Fluke 43 Service Manual

43

®

Power Quality A nal yzer

Service Manual

4822 872 05377
September 1998, Rev. 3, 07/ 00

© 1998, 2000 Fluke Corporation, All rights reserv ed. Printed in the Netherlands
All product names are trademarks of their respective companies.

SERVICE CENTERS

To locate an authorized service center, visit us on the World Wide Web:

http://www.fluke.com

or call Fluke using any of the phone num bers li ste d bel ow:

[phone] in U.S.A. and Canada

[phone] in Europe

[phone] from other countries

Table of Contents

Chapter Title Page

1 Safety Instructions............................................................................. 1-1

1.1 Introduction............................................................................................. 1-3

1.2 Safet y Precautions ................................................................................... 1-3

1.3 Caution and Warning Statements............................................................. 1-3

1.4 Symbols.................................................................................................. 1-3

1.5 Impaired Safety....................................................................................... 1-4

1.6 General Safety Information...................................................................... 1-4

2 Characteristics................................................................................... 2-1

2.1 Introduction............................................................................................. 2-3

2.2 Safety Specifications............................................................................... 2-3

2.3 Function Specifications........................................................................... 2-4

2.3.1 Electrical functions........................................................................... 2-4

2.3.2 Scope............................................................................................... 2-5

2.3.3 Meter................................................................................................ 2-7

2.3.4 Record.............................................................................................. 2-7

2.4 Miscellaneous.......................................................................................... 2-8

2.5 Current Probe.......................................................................................... 2-8

2.6 Environmental Conditions....................................................................... 2-9

2.7 Electromagnetic Immunity....................................................................... 2-10

3 Circuit Descriptions........................................................................... 3-1

3.1 Introduction............................................................................................. 3-3

3.2 Block Diagram........................................................................................ 3-3

3.2.1 Input 1 - Input 2 Measurement Circuits ............................................ 3-3

3.2.2 Trigger Circuit.................................................................................. 3-5

3.2.3 Digital Circuit.................................................................................. 3-5

3.2.4 Power Circuit................................................................................... 3-6

3.2.5 Start-up Sequence, Operating Modes................................................ 3-7

3.3 Detailed Circuit Descriptions................................................................... 3-9

3.3.1 Power Circuit................................................................................... 3-9

3.3.2 Input 1 - Input 2 Measurement Circuits ............................................ 3-14

3.3.3 Trigger Circuit.................................................................................. 3-20

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Service Manual

3.3.4 Digital Circuit.................................................................................. 3-24

4 Performance Verification.................................................................. 4-1

4.1 Introduction............................................................................................. 4-3

4.2 Equipment Required For Verification...................................................... 4-3

4.3 How To Verify........................................................................................ 4-3

4.4 Display and Backlight Test...................................................................... 4-4

4.5 Input 1 and Input 2 Tests in the SCOPE MODE. ..................................... 4-5

4.5.1 Input 1 Trigger Sensitivity Test........................................................ 4-6

4.5.2 Input 1 Frequency Response Upper Transition Point Test................. 4-7

4.5.3 Input 1 Frequency Measurement Accuracy Test................................ 4-7

4.5.4 Input 2 Frequency Measurement Accuracy Test................................ 4-9

4.5.5 Input 2 Trigger Level and Trigger Slope Test ................................... 4-10

4.5.6 Input 2 Trigger sensitivity Test......................................................... 4-12

4.5.7 Input 1 Trigger Level and Trigger Slope Test ................................... 4-13

4.5.8 Input 1 and 2 DC Voltage Accuracy Test.......................................... 4-15

4.5.9 Input 1 and 2 AC Voltage Accuracy Test.......................................... 4-17

4.5.10 Input 1 and 2 AC Input Coupling Test............................................ 4-19

4.5.11 Input 1 and 2 Volts Peak Measurements Test.................................. 4-20

4.5.12 Input 1 and 2 Phase Measurements Test.......................................... 4-21

4.5.13 Input 1 and 2 High Voltage AC & DC Accuracy Test..................... 4-22

4.6 Ohms/Continuity/Capacitance................................................................. 4-25

4.6.1 Resistance Measurements Test. ........................................................ 4-25

4.6.2 Diode Test Function Test ................................................................. 4-26

4.6.3 Continuity Function Test.................................................................. 4-26

4.6.4 Capacitance Measurements Test....................................................... 4-27

4.7 Inrush Current......................................................................................... 4-28

4.8 Sags & Swells......................................................................................... 4-29

4.9 Harmonics............................................................................................... 4-30

4.10 VOLT/AMPS/HERTZ........................................................................... 4-30

4.11 POWER. ............................................................................................... 4-31

4.12 Transients. ............................................................................................. 4-32

5 Calibration Adjustment...................................................................... 5-1

5.1 General.................................................................................................... 5-3

5.1.1 Introduction...................................................................................... 5-3

5.1.2 Calibration number and date............................................................. 5-3

5.1.3 General Instructions.......................................................................... 5-4

5.2 Equipment Required For Calibration....................................................... 5-4

5.3 Starting Calibration Adjustment.............................................................. 5-4

5.4 Contrast Calibration Adjustment.............................................................. 5-6

5.5 Warming Up & Pre-Calibration............................................................... 5-7

5.6 Final Calibration...................................................................................... 5-7

5.6.1 HF Gain Input 1. .............................................................................. 5-8

5.6.2 Delta T Gain, Trigger Delay Time & Pulse Adjust Input 1 ............... 5-9

5.6.3 Gain DMM (Gain Volt).................................................................... 5-10

5.6.4 Volt Zero.......................................................................................... 5-12

5.6.5 Gain Ohm......................................................................................... 5-12

5.6.6 Capacitance Gain Low and High ...................................................... 5-13

5.6.7 Capacitance Clamp & Zero............................................................... 5-14

5.6.8 Capacitance Gain.............................................................................. 5-14

5.7 Save Calibration Data and Exit................................................................ 5-15

6 Disassembling ................................................................................... 6-1

ii

Contents (continued)

