FLUKE 45 Dual Display Multimeter. Service Manual (For IEC 1010 Meters Only)

General Maintenance

Fuse Test and Replacement

3. Insert the test lead probe into the 100 mA input terminal. If the fuse is good, the

meter will read between 11 and 15 Ω. If the fuse is blown, the meter will

read >10 MΩ to OL.

4. Remove the test lead probe from the 100 mA input terminal, and insert it into

the 10 A input terminal.

If the fuse is good, the meter will read between .04 and 1.0Ω. If the fuse is blown, the

meter will read >10 MΩ to OL.

3-12. Replacing the 500 mA and 440 mA Input Fuses (F1 and F5)

The 100 mA jack is protected by 2 fuses, F1 and F5. F1 is mounted in the front panel

100 mA input jack (Figure 3-2) and F5 is located inside the meter.

To replace F1, first unplug the line cord. Then press in on the input jack and turn it 90

degrees counterclockwise. Slide out the fuse holder and fuse.

Replace a blown fuse with one of identical rating (see Table 3-1), and reinsert the fuse

and holder into the input terminal socket. Secure the fuse holder by pressing in and

turning the holder 90 degrees clockwise.

To change the internal F5 fuse, see “Replacing the 10 A Input Fuse” later in this section.

Rear Panel

Power-Line Cord Connector

To remove,

Squeeze and slide out

F3 Line Fuse

(T 125 mA, 250 V, Slow Blow)

Fuse Holder

(Spare fuse provided)

qb12f.eps

Figure 3-1. Replacing the Line Fuse (F3)

3-5

Service Manual

Front Panel Input Terminal

F1 Fuse (500 mA, 250V, Fast Blow)

1500 A Minimum Breaking Capacity

100 mA Input Socket

Fuse Holder

To remove, push in and turn counter clockwise.

To insert, reverse this procedure.

qb13f.eps

Figure 3-2. Replacing the External 100 mA Input Fuse (F1)

Table 3-1. Fuses

Item

Description

Fluke Part No.

100 mA Input Fuse. F 500 mA, 250 V, (fast blow), 1500 A breaking

838151

capacity.

10 A Input Fuse. F 11 A, 1000 V, (fast blow), 17,000 breaking

943118

capacity.

Line Fuse. T 125 mA, 250 V, (slow blow)

822254

100 mA Input Fuse. F440 mA, 1000 V, 10,000 A minimum interrupt.

943121

3-13. Replacing the 10 A Input Jack Fuse (F2)

The 10 A input jack is protected by an 11 A fuse (F2), located inside the meter. The

following procedure explains how to access and change this fuse. This procedure can

also be used to change F5.

1. Remove the single Phillips-head screw on the bottom of the case and the Phillips-

head screw on each side of the rear bezel.

Warning

Opening the case may expose hazardous voltages. Always

disconnect the power cord and measuring inputs before

opening the case.

2. Remove the bezel and slip the case back from the front of the meter. The fuse and

fuse clip are visible at the front of the main printed circuit assembly (pca) near the

input terminals.

3. Carefully remove the fuse and install a properly-rated replacement.

3-6

General Maintenance

Disassembly Procedures

3-14. Disassembly Procedures

The following paragraphs describe disassembly of the Fluke 45 in sequence (from the

fully assembled meter to the chassis level.) Start and end your disassembly at the

appropriate heading levels.

3-15. Remove the Meter Case

Use the following procedure to remove the meter case.

1. Make sure the meter is turned off and unplugged from the power outlet.

2. Discharge the power supply capacitor by turning on the meter (with the meter

unplugged from the power line). After five seconds, turn the meter off.

3. Remove the screw from the bottom of the case, and remove the two screws from the

rear bezel as shown in Figure 3-3 section A. While holding the front panel, slide the

case and rear bezel off the chassis. (See Figure 3-3 section B.) (At this point, the rear

bezel is not secured to the case.)

Caution

If the Main PCA is to be serviced and the Battery Option is

installed, first unplug the battery ribbon cable from the Main

PCA, or disconnect the wires to the battery. This measure

prevents damage to the meter when you are servicing the Fluke

45 Main PCA.

Rear Bezel

Mounting Screw (2)

Case

Grounding Screw (2)

Chassis

qb14f.eps

Figure 3-3. Removing the Case

3-16. Remove Handle and Mounting Brackets

Refer to Figure 3-4 during this procedure. Pull each handle pivot out slightly at the

handle mounting brackets, then rotate the handle up over the display. With the handle

pointing straight up, pull out and disengage one pivot at a time.

3-7

Service Manual

Use a Phillips head screwdriver to remove the two handle mounting brackets. Note that

these brackets must be reinstalled in their original positions. Therefore, the inside of

each bracket is labeled with an "R" or an "L", referenced to the front view of the meter.

qb15c.eps

Figure 3-4. Removing the Handle and Handle Mounting Brackets

3-17.

Remove the Front Panel Assembly

Remove all leads connected to the input terminals. Then remove the front panel 100 mA

fuse. Using needle nose pliers, disconnect the wires at the rear of the

, [COM],

and [10 A] input terminals. At the rear of the [100 mA] terminal, carefully dislodge and

withdraw the spring (attached to the white wire) from the fuse holder.

Locate the display ribbon cable connector on the Main PCA ("A" in Figure 3-5.) Using

needle nose pliers, disconnect this cable by alternately pulling up on each end of its

connector. Avoid breaking the alignment tabs on the Main PCA half of this connection.

Now remove the Front Panel Assembly by releasing the four snap retainers ("B" in

Figure 3-5) securing it to the chassis.

3-18.

Remove the Display PCA

The Display PCA is held in place with a set of tabs around its periphery. In sequence,

release the tabs along the top, left side, and right side. Then slide the pca up and out,

away from the bottom tabs.

Note

The Display PCA provides a space for a center securing screw. If the

peripheral tabs are intact, this screw is not necessary. If some of the tabs

are broken, the screw can be used as an additional securing device.

The elastomeric Keypad Assembly ("C" on Figure 3-5) can now be lifted away from the

Front Panel Assembly.

Remove the display window ("D" on Figure 3-5) by releasing the two snaps along its

inside, bottom edge. Use a gentle levering action between each snap and an adjacent

edge on the Display Assembly.

3-8

General Maintenance

Disassembly Procedures

Caution

Avoid using ammonia or methyl-alcohol cleaning agents on

either the Front Panel of the display window. These types of

cleaners can damage surface features and markings. Use an

isopropyl-based cleaning agent or water to clean the Front

Panel and the display window.

3-19.

Remove the IEEE-488 Option

Chapter 8 of this manual provides a detailed removal procedure for the IEEE-488 option.

The following removal instructions provide the essentials of this procedure. If necessary,

refer to the complete procedure in Chapter 8, paying particular attention to Figures 8-2

and 8-3.

1. Use needle nose pliers to disconnect the 24-line cable assembly at the IEEE-488

PCA. Alternately pull on each end of the cable connector.

2. Remove the panhead Phillips screw at the rear of the IEEE-488 PCA.

3. Use needle nose pliers to detach the two ribbon cables at the front of the IEEE-488

PCA. Alternately pull on each end of the cable connector. Do not remove these

cables at their Main PCA connections.

Note

The IEEE-488 ribbon cables are not interchangeable with the Display

Assembly ribbon cable. Connectors on these cables are aligned

differently, allowing for proper cable routing.

4. Remove the IEEE-488 PCA, disengaging the board from both the small slot in the

side of the meter chassis and the plastic standoff at the front corner of the board.

3-20.

Remove the Main PCA

With the IEEE-488 option and the Display Assembly removed, the Main PCA can be

removed with the following procedure:

1. Remove the power switch activator rod ("E" in Figure 3-5) from the bottom of the

Main PCA.

2. Detach the transformer connector (right rear corner of the Main PCA, "F" in Figure

3-5) and the RS-232 connector (center of the Main PCA, "G" in Figure 3-5.) If the

Battery Option is installed, detach its connector at the center-rear of the Main PCA.

3. Now remove the securing screw (near the battery connector, "H" in Figure 3-5), and

slide the Main PCA forward. Match the pca edge indentations to the guide tabs on

each chassis side, then lift the Main PCA up and away from the chassis.

To remove the transformer insulator (center rear of the Main PCA, "I" in Figure 3-5),

detach the two tabs and pull up.

3-21.

Remove the Analog Measurement Processor Shields

The Analog Measurement Processor resides within a plastic shield on the top of the

Main PCA. Although having the appearance of a dark gray piece of plastic, this shield is

electrically conductive; treat it as you would any other conducting surface. On the

bottom of the Main PCA, the Analog Measurement Processor is protected with a

metallic shield. Access the Analog Measurement Processor with the following

procedure:

3-9

Service Manual

• Working from the bottom of the Main PCA, remove the single Phillips head screw

("J" in Figure 3-6) securing the metallic shield, then lift the plastic shield ("M")

away from the top of the Main PCA.

• If necessary, remove the metallic shield ("K".) Avoid contacting any circuit traces

during this procedure. First rotate the shield toward the pca edge, then pry the shield

free from its nylon standoff ("L").

3-22.

Remove the Rms PCA

The rms pca is soldered in place on the Main PCA (within the Analog Measurement

Processor shield.) For access procedures, refer to "Remove the Analog Measurement

Processor Shields". Use standard desoldering techniques (e.g. solder sucker or solder

wick) when removing this assembly.

3-23.

Remove the Battery Option

Use the following procedure to remove the Battery Option. Refer to Figures 7-2 and 7-3

(Chapter 7) to identify features and techniques mentioned here. If necessary, refer to

Chapter 7 for a detailed description of Battery Option removal.

1. Disconnect the flat white battery option connecting cable at the Battery Option PCA.

2. Remove the two #6-32 x 1/4" panhead Phillips screws securing the Battery Option.

3. Carefully slide the Battery Option out of the meter. Do not pinch the wires running

from the pca to the battery terminals.

3-24.

Disconnect Miscellaneous Chassis Components

The following procedures can be used to disconnect remaining hardware from the

chassis:

1. Use needle nose pliers to remove the internal connections at the line power plug.

2. Remove the power plug by releasing its two snaps, one at a time.

3. Disconnect the power transformer by removing the four screws ("N" in Figure 3-5)

that secure it to the right side of the chassis.

4. Remove the RS-232 connector ("O") on the rear of the chassis. Use a 3/16-inch nut

driver to loosen the connector securing hardware. Also, disconnect the ground wire

at its chassis connection.

5. Remove the IEEE connector.

3-25. Assembly Procedures

Generally, assembly procedures follow a reverse sequence of disassembly procedures.

As some differences do apply, assembly is described separately in the following

paragraphs. Begin assembly at the appropriate level, as defined by the heading.

References are made to items in Figure 3-5 for assembly details of standard meter parts.

