 25, 30, 50, P60, 70, and 80). RS-232 modem cable. Connects the Fluke 45 to a modem. QuickStartTM, a PC software package, simplifies operation of the Fluke 45 when using the RS-232 computer interface. Readings are recorded in files that can be accessed by Lotus 1-2-3, dBase III and other graphics packages. Shielded IEEE-488 one-meter (39.4 inches) cable, with plug and jack at each end. Shielded IEEE-488 two-meter (78.8 inches) cable, with plug and jack at each end. Shielded IEEE-488 four-meter (13 feet) cable, with plug and jack at each end.

RS41 S45

Y8021 Y8022 Y8023

QuickStart 45 is a trademark of Fluke Corporation. Lotus is a registered trademark of Lotus Development Co. dBase III is a registered trademark of Ashton-Tate. IBM PC and IBM PC/XT are registered trademarks of International Business Machines.

1-4. 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 manual. A comprehensive table of contents is presented at the front of the manual; local tables of contents are also presented at the beginning of each chapter for ease of reference. If you know the topic name, the index at the end of the manual is probably a good place to start. The following chapter descriptions serve to introduce the manual:

Chapter 1. Introduction and Specifications Introduces the Fluke 45 Dual Display Multimeter, describing its features, options, and accessories. This chapter also discusses use of the Service Manual and the various conventions used in describing the meter's circuitry. Finally, a complete set of specifications is presented.

1-4

Introduction and Specifications Conventions

1

Chapter 2. Theory of Operation This chapter first categorizes meter circuitry into functional blocks, with a description of each block's role in overall operation. A detailed circuit description is then given for each block. These descriptions explore operation to the component level and fully support troubleshooting procedures defined in Chapter 5. Chapter 3. General Maintenance Provides maintenance information covering handling, cleaning, and fuse replacement. Access and reassembly procedures are also explained in this chapter. Chapter 4. Performance Testing and Calibration This chapter provides performance verification procedures that are tied to the specifications presented in Chapter 1. To maintain these specifications, a full calibration procedure is also presented. Chapter 5. Diagnostic Testing and Troubleshooting The troubleshooting procedures presented in this chapter rely closely on both the Theory of Operation presented in Chapter 2 and the Schematic Diagrams shown in Chapter 9. Chapter 3 provides access information. Chapter 6. List of Replaceable Parts Includes parts lists for all standard assemblies. Information on how and where to order parts is also provided. Chapter 7. Option -01 Battery Pack Each option is allocated a separate chapter: 7 for the Battery Pack Option -01 and 8 for the IEEE-488 Interface Option -05. Option -15 incorporates both Options -01 and -05. Chapter 7 includes the full range of Service Manual topics (specifications, theory of operation, maintenance, list of replaceable parts, etc.) for the Battery Pack option. Schematic diagrams for the options are found in Chapter 9. Chapter 8. Option -05 IEEE-488 Interface Includes the full range of Service Manual topics (specifications, theory of operation, maintenance, list of replaceable parts, etc.) for the IEEE-488 Interface option. Schematic diagrams for the options are found in Chapter 9. Chapter 9. Schematic Diagrams Includes schematic diagrams for all standard and optional assemblies. A list of mnemonic definitions is also included to aid in identifying signal name abbreviations.

1-5. Conventions
Throughout the manual set, certain notational conventions are used. A summary of these conventions follows: Instrument Reference The Fluke 45 Dual Display Multimeter is usually called the "meter." Printed Circuit Assembly

1-5

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The term "pca" is used to represent a printed circuit assembly and its attached parts. Signal Logic Polarity On schematic diagrams, a signal name followed by a "*" is active (or asserted) low. Signals not so marked are active high. Circuit Nodes Individual pins or connections on a component are specified with a dash (-) following the component reference designator. For example, pin 19 of U30 would be U30-19. User Notation For front panel operation, XXX An uppercase word or symbol without parentheses indicates a button to be pressed by the user. Buttons can be pressed in four ways: 1. Press a single button to select a function or operation. 2. Press a combination of buttons, one after the other. 3. Press and hold down a button, then press another button. 4. Press multiple buttons simultaneously. For computer interface operation, XXX (xxx) An uppercase word without parentheses identifies a command by name. Angle brackets around all uppercase letters mean press the key. When associated with a keyword, a lowercase word in parentheses indicates an input required by the user.