6.1. Introduction............................................................................................ 6-3

6.2. Disassembling Procedures...................................................................... 6-3

6.1.1 Required Tools................................................................................. 6-3

6.2.2 Removing the Battery Pack.............................................................. 6-3

6.2.3 Removing the Bail............................................................................ 6-3

6.2.4 Opening the Test Tool...................................................................... 6-3

6.2.5 Removing the Main PCA Unit.......................................................... 6-5

6.2.6 Removing the Display Assembly...................................................... 6-6

6.2.7 Removing the Keypad and Keypad Foil............................................ 6-6

6.3 Disassembling the Main PCA Unit.......................................................... 6-6

6.4 Reassembling the Main PCA Unit........................................................... 6-8

6.5 Reassembling the Test Tool..................................................................... 6-8

7 Corrective Maintenance .................................................................... 7-1

7.1 Introduction............................................................................................. 7-3

7.2 Starting Fault Finding.............................................................................. 7-4

7.3 Charger Circuit........................................................................................ 7-4

7.4 Starting with a Dead Test Tool................................................................ 7-6

7.4.1 Test Tool Completely Dead .............................................................. 7-6

7.4.2 Test Tool Software Does not Run..................................................... 7-7

7.4.3 Software Runs, Test Tool not Operative........................................... 7-7

7.5 Miscellaneous Functions ......................................................................... 7-7

7.5.1 Display and Back Light.................................................................... 7-7

7.5.2 Fly Back Converter .......................................................................... 7-8

7.5.3 Slow ADC........................................................................................ 7-9

7.5.4 Keyboard.......................................................................................... 7-10

7.5.5 Optical P o rt (S eri al R S232 Interface)................................................ 7-11

7.5.6 Input Channel 1 and 2 Voltage Measurements.................................. 7-11

7.5.7 Ohms and Capacitance Measurements.............................................. 7-12

7.5.8 Trigger Functions............................................................................. 7-13

7.5.9 Reference Voltages........................................................................... 7-14

7.5.1 0 Buzzer Circuit ................................................................................ 7-14

7.5.11 Reset ROM Line (ROMRST)......................................................... 7-14

7.5.12 RAM Test...................................................................................... 7-14

7.5.13 Power ON/OFF.............................................................................. 7-15

7.5.14 PWM Circuit.................................................................................. 7-15

7.5.15 Randomize Circuit.......................................................................... 7-15

8 List of Replaceable Parts.................................................................. 8-1

8.1 Introduction............................................................................................. 8-3

8.2 How to Obtain Parts................................................................................ 8-3

8.3 Final Assembly Parts............................................................................... 8-4

8.4 Main PCA Unit Parts............................................................................... 8-6

8.5 Main PCA Parts ...................................................................................... 8-7

8.6 Accesso ry Replacement Parts .................................................................. 8-23

9 Circuit Diagrams................................................................................ 9-1

9.1 Introduction............................................................................................. 9-3

9.2 Schematic Diagrams ................................................................................ 9-3

10 Modifications...................................................................................... 10-1

10.1 Software modifications.......................................................................... 10-3

10.2 Hardware modifications......................................................................... 10-3

iii

List of Tables

Table Title Page

1-1. Symbols............................................................................................................ 1-3

2-1. No Visible Disturbance...................................................................................... 2-10

2-2. Disturbance < 1 %............................................................................................. 2-10

2-3. Disturbance < 10 %........................................................................................... 2-10

3-1. Fluke 43 Main Blocks....................................................................................... 3-3

3-2. Fluke 43 Operating Modes ................................................................................ 3-8

3-3. Input 1 Volt age Ranges And Trace S ensitivity................................................... 3-17

3-4. Ohms Ranges , Trace Sensitivity, and Current.................................................... 3-18

3-5. Capacitance Ranges, Current, and Pulse Width.................................................. 3-19

3-6. D-ASIC PWM Signals ...................................................................................... 3-27

4-1. Input 1 Frequency Measurement Accuracy Test................................................. 4-8

4-2. Volts DC Measurement Verification Points....................................................... 4-17

4-3. Volts AC Measurement Verification Points....................................................... 4-19

4-4. Input 1 and 2 AC Input Coupling Verification Points ........................................ 4-20

4-5. Volts Peak Measurement Verification Points..................................................... 4-21

4-6. Phase Measurement Verification Points............................................................. 4-22

4-7. V DC and V AC High Voltage Verification Tests.............................................. 4-25

4-8. Resistance Measurement Verification Points...................................................... 4-26

4-9. Capacitance Measurement Verification Points................................................... 4-27

4-10. Volts/AMPS/HERZ verification points.............................................................. 4-31

4-11. Power Measurement Verification points............................................................ 4-31

5-1. HF Gain Calibration Points Fast ........................................................................ 5-9

5-2. HF Gain Calibration Points Slow....................................................................... 5-9

5-3. Volt Gain Calibration Points <300V .................................................................. 5-11

5-4. Ohm Gain Calibration Points............................................................................. 5-13

7-1. Starting Fault Finding........................................................................................ 7-4

8-1. Final Assembly Parts......................................................................................... 8-4

8-2. Main PCA Unit................................................................................................. 8-6

8-3. Main PCA......................................................................................................... 8-7

9-1. Parts Location Main PCA Side 1....................................................................... 9-4

9-2. Parts Location Main PCA Side 2....................................................................... 9-5

v

List of Figures

Figure Title Page

2-1. Max. Input Voltage vs. Frequency..................................................................... 2-4

3-1. Fluke 43 Block Diagram.................................................................................... 3-2

3-2. Fluke 43 Start-up Sequence, Operating Modes................................................... 3-8

3-3. Power Supply Block Diagram............................................................................ 3-9

3-4. C HAGATE Cont rol Volt age.............................................................................. 3-11

3-5. Fly-Back Converter Current and Control Voltage.............................................. 3-12

3-6. Fly-Back Converter Block Diagram................................................................... 3-13

3-7. Back Light Converter Voltages.......................................................................... 3-14

3-8. C-ASIC Block Diagram..................................................................................... 3-15

3-9. Capacitance Measurement................................................................................. 3-19

3-10. T-ASIC Trigger Section Block Diagram............................................................ 3-20

3-11. Random Repetitive Sampling Mode .................................................................. 3-22

3-12. Reference Voltage Section................................................................................. 3-23

3-13. LCD Control..................................................................................................... 3-26

4-1. Display Pixel Test Pattern ................................................................................. 4-4

4-2. Test Tool Input 1 to 5500A Scope Output 50Ω.................................................. 4-6

4-3. Test Tool Input 2 to 5500A NORMAL output................................................... 4-9

4-4. Test Tool Input 1 to 5500A Normal Output....................................................... 4-13

4-5. Test Tool Input 1-2 to 5500A Normal Output.................................................... 4-15

4-6. Test Tool Input 1-2 to 5500A Normal Output for >300V................................... 4-22