3-26. Install Miscellaneous Chassis Components

Use the following procedure to replace any items that have been removed from the basic

chassis.

1. Install the IEEE connector on the rear of the chassis.

3-10

General Maintenance

Assembly Procedures

2. Replace the RS-232 connector ("O") on the rear of the chassis. Use a 3/16-inch nut

driver to tighten the connector hardware. Also, attach the ground wire at its chassis

connection.

3. Replace the power transformer along the right side of the chassis. Use four 6-32 x

.25 FHU screws ("N"), inserted from the exterior of the meter.

4. Snap the power plug into position.

5. Use needle nose pliers to replace the interior connections at the power plug.

3-27.

Install the Battery Option

Installation is fully described in both the instruction sheet supplied with the Battery

Option and in Chapter 7 of this manual. The following procedure presents installation

essentials. Figures 7-2 and 7-3 can be used in identifying features and techniques

mentioned here.

1. Carefully slide the battery kit into the area reserved for it in the back of the meter.

Make sure that both the retaining slots line up and the mounting holes mate. Do not

pinch wires running from the circuit assembly to the battery terminals.

2. Secure the battery kit with two #6-32 x 1/4" panhead Phillips screws.

3. Attach the flat, white connecting cable at the Battery Option PCA. The single blue

marking line of the cable should be to the rear of the meter. Align the plastic socket

on the cable end, then seat it securely in place.

3-28.

Install the Rms PCA

With the Analog Measurement Processor shields removed, solder the Rms PCA into

place on the upper side of the Main PCA. The component side of the Rms PCA faces

forward.

3-29.

Install the Analog Measurement Processor Shields

The Analog Measurement Processor resides within a plastic shield on the top of the

Main PCA. Although having the appearance of a dark gray piece of plastic, this shield is

electrically conductive; treat it as you would any other conducting surface. On the

bottom of the Main PCA, the Analog Measurement Processor is protected with a

metallic shield.

Press the conductive plastic shield ("M") into place on the top of the Main PCA. From

the bottom of the Main PCA, install the metallic shield ("K".) Avoid contacting any

circuit traces during this procedure. Then replace the single Phillips head screw ("J")

securing the metallic shield.

3-30.

Install the Main PCA

1. Prior to installing the Main PCA, verify the following:

• If necessary, reinstall the transformer insulator ("I"), tabs down, around the right

side of the transformer. Once the insulator is in place, pull each tab through the

Main PCA from bottom side with a needle nose pliers.

• If the nylon standoff ("L") used between the Main PCA and the metallic shield

surrounding the Analog Measurement Processor has been removed, verify that

proper orientation is maintained during installation. The standoff end with the

shorter, beveled indent fits into the metallic shield. Press the standoff end with

the wider, straighter indent into the Main PCA with a 3/16 nut driver.

3-11

Service Manual

2. Ensure that the nylon standoff support (front-center of the Main PCA) is in place.

Then slide the Main PCA onto the chassis slider taps.

3. Fasten the Main PCA to the chassis with a 6-32, 1/4-inch panhead screw ("H").

4. Connect the transformer cable ("F") and RS-232 cable ("G") at the Main PCA.

3-31.

Install the IEEE-488 Option

Both the instruction sheet provided with the IEEE-488 Option and Chapter 8 of this

manual fully describe installation. The following instructions provide installation

procedure essentials. If necessary, refer to Chapter 8, paying particular attention to

Figures 8-2 and 8-3.

1. Check that the plastic standoff remains in the appropriate hole in the Main PCA

(narrow end of the standoff down.)

2. If necessary, install the two ribbon cables on the IEEE-488 circuit board. Each cable

fits in only one socket and in only one direction. Make sure the cables lock firmly in

place.

3. Attach opposite ends of the ribbon cables onto the Fluke 45 Main PCA.

4. Install the IEEE-488 PCA into the small slot in the side of the Fluke 45 (two ribbon

cables facing forward.) The end of the plastic standoff fits into the hole in the IEEE-

488 PCA. Make sure the IEEE-488 PCA is firmly gripped against the retainer on the

standoff and that the rear of the pca rests upon the support just forward of the

transformer.

5. Secure the rear of the IEEE-488 PCA with the panhead Phillips screw.

6. Connect the 24-line cable assembly to the IEEE-488 circuit board.

3-32.

Assemble the Front Panel Assembly

As appropriate, use the following steps to assemble the Front Panel Assembly.

1. Clean the lens ("D") with deionized air and, if necessary, isopropyl alcohol. Then

gently snap the lens into the front panel tabs.

2. Install the elastomeric keypad assembly ("C"). Make sure that the four front panel

guide pins protrude through the keypad.

3. On the Display PCA, clean the display with deionized air and, if necessary,

isopropyl alcohol.

4. Slide the Display PCA into the bottom securing tabs on the back of the Front Panel

Assembly. Then gently snap the pca into the remaining tabs along its periphery.

Note

The Display PCA provides a space for a center securing screw. If the

peripheral tabs are intact, this screw is not necessary. If some of the tabs

are broken, the screw can be used as an additional securing device.

5. Connect the 20-pin cable connector ("A") to the Display PCA.

3-12

General Maintenance

Assembly Procedures

3-33.

Install the Front Panel Assembly

Use the following procedure when installing the Front Panel Assembly:

1. Snap the Front Panel Assembly into place in the four tab retainers ("B").

2. Observing the alignment orientation provided by tabs on the connector, attach the

display ribbon cable connector ("A") on the Main PCA.

3. Attach the wires at the rear of the front panel input terminals. Observe the following

color coding:

• At the rear of the 100 mA input terminal, carefully insert the spring (attached to

the white wire) into the fuse holder.

• Using needle nose pliers, connect the wires at the rear of the input terminals as

follows:

Red

[COM] Black

[10 A]

Yellow

• Install the front panel 100 mA input fuse (F1).

3-34.

Install the Handle and Mounting Brackets

Refer to Figure 3-4 during the following procedure. Use a Phillips head screwdriver to

attach the two handle mounting brackets. Note that these brackets must be reinstalled in

their original positions. Therefore, the inside of each bracket is labeled with an "R" or an

"L", in reference to the front view of the meter.

Now, engage the handle. Point the handle straight up. Then pull out on each end of the

handle to engage the respective pivot in its bracket. Pull out slightly on both pivots to

rotate the handle to the desired position.

3-35.

Install the Meter Case

Reinstall the meter case, checking that it seats properly in the front panel. Attach the rear

bezel with the two panhead Phillips screws and secure the case with the flathead Phillips

screw in the bottom. Refer to Figure 3-3.

3-15

Chapter 4

Performance Testing and Calibration

Title

Page

4-1.

Introduction

4-3

4-2.

Required Equipment

4-3

4-3.

Performance Tests

4-4

4-4.

Front Panel Calibration

4-7

4-5.

Introduction

4-7

4-6.

Entering Calibration Mode

4-8

4-7.

Exiting Calibration Mode

4-9

4-8.

DC Volts Calibration (Front Panel)

4-9

4-9.

AC Volts Calibration (Front Panel)

4-9

4-10.

DC and AC Milliamp Calibration (Front Panel)

4-9

4-11.

DC and AC Amps Calibration (Front Panel)

4-11

4-12.

Ohms Calibration (Front Panel)

4-11

4-13.

Alternate Ohms Calibration (Front Panel)

4-13

4-14.

Continuity/Hysteresis Threshold Calibration (Front Panel)

4-13

4-15.

Frequency Calibration (Front Panel)

4-13

4-16.

C2 Adjustment Procedure

4-13

4-17.

Editing the Prompt for Different Calibration Points

4-14

4-18.

Calibration Using the Computer Interface

4-15

4-19.

Setup

4-15

4-20.

RS-232 Interface

4-15

4-21.

IEEE-488 Interface

4-16

4-22.

The Calibration Procedure

4-18

4-23.

DC Volts Calibration (Computer Interface)

4-19

4-24.

AC Volts Calibration (Computer Interface)

4-19

4-25.

DC and AC Milliamps Calibration (Computer Interface)

4-19

4-26.

DC and AC Amps Calibration (Computer Interface)

4-19

4-27.

Ohms Calibration (Computer Interface)

4-19

4-28.

Continuity/Hysteresis Threshold Calibration (Computer Interface)

4-20

4-29.

Frequency Calibration (Computer Interface)

4-20

4-30.

Concluding Calibration Using the Computer Interface

4-20

4-31.

Alternate Ohms Calibration (Computer Interface)

4-20

4-1

Performance Testing and Calibration

Introduction

4-1. Introduction

This chapter of the Service Manual provides performance tests that can be used at any

time to verify Fluke 45 operation within published specifications. A complete calibration

procedure is also included. The performance test and, if necessary, the calibration

procedure can be performed periodically and after service or repair.

4-2. Required Equipment

Equipment required for performance testing and calibration is listed in Table 4-1.

Table 4-1. Recommended Test Equipment

Instrument

Recommended

Minimum Specifications

Type

Model

Multifunction

DC Voltage:

Fluke 5700A

Calibrator

Range = 90 mV to 1000 V dc

with wideband

Accuracy = .005%

option

AC Voltage:

Frequency

Voltage

Accuracy

1 kHz

29 mV to 750 V

0.05%

100 kHz

15 mV to 300 mV

1.25%

AC Milliamps:

Frequency

Current

Accuracy

1 kHz

29 mA to 100 mA

0.125%

DC Milliamps:

Frequency

Voltage

Accuracy

10 kHz

1 V

0.125%

Boost

DC Amps:

Current

Accuracy

Fluke 5725A

Amplifier

10 A

.05%

AC Amps:

1 kHz

2A and 10 A

0.25%

Decade

General

Resistance

Ohms

Accuracy

Resistance Inc.

Source

Model RDS 66A

290 Ω

0.0125%

2.9 kΩ

0.0125%

29 kΩ

0.0125%

290 kΩ

0.0125%

2.9 MΩ

0.0125%

Note

The 5700A Calibrator can be used for 0.05% accuracy (rated) on the

3.0 kΩ, 30 kΩ, 300 kΩ, and 3.0 MΩ ranges. This calibrator can be used

for 0.06% accuracy on the 100 Ω and 300 Ω ranges.

4-3

Service Manual

4-3.

Performance Tests

The following performance tests are provided to ensure that the meter is in proper

operating condition. If the meter fails any of the performance tests, calibration

adjustment and/or repair is needed. To perform these tests, you will need a Fluke 5700A

Multifunction Calibrator and a 5725A Amplifier or equipment meeting the minimum

specifications given in Table 4-1.

Each of the measurements listed in the following steps assumes the meter is being tested

after a one-hour warmup in an environment with an ambient temperature of 18 to 28ºC

and a relative humidity of less than 90% (70% for MΩ ranges). The limits in Table 4-2

represent the 1-year calibration cycle.