1-6. Specifications
The following contains the specifications for the Fluke 45 Dual Display Multimeter. These specifications assume: A 1-year calibration cycle An operating temperature of 18 to 28C Relative humidity not exceeding 90% (non-condensing)

Accuracy is expressed as (percentage of reading + counts).

Reading Rates and Display Counts
Rate Slow Medium Fast * Ohms full range will typically be 98,000 counts Readings per Second 2.5 5 20 Full Range Display Counts 99,999* 30,000 3,000

1-6

Introduction and Specifications Specifications

1

Response Times Refer to Chapter 4 of the Users Manual for detailed information. DC Voltage
Resolution Range 300 mV 3V 30 V 300 V 1000 V 100 mV 1000 mV 10 V 100 V 1000 V -1 V 10 V 100 V 1 mV 10 mV Slow Medium 10 V 100 V 1 mV 10 mV 100 mV Fast 100 V 1 mV 10 mV 100 mV 1V Accuracy (6 months) 0.02% + 2 0.02% + 2 0.02% + 2 0.02% + 2 0.02% + 2 0.02% + 6 0.02% + 6 0.02% + 6 0.02% + 6 0.02% + 6 (1 year) 0.025%+2 0.025% +2 0.025%+2 0.025% +2 0.025%+2 0.025%+6 0.025% +6 0.025%+6 0.025% +6 0.025%+6

Input Impedance 10 M in parallel with <100 pF
Note In the dual display mode, when the volts ac and volts dc functions are selected, the 10 M dc input divider is in parallel with the 1 M ac divider.

Normal Mode Rejection Ratio >80 dB at 50 or 60 Hz, slow and medium rates >54 dB for frequencies between 50-440 Hz, slow and medium rates >60 dB at 50 Hz, fast rate (Note: Fast rate has no filtering) Maximum Allowable AC Voltage While Measuring DC Voltage
Peak Normal Mode Signal Range 300 mV 3V 30 V 300 V 1000 V Max Allowable Peak AC Voltage 100 mV 1000 mV 10 V 100 V 1000 V 20 V 20 V 1000 V 1000 V 1000 V NMRR* >80dB** 15 V 15 V 50 V 50 V 200 V NMRR >60 dB** 15 V 15 V 300 V 300 V 1000 V

* NMRR is the Normal Mode Rejection Ratio ** Normal Mode Rejection Ratio at 50 or 60 Hz 0.1%

Common Mode Rejection Ratio >90 dB at dc, 50 or 60 Hz, (1 k unbalanced, medium and slow rates)
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Maximum Functional Input 1000 V dc or peak ac on any range True Rms AC Voltage, AC-Coupled
Range Slow 300 mV 3V 30 V 300 V 750 V Resolution Medium 10 V 100 V 1 mV 10 mV 100 mV Fast 100 V 1 mV 10 mV 100 mV 1V

100 mV 1000 mV 10 V 100 V 750 V

1 V 10 V 100 V 1 mV 10 mV

-

-

Accuracy
Max Input at Upper Freq

Frequency Slow 20-50 Hz 50 Hz -10 kHz 10 - 20 kHz 20 - 50 kHz 50 - 100 kHz 1% + 100

Linear Accuracy Medium 1% + 10 0.2% + 10 0.5% + 10 2% + 20 5% + 50 Fast 7% + 2 0.5% + 2 0.5% + 2 2% + 3 5% + 6

dB Accuracy Slow/Med 0.15 0.08 0.11 0.29 0.70 Fast 0.72 0.17 0.17 0.34 0.78

Power*

2% + 10

750 V

0.2% + 100 0.5% + 100 2% + 200 5% + 500

0.4% + 10 750 V 1% + 10 4% + 20 10% + 50 750 V 400 V 200 V

* Error in power mode will not exceed twice the linear accuracy specification

Accuracy specifications apply within the following limits, based on reading rate: Slow Reading Rate: Medium Reading Rate: Fast Reading Rate: Between 15,000 and 99,999 counts (full range) Between 1,500 and 30,000 counts (full range) Between 150 and 3,000 counts (full range)