4-7. Test Tool Input 1 to 5500A Normal Output 4-Wire ........................................... 4-25

4-8. Test Tool Input 2 to 5500A NORMAL output................................................... 4-28

4-9. Test Tool Input 1 & 2 5500A Normal Output .................................................... 4-29

4-10. Bargraph Harmonics Volt.................................................................................. 4-30

4-11. Bargraph Harmonics Ampere............................................................................. 4-30

4-12. Test Tool Input 1 to 5500A Normal Output ....................................................... 4-32

5-1. Version & Calibration Screen ............................................................................ 5-3

5-2. Display Test Pattern .......................................................................................... 5-7

5-3. HF Gain Calibration Input Connections............................................................. 5-8

5-4. 5500A Scope Output to Input 1 ......................................................................... 5-10

5-5. Volt Gain Calibration Input Connections <300V............................................... 5-11

5-6. Volt Gain Calibration Input Connections 500V ................................................. 5-12

5-7. Four-wire Ohms calibration connections............................................................ 5-13

5-8. Capacitance Gain Calibration Input Connections............................................... 5-14

6-1. Fluke 43 Main Assembly................................................................................... 6-4

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Service Manual

6-2. Flex Cable Connectors....................................................................................... 6-5

6-3. Main PCA Unit Assembly................................................................................. 6-7

6-4. Mounting the display shielding bracket.............................................................. 6-9

6-5. Battery pack installation.................................................................................... 6-9

7-1. Operative Test Tool without Case...................................................................... 7-3

8-1. Fluke 43 Final Assembly................................................................................... 8-5

8-2. Main PCA Unit................................................................................................. 8-7

9-1. Circuit Diagram 1, Channel 1 Circuit ................................................................ 9-7

9-2. Circuit Diagram 2, Channel 2 Circuit ................................................................ 9-8

9-3. Circuit Diagram 3, Trigger Circuit..................................................................... 9-9

9-4. Circuit Diagram 4, Digital Circuit ..................................................................... 9-10

9-5. Circuit Diagram 4 (cont), Digital Circuit Keyboard ........................................... 9-11

9-6. Circuit Diagram 5, Power Circuit...................................................................... 9-12

9-7. Main PCA side 1, PCB Version <3.................................................................... 9-13

9-8. Main PCA side 2, PCB Version <3.................................................................... 9-14

9-9. Main PCA side 1, PCB version 3....................................................................... 9-15

9-10. Main PCA side 2, PCB version 3....................................................................... 9-16

viii

Chapter 1

Safety Instructions

Title Page

1.1 Introduction............................................................................................. 1-3

1.2 Safet y Precautions ................................................................................... 1-3

1.3 Caution and Warning Statements............................................................. 1-3

1.4 Symbols.................................................................................................. 1-3

1.5 Impaired Safety....................................................................................... 1-4

1.6 General Safety Information...................................................................... 1-4

1-1

1.1 Introduction

Read these pages carefully before beginning to install and use the instrument.
The following paragraphs contain information, cautions and warnings which must be

followed to ensure safe operation and to keep the instrument in a safe condition.

Servicing described in this manual is to be done only by
qualified ser vice personnel. To avoid electrical shock, do not
service the instrument unless you are qualified to do so.

1.2 Safety Precautions

For the correct and safe use of this instrument it is essential that both operating and
service personnel follow general l y accept ed safet y procedures i n addition to the safety
precautions s p eci fied in this manual. S pecific warning and cau t i o n s tatements, where
they apply, will be found throughout the manual. Where necessary, the warning an d
caution s t at em en t s an d / o r s y m b o l s are m ark ed o n t h e i n s t ru m en t .

Warning

Safety Instructions

1.1 Introduction

1

1.3 Caution and Warning Statements

Caution

Used to indicate correct operating or mainte nance procedures
to prevent damage to or destruction of the equipment or other
property.

Warning

Calls attention to a potential danger that requires correct
procedures or practices to prevent personal injury.

1.4 Symbols

Table 1-1 shows the symbols used on the test tool or in this manual.

Table 1-1. Symbols

Read the safety information in the Users
Manual

Equal potential inputs, connected
internally

DOUBLE INSULATION (Protection
Class)

Static sensitive components
(black/yellow).

Live voltage Recycling information

Earth Disposal information

Conformité Européenne

1-3

43

Service Manual

1.5 Impaired Safety

1.6 General Safety Information

Whenever it is likely that safety has been impaired, the instrument must be turned off
and disconnected from line power. The matter should then be referred to qualified
technicians. Safety is likely to be impaired if, for example, the instrument fails to
perform the intended measurements or shows visible damage.

Warning

Removing the instrument covers or removing parts, except
those to which access can be gained by hand, is likely to
expose live parts and accessible terminals which can be
dangerous to life.

The instrument shall be disconnected from all voltage sources before it is opened.
Capacitors i n s i d e t h e i n s t ru m en t can h o l d t h ei r ch arge ev en i f t h e i n s t ru m en t h as been

separated from all voltage sources.
Components which are import ant for t he s afety of t h e in st rum ent m ay only be repl aced

by components obtained through your local FLUKE organization. These parts are
indicated wi t h an as t eri s k (* ) i n t h e L i s t o f R ep l aceab l e P art s , Chapter 8.

1-4

Chapter 2

Characteristics

Title Page

2.1 Introduction............................................................................................. 2-3

2.2 Safety Specifications............................................................................... 2-3

2.3 Function Specifications........................................................................... 2-4

2.3.1 Electrical functions........................................................................... 2-4

2.3.2 Scope............................................................................................... 2-5

2.3.3 Meter................................................................................................ 2-7

2.3.4 Record.............................................................................................. 2-7

2.4 Miscellaneous.......................................................................................... 2-8

2.5 Current Probe.......................................................................................... 2-8

2.6 Environmental Conditions....................................................................... 2-9

2.7 Electromagnetic Immunity....................................................................... 2-10

2-1

2.1 Introduction

Safety Characteri s ti cs

The Fluke 4 3 h as b een d esigned and tested in accordance wi t h S t an d ard s ANSI/ISA
S82.01-1994, EN 61010.1 (1993) (IEC 1010-1), CAN/CSA-C22.2 No. 1010. 1-92
(including approval), UL3111-1 (including approval) Safety Requirements for
Electrical Equipment for Measurement, Control, and Laboratory Use.

This manual contains information and warnings that must be followed by the user to
ensure safe operation and to keep the instrument in a safe condition. Use of this
equipment in a manner not specified by the manufacturer may impair protection
provided by the equipment.