Note

All measurements listed in the performance test tables are made in the

medium reading rate unless otherwise noted.

1. Power up the meter and allow it to stabilize for one hour.

2. Connect a cable from the Output VA HI and LO connectors of the 5700A to the

and COM connectors on the Fluke 45. Select the function and range on the

Fluke 45 and the input level from the 5700A using the values listed in Table 4-2. The

display should read between the minimum and maximum values listed in the table.

3. Connect a cable from the Output VA HI and LO connectors of the 5700A to the

[100 mA] and COM connectors on the Fluke 45. Select the function and range on the

Fluke 45 and the input level from the 5700A using the values contained in Table 4-3.

The display should read between the minimum and maximum readings listed in the

table.

4. The following tests require a Fluke 5725A Amplifier (or equivalent) to be used with

the 5700A. The input level for the performance test will be set on the 5700A but will

be output from the 5725A Amplifier.

Connect a cable from the Output VA HI and LO connectors of the 5725A to the [10 A]

and COM connectors on the Fluke 45. Select the function and range on the Fluke 45 and

the input level from the 5700A using the values contained in Table 4-4. The display

should read between the minimum and maximum readings listed in the table.

4-4

Performance Testing and Calibration

Performance Tests

Table 4-2. Performance Tests for Volts, Diode Test, Ohms, and Frequency Functions

Function

Range (Rate)***

Input Level

Frequency

Display

Min

Max

100 mV (slow)

short

-0.006

0.006

90 mV

89.971

90.029

1000 mV (slow)

900 mV

899.71

900.29

300 mV

short

-0.02

0.02

300 mV

299.90

300.10

3 V

-3 V

-3.0010

-2.9990

30 V

-30 V

-30.010

-29.990

300 V

-300 V

-300.10

-299.90

1000 V

-1000 V

-1000.5

-999.5

30 V

29.990

30.010

300 V

299.90

300.10

1000 V

999.5

1000.5

short

-0.0008

0.0008

(tone)

open

300 mV

short

<0.75

15 mV

1 kHz

14.87

15.13

100 kHz

13.75

16.25

300 mV

1 kHz

299.30

300.70

100 kHz

284.50

315.50

3 V

3.0 V

1 kHz

2.9930

3.0070

30 V

1 kHz

29.930

30.070

300 V

1 kHz

299.30

300.70

750 V

1 kHz

747.5

752.5

Using decades of 3:

300 Ω*

short

0.00

0.04

300 Ω

299.83

300.19

3 kΩ*

short

0.000

0.0002

3 kΩ

2.9983

3.0017

30 kΩ

29.983

30.017

300 kΩ

299.83

300.17

3 MΩ

2.9980

3.0020

30 MΩ**

30 MΩ

29.922

30.078

300 MΩ

294.0

306.0

Using decades of 1.9:

300 Ω*

short

0.00

0.04

190 Ω

189.88

190.14

4-5

Service Manual

Table 4-2. Performance Tests for Volts, Diode Test, Ohms, and Frequency Functions (cont)

Function

Range (Rate)***

Input

Frequency

Display

Level

Min

Max

3k Ω*

short

0.0000

0.0002

1.9 kΩ

1.8988

1.9012

30 kΩ

19 kΩ

18.988

19.012

300 kΩ

190 kΩ

189.88

190.12

3 MΩ

1.9 MΩ

1.8987

1.9013

30 MΩ**

19 MΩ

18.949

19.051

300 MΩ**

190 MΩ

186.2

193.8

Using decades of 1.0:

300 Ω*

short

0.00

0.04

100 Ω

99.93

100.09

3 kΩ

short

0.0000

0.0002

1 kΩ

0.9993

1.0007

30 kΩ

10 kΩ

9.993

10.007

300 kΩ

100 kΩ

99.93

100.07

3 MΩ

1 MΩ

0.9992

1.0008

30 MΩ**

10 MΩ

9.972

10.028

300 MΩ**

100 MΩ

98.0

102.0

10/100 kHz

0.1 to 10 V

10 kHz

9.994

10.006

* Use either 2-wire compensation on the 5700A or the relative (REL) mode on the 45.

** Optional test points that can be used if standards are available.

*** All measurement rates are in medium speed unless otherwise specified.

4-6

Performance Testing and Calibration

Table 4-3. Performance Tests for mA Current Functions

Function

Range (Rate)

Input Level

Frequency

Display

Min

Max

(mA)

30 mA

+30 mA

29.982

30.018

100 mA

+100 mA

99.93

100.07

(mA)

30 mA

1 kHz

29.840

30.160

100 mA

1 kHz

99.40

100.60

Table 4-4. Performance Tests for Current Functions

Function

Range (Rate)

Input Level

Frequency

Display

Min

Max

10 A

+10 A

9.975

10.025

10 A

1 kHz

9.890

10.110

4-4.

Front Panel Calibration

The Fluke 45 features closed-case calibration using known reference sources. The

multimeter automatically prompts you for the required reference sources, measures

them, calculates correction factors, and stores the correction factors in the nonvolatile

calibration memory.

Closed-case calibration has many advantages. There are no parts to disassemble, no

mechanical adjustments to make, and the Fluke 45 can be calibrated by an automated

instrumentation system.

The Fluke 45 should normally be calibrated on a regular cycle, typically every 180 days

or 1 year. The chosen calibration cycle depends on the accuracy specification you wish

to maintain. The Fluke 45 should also be calibrated if it fails the performance test or has

undergone repair. To meet the specifications in Chapter 1, the Fluke 45 should be

calibrated with equipment meeting the minimum specifications given in Table 4-1.

The following paragraphs first present a basic calibration procedure for use with front

panel control. This is followed by a description of editing prompts for different

calibration points, then by a description of calibration using the IEEE-488 or RS-232

computer interface.

4-5.

Introduction

The basic calibration consists of sets of steps for DC Volts, AC Volts, DC and AC

Milliamps, DC and AC Amps, Ohms, Continuity/Hysteresis Threshold, and Frequency.

Normally, it is recommended that the entire calibration procedure be performed.

However, it is possible to calibrate any function individually. This might be useful

during troubleshooting, when looking for a problem in a specific function. Whenever the

VDC function is calibrated, the entire calibration procedure for all functions should be

performed. Any function except VDC can be calibrated independently without affecting

calibration of another function.

If calibration of any function is discontinued prior to completion, no changes are made to

nonvolatile calibration memory for that function.

Some calibration steps take longer to execute than others. When the Fluke 45 is

executing a calibration step, it ignores all of the front panel buttons and postpones

execution of all computer interface commands.

4-7

Service Manual

4-6.

Entering Calibration Mode

Always begin the calibration procedure as follows:

1. Allow the Fluke 45 to stabilize in an environment with ambient temperature of 18 to

28ºC and relative humidity of less than 70%. Then turn the Fluke 45 on, and allow it

to warm up for at least 1 hour.

2. The Cal Enable button is located on the right side of the display and is recessed

beneath a calibration seal. Enable the calibration mode by pressing the Cal Enable

button for about three seconds (CAL appears in secondary display.) Use a small

screwdriver or equivalent blunt-tipped object. Avoid using sharper-tipped objects

(such as pencils).

When the calibration mode is enabled, the unit first beeps, then displays VDC CAL.

From this point the calibration menu can be scrolled to a specific function using the

and

editor buttons. To display the first prompt for the selected calibration function

press the

button. In the calibration mode, most buttons are disabled; only the

, and

edit buttons and the Cal Enable button remain active. These buttons are

described more fully as follows:

1. Cal Enable button: Enables the calibration mode when pressed for 3 seconds. Exits

the calibration mode when pressed momentarily.

Editor buttons: Used to scroll to the desired calibration function in the

calibration menu or to edit the displayed calibration prompt.

• Once calibration mode has been entered, the calibration menu appears in the

following sequence:

VDC

VAC mA DC mA AC A DC A AC Ω

The menu does not wrap; going from Hz back to V DC can only be accomplished by

successively pressing the

button.

• Once

has been pressed to initiate calibration prompting, press either

once initially to enter the editor mode. Then use these buttons to edit the

calibration prompt value.

The calibration prompt value can be edited by digit. Use

to select the digit

to edit. Use

to increment the selected digit. To select a lower digit value,

continue incrementing with

; the meter wraps from 9 back to 0. Press

when the edited value is correct.

button: Used to select a calibration function, calibrate (store constants derived

from input source into memory), or exit editor mode.

Each time the Fluke 45 prompts you for a reference source, apply the requested source to

the appropriate input and COM terminals, allow for both calibrator and meter settling

time, and press the

button. When

is pressed, the numeric display field blanks

while the Fluke 45 performs the necessary calculations. (Do Not change the reference

source while the display is blank.) If the calibration step is successful, the Fluke 45

displays an intensified reading equal to the calibration prompt value before changing to

the next prompt.

Note

The meter emits a beep and displays ’Error’ if a calibration step fails.

Usually, this happens if the reference is not within an anticipated range (5

to 15%, depending on the step.) At this point, the intensified reading equals

the raw uncalibrated reading taken on the reference input. Refer to

Calibration Failures in Chapter 5 for more information.

4-8

Performance Testing and Calibration

Front Panel Calibration

4-7.

Exiting Calibration Mode

Calibration mode can be exited at any time by pressing the Cal Enable button. However,

if this button is pressed prior to completion of all calibration points for any function, no

changes are made to nonvolatile calibration memory for that function.

If calibration mode is exited after completion of calibration of any function except VDC,

constants for other functions are not affected. But remember, whenever VDC is

calibrated, the calibration procedure for all other functions should be performed.

To exit the calibration mode, press the Cal Enable button with a small screwdriver or

equivalent blunt-tipped object. Avoid using sharper-tipped objects (such as pencils).

4-8.

DC Volts Calibration (Front Panel)

To perform VDC calibration, proceed as follows:

1. Press the Cal Enable button for 3 seconds to enter the calibration mode. Or, if the

meter is already in calibration mode, but set for a different type of calibration, press

the

button to return to VDC calibration.

2. Press the

button to select the first prompt (0.000 mV DC) for the VDC

function.

3. Apply a shorting bar to the

and COM inputs of the meter and allow 5

seconds for meter settling.

Note

After voltage is applied to the

input, the meter can take up to 4

minutes to settle to zero within one microvolt once the voltage is removed.

For this reason, no voltage should be applied to the input for 4 minutes

before doing zero mV cal.

4. Push the

button to calibrate the meter zero mV calibration point.

5. Remove the short and connect the dc volts source to the

and COM inputs of

the meter.

6. Complete calibration steps 2 through 10 in Table 4-5.

4-9.