Decibel Resolution
Resolution Slow & Medium 0.01 dB Fast 0.1 dB

1-8

Introduction and Specifications Specifications

1

Input Impedance 1 M in parallel with <100 pF Maximum Crest Factor 3.0 Common Mode Rejection Ratio >60 dB at 50 or 60 Hz (1 k unbalanced medium rate) Maximum Input 750 V rms, 1000 V peak
2 x 107 Volt-Hertz product on any range, normal mode input 1 x 106 Volt-Hertz product on any range, common mode input

(AC + DC) Voltage Accuracy Total Measurement Error will not exceed the sum of the separate ac and dc accuracy specifications, plus 1 display count. Refer to the table under "Maximum Allowable AC Voltage While Measuring DC Voltage or (AC + DC) Voltage" located on page 1-6.
Note When measuring AC + DC, (or any dual display combination of AC and DC) in the fast reading rate, the Fluke 45 may show significant reading errors. This results from a lack of filtering on the DC portion of the measurement for the fast reading rate. To avoid this problem, use only the "slow" and "medium" reading rates for AC + DC or AC and DC combinations.

Maximum Frequency of AC Voltage Input While Measuring AC Current When the meter makes ac current and ac voltage measurements using the dual display, the maximum frequency of the voltage input is limited to the maximum frequency of the current function. For example, if you are making an ac current measurement on the 10 A range, the maximum frequency of the voltage input must be less than 2 kHz. DC Current
Range Slow 30 mA 100 mA 10 A 10 mA 100 mA 10 A *Typical at full range 100 nA 1 A 100 A Resolution Medium 1 A 10 A 1 mA Fast 10 A 100 A 10 mA Accuracy 0.05% + 3 0.05% + 2 0.2% + 5 .05% + 15 0.05% + 5 0.2% + 7 Burden Voltage* 0.45 V 1.4 V 0.25 V 0.14 V 1.4 V 0.25 V

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Maximum Input mA 300 mA dc or ac rms. Protected with a 500 mA, 250 V, IEC 127-sheet I, fast blow fuse and a 440 mA, 1000 V, fast blow fuse.
A 10 A dc ac rms continuous, or 20 A dc or ac rms for 30 seconds maximum. protected with a 11 A, 1000 V, 17,000 A interrupt rating, fast blow fuse. Note Resistance between the COM binding post and the meter's internal measuring circuits is approximately .003

AC Current
Resolution Range 10 mA 30 mA 100 mA 10 A * Typical at full range Slow 100 A 1 A 100 A Medium 1 A 10 A 1 mA 10 A 100 A 10 mA Fast Burden Voltage* 0.14 V 0.45 V 1.4 V 0.25 V

Accuracy
Accuracy Range mA (To 100 mA) mA (To 100 mA) mA (To 100 mA) A (1-10 A) A (1 - 10 A) A (0.5 to 1 A) A (0.5 to 1 A) Frequency 20-50 Hz 50 Hz - 10 kHz 10 - 20 kHz 20 - 50 Hz 50 Hz - 2 kHz 20 - 50 Hz 50 Hz - 2 kHz Slow 2% + 100 0.5% + 100 2% + 200 2% + 100 1% + 100 2% + 300 1% + 300 Medium 2% + 10 0.5% + 10 2% + 20 2% + 10 1% + 10 2% + 30 1% + 30 Fast 7% + 2 0.8% + 2 2% + 3 7% + 2 1.3% + 2 7% + 4 1.3% + 4

mA accuracy specifications apply within the following limits, based on reading rate: Slow Reading Rate: Between 15,000 and 99,999 counts (full range) Medium Reading Rate: Between 1,500 and 30,000 counts (full range) Fast Reading Rate: Between 150 and 3,000 counts (full range)

1-10

Introduction and Specifications Specifications

1

Maximum Crest Factor 3.0 Maximum Input mA 300 mA dc or ac rms. Protected with a 500 mA, 250 V, IEC 127-sheet I, fast blow fuse and a 440 mA, 1000 V, fast blow fuse.
A 10 A dc or ac rms continuous, or 20 A dc or ac rms for 30 seconds maximum. Protected with a 11 A, 1000 V, 17,000 A interrupt rating, fast blow fuse. Note Resistance between the COM binding post and the meter's internal measuring circuits is approximately .003 .