Performance Cha racteri s tics

FLUKE guarantees the properties expressed in numerical values with the stated
tolerance. Specified non-tolerance numerical values indicate those that could be
nominally expected from the mean of a range of identical ScopeMeter test tools.

Environmental Data

The environmental data mentioned in this manual are based on the results of the
manufacturer’s verification procedures.

Characteristics

2.1 Introduction

2

2.2 Safety Specifications

Safety Characteri s ti cs

Designed and tested for measurements on 600 Vrms Category III, Pollut i on Degree 2
in accordance wit h :

• EN 61010.1 (1993) (IEC 1010-1)

• ANSI/ISA S82.01-1994

• CAN/CSA-C22.2 No.1010.1-92 (including approval)

• UL3111-1 (including approval)

Installat i o n Category III refers to distributi o n l ev el and fi x ed i n s t al l at i o n ci rcu i t s
inside a building.

Maximum input voltage Input 1 and 2

Direct on inputs or with test leads TL24............................................. (see Figure 2-1)

0 to 66 kHz..............................................................................................600 Vrms

> 66 kHz....................................................................................derating to 5 Vrms

With Shielded Banana-to-BNC Adapter Plug BB120 ......................... (see Figure 2-1)

0 to 400 kHz............................................................................................300 Vrms

> 400 kHz..................................................................................derating to 5 Vrms

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Service Manual

ST8571

Figure 2-1. Max. Input Voltage vs. Fr equency

Maximum floating voltage

From any terminal to ground

0 to 400 Hz ............................................................................................. 600 Vrms

2.3 Function Specifications

The accuracy of all measurements i s wi thin ± (% of reading + number of counts) from
18 °C to 28 °C. For all specifications, probe specifications must be added.

2.3.1 Electrical functions

Specifications are valid for signals with a fundamental between 40 and 70 Hz.

Minimum input voltage ............................................................................. 4 V peak-peak

Minimum input current ............................................................ 10 A peak-peak (1 mV/A)

Input bandwidth.............................................. DC to 15 kHz (unless specified otherwise)

Volts / Amps / Hertz

Readings...................................................................Vrms (ac+dc), Arms (ac+dc), Hz

Voltage ranges (auto)..................................................... 5 V; 50 V; 500 V; 1250 V

minimum step...........................................................1 mV; 10 mV; 100 mV; 1 V

Current ranges (auto)............................................... 50.00 A to 500.0 kA, 1250 kA

minimum step.................................................... 10 mA; 0.1 A; 1 A; 100 A, 1 kA

Frequency range...................................................................... 10.0 Hz to 15.0 kHz

40.0 to 70.0 Hz...................................................................... ±(0.5 % + 2 counts)

resolution.................................................................0.1 Hz; 1 Hz; 10 Hz; 100 Hz

Power

Readings.......................................................................Watt, VA, VAR, PF, DPF, Hz

Watt, VA, VAR ranges (auto) ....................250 W to 250 MW, 625 MW, 1. 56 GW

when selected: t o t al ( %r): ......................................................±(2 % + 6 counts)

when selected: fundamental ( %f):..........................................±(4 % + 4 counts)

DPF.....................................................................................................0.00 to 1.00

0.00 to 0.25....................................................................................not specified

0.25 to 0.90..............................................................................................± 0.04

0.90 to 1.00..............................................................................................± 0.03

±(1 % + 10 counts)

±(1 % + 10 counts)

2-4

Characteristics

2.3 Function Spec ifications

PF ........................................................................................................ 0.00 to 1.00

Frequency range.......................................................................10.0 Hz to 15.0 kHz

40.0 to 70.0 Hz...................................................................±(0.5 % + 2 counts)

Harmonics

Number of harmonics ............................................................ DC..21, DC..33, DC..51

Readings / Cursor readings

Vrms... fund. ±(3 % + 2 counts).... 31

Irms.... fund. ±(3 % + 2 counts)....31

Watt.... fund. ±(5 % + 10 counts). . 31

st

±(5 % + 3 counts)... 51st ±(15 % + 5 counts)

st

±(5 % + 3 counts)... 51st ±(15 % + 5 counts)

st

±(10 % + 10 counts)51st ±(30 % + 5 counts)

Frequency of fundamental....................................................................... ± 0.25 Hz

Phase.................................................................................... fund. ±3° ... 51

K-factor (in Amp and Watt).........................................................................± 10 %

Sags & Swells

Recording times (selectable)............................. 4 minutes to 8 days, endless (16 days)

Readings / Cursor Readings

Vrms actual, Arms actual (cycle by cycle calculation)............... ±(2 % + 10 counts)

Vrms max, Arms max (idem at cursor)......................................±(2 % + 12 counts)

Vrms average, Arms average (only at cursor)............................ ±(2 % + 10 counts)

Vrms min, Arms min (idem at cursor).......................................±(2 % + 12 counts)

± 0.04

st

± 15°

2

Transients

Detection of voltage transients......................................................................... > 40 ns

Useful input bandwidth input 1 (with test leads TL24)............................DC to 1 MHz

Reference signal............................................................................................Vrms, Hz

Detection wh en transients ex ceed s p eci fi ed v o l t ag e l evel (selectable)

Number of transient memories (temporary)..............................................................40

Cursor readi ng

Inrush

Graphic display

Cursor readings

2.3.2 Scope

Input Impedance

Input 1.....................................................................................1 MΩ // 12 pF (± 2 pF)

Input 2.....................................................................................1 MΩ // 10 pF (± 2 pF)

After START, the Vrms and frequency of the signal are measured.
From th es e d at a a p u re s i n e wav e i s cal cu l at ed .

Voltage levels.................................. 20 %, 50 %, 100 %, 200 % of reference signal

Vpeak min, Vpeak max at cursor............................................... ± 5 % of full scale

Current ranges (selectable).................1 A, 5 A, 10 A, 50 A, 100 A, 500 A, 1000 A

Inrush times (selectable).........................................1 s, 5 s, 10 s, 50 s, 100 s, 5 min

A peak max at cursor 1 ...............................................................± 5 % of full scale

A peak max at cursor 2 ...............................................................± 5 % of full scale

Time between cursors...............................................................±(0.2 % + 2 pixels)

Horizontal

Time base modes (selectable).......................................................Normal, Single, Roll

Ranges (selectable within modes)

In Normal.......................................................................................5 s to 20 ns/div

In Single shot....................................................................................5 s to 1 µs/div

In Roll mode.....................................................................................60 s to 1 s/div

Time base error............................................................................ < ±(0.4 % + 1 pixel)

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Service Manual

Maximum sampling rate

10 ms to 60 s................................................................................................5 MS/s

20 ns to 10 ms............................................................................................25 MS/s

Trigger source (auto)........................................................................ Input 1 or Input 2

Trigger

Mode....................................................................................................auto triggering

Sources......................................Input 1, Input 2, Automatic (not manually selectable)

Error for frequencies < 1 MH z

Voltage Level............................................................................................± 0.5 div

at positive slope the top of the trigger symbol and at negative trigger the bottom of
the trigger symbol is the trigger point.