AC Volts Calibration (Front Panel)

To perform ac volts calibration, proceed as follows:

1. If the meter is already in calibration mode, press the

button to select

VAC calibration. Otherwise, select calibration mode first (press Cal Enable button

for three seconds), then select VAC calibration by pressing the

button once.

2. Connect the ac source to the

and COM inputs of the meter.

3. For each of steps 11 through 17 (Table 4-5), apply the source output indicated and

calibrate the meter by pressing the

button.

4-10.

DC and AC Milliamp Calibration (Front Panel)

Perform the dc and ac milliamps calibration as follows:

1. If the meter is already in calibration mode, press the

button to select

mA DC calibration. Otherwise, select calibration mode first (press Cal Enable button

for three seconds), then select mA DC calibration by pressing the

button twice.

2. Connect the dc milliamps source to the [100 mA] and COM inputs.

3. Apply the dc milliamp outputs indicated in Table 4-5 (steps 18 and 19), and calibrate

the meter with the

button.

4. Press the

button to select mA AC calibration.

4-9

Service Manual

5. Connect the ac milliamps source to the [100 mA] and COM inputs.

6. Apply the ac milliamp outputs indicated in Table 4-5 (steps 20 and 21), and

calibrating each step by pressing the

button.

Table 4-5. Front Panel Calibration

Note

Before proceeding, allow for settling time of at least 30 seconds with no

input applied.

Step

Meter Cal Prompt

Source Input

Meter Settling Time

Before Pressing

DC Volts Calibration

0.000 mV DC

short

5 s

90.000 mV DC

90 mV dc

2 s

-90.000 mV DC

-90 mV dc

2 s

900.00 mV DC

900 mV dc

2 s

90.000 mV DC

90 mV dc

5 s

290.00 mV DC

290 mV dc

1 s

2.9000 V DC

2.9 V dc

1 s

29.000 V DC

29 V dc

1 s

290.00 V DC

290 V dc

1 s

1000.0 V DC

1000 V dc

1 s

Note

Settling times mentioned here assume that steps 1 through 32 are followed

in sequence. If you have just calibrated dc volts (steps 1 through 10), but

do not follow the subsequent sequence, a special settling period of 4

minutes may be required due to dielectric absorption caused by the 1000 V

dc input in step 10. Examples of this requirement include re-checking dc

volts calibration (going from step 10 back to step 1) or skipping to ohms

calibration (going from step 10 to step 25.)

AC Volts Calibration

29.000 mV AC

29 mV 1 kHz

3 s

290.00 mV AC

290 mV 1 kHz

3 s

0.2900 V AC

290 mV 1 kHz

3 s

2.9000 V AC

2.9 V 1 kHz

3 s

29.000 V AC

29 V 1 kHz

3 s

290.00 V AC

290 V 1 kHz

3 s

750.00 V AC

750 V 1 kHz

3 s

DC Milliamps Calibration

29.000 mA DC

29 mA dc

1 s

100.00 mA DC

100 mA dc

1 s

AC Milliamp Calibration

29.000 mA AC

29 mA 1 kHz

3 s

100.00 mA AC

100 mA 1 kHz

3 s

DC and AC Amps Calibration

10.000 A DC

10 A DC

3 s

2.000 A AC

2 A 1 kHz

5 s

10.000 A AC

10 A 1 kHz

5 s

4-10

Performance Testing and Calibration

Front Panel Calibration

Table 4-5. Front Panel Calibration (cont)

Ohms Calibration

Step

Initial Meter Cal

5700A Source

Edit Meter Cal Prompt

Meter Settling Time

Prompt

Output

To:

Before Pressing

290.00 Ω

190 Ω*

5700A Display

1 s

2.9000 kΩ

1.9 kΩ

1 s

29.000 kΩ

19 kΩ

2 s

28**

290.00 kΩ

190 kΩ

3 s

29**

2.9000 MΩ

1.9 MΩ

3 s

Continuity/Hysteresis Threshold Calibration

Step

Meter Cal

Source Output

Meter Settling Time Before Pressing

Prompt

0.000 V

0.000 mV

1 s

0.020 V

20.00 mV

1 s

Frequency Calibration

2.000 V p-p

10 kHz

2 s

* A 190 Ω source calibrates the 300 Ω range on the Fluke 45 to 0.06%+2 digits +0.02 Ω. For calibration of

this range to 0.05%+2 digits +0.02 Ω, use a 290 Ω source and the procedure detailed under Alternate

Ohms Calibration (Front Panel). This procedure can also be used with appropriate discrete resistor

values (such as a decade box) on all ranges.

** Note that the 300 kΩ and 3 MΩ ranges are quite sensitive to noise. Any movement of the input leads

or movement of the hands or body in the vicinity of the leads can cause noisy readings. This causes an

error in the calibration if the

button is pushed during a bad reading. To avoid this, use shielded

leads during this calibration and hold very steady for several seconds with your index finger resting on

the

button before pressing it. These two cal points should be verified for accuracy at the

conclusion of calibration.

4-11. DC and AC Amps Calibration (Front Panel)

The dc and ac amps calibration requires a boost amplifier or transconductance amplifier

capable of 10 A output at both dc and 1 kHz.

1. If the meter is already in calibration mode, press the

button to select A

DC calibration. Otherwise, select calibration mode first (press Cal Enable button for

three seconds), then select A DC calibration by pressing the

button four times.

2. Connect the output of the boost amplifier to the [10 A] and COM inputs of the

meter.

3. Apply the dc amp output indicated in Table 4-5 (step 22), and calibrate using the

button.

4. Select A AC calibration on the meter by pressing the

button once.

5. Apply the two ac amp outputs called for in steps 23 and 24 of Table 4-5, calibrating

each step by using the

button.

4-12. Ohms Calibration (Front Panel)

If you do not have the value resistors (290 Ω, 2.9 kΩ, 29 kΩ, etc.) required by the Fluke

45 calibration prompts, the requested value (prompt) must be edited to the value

available. (See "Editing the Prompt for Different Calibration Points", later in this

4-11

Service Manual

chapter.) In the following procedure, the Fluke 5700A Multifunction Calibrator is used

as the ohms source, with input values of 190 Ω, 1.9 kΩ, 19 kΩ, 190 kΩ, and 1.9 MΩ.

1. If the meter is already in calibration mode, press the

button to select Ω

calibration. Otherwise, select calibration mode first (press Cal Enable button for

three seconds), then select Ω calibration by pressing the

button six times.

2. Connect the ohms source to the meter in a four-wire configuration. Refer to Figure

4-1.

3. On the 5700A, select 2-wire compensation ON, with external sense. Then program

the 5700A for the output in step 25 of Table 4-5.

4. Edit the meter prompt display to read the same value as the 5700A output display.

5. On the meter, press the

button to calibrate this step. Then continue with steps

26 through 29 in Table 4-5.

CAUTION

: ON

COMP

EX SNS

USE CONNECTIONS WITH

EXPOSED PLUG TIPS FOR

: OFF

EX GRD

THE OHMS FUNCTION ONLY.

UUT

5700A

2-WIRE

COMP

5700A

OUTPUT

SENSE

V Ω A

Ω

WIDEBAND

AUX

GUARD GROUND

CURRENT

45 DUAL DISPLAY MULTIMETER

10A

REMOTE

SMF MAX dB REL AUTO

EXT TRG

MIN HOLD

600V

mVDCAC

UNCAL mA

DC AC

CAL

1000V CAT

Mk Hz

ENABLE

COM

100

FUSE F1

REL

2ND

500 mA

F 250V

REF#

REF

LOCAL

FUSED

FREQ

AUTO

HOLD

MN MX

RATE

COMP

LO THRESH

ADDR

BAUD

POWER

qb18f.eps

Figure 4-1. Four-Wire Configuration

4-12

Performance Testing and Calibration

Front Panel Calibration

4-13.

Alternate Ohms Calibration (Front Panel)

The following procedure can be used with discrete resistor values (such as a decade

box). On the 300 Ω range, this alternate procedure uses a 290 Ω source and yields a

specification of 0.05%+2 digits +0.02 Ω. Alternate calibration of this range is detailed

below, although discrete resistor values can be used for all ranges. Lead and source zero

resistances are only taken into account for the lowest two ranges (300 Ω and 3 kΩ).

1. Connect the ohms source to the meter. Apply zero ohms.

2. Measure and record the residual lead and source zero resistance on the 300Ω range.

3. Add the value from the lead and source zero resistance from step 2 above to the

certified value of the source resistor.

4. Set the meter to the calibration mode (press the Cal Enable button.) Select ohms

calibration.

5. Using the editor buttons, edit the meter display prompt to the value calculated in step

6. Press

to calibrate this range.

4-14.

Continuity/Hysteresis Threshold Calibration (Front Panel)

Perform the calibration as follows:

1. If the meter is already in calibration mode, press the

button to select

calibration. Otherwise, select calibration mode first (press Cal Enable button

for three seconds), then select

calibration by pressing the

button seven

times.

2. Connect the output of the dc voltage source to the

and COM input of the

meter.

3. Apply the outputs indicated in Table 4-5, and calibrate using the

button.

4-15.

Frequency Calibration (Front Panel)

If the meter is already in calibration mode, press the

button to select Hz calibration.

Otherwise, select calibration mode first (press Cal Enable button for three seconds), then

select Hz calibration by pressing the

button eight times. Complete step 32 of Table

4-5

4-16.

C2 Adjustment Procedure

The following procedure can be performed on meters that fail to meet the performance

test limits for high frequency VAC. The procedure is performed separately after all other

VAC calibration steps are completed. It is not necessary to enter the calibration mode to

adjust C2.

Remove the top shield (MP11).

Set the UUT to VAC

Apply 15 mV, 1 kHz to the UUT input.

Record the UUT display reading.

Apply 15 mV, 20 kHz to the UUT input.

Adjust C2 until the UUT display reads 40 µV less that the reading recorded in Step

4-13

Service Manual

Remove the adjustment tool from the vicinity of C2 and let the reading settle.

The reading should remain stable.

Readjust if necessary.

10. Re-install the top shield (MP11).

11. Complete the performance test for ACV.

AC Buffer Amp

qb58sc.eps

Figure 4-2. C2 Location

4-17.

Editing the Prompt for Different Calibration Points

Except for the first three prompts in VDC (0.000 mV, +90.000 and -90.000 mV are

calibration constants), the Fluke 45 can be calibrated using calibration points other than

the prompted values. To do this, you must edit the prompt to the reference source value

as follows:

1. Press the

editor button. This intensifies the left-most digit of the numeric

display and turns the EDIT annunciator on.

2. Press the

editor button to increment the intensified digit from 0-9.

3. Press the

editor button again to intensify the next digit to be edited.

4. Once the edited value is equal to the reference source value, push the

button to

exit the edit mode.

Holding down the editor buttons causes continual incrementing until the button is

released.