Ohms
Range Slow 300 3 k 30 k 300 k 3 M 30 M 300 M* 100 1000 10 k 100 k 1000 k 10 M 100 M 1 m 10 m 100 m 1 10 100 100 k Resolution Medium 10 m 100 m 1 10 100 1 k 100 k Fast 100 m 1 10 100 1 k 2% 1 M 0.05% + 2 + 0.02 0.05% + 2 0.05% + 2 0.05% + 2 0.06% + 2 0.25% + 3 2% 0.05% + 8 + 0.02 0.05% + 8 + 0.02 0.05% + 8 0.05% + 8 0.06% + 8 0.25% + 6 2% + 2 0.25 0.24 0.29 0.29 0.3 2.25 2.0 0.09 0.10 0.11 0.11 0.12 1.5 2.75 1 mA 120 A 14 A 1.5 A 150 A 320 A 320 A 1 mA 12 A 14 A 1.5 A 150 A 150 A 320 A Accuracy Typical Max Current Full Scale Through the Voltage Unknown

* Because of the method used to measure resistance, the 100 M (slow) and 300 M(medium and fast) ranges cannot measure below 3.2 M and 20 M, respectively. "UL" (underload) is shown on the display for resistances below these nominal points, and the computer interface outputs "+1E-9".

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Open Circuit Voltage 3.2 volts maximum on the 100 , 300 , 30 M, 100 M, and 300 M ranges, 1.5 volts maximum on all other ranges. Maximum Rated Input (Input Protection) 1000 V dc or rms ac on all ranges Diode Test/Continuity
Maximum Reading Slow Medium Fast 999.99 mV 2.5 V 2.5 V Resolution 10 V 100 V 1 mV

Test Current Approximately 0.7 mA when measuring a forward-biased junction. Audible Tone Continuous tone for continuity. Brief tone for normal forward biased diode or semiconductor junction. Open Circuit Voltage 3.2 volts maximum Continuity Capture Time 50 s maximum, 10 s typical Maximum Rated Input (Input Protection) 1000 volts dc or rms ac

1-12

Introduction and Specifications Specifications

1

Frequency 5 Hz to > 1 MHz Applicable Functions Volts AC and Current AC
Resolution Range 1000 Hz 10 kHz 100 kHz 1000 kHz 1 MHz Slow & Medium .01 Hz .1 Hz 1 Hz 10 Hz 100 Hz Fast .1 Hz 1 Hz 10 Hz 100 Hz 1 kHz Accuracy .05% + 2 .05% +1 .05% +1 .05% +1 *

* For measurement of 1 MHz and lower, accuracy is .05% + 1. For measurement above 1 MHz, accuracy is not specified.

Sensitivity of AC Voltage
Frequency 5 Hz - 100 kHz 100 kHz - 300 kHz 300 kHz - 1 MHz Above 1 MHz Level (Sine Wave) 30 mV rms 100 mV rms 1 V rms Not Specified

Sensitivity Level of AC Current
Frequency 5 Hz - 20 kHz 45 Hz - 2 kHz Input 100 mA 10 A Level >3 mA rms >3 A rms

Note When the meter is set to measure frequency and there is no input signal (i.e., the input terminals are open), the meter may read approximately 25 kHz (rather than zero). This is due to internal capacitive pickup of the inverter power supply into the high-impedance, input circuitry. With source impedance of < 2 k, this pickup will not affect the accuracy or stability of the frequency reading.

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Environmental Warmup Time 1 hour to rated specifications Temperature Coefficient <0.1 times the applicable accuracy specification per degree C for 0C to 18C and 28C to 50C Electromagnetic Compatibility In an RF field of 1 V/m on all ranges and functions:
Total Accuracy = Specified Accuracy + .4% of range. Performance above 1 V/m is not specified.