Time Delay Real Time sampling............................................................ ± 1 sample

Time Delay Quasi Random sampling.......................................................... ± 10 ns

Sensitivity input 1

@ 40 MHz...................................................................................................≥ 4 div

@ 25 MHz................................................................................................≥ 1.5 div

@ DC - 5 MHz............................................................................≥ 0.5 div or 5 mV

Sensitivity input 2

@ DC – 20 kHz ........................................................................................≥ 0.5 div

Slope Selection................................................................................Positive, negative

Level Control

Range Manual control...........................................> ± 4 div, within dynamic range

Delay ( horizontal move )......... -10 div - 0 div, used for horizontal move functionality

Vertical

Voltage ranges.....................................................................50.0 mV/div to 500 V/div

Trace accuracy .............................................................................±(1 % + 2 pixels)

Bandwidth input 1 (voltage)

excluding test leads or probes.............................................. DC to 20 MHz (-3 dB)

with test leads TL24.............................................................. DC to 1 MHz (-3 dB)

with 10:1 probe PM8918 (optional)..................................... DC to 20 MHz (-3 dB)

with shielded test leads STL120 (optional)........................DC to 12.5 MHz (-3 dB)

DC to 20 MHz (-6 dB)

Lower transition point (ac coupling)..................................................10 Hz (-3 dB)

Bandwidth input 2 (current)

with Banana-to-BNC adapter.............................................................DC to 15 kHz

Lower transition point (ac coupling)..................................................10 Hz (-3 dB)

Scope readings

The accuracy of all s co p e read i n g s i s v al i d fro m 1 8 °C to 28 °C with relative humidity
up to 90 % for a period of one year after calibration. Add 0.1 x (the specified
accuracy) for each °C below 18 °C or above 28 °C. More than one waveform period
must be visible on the screen.

V dc, A dc.....................................................................................±(0.5 % + 5 counts)

V ac and V ac+dc (True RMS) input 1

DC to 60 Hz..............................................................................±(1 % + 10 counts)

60 Hz to 20 kHz.....................................................................±(2.5 % + 15 counts)

20 kHz to 1 MHz......................................................................±(5 % + 20 counts)

1 MHz to 5 MHz.....................................................................±(10 % + 25 counts)

5 MHz to 20 MHz...................................................................±(30 % + 25 counts)

A ac and A ac+dc (True RMS) input 2

DC to 60 Hz..............................................................................±(1 % + 10 counts)

60 Hz to 15 kHz......................................................................±(30 % + 25 counts)

2-6

Frequency (Hz), Pulse width, Duty cycle (2.0 % to 98.0 %)

Phase (Input 1 to Input 2)

Peak voltage

Crest

2.3.3 Meter

Ohm

Ranges..................................................................... 500.0 Ω to 5.000 MΩ, 30.00 MΩ

Max. Measurement Current.............................................................................. 0.5 mA

Measurement Voltage at open circuit..................................................................< 4 V

Characteristics

2.3 Function Spec ifications

1 Hz to 1 MHz.........................................................................±(0.5 % + 2 counts)

1 MHz to 10 MHz.......................................................................±(1 % + 2 counts)

10 MHz to 30 MHz.................................................................. ±(2.5 % + 2 counts)

Up to 60 Hz...................................................................................................... ±2°

60 Hz to 400 Hz................................................................................................ ±5°

Peak max, Peak min....................................................................± 5 % of full scale

Peak-peak.................................................................................± 10 % of full scale

Range.................................................................................................... 1.0 to 10.0

±(5 % + 1 count)

±(0.6 % + 5 counts)

2

Diode

Accuracy...........................................................................................±(2 % +5 counts)

Max. Measurement Current.............................................................................. 0.5 mA

Measurement Voltage at open circuit..................................................................< 4 V

Continuity

Beep.................................................................................................... < 30 Ω (± 5 Ω)

Measurement Current.......................................................................................0.5 mA

Detection of shorts............................................................................................ > 1 ms

Capacitance

Ranges........................................................................................ 50.00 nF to 500.0 µF

Max. Measurement Current.............................................................................. 0.5 mA

Temperature

Ranges (°C or °F)..................................... -100.0 to +400.0 °C or -200.0 to +800.0 °F

2.3.4 Record

Record times (selectable)............................................. 4 min to 8 days, endless (16 days)

Number of readings.........................................................................1 or 2 simultaneously

Record is av ai l ab l e fo r t h e fun ct i o n s :

• volts / amps / hertz

• power

• harmonics

• ohms / continuity / capacitance

• temperature

• scope

±(2 % +10 counts)

±(0.5 % + 5 counts)

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2.4 Miscellaneous

Display

Useful screen area............................................................ 72 x 72 mm (2.83 x 2.83 in)

Resolution..........................................................................................240 x 240 pixels

Backlight ............................................................... Cold Cathode Fluorescent (CCFL)

Power
External

Power Adapter .......................................................................................... PM8907

Input Voltage.....................................................................................10 to 21 V dc

Power....................................................................................................5 W typical

Internal

Rechargeable Ni-Cd battery pack.................................................................BP120

Voltage range........................................................................................ 4 to 6 V dc

Operating Time........................................................................................... 4 hours

Charging Time ................................................................ 4 hours with Fluke 43 off

12 hours with Fluke 43 on

Refresh cycle......................................................................................8 to 14 hours

Memory

Number of screen memories.....................................................................................10

Number of transient memories (temporary).............................................................. 40

Mechanical

Height x width x depth........................................232 x 115 x 50 mm (9.1 x 4.5 x 2 in)

Weight (including battery pack)............................................................1.1 kg (2.5 lb.)

Interface ...................................................................................RS232, optically isolated

Supported Printers........................ HP Deskjet

Serial via PM9080 (optically isolated RS232 Adapter/Cable).