For calibration at points other than full scale, you must account for the effect of non-

linearity and noise on the accuracy specifications. This effect is expressed as a

percentage added to the Fluke 45 specification.

Table 4-6 shows additional errors to be added to the specifications when calibration is

conducted at points other than full range.

For example, if ohms is calibrated using decades of 1.9 (190 Ω, 1.9 kΩ, etc.), the

additional error on the 300 Ω and 100 Ω ranges is 0.01%. Therefore, since calibration

has been performed at less than full scale, 0.01% must be added to the Fluke 45 300 Ω

and 100 Ω range accuracy to arrive at the new specification.

4-14

Performance Testing and Calibration

Calibration Using the Computer Interface

Note that the first three calibration points (0, 90 mV, and -90 mV) cannot be edited.

Also, to provide accuracy at full range, calibration is not recommended below one-third

of full range (10000 counts).

Table 4-6. Specifications Increase with Different Calibration Points

Cal Point In Display Counts

Function

20000

19000

10000

.006%

.012%

.045%

.05%

.09%

300 Ω/100 Ω

.01%

.02%

kΩ/MΩ

.01%

4-18. Calibration Using the Computer Interface

4-19.

Setup

Before performing this type of calibration, make sure that computer interface

connections are made to the Fluke 45. Then verify the ac power connection to the Fluke

45, and turn the meter on.

4-20.

RS-232 Interface

For RS-232 interface operation, use the following procedure from the front panel:

1. Press

, then press

2. Use

to scroll to the desired baud rate. Then press

to select the

displayed rate.

3. Use

to scroll to the desired parity ("E" for even, "Odd" for odd, or "no"

for none.) Then press

to select the displayed parity.

4. Use

to display "OFF" or "On" for command echo mode. Then press

to make the selection.

5. Send the following command from the computer interface:

*IDN?<CR>

6. Check for a response in the following format:

FLUKE, 45, nnnnnnn, n.n Dn.n <CR><LF> =><CR><LF>

where ’nnnnnnn’ is the multimeter serial number, ’n.n’ identifies the main software

version, ’Dn.n’ identifies the display software version, and ’=>’ is the RS-232 prompt.

If echo mode is ON, the response to the CALSTEP? command called for in Table 4-7

(step 12) appears in the form:

CALSTEP?<CR><LF>

+290.00E-3<CR><LF>

=><CR><LF>

where => is the prompt returned by the Fluke 45. The response to CALREF? also

follows this format.

4-15

Service Manual

4-21. IEEE-488 Interface

For IEEE-488 interface operation, use the following front panel procedure:

1. Press

, then press

2. Use

to scroll to "IEEE". Then press

to enable the IEEE-488 interface.

3. Send the following to the meter over the IEEE-488 bus:

Note

The following example uses Fluke BASIC commands entered from a Fluke

1722A Instrument Controller. Syntax may vary for other controllers.

INIT PORT 0<CR>

CLEAR PORT 0<CR>

PRINT @<address of meter>,"*IDN?"<CR>

INPUT LINE @<address of meter>,A$<CR>

PRINT A$<CR>

4. Check for the following response format:

FLUKE, 45, nnnnnnn, n.n Dn.n

where ’nnnnnnn’ is the multimeter serial number, ’n.n’ identifies the main software

version, and ’Dn.n’ identifies the display software version.

4-16

Performance Testing and Calibration

Calibration Using the Computer Interface

Table 4-7. Calibration Using the Computer Interface

Note

Before proceeding, allow for settling time of at least 30 seconds with no

input applied.

Step

Apply Input

Wait For Meter Settling Time

Send

0.0000 mV dc

5 s

CALSTEP?

90.000 mV dc

2 s

CALSTEP?

-90.000 mV dc

2 s

CALSTEP?

900.00 mV dc

2 s

CALSTEP?

90.000 mV dc

5 s

CALSTEP?

290.00 mV dc

1 s

CALSTEP?

2.9000 V dc

1 s

CALSTEP?

29.000 V dc

1 s

CALSTEP?

290.00 V dc

1 s

CALSTEP?

1000.0 V dc

1 s

CALSTEP?

Note

Settling times mentioned here assume that steps 1 through 32 are followed in sequence. If you

have just calibrated dc volts (steps 1 through 10), but do not follow the subsequent sequence, a

special settling period of 4 minutes may be required due to dielectric absorption caused by the

1000 V dc input in step 10. Examples of this requirement include re-checking dc volts calibration

(going from step 10 back to step 1) or skipping to ohms calibration (going from step 10 to step

25.)

AC Volts Calibration

29.000 mV ac, 1 kHz

3 s

CALSTEP?

290.00 mV ac, 1 kHz

3 s

CALSTEP?

290.00 mV ac, 1 kHz

3 s

CALSTEP?

2.9000 V ac,

1 kHz

3 s

CALSTEP?

29.000 V ac,

1 kHz

3 s

CALSTEP?

290.00 V ac,

1 kHz

3 s

CALSTEP?

750.00 V ac

1 kHz

3 s

CALSTEP?

DC Milliamps Calibration

29.000 mA DC

1 s

CALSTEP?

100.00 mA DC

1 s

CALSTEP?

DC Amps Calibration

10.000 A DC

3 s

CALSTEP?

AC Amps Calibration

2.000 A AC, 1 kHz

5 s

CALSTEP?

10.000 A AC, 1 kHz

5 s

CALSTEP?

Ohms Calibration

Step

Range

Input

Wait for Meter Settling

Send

Time

190.0 Ω*

1 s

CALREF xxx.xx

CALSTEP?

1.900 kΩ

1 s

CALREF xxxx.x

CALSTEP?

19.00 kΩ

2 s

CALREF xxxxx

CALSTEP?

28**

190.0 kΩ

3 s

CALREF xxxxxx

CALSTEP?

29**

1.900 MΩ

3 s

CALREF xxxxxxx

CALSTEP?

4-17

Service Manual

Table 4-7. Calibration Using the Computer Interface (cont)

Continuity/Hysteresis Threshold Calibration

Step

Apply input

Wait for meter settling time

Send

0.000 mV dc

1 s

CALSTEP?

20.00 mV dc

1 s

CALSTEP?

Frequency Calibration

10 kHz, 2.000 V p-p

2 s

CALSTEP?

(xxxx... represents the known exact ohms value of the source)

* A 190 Ω source calibrates the 300 Ω range on the Fluke 45 to 0.06%+2 digits +0.02 Ω. For calibration of

this range to 0.05%+2 digits +0.02 Ω, use a 290 Ω source and the procedure detailed under Alternate

Ohms Calibration (Computer Interface). This procedure can also be used with appropriate discrete resistor

values (such as a decade box) on all ranges.

** Note that the 290 kΩ and 2.9 MΩ ranges are quite sensitive to noise. Any movement of the input leads

or movement of the hands or body in the vicinity of the leads can cause noisy readings. Use shielded

leads during this calibration. These two cal points should be verified for accuracy at the conclusion of

calibration.

4-22.

The Calibration Procedure

Now select calibration mode on the Fluke 45. Using a thin, blunt-tipped object, press the

recessed Cal Enable button for three seconds. Avoid using sharp objects that might

damage this button. Refer to Table 4-8 for brief descriptions of calibration mode

commands.

The CALREF xxx.xx command tells the Fluke 45 to change the calibration prompt to the

exact value of the input from the calibrator. Use of this command is equivalent to the act

of editing the calibration prompt from the front panel when other than exact calibration

points are to be used.

The CALSTEP? command normally returns the calibrated value of the input. If the input

is not within an anticipated range of the expected value (5 to 15%, depending on the

step), a beep is sounded at the front panel, a device dependent error is returned over the

computer interface, and the measured reading is returned.

The response to CALSTEP? must be received before each new step can begin. With

some steps (such as step 31), a noticeable delay may be encountered.

Before beginning calibration, consider the functions that will be affected. AC volts, dc

amps, ac amps, and ohms are all influenced by dc volts calibration. If you calibrate dc

volts, you must re-calibrate these other functions. But, calibration of ac volts, dc amps,

ac amps, and/or ohms influences only the function being calibrated.

If you plan to include the ohms function in your calibration procedure, determine the

residual lead and source zero resistance before you place the meter in calibration mode.

Use the following procedure:

1. Send: OHMS; RANGE 1

2. Measure the residual lead and source zero resistance on the 300 Ω range by sending:

VAL?

3. Record the response. This value is used if you elect to perform the Alternate Ohms

Calibration.

4. Now continue on with the calibration procedures in the following paragraphs.

4-18

Performance Testing and Calibration

Calibration Using the Computer Interface

4-23.

DC Volts Calibration (Computer Interface)

1. Connect the DC Calibrator to the Fluke 45

and COM inputs. Then send:

CAL 1

2. Complete steps 1 through 10 in Table 4-7. Then clear the dc volts source.

4-24.

AC Volts Calibration (Computer Interface)

1. Connect the AC Calibrator to the Fluke 45

and COM inputs. Then send:

CAL 2

2. Complete steps 11 through 17 in Table 4-7. Then clear the ac volts source.

4-25.

DC and AC Milliamps Calibration (Computer Interface)

1. Connect the mA Calibrator to the Fluke 45 [100 mA] and COM inputs. Then send:

CAL 3

2. Complete steps 18 and 19 in Table 4-7.

3. Now send:

CAL 4

4. Complete steps 20 and 21 in Table 4-7. Then clear the milliamp source.

4-26.

DC and AC Amps Calibration (Computer Interface)

1. Connect the Amps Calibrator to the Fluke 45 [10 A] and COM inputs. Then send:

CAL 5

2. Complete step 22 in Table 4-7.

3. Clear the dc amps source. Then send:

CAL 6

4. Complete steps 23 and 24 in Table 4-7, and clear the amps source.

4-27.

Ohms Calibration (Computer Interface)

If you do not have the value resistors (290 Ω, 2.9 kΩ, 29 kΩ, etc.) required by the Fluke

45 calibration prompts, the requested value (prompt) may be set to the value available. In

the following procedure, the Fluke 5700A Multifunction Calibrator is used as the ohms

source, with input values of 190 Ω, 1.9 kΩ, 19 kΩ, 190 kΩ, and 1.9 MΩ.

Note

If you are using an ohms calibrator without active 2-wire compensation,

take a zero ohms measurement before entering calibration mode. Use the

test leads that will be used for ohms calibration. Record this zero ohms

value. The CALREF xxx.xx command tells the Fluke 45 to calibrate to the

exact ohms value of the calibrator resistance. For the 290 Ω and 2.9 kΩ

steps, xxx.xx should be the calibrator value plus the recorded zero ohms

value.