Operating Temperature 0C to 50C Storage Temperature 40C to + 70C
Elevated temperature storage of battery will accelerate battery self-discharge. Maximum storage time before battery must be recharged: 20 - 25C 50C 70C 1000 days 180 days 40 days

Relative Humidity To 90% at 0C to 28C , (non condensing) To 80% at 28C to 35C, To 70% at 35C to 50C except to 70% at 0C to 50C for the 1000 k, 3 M, 10 M, 30 M, 100 M, and 300 M ranges. Altitude Operating Non-operating Vibration 3 G @ 55 Hz Shock
Half sine 40G. Per Mil-T- 28800D, Class 3, Style E. Bench Handling. Per Mil-T-28800D, Class 3.

0 to 10,000 feet 0 to 40,000 feet

General Common Mode Voltage 1000 V dc or rms ac maximum from any input to earth
1-14

Introduction and Specifications Specifications

1

Size
9.3 cm high, 21.6 cm wide, 28.6 cm deep

Weight
Net, 2.4 kg without battery; 3.2 kg with battery; Shipping, 4.0 kg without battery, 4.8 with battery.

Power
90 to 264 V ac (no switching required), 50 and 60 Hz. 15 VA maximum

Safety
Compliant with the following standards: ANSI/ISA S82.01-1994 CAN/CSA-C22.2 No. 1010. 1-92 EN61010.1:1993 to 1000 V Overvoltage Cat I, 600 V Overvoltage Cat II UL3111-1. See the following for an explanation of CATI and CATII categories. CAT I: OVERVOLTAGE (Installation) CATAGORY I, Pollution Degree 2 per IEC1010-1 refers to the level of Impulse Withstand Voltage protection provided. Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in which measures are taken to limit the transient over voltages to an appropriate low level. Examples include protect electronic circuits. CAT II: OVERVOLTAGE (Installation) CATAGORY II, Pollution Degree 2 per IEC1010-1 refers to the level of Impulse Withstand Voltage protection provided. Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be supplied from the fixed installation. Examples include household, office, and laboratory appliances.

Electromagnetic Compatibility
Meets FCC Part 15 Subpart J. EN61326-1 (1998)

RS-232-C
Baud rates: 300, 600, 1200, 2400, 4800 and 9600 Odd, even or no parity One stop bit

Options Battery (Option -01K)
Type 8 V, Lead-Acid Operating Time 8 hours (typical). N lights when less than 1/2 hour of battery operation remains. Meter still meets specifications.
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Recharge Time 16 hours (typical) with meter turned off and plugged into line power. Battery will not charge when meter is turned on.

IEEE-488 (Option -05K)
Capability Codes SH1, AH1, T5, L4, SR1, RL1, PP0, DC1, DT1, E1, TE0, LE0 and C0 External Trigger Input VIH 1.35 V minimum VIL 1.25 V maximum Input Threshold Hysteresis 0.6 V minimum

1-16

Chapter 2

Theory of Operation

Title 2-1. 2-2. 2-3. 2-4. 2-5. 2-6. 2-7. 2-8. 2-9. 2-10. 2-11. 2-12. 2-13. 2-14. 2-15. 2-16. 2-17. 2-18. 2-19. 2-20. 2-21. 2-22. 2-23. 2-24. 2-25. 2-26. 2-27. 2-28. 2-29. 2-30. 2-31. 2-32. 2-33. 2-34. 2-35. Introduction ............................................................................................ Functional Block Description ................................................................. Power Supply ..................................................................................... Analog Measurement Processor ......................................................... Input Protection Circuit ...................................................................... Input Signal Conditioning .................................................................. Analog-to-Digital (A/D) Converter .................................................... Serial Communication (Guard Crossing) ........................................... Digital Kernel ..................................................................................... Display Assembly............................................................................... IEEE-488 Interface Option (-05)........................................................ Battery Pack Option (-01) .................................................................. Detailed Circuit Description ................................................................... Power Supply Circuit Description ...................................................... Raw DC Supply ............................................................................. 5-Volt Switching Supply................................................................ Inverter........................................................................................... Analog Measurement Processor ......................................................... Input Protection .................................................................................. Input Signal Conditioning .................................................................. Relays............................................................................................. DC Volts ........................................................................................ Ohms .............................................................................................. 100 M and 300 M Ranges ........................................................ AC Volts ........................................................................................ DCmA ............................................................................................ ACmA ............................................................................................ Amps .............................................................................................. Diode/Continuity Test.................................................................... Frequency....................................................................................... Active Filter........................................................................................ A/D Converter .................................................................................... Serial Communication (Guard Crossing) ........................................... Digital Kernel ..................................................................................... RS-232 Interface ............................................................................