Parallel via PAC91 (optically isolated Print Adapter Cable, optional).

To PC....................................................................... Dump and load settings and data

Serial via PM9080 (optically isolated RS232 adapter/cable),

using SW43W (FlukeView

2.5 Current Probe

Safety Characteri s ti cs

Designed for measurements on 600 Vrms Category III. Protection class II, doubl e or
reinforced ins u l at i o n req uirements in accord an ce wi t h :

• IEC 1010-1

• ANSI/ISA S82

• CSA-C22.2 No.1010.1-92

• UL1244

®

, Laserjet®, PostScript and Epson FX80

®

Power Quality Analyzer software).

2-8

Electrical S pecifications

Current range.....................................................................................1 A to 500 Arms

AC current over range limit.......................................................................... 700 Arms

Maximum 10 minutes, followed by removal from current carrying conductor

for 30 minutes.

Output Signal......................................................................................... 1 mV ac/A ac

Characteristics

2.6 Environmental Conditions

Accuracy

5 to 10 Hz

1 to 500 A........................................................................................-3 dB typically

10 to 20 Hz

1 to 300 A......................................................................................................± 5 %

300 to 400 A................................................................................................ ± 15 %

400 to 500 A................................................................................................ ± 25 %

20 to 45 Hz

1 to 500 A......................................................................................................± 5 %

45 to 65 Hz

1 to 20 A...........................................................................±5 % of reading + 0.3 A

20 to 100 A .................................................................................... ±5 % of reading

± 3 ° phase shift

100 to 500 A..................................................................................±2 % of reading

± 5 ° phase shift

65 Hz to 3 kHz

1 to 50 A......................................................................................... ±(5 % + 0.4 A)

50 to 500 A ....................................................................................................± 5 %

Influence of tem p erat u re o n accu racy ..................................<0.15 % per 10 °C (18 °F)

Altitude

During operation............................................................................. 2.0 km (6560 feet)

While stored ................................................................................. 12 km (40 000 feet)

2

2.6 Environmental Conditions

Environmental...................................................MIL 28800E, Type 3, Class III, S t yle B

Temperature

During operation................................................................... 0 to 50 °C (32 to 122 °F)

While stored .......................................................................-20 to 60 °C (-4 to 140 °F)

Humidity

During operation:

0 to 10 °C (32 to 50 °F) ............................................................... non-condensing

10 to 30 °C (50 to 86 °F)......................................................................95 % ± 5 %

30 to 40 °C (86 to 104 °F).....................................................................75 % ± 5 %

40 to 50 °C (104 to 122 °F)...................................................................45 % ± 5 %

While st or ed:

-20 to 60 °C (-4 to 140 °F)............................................................. non-condensing

Altitude

During operation.......................................................................... 4.5 km (15 000 feet)

The maximum input and floating voltage is 600 Vrms up to 2 km.
Linearly derating from 600 down to 400 Vrms between 2 km to 4.5 km.

While stored ................................................................................. 12 km (40 000 feet)

Vibration........................................................................................................... max. 3 g

Shock................................................................................................................max. 30 g

Electromagnetic Compatibility (EMC)

Emission..............................................EN 50081-1 (1992): EN55022 and EN60555-2

Immunity.................................................EN 50082-2 (1992): IEC1000-4-2, -3, -4, -5

(See also Tables 2-1 to 2-3)

Enclos ure Protection ......................................................................... IP51, ref.: IEC529

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2.7 Electromagnetic Immunity

The Fluk e 43 , includi ng s t an d ard acces s o ri es , conforms wi t h t h e E EC directive 89 / 3 3 6
for EMC immunity, as defined by IEC1000-4-3, with the addition of the following
tables.

Disturbance wi th tes t lead s T L 24 or Cu rren t Cl amp 80i -500s

• Volts / amps / hertz

• Resi s t an ce, Capacitan ce

• Power

• Harmonics

Table 2-1. No Visibl e Di st ur bance

No visible distur bance E = 3 V/m E = 10 V/m

Frequency: 10 kHz - 27 MHz
Frequency: 27 MHz - 1 GHz

(-)
(-)

(-): no visi b l e d i s t u rb ance

Disturbance with test leads TL24 in scope mode

• V ac+dc (True R M S )

Table 2-2. Distur bance < 1 %

Disturbance less than 1 %

of full scale

Frequency: 10 kHz - 27 MHz
Frequency: 27 MHz - 200 MHz
Frequency: 200 MHz - 1 GHz

E = 3 V/m E = 1 0 V/m

2 V/div - 500 V/div
500 mV/div -

500V/div
(-)

(-): no visi b l e d i s t u rb ance

Table 2-3. Distur bance < 10 %

Disturbance less than 10 %

of full scale

Frequency: 10 kHz - 27 MHz

E = 3 V/m E = 10 V/m

1 V/div

(-)
(-)

10 V/div - 500 V/div
2 V/div - 500 V/div
5 mV/div - 500 V/div

5 V/div

2-10

Frequency: 27 MHz - 200 MHz
Frequency: 200 MHz - 1 GHz

200 mV/div
(-)

1 V/div
(-)

(-): no visi b l e d i s t u rb ance
Ranges not specified in Tables 2 and 3 may have a disturbance of more than 10 % of full

scale.

Chapter 3

Circuit Descript ions

Title Page

3.1 Introduction............................................................................................. 3-3

3.2 Block Diagram........................................................................................ 3-3

3.2.1 Input 1 - Input 2 Measurement Circuits ............................................ 3-3

3.2.2 Trigger Circuit.................................................................................. 3-5

3.2.3 Digital Circuit.................................................................................. 3-5

3.2.4 Power Circuit................................................................................... 3-6

3.2.5 Start-up Sequence, Operating Modes................................................ 3-7

3.3 Detailed Circuit Descriptions................................................................... 3-9

3.3.1 Power Circuit................................................................................... 3-9

3.3.2 Input 1 - Input 2 Measurement Circuits ............................................ 3-15

3.3.3 Trigger Circuit.................................................................................. 3-20

3.3.4 Digital Circuit.................................................................................. 3-24

3-1

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3-2

ST7965.EPS

Figure 3-1. Fluke 43 Bl ock Di agr am

3.1 Introduction

Section 3.2 describes the functional block diagram shown in Figure 3-1. It provides a
quick way to get familiar with the test tool basic build-up.