1. Connect the Ohms Calibrator to the Fluke 45

and COM inputs. Then send:

CAL 7

4-19

Service Manual

Note that the 300 kΩ and 3 MΩ ranges are quite sensitive to noise. Any movement

of the input leads or movement of the hands or body in the vicinity of the leads can

cause noisy readings. Use shielded leads during this calibration. Verify these two

calibration points for accuracy at the conclusion of the calibration procedure.

2. Complete steps 25 through 29 in Table 4-7. Then clear the ohms source.

4-28.

Continuity/Hysteresis Threshold Calibration (Computer Interface)

1. Connect the DC Volts Calibrator to the Fluke 45

and COM inputs. Then

send:

CAL 8

2. Complete steps 30 and 31 in Table 4-7, and clear the source.

4-29.

Frequency Calibration (Computer Interface)

1. Connect the Frequency Calibrator to the Fluke 45

and COM inputs. Then

send:

CAL 9

2. Complete step 32 in Table 4-7. Then clear the frequency source.

4-30.

Concluding Calibration Using the Computer Interface

At the conclusion of this type of calibration, first make sure the source is cleared. Then

press the Cal Enable button on the meter to exit calibration mode.

Calibration mode can also be exited at any time by sending the *RST command. If this

command is sent prior to completion of all calibration points for the selected function, no

changes are made to nonvolatile calibration memory for that function.

If calibration mode is exited after completion of calibration of any function except VDC,

constants for other functions are not affected. But remember, whenever VDC is

calibrated, the calibration procedure for all other functions should be performed.

4-31.

Alternate Ohms Calibration (Computer Interface)

This procedure can be used with discrete resistor values (such as a decade box). On the

300 Ω range, this alternate procedure uses a 290 Ω source and yields a specification of

0.05%+2 digits +0.02 Ω. Alternate calibration of this range is detailed below, although

discrete resistor values can be used for all ranges. Lead and source zero resistances are

only taken into account for the lowest two ranges (300 Ω and 3 kΩ).

1. Add the value of lead and source zero resistance to the certified value of the source

resistor. Lead and source zero resistance is the value obtained with the VAL?

command, immediately prior to entering dc volts calibration. Use this total value as

’xxx.xx’ in the following command:

CALREF xxx.xx

2. Now send

CALSTEP?

Table 4-8. Calibration Mode Computer Interface Commands

4-20

Performance Testing and Calibration

Calibration Using the Computer Interface

CAL x

Start calibration of a new function, where x = 1 through 9, defined as follows:

VDC calibration

VAC calibration

DC Milliamps calibration

AC Milliamps calibration

DC Amps calibration

AC Amps calibration

Ohms calibration

Frequency comparator

Frequency calibration

CALCLR

Reset all calibration constants to nominal values, destroying present calibration.

CALCONST? xx

Return the value of the calibration constant indicated by xx. See Table 4-9.

CALREF?

Return the present calibration reference.

CALREF xxx.xx

Calibrate to the exact value xxx.xx, rather than the nominal (expected) cal value.

CALSTEP?

Return the calibrated value of the input.

EEREG? xx

Return the contents of the specified EEROM register (xx).

The following additional computer interface commands can be used in Calibration Mode. Use of any

other command results in an execution error.

*CLS

BUTTON?

*ESE

FORMAT?

*ESE?

LOCS

*ESR?

LWLS

*IDN?

REMS

*OPC

RWLS

*OPC?

SERIAL?

*RST

FORMAT

*SRE

VAL?

*SRE?

VAL1?

*STB?

*TRG

*WAI

4-21

Service Manual

Table 4-9. EEROM Calibration Constants

Calconst?

Valid Range

Description

0.97025 to 1.03775

VDC, range 1

0.97025 to 1.03775

VDC, range 2

0.97267 to 1.04554

VDC, range 3

0.96782 to 1.04035

VDC, range 4

0.96792 to 1.04045

VDC, range 5

0.9975 to 1.0025

100 mV gain

0.9975 to 1.0025

320 mV gain

0.9975 to 1.0025

3.2 V gain

-100 to 100

VAC offset, range 1

0.9725 to 1.0275

VAC, range 1

-100 to 100

VAC offset, ranges 2 through 4

0.9725 to 1.0275

VAC, range 2

0.9725 to 1.0275

VAC, range 3

0.9725 to 1.0275

VAC, range 4

0.9725 to 1.0275

VAC, range 5

0.9500 to 1.0500

ADC, range 1

0.9500 to 1.0500

ADC, range 2

0.9500 to 1.0500

ADC, range 3

0.9225 to 1.0775

AAC, range 1

0.9225 to 1.0775

AAC, range 2

-100 to 100

AAC offset, range 3

0.9225 to 1.0775

AAC, range 3

0.9990 to 1.0090

OHMS, range 1

1.0000 to 1.0100

OHMS, range 2

1.0040 to 1.0140

OHMS, range 3

0.9990 to 1.0090

OHMS, range 4

0.9990 to 1.0090

OHMS, range 5

0.9990 to 1.0090

OHMS, range 6

0.9886 to 1.0035

Slow Siemens

0.9910 to 1.0010

Medium and Fast Siemens

0.9999 to 1.0001

Frequency calibration

-10.0 to 10.0

Slow offset

1.0000 to 1.0006

Slow negative gain

4-22

Chapter 5

Diagnostic Testing and Troubleshooting

Title

Page

5-1.

Introduction

5-3

5-2.

Servicing Surface-Mount Assemblies

5-3

5-3.

Error Codes

5-4

5-4.

General Troubleshooting Procedures

5-10

5-5.

Power Supply Troubleshooting

5-10

5-6.

Raw DC Supply

5-10

5-7.

5-Volt Switching Supply

5-11

5-8.

Inverter

5-12

5-9.

Analog Troubleshooting

5-13

5-10.

Uart Test

5-13

5-11.

DC Volts Troubleshooting

5-14

5-12.

AC Volts Troubleshooting

5-14

5-13.

Ohms Troubleshooting

5-14

5-14. Digital Troubleshooting

5-15

5-15. Display Assembly Troubleshooting

5-17

5-16. Calibration Failures

5-19

5-17.

Introduction

5-19

5-18.

Calibration-Related Components

5-20

5-19.

Calibration Interrelationships

5-21

5-20.

Retrieving Calibration Constants

5-21

5-21.

Replacing the EEROM A1U5

5-21

5-1

Diagnostic Testing and Troubleshooting

Introduction

5-1.

Introduction

The Fluke 45 provides error code information and semi-modular design to aid in

troubleshooting. This chapter explains the error codes and describes procedures needed

to isolate a problem to a specific functional area. Finally, troubleshooting hints for each

functional area are presented.

But first, if the meter fails, check the fuses and replace as needed. If the problem

persists, verify that you are operating the meter correctly by reviewing the operating

instructions found in the User’s Manual.

Warning

Opening the case may expose hazardous voltages. Always

disconnect the power cord and measuring inputs before

opening the case. And remember that repairs or servicing

should be performed only by qualified personnel.

Required equipment is listed in Chapter 4 of this manual.

Signal names followed by a ’*’ are active (asserted) low. Signal names not so marked are

active high.

5-2.

Servicing Surface-Mount Assemblies

The 45 Dual Display Multimeter incorporates Surface-Mount Technology (SMT) for

printed circuit assemblies (pca’s). Surface-mount components are much smaller than

their predecessors, with leads soldered directly to the surface of a circuit board; no plated

through-holes are used. Unique servicing, troubleshooting, and repair techniques are

required to support this technology. The information offered in the following paragraphs

serves only as an introduction to SMT. It is not recommended that repair be attempted

based only on the information presented here.

Since sockets are seldom used with SMT, "shotgun" troubleshooting cannot be used; a

fault should be isolated to the component level before a part is replaced. Surface-mount

assemblies are probed from the component side. The probes should make contact only

with the pads in front of the component leads. With the close spacing involved, ordinary

test probes can easily short two adjacent pins on an SMT IC.

This Service Manual is a vital source for component locations and values. With limited

space on the circuit board, chip component locations are seldom labeled. Figures

provided in Chapter 6 of this manual provide this information. Also, remember that chip

components are not individually labeled; keep any new or removed component in a

labeled package.

Surface-mount components are removed and replaced by reflowing all the solder

connections at the same time. Special considerations are required.

• Use a solder tool with regulated hot air to melt the solder; there is no direct contact

between the tool and the component.

• Surface-mount assemblies require rework with wire solder rather than with solder

paste. A 0.025 inch diameter wire solder composed of 63% tin and 37% lead is

recommended. A 60/40 solder is also acceptable.

A good connection with SMT requires only enough solder to make a positive metallic

contact. Too much solder causes bridging, while too little solder can cause weak or open

solder joints. With SMT, the anchoring effect of the through-holes is missing; solder

provides the only means of mechanical fastening. Therefore, the pca must be especially

5-3

Service Manual

clean to ensure a strong connection. An oxidized pca pad causes the solder to wick up

the component lead, leaving little solder on the pad itself.

5-3.

Error Codes

At reset, the Fluke 45 software attempts power-up self-tests and initialization of ROM,

RAM, Display, EEROM, and measurement hardware. Self-test failures are reported on

the display with "error" in the secondary display and an error code (1-9) in the primary

display.

Several of these error codes might never be displayed. Certainly, errors 4 and 5, which

signify a faulty or dead display, could not be reported in the normal (displayed) manner.

Other errors might not appear on the display.

The keyboard scan lines (A1U6, SWR1-5), which are also used as status indicators, can

be checked as a last resort for accessing error information. The software sets SWR1

(A1U6-21) low to indicate that the basic operation of the processor, ROM, and ROM

decode circuitry is intact. SWR2 (A1U6-22) is set low if the ROM check passes. SWR3

(A1U6-23) is set low if the external RAM (A1U10) check passes, and SWR4 (A1U6-24)

is set low if the internal RAM (A1U6) check passes. Then, if the display self-check

passes, SWR5 (A1U6-25) is set low to indicate that the display is operational.

Table 5-1 describes the error codes.

Note

Each error code is displayed for 2 seconds. Any button press during this

period aborts the error display

5-4

Diagnostic Testing and Troubleshooting

Error Codes

Table 5-1. Error Codes

Error No.

Meaning

ROM test failed

External RAM test failed

Internal RAM test failed

Display self-test failed

Display dead

EEROM meter configuration corrupted

EEROM calibration data corrupted ("UNCAL" annunciator also lights)

A/D chip dead

Measurement self-test failed

Refer to Troubleshooting information later in this chapter.

Error 1

ROM (A1U8) checksum match failed.

All the bytes in the ROM (including a checksum byte) are summed

Error 2

External RAM (A1U10) check failed.

Error 3

Internal RAM (A1U6) check failed.

Complementary patterns are alternately written and read from each RAM location for

both external RAM and the 256 bytes internal to the 6303Y Main Processor (A1U6). If the

pattern read from any RAM location is not the same as the pattern written, the test fails.