Page 2-3 2-3 2-3 2-3 2-3 2-3 2-3 2-3 2-5 2-5 2-5 2-5 2-5 2-5 2-6 2-6 2-7 2-7 2-10 2-10 2-11 2-12 2-12 2-14 2-14 2-15 2-15 2-15 2-15 2-15 2-16 2-17 2-18 2-18 2-19
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2-36. 2-37. 2-38. 2-39. 2-40. 2-41. 2-42. 2-43. 2-44. 2-45. 2-46. 2-47.

Microprocessor............................................................................... EEROM.......................................................................................... RAM .............................................................................................. ROM .............................................................................................. IEEE-488 Option Connections....................................................... Display Assembly............................................................................... Main Assembly Connector............................................................. Front Panel Switches...................................................................... Display ........................................................................................... Beeper Drive Circuit ...................................................................... Watchdog Timer and Reset Circuit ................................................ Display Controller with FIP ...........................................................

2-19 2-19 2-20 2-20 2-20 2-20 2-20 2-20 2-21 2-21 2-21 2-22

2-2

Theory of Operation Introduction

2

2-1. 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.

2-2. Functional Block Description
Refer to Figure 2-1, Overall Functional Block Diagram, during the following functional block descriptions.

2-3. Power Supply The Power Supply functional block provides voltages required by both the vacuumfluorescent display (-30 V dc, -5.2 V dc, and 5 V ac) and the in-guard circuitry (-5.25 V dc and 5.25 V dc). Within the Power Supply, the Raw DC Supply converts ac line voltage to dc levels and the 5 V Switching Supply converts this raw dc to 5 V 0.25 V dc, which is used by the Inverter in generating the above-mentioned outputs. 2-4. Analog Measurement Processor The Analog Measurement Processor (A1U1) provides input signal conditioning, ranging, a/d conversion, and frequency measurement. This custom chip is controlled by the Main Processor (A1U6), with communication carried out over a special serial interface. 2-5. Input Protection Circuit Input protection safeguards the meter against a number of over-voltage and over-current conditions. Depending on the type of input, protection circuits or fuses are used. 2-6. Input Signal Conditioning The input signal (voltage, current, or resistance) must be scaled or conditioned to a dc voltage 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 an active filter. AC measurements (ac volts and ac current) are passively filtered after being converted to a dc voltage. 2-7. Analog-to-Digital (A/D) Converter The voltage level from the signal conditioning circuits charges (or integrates) a capacitor for an exact amount of time. The capacitor discharge time, which is proportional to the level of the unknown input signal, is measured by the digital circuits in the Analog Measurement Processor and sent to the microprocessor. 2-8. Serial Communication (Guard Crossing) This functional block provides a high isolation voltage communication path between the Digital Kernel and the Analog Measurement Processor. This bi-directional communication circuit also requires power supply voltages from the Power Supply block.

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Inputs

Input Protection

Input Signal Conditioning

Analog Measurement Processor (A/D Converter)

Serial Communication

Guard Crossing

Vacuum Fluorrescent Display RS-232 Display Controller RAM Front Panel Switches Display Assembly EEPROM Calibration Constants ROM IEEE-488 Option -05

Digital Kernel

Battery Assembly Option -01

Power Supply 5.25 Vdc -5.25 Vdc

5 Vac -5.2 Vdc -30 Vdc

qb01.eps

Figure 2-1. Overall Functional Block Diagram

2-4

Theory of Operation Detailed Circuit Description

2

2-9. Digital Kernel The Digital Kernel functional block is responsible for the coordination of all activities within the meter. This block requires power supply voltages from the Power Supply and reset signals from the Display Assembly.
Specifically, the Digital Kernel Microprocessor performs the following functions: Executes the instructions in ROM Stores temporary data in RAM Store meter configuration and calibration data in EEROM Communicates with the Analog Measurement Processor via th