Section 3.3 describes the principle of operation of the test tool functions in detail, on the
basis of the circuit diagrams shown in Figures 9-1 to 9-5.

For all measurements, input signals are applied to the shielded input banana jackets.
Traces and readings are derived from the s ame input s i gnal sam pl es.

3.2 Block Diagram

In the block diagram Figure 3-1, the test tool is divided in five main blocks. Each block
represents a functional part, build up around an Application Specific Integrated Circuit
(ASIC). A d et ai l ed ci rcu i t d i ag ram of each b l o ck i s s ho wn i n Section 9.

Table 3-1 provides an overview of the blocks in which the test tool is broken down, the
main block function, the ASIC name, and the applicable circuit diagram.

Circuit Descri ptions

3.1 Introduction

3

Table 3-1. Fluke 43 Main Blocks

Block Main Functions ASIC Circuit

Diagram

INPUT 1 Input 1 signal conditioning C(hannel)-ASIC OQ0258 Figure 9-1
INPUT 2 Input 2 signal conditioning C(hannel)-ASIC OQ0258 Figure 9-2
TRIGGER Tr igger select ion and conditioning

Current source for resist ance, capacitance,
continuity, and diode measurements
AC/DC input coupling and
Voltage reference source

DIGITAL Analog to Digital Conversion

Acquisition of ADC samples
Micro controller (
Keyboard- and LCD control

POWER Power supply, bat t er y char ger

LCD back light voltage converter
Optical interface input

µP-ROM-RAM)

Ω/F relay control

T(rigger)-ASIC OQ 0257 Figure 9-3

D(igital)-ASIC MOT0002 Figure 9-4

P(ower)-ASIC OQ0256 Figure 9-5

All circuit s , except the LC D un i t an d the KEYBOARD, are l o cat ed on on e P r i nt ed
Circuit Board (PCB), called the MAIN PCB.

The ASIC’s are referred t o as C -ASIC (Channel AS IC ), T-ASIC (Trigger AS IC),
P-ASIC (Po wer AS IC ), and D-ASIC (Digi t al ASIC).

3.2.1 Input 1 - Input 2 Measurement Circuits

The basic input signal for the Input 1 and Input 2 circuits (hardware) is voltage. The
reading of Input 1 is in (milli)Volts. The reading of Input 2 is in Amperes. So the
voltage on Input 2 is assumed to be supplied by a current clamp. From the measured
voltage sam p l es the readings are cal cu l at ed by t h e i n s t ru m en t fi rm ware. For exampl e:
power readings are calculated from the Input 1 and Input 2 voltage samples.

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Service Manual

The Input 1 and Input 2 measurement circuits are partially identical. The differences are:

• Only Input 1 provides facilities for Ohms, Continuity, Diode, and Capacitance

measurements.

• The bandwidth of the Input 1 circuit is 20 MHz, the bandwidth of Input 2 is 15 kHz.

• Input 2 has an additional hum rejection circuit.

The circuit description below applies to the Input 1 and Input 2 circuit.

Input 1 and Input 2 measurement principle

An input voltage applied to Input 1 or Input 2 is supplied to the C-ASIC via the HF path
(Input 1 only) and the LF path. Depending on the actual measurement function the
Input-1 HF path in the C-ASIC is enabled or disabled. The HF DECade ATTenuator and
LF DECade ATTenuator are external components for the HF and LF path. The C-ASIC
converts (attenuates, amplifies) the input signal to a normalized output voltage
ADC-A/ADC-B, which is supplied to the Analog to Digital Converters (ADC-A and
ADC-B) on the DIGITAL part. The D-ASIC acquires the digital samples to build the
traces, and t o cal cu l ate readings.
For the electrical functions the current Input 2 circuit is operating in low voltage ranges.
For example a current of 10A measured with a 1 mV/A current clamp generates 10 mV
(voltage range 10 mV/div). To minimize the influence of interference voltages, Input 2
has no HF path, and has an additional hum reject circuit.
The lowest Input 1 voltage range for electrical measurements is 4V/div, which is high in
comparison with the Input 2 range.

Ohms, Continuity, and Diode measurement function (Input 1 only)

The T-ASIC s up p l i es a cu rren t v i a t h e Ω/F relays to the unknown resistance Rx or diode
connected to the Input 1 and the COM input jacket. The voltage drop across Rx or the
diode is measured according to t he Input 1 m easurem ent pri nci pl e.

Capacitance measurement function (Input 1 only)

The T-ASIC s up p l i es a cu rren t v i a t h e Ω/F relays to the unknown capacitance Cx,
connected to the Input 1 and the COM input jacket. Cx is charged and discharged by this
current. The C-ASIC converts the charging time and the discharging time into a pulse
width signal. This signal is supplied to the T-ASIC via the C-ASIC trigger output
TRIG-A. The T-ASIC shapes and levels the signal, and supplies the resulting pulse
width signal ALLTRIG to the D-ASIC. The D-ASIC counts the pulse width and
calculates t h e cap aci t an ce read i n g .

Scope measurement functi o n

In the Scop e m eas u rem en t s fu n ct i o n t h e t es t t o o l s h o ws the traces and readings derived
from the input signals. The Input 1 HF path is enabled, which results in a 20 MHz
bandwidth. The Input 2 bandwidth is 15 kHz.

Other measu rement function s

Volts/Amperes/Hertz (LF), Power (LF), Harmonics (LF), Sags & Swells (LF),
Transient s , In ru s h C u rrent (LF), and T em p erat u re m eas u rem en t res u l t s are cal cu l at ed
from acquired input voltage samples. For functions with (LF), the HF path of Input 1 is
disabled, which results in a 15 kHz bandwidth for both Input channels.

3-4

Miscellaneous

Control of the C-ASIC, e.g. selecting the attenuation factor, is done by the D-ASIC via
the SDAT and SCLK serial communicati o n lines.

An offset com pen s at i o n v ol tage and a trace pos ition control voltage are provided by the
D-ASIC via the AP WM bus.

The C-ASIC’s also provide conditioned input voltages on the TRIG-A/TRIG-B line. One
of these voltages will automatically be selected as trigger source by the T-ASIC.

3.2.2 Trigger Circuit

The T ASIC selects one of the possible trigger sources TRIG-A (Input 1) or TRIG-B
(Input 2). For triggering on transients the selected trigger source signal is processed via
the high pass Trigger Filter (TVOUT-TVSYNC lines). Two adjustable trigger levels are
supplied by the D-ASIC via the PWM FILTERS (TRIGLEV1 and TRIGLEV2 l in e).
Depending on the selected trigger conditions (- source, - level, - edge, - mode), the
T-ASIC generates the final trigger signal TRIGDT, which is supplied to the D-ASIC.