Error 4

Display self-check failed

Error 5

Display dead.

The display processor automatically performs a self-check on power-up, and the Main

Processor attempts to read the result of this test.

Error 6

EEROM (A1U5) meter configuration corrupted or EEROM not initialized.

At power up, A1U6 reads CRC from EEROM (A1U5) location, then reads configuration

data from another location in EEROM, calculates an algorithm to compare to the CRC. If

an error is determined, the meter configuration is set to factory default and Error 6 is

displayed.

Error 7

EEROM (A1U5) calibration data corrupted.

The EEROM is divided into two storage areas: the default meter configuration storage and

calibration data storage. Each area uses a Cyclic Redundancy Checksum, against which

the data is checked on power-up. In addition, the calibration data includes parity

information for each calibration constant, which is also checked.

If the meter configuration check finds an error, the meter configuration is set to factory

defaults, and Error 6 is reported.

If the parity check or the calibration data checksum finds an error, the front panel UNCAL

annunciator is turned on, and Error 7 is reported.

Note

Errors 6 and 7 should always appear the first time a meter is

powered up with a new, uninitialized EEROM. Error 7

continues to appear at subsequent power-ups until the meter

is fully calibrated.

Error 8

Analog Measurement Processor (A1U1) dead.

Error 9

Measurement self-check failed.

The Analog Measurement Processor is programmed to do self test measurements. If the

Analog Measurement Processor does not respond, it is considered dead.

5-5

Service Manual

REFJ

FA0

FAI

GUARD

AFI

RRS

MOF

AF0

RA-

RA+

GUARD

RA0

V2F

VREF-

VREF+

GUARD

B.3

0/VS

B.1

GUARD

SUM

AGND1 25

INT

44 VSS

A1U1 ANALOG MEASUREMENT PROCESSOR

DIGR P20

P32 D2

DIGS P21

P33 D3

DSCLK P22

P34 D4

RX P23

P35 D5

TX P24

P36 D6

DISRX P25

P37 D7

DISTX P26

EESK P27

P10 A0

P11 A1

P50

P12 A2

IRRQ2* P51

P13 A3

SWR1 P52

P14 A4

SWR2 P53

P15 A5

SWR3 P54

P16 A6

SWR4 P55

P17 A7

SWR5 P56

Vss

SWR6 P57 26

44 P40 A8

A1U6 MAIN PROCESSOR

qb19f.eps

Figure 5-1. Test Point Locator

5-6

Service Manual

5-4.

General Troubleshooting Procedures

The Fluke 45 allows for some fault isolation using self-diagnostic routines and

descriptive error codes. However, these features are somewhat limited and do not

provide in-depth troubleshooting tools.

The Fluke 45 incorporates a semi-modular design; determining modules not related to a

problem constitutes the first step in the troubleshooting process. Disconnect the Battery

Option cable at the Main PCA. Disconnect the IEEE-488 Interface Option at P2 and P3

on the IEEE-488 Interface PCA. If either of these assemblies is causing the meter failure,

refer to troubleshooting information in Chapters 7 and 8 (7 for the Battery Pack Option,

8 for the IEEE-488 Interface Option.)

Measuring the power supplies helps to isolate a problem further. Refer to Table 5-2 and

Figure 5-1 for test point identification and readings. If power supply loading is

suspected, disconnect the Display PCA at J4 on the Main PCA. If this action solves the

loading problem, proceed to Display Assembly Troubleshooting elsewhere in this

chapter. Otherwise, refer to Power Supply Troubleshooting.

If the power supplies appear good, check the E clock signal to determine whether the

Main PCA or the Display PCA is causing the problem. A correct display depends on the

E clock signal. Missing segments, intensified digits, a strobing display, or a blank

display can be caused by a faulty E clock.

Use an oscilloscope to check for the E clock at microcomputer A1U6, pin 68. Look for a

921.6 kHz square wave that transitions from 0 to 5 V dc (VCC).

• If this signal is present, the problem is probably on the Display PCA. Refer to

Display Assembly Troubleshooting elsewhere in this chapter.

• If the E clock is something other than a 921.6 kHz square wave, isolate the digital

chapter of the Main PCA by disconnecting the Display PCA at J4. Then check the E

clock again, and refer to Digital Troubleshooting elsewhere in this chapter for

further problem isolation.

5-5.

Power Supply Troubleshooting

5-6.

Raw DC Supply

With the meter off (but connected to line power), check for approximately 16 V dc (at

120 V ac line voltage) between the ground test point and the cathode of either A1CR2 or

A1CR3. If necessary, check for transformer secondary voltage of approximately 24 V ac.

With the meter on, check for 19 V dc from A1U11, pin 8 to the ground test point. This

voltage is approximately 5 volts greater than the raw supply voltage when the switching

supply is operating properly. The controller IC, A1U11, starts operating when its supply

voltage is approximately 2.5 V dc.

5-10

Diagnostic Testing and Troubleshooting

Power Supply Troubleshooting

Table 5-2. Power Supplies

Supply Name

Measure

Supply Range

From:

To:

Main PCA (In-Guard Circuits)

VDD

A1TP10

COM, A1R2, or A1R3*

4.95 to 5.45 V dc

VSS *

A1TP12

COM, A1R2, or A1R3

-4.95 to -5.45 V dc

+VAC

COM, A1R2, or A1R3*

4.7 to 5.35 V

-VAC

COM, A1R2, or A1R3*

-4.7 to -5.35 V

Main PCA (Out-Guard Circuits)

VCC

A1TP18

A1TP17

4.85 to 5.35 V dc

VEE

A1TP16

A1TP17

-5.0 to -6.0 V dc

VLOAD

A1TP15

A1TP17

-28.5 to -32.0 V dc

Display PCA (Out-Guard Circuits)

VCC

A2U1-21

A2TP3 or A2U1-42

4.85 to 5.35 V dc

VEE

A2U1-4

A2TP3 or A2U1-42

-5.0 to -6.0 V dc

VLOAD

A2U1-5

A2TP3 or A2U1-42

-28.5 to -32.0 V

* These points are at ’Common.’ ’Ground’ is also used in the meter, but in relation to Out-

Guard circuits only. For example, the A2 Display PCA uses ’Ground’.

5-7.

5-Volt Switching Supply

Use an oscilloscope to troubleshoot the 5-volt switching supply. Check the waveform at

either A1U11, pin 6 (switch transistor collector) or A1T1, pin 2 to determine the loading

on the 5-volt switching supply.

•

Normal load:

The waveform is a square wave with a period of approximately 20 to 25 us and an

ON (voltage is low) duty ratio of about 0.35 when the line voltage is about 120 V ac.

The amplitude is usually about 15 V p-p. The positive-going edge of the waveform

will be "fuzzy" as the duty ratio is varying to compensate for the ripple of the raw

supply and the pulsing load due to the switching of the inverter. See Figure 5-2.

•

Very Light or No Load:

The OFF interval (voltage is high) part of the waveform will have a damped ringing

sine wave of 2 to 10 cycles.

•

Heavy Load or Shorted:

The waveform is a square wave with a very low ON duty ratio (approximately 0.1.)

If no square wave signal is present, the functioning of the oscillator can be checked

by looking at the waveform at A1U11, pin 3. Use the oscilloscope with ac coupling

to make this measurement. This waveform should be a sawtooth signal with an

amplitude of 0.5 V p-p and a period of approximately 20 to 25 µs.

The output current of the 5-volt switching supply can be determined by measuring

the voltage across the current limit current sense resistors (A1R47, A1R48, A1R49).

The current shunt is approximately 0.167 ohms. With line voltage at 120 V ac,

typical voltages across the current sense resistors are as follows:

•

Meter without options: 42 mV

•

Meter with IEEE-488 Interface Option: 72 mV

5-11

Service Manual

• Meter with Battery Option

Line Operation: 54 mV

Battery Operation: 43 mV

• Meter with IEEE-488 Interface and Battery Options

Line Operation: 85 mV

Battery Operation: 43 mV

5m s

NORMAL LOAD ON 5V SUPPLY

NO LOAD OR VERY LIGHT LOAD ON 5V SUPPLY

5m s

5V SUPPLY OUTPUT SHORTED

HEAVY LOAD ON 5V SUPPLY

qb23f.eps

Figure 5-2. Volt Switching Supply

5-8.

Inverter

Use an oscilloscope to troubleshoot the inverter. Check for a 9.6 V p-p signal (with a

period of approximately 30 to 40 µs) across the primary winding of the inverter

transformer (A1T2). If this signal is measured with reference to ground, the amplitude of

the square wave should be approximately 4.8 V p-p.

5-12

Diagnostic Testing and Troubleshooting

Analog Troubleshooting

Note

When making voltage measurements in the inverter circuit, remember that

there are two separate grounds. The out-guard ground is the ’GRD’ test

point, and the in-guard ground or common is the ’common’ test point.

The normal input current to the inverter supply is about 210 mA, or 1.05 V across

A1R46.

5-9.

Analog Troubleshooting

Analog circuit problems are evidenced by Error 8 or Error 9 in the display. These errors

signify either that the Main Processor (A1U6) is not communicating with the in-guard

circuitry or that the Analog Measurement Processor (A1U1) is not functioning correctly.

First, check the in-guard power supplies referenced to common:

Power

Supply

Testpoint Range

VDD

A1TP10

4.95 to 5.45 V dc

VSS

A1TP12

-4.95 to -5.45 V dc

+VAC

+4.7 to +5.35

-VAC

-4.7 to -5.35

Check the out-guard to in-guard communication for activity whenever a front panel

button is pressed. If necessary, press a button repeatedly while looking for the following

communication activity:

A1TP8 = GROUND to VCC pulses

A1TP4 = COMMON to VDD pulses

Check the in-guard to out-guard communication:

A1TP5 = VDD to 0.7 V above COMMON pulses

A1TP7 = GROUND to VCC pulses

Check the crystal oscillator referenced to COMMON:

A1TP3 = a 3.84 MHz sine wave (260 ns period)

Check the integrator waveform referenced to COMMON:

A1U1-45 should be a triangle wave when an input is being measured.

Check the 1.1 V reference:

A1TP2 to A1TP1 = +1.1 V

In general, check that the relays are getting the proper drive signals and that they are in

the correct position.

The 10 A current shunt (A1R3) or the mA current shunt (A1R2) can be used as a

convenient COMMON test point.

5-10.

Uart Test

This test checks both the optoisolators (A1U3 and A1U4) and the Analog Measurement

Processor (A1U1) UART circuitry. The Main Processor (A1U6) first sends a break

signal (5 V dc, logic high) to A1U1, then waits for a break signal in response from

A1U1. Once this occurs, A1U6 commands A1U1 to remove its break signal response.