The TRIG-A input is also used for capacitance measurements (see Section 3.2.1).
The T-ASIC i n cl u d es a co n s t an t cu rrent source for resis t an ce an d capacitance

measurements. The current i s s uppli ed vi a t he GENOUT out put and th e Ω/F relays to
the unknown resistance Rx or capacitance Cx connected to Input 1. The SENSE signal
senses the v o l t ag e acros s Cx and controls a CLAMP ci rcu i t in the T-ASIC . This circui t
limits the voltage on Input 1 at capacitance measurements. The protection circuit
prevents the T-ASIC from being damaged by voltages supplied to the input during
resistance o r cap aci tance measuremen t s .

Circuit Descri ptions

3.2 Block Diagram

3

The T-ASIC contains opamps to derive reference voltages from a 1.23 V reference
source. The g ai n fact o rs fo r t h es e op am p s are d et erm i n ed b y res i s t o rs i n t h e R E F GAIN
circuit. The reference voltages are supplied to various circuits.

The T-ASIC also controls the Input 1/2 AC/DC input coupling relays, and the Ω/F relay.
Control data for the T-ASIC are provided by the D-ASIC via the SDAT and SCLK serial

communication lines.

3.2.3 Digital Circuit

The D-ASIC includes a micro processor, ADC sample acquisition logic, trigger logic,
display and keyboard control logic, I/O ports, and various other logic circuits.

The instrument software is stored in the 8M FlashROM; the 4M RAM is used for
temporary data storage.

For Voltage and Resistance measurements, the conditioned Input 1/2 voltages are
supplied to the ADC-A and ADC-B ADC. The voltages are sampled, and digitized by
the ADC’s. The output data of the ADC’s are acquired and processed by the D-ASIC.
For capacitance measurements the pulse width of the T-ASIC output signal ALLTRIG,
which is proportional to the unknown capacitance, is counted by the D-ASIC.

The DPWM-BUS (Digital Pulse Width Modulation) supplies square wave signals with a
variable duty cycle to the PWM FILTERS circuit (RC filters). The outgoing
APWM-BUS (Analog PWM) provides analog signals of which the amplitude is
controll ed b y t h e D-AS IC. These vol tages are used to con t ro l e.g. the t race p ositions
(C-ASIC), t he trigger levels (T-ASIC), and th e b at t ery ch arge cu rren t (P -ASIC).

In random sampling mode (Scope mode time base faster than 1 µs/d), a trace is bu ilt-up
from several acqu i s i tion cycles. During each acqu i s i t i o n , a number of trace s am p l es are
placed as pix els i n t h e LC D. The RANDOMIZE circuit takes care that t h e st arting
moment o f each acq u i s ition cycle (trigger release signal HOLDOFF goes low) is random.

3-5

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Service Manual

This prev ents that at each n ex t acq u i s ition th e t race is sampled at the same time
positi o n s , and that t h e d i s p l ay ed t r ace m i s s es s am p l es at s o m e p l aces o n t h e LCD.

The D-ASIC supplies control data and display data to the LCD module. The LCD
module is connected to the main board via connector X453. It consists of the LCD, LCD
drivers, and a fluorescent back light lamp. As the module is not repairable, no detailed
description and diagrams are provided. The back light supply voltage is generated by the
back light converter on the POWER part.

The keys of the keyboard are arranged in a matrix. The D-ASIC drives the rows and
scans the matrix. The contact pads on the keyboard foil are connected to the main board
via connector X452. The ON-OFF key is not included in the matrix, but is sensed by a
logic circuit in the D-ASIC, that is active even when the test tool is turned off.

Via the PROBE-A and PROBE-B lines, connected to the Input 1 and Input 2 banana
shieldi n g, the D-ASIC can d et ect i f a p ro be is connected.

The D-ASIC sends commands to the C-ASICs and T-ASIC via the SCLK and SDAT
serial control lines, e.g. to select the required trigger source.

Various I/O lines are provided, e.g. to control the B UZZER and the S low-ADC (vi a the
SADC bus).

3.2.4 Power Circuit

The test t o ol can be powered vi a t h e p o wer ad ap t er, or by the b at t ery pack .
If the power adapt er i s co n n ect ed , it powers th e t es t t o o l an d ch arg es t h e bat tery via the
CHARGER-CONVERTER ci rcuit . The battery charge current is sensed by sense
resistor Rs (signal IBAT). It is controlled by changing the output current of the
CHARGER-CONVERTER (cont rol si gnal C HAGATE).
If no power adapter is connected, the battery pack supplies the VBAT voltage. The
VBAT voltage powers the P-ASIC, and is also supplied to the FLY BACK
CONVERTER (switched mode power supply).
If the test tool is turned on, the FLY BACK C ONVER TER generates supply voltages for
various test tool circuits.
The +3V3GAR supply voltage powers the D-ASIC, RAM and ROM. If the test tool is
turned off, the battery supplies the +3V3GAR voltage via transistor V569. This
transistor is controlled by the P-ASIC. So when the test tool is turned off, the D-ASIC
can still control the battery charging process (CHARCURR signal), the real time clock,
the on/off key, and the seri al R S232 interface (to turn the tes t t ool on).

To monitor and control the battery charging process, the P-ASIC senses and buffers
battery signals as temperature (TEMP), voltage (BATVOLT), current (IBAT).

Via the SLOW ADC various analog signals can be measured by the D-ASIC. Involved
signals are: battery voltage (BATVOLT), battery type (IDENT), battery temperature
(TEMP), battery curren t (B ATC UR ) LC D t em perat u re (LC DTEMP, from LCD uni t ),
and 3 test output pins of the C-ASIC’s, and the T-ASIC (DACTEST). The signals are
used for control and test purposes.

3-6

The BACK LIGHT CONVERTER generat es t he 400V ! supply voltage for the LCD
fluorescent back light lamp. If the lamp is defective a 1.5 kV voltage can be present for

0.2 second maximum. The brightness is controlled by the BACKBRIG signal supplied
by the D-ASIC.

Serial communication with a PC or printer is possible via the RS232 optically isolated
interface. The P-AS IC buffers t h e recei ved data l i ne (RXDA) and supplies the buffered
data (RXD) to the D-ASIC. The transmit data line TXD is directly connected to the
D-ASIC.