5-13

Service Manual

To initiate the UART test, hold the

button down for three seconds. If the test passes,

"PASS" is shown in the secondary display. If the test fails, "FAIL" is shown in the

secondary display. The test is run repeatedly, updating the "PASS" or "FAIL" display

each time. An oscilloscope can thereby be used to trace the rectangular wave forms

across optoisolators A1U3 and A1U4.

To exit the UART Test, turn the meter off, wait three seconds, then turn the meter back

on.

5-11.

DC Volts Troubleshooting

Put the meter in the 300 mV or 3 V range, and apply an input. Then trace this signal as

described in Table 5-3.

5-12.

AC Volts Troubleshooting

Apply a signal with the multimeter set for the 300 mV ac range. Then trace this signal as

described in Table 5-4.

5-13.

Ohms Troubleshooting

Use a meter with high input impedance to measure the open circuit voltage for each

ohms range listed below. If a high input impedance meter is not available, the following

checks can be made on the 30 kΩ and lower ranges only.

RANGE

VOLTAGE:

300 Ω

3 V

3 kΩ

1.3 V

30 kΩ

1.3 V

300 kΩ

1.3 V

3 MΩ

1.3 V

30 MΩ

3 V

300 MΩ

3 V

With failures with these tests, suspect components are A1R5, A1RT1, A1K2, A1Q1,

A1Z1, and A1U1.

Now check the signal path at the following points: W1, A1U1-23 (OVS), A1U1-58

(AFI), and A1U1-56 (AFO). Suspect components for these checks are A1R6, A1R7,

A1K1, and A1U1.

Table 5-3. DC Volts Troubleshooting

Checkpoint

Description

Possible Fault

A1U1-23 (OVS)

Input signal

A1W1, A1R6, A1R7, A1K1

A1U1-58 (AFI)

Input signal, active filter input

A1U1

A1U1-56 (AFO)

Input signal, active filter output

A1U1

A/D low path

Check continuity among A1U1-13, RRS, and

A1R9, A1K2

COMMON.

5-14

Diagnostic Testing and Troubleshooting

Digital Troubleshooting

Table 5-4. AC Volts Troubleshooting

Checkpoint

Description

Possible Fault

A1Z2-1

Input signal

A1R5, A1R5, A1C1, A1K3

A1U1-2 (ACBO)

Amplified input (input x 2.5)

A1U1, A1R11-A1R14, A1Q2-A1Q8, A1Z2,

A1AR1, A1C7, A1R16, A1R17

A1U1-68 (RMSI)

Amplified input

A1U1

A6U1-14

Amplified input

A6U1

A1Z4-2

DC equivalent of amplified input

A6U1

A1U1-61 (RMSF)

DC equivalent of original input

A1Z4, A1R19, A1C10

5-14. Digital Troubleshooting

At power-up, if the display does not light or lights up and fails to report errors or begin

operation, use the following troubleshooting procedures.

First check the state of SWR1 (A1U6-21). If this status line is less than 0.8 V, basic

processor operation is intact. Examining SWR2 through SWR5 (A1U6-22 through -25,

respectively) should indicate how far the software progressed before finding an error. If

the state of SWR1 is not less than 0.8 V, the problem may be in the 6303Y Main

Processor (A1U6), the ROM or RAM decode circuitry (A1U9), the ROM (A1U8) or

RAM (A1U10), or the address/data lines among these parts.

Note

The functions of SWR1 through SWR5 as power-up status lines only

persist for 2 to 3 seconds. These functions end when the keyboard scanner

begins operation (if it can). Extremely difficult cases may require the use of

an oscilloscope triggered on the falling edge of SWR1 to examine the states

of SWR2 through SWR5.

To determine the relative health of the 6303Y Main Processor (A1U6), first check for a

valid E clock at pin 68. The default for the E clock after reset is a rectangular wave with

a period of 1.628 us and a duty cycle of about 67%.

If the processor is able to fetch instructions from the ROM, the software initializes the

processor, and the E clock becomes a square wave with a period of 1.085 us. Since this

initialization occurs almost immediately with a working meter, the resulting square wave

on the E clock line is a good indication that the software has begun to execute.

If the E clock remains a 1.628 us rectangular wave, the SWR2 (A1U6-22) keyboard scan

line may be shorted to ground. This condition would cause the Main Processor to HALT

after reset. Check whether the 6303Y Main Processor is attempting to access ROM;

LIR* (pin 64) should transition for a short period of time after reset. If it does, the

6303Y Main Processor is probably operational, and the problem is external to the

processor.

The processor can execute an instruction that stops both itself and the E clock.

Therefore, the absence of any activity on pin 68 does not necessarily mean that A1U6 or

A1Y2 is bad. If some other failure prevents proper ROM access, the processor may have

just "gone to sleep". This can be verified by checking for a rectangular wave occurring at

pin 68 for a short time after RESET* transitions high on pin 7. A1U6 and A1Y2 are

probably operational if this rectangular wave is present.

5-15

Service Manual

t cyc

2.4V

0.8V

tAD

AH1

A0~A15

2.4V

R/W

0.8V

AH2

HRW

RWD

2.4V

RD,WR

0.8V

HW2

DDW

HW1

MCU Write

2.4V

D0 ~ D7

0.8V

ACC

DSR

MCU Read

2.0V

D0 ~ D7

0.8V

DLR

HLR

LIR

0.8V

qb24f.eps

Figure 5-3. Main Processor Timing

To check the ROM decode circuitry, verify that A1U9-6 is transitioning low and that

these transitions correspond roughly to the low-going transitions of LIR*. Pin 6 must be

low when LIR* is low; see Figure 5-3. Verify that this signal also appears at the ROM

Chip Enable, A1U8-20. If the ROM Chip Enable is present, the problem is with the

ROM itself or there is a fault in the address/data lines among the 6303Y Main Processor,

ROM, RAM, and IEEE option connector.

If SWR1 (A1U6-21) and SWR2 (A1U6-22) transition low, but SWR3 (A1U6-23)

remains high, the problem is with the RAM decode circuitry (A1U9), the external RAM

(A1U10), or the address/data/control lines between the RAM and the 6303Y Main

Processor.

To check the RAM decode circuitry, verify that A1U9-8 is transitioning low and that

these transitions correspond approximately to the low-going transitions of WR* (A1U6-

66). It may be necessary to continually reset (power on) the meter to check these lines,

since the activity probably halts quickly when the meter software goes awry. Verify that

the signal on A1U9-8 also appears at the RAM Chip Enable, A1U10-20. If the RAM

5-16

Diagnostic Testing and Troubleshooting

Display Assembly Troubleshooting

Chip Enable is present, the problem is with either the RAM itself or the address, data,

RD*, or WR* lines between the 6303Y Main Processor and the external RAM.

Figure 5-3 shows the timing relationships of the 6303Y Main Processor lines LIR* and

WR* to the system clock (E) and the address lines A0..A15. The ROM and RAM Chip

Enables correspond to the active (low) region shown for the address lines.

5-15. Display Assembly Troubleshooting

The following discussion is helpful if it has been determined that the Display Assembly

is faulty. This initial determination may not be arrived at easily, since an improperly

operating display may be the result of a hardware or software problem that is not a direct

functional part of the Display Assembly. Consult the General Troubleshooting

Procedures found earlier in this chapter for procedures to isolate the fault to the Display

Assembly. Use the following discussion of display software operation when

troubleshooting problems within a known faulty Display Assembly. A Display Extender

Cable is available (PN 867952) for use during troubleshooting.

Figure 5-4 shows the timing of communications between the main processor and the

display controller.

The Display Controller reads the DTEST* and LTE* inputs to determine how to

initialize the display memory. DTEST* and LTE* default to logic 1 and logic 0,

respectively, to cause all display segments to be initialized to "on". DTEST* is

connected to test points A2TP4, and LTE* is connected to A2TP5. Either test point can

be jumpered to VCC (A2TP6) or GND (A2TP3) to select other display initialization

patterns. Display Test Patterns #1 and #2 are a mixture of "on" and "off" segments with a

recognizable pattern to aid in troubleshooting problems involving individual display

segments. When either of the special display patterns is selected, the beeper is also

sounded for testing without interaction with the main processor. Table 5-5 indicates the

display initialization possibilities. Figures 5-5 and 5-6 show grid and anode assignments

for primary and secondary displays, respectively.

DSCLK

DISTX

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

DISRX

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

Clear to receive

qb09.eps

Figure 5-4. Display Controller to Microprocessor Signals

5-17

Service Manual

Table 5-5. Display Initialization

A2TP4 Dtest*

A2TP5 LTE*

Power-Up Display

Initialization

All Segments OFF

All Segments ON (default)

Display Test Pattern #1

Display Test Pattern #2

GRID(10)

GRID(9)

GRID(8)

GRID(7)

GRID(6)

GRID(5)

REMOTE

SMF

MAX

AUTO

ANODE(13)

EXT TRG

MIN

HOLD

ANODE(12)

m A

ANODE(10)

m V AC DC

M k Ω Hz

qb26f.eps

Figure 5-5. Primary Display

GRID(4)

GRID(3)

GRID(2)

GRID(1)

GRID(0)

ANODE(9)

UNCAL

m A

m V

ANODE(13)

TOTAL

M k

Ω

ANODE(12)

qb27f.eps

Figure 5-6. Secondary Display

When a Fluke 45 display is initially powered up, all display segments should come on

automatically. If this display does not appear, proceed with the following steps:

Note

If the display is operational but has problems with front-panel button

presses, proceed directly to step 9.

5-18

Diagnostic Testing and Troubleshooting

Calibration Failures

Check the three power supplies with respect to GND (A2TP3 or A2U1-42) on the

Display Assembly.

•

VCC (A2U1-6) 4.85 to 5.35 V dc

•

VEE (A2U1-19)-5.0 to -6.0 V dc

•

VLOAD (A2U1-18)-28.5 to -32.0 V dc

Check the filament drive signals FIL1 and FIL2; these connect to the last two pins

on each end of A2DS1. These signals should be 5.0 V ac centered on a -25 V dc

level. FIL1 and FIL2 should be 180 degrees out of phase. If the dc bias of the

filament signals is not at about -25 V dc, the display segments that should be "off"

will show a shadowing (or speckling) effect.

Note

It may be necessary to disable the watchdog reset by jumpering A2TP1

(A1U5-3, A1U5-11) to GND (A2TP3) to verify the following items.

Check the clock signal at A2TP2. This signal should be 4.19 MHz

(.238 µs per cycle).

If the signal is not 4.19 MHz, the ceramic resonator, U2 is probably defective.

Check the state of the RESET signal (A2U1-1). This signal should be low once the

reset time is completed (after power-up).

Verify that the DISRX signal (A2U1-39) goes low after RESET (A2U1-1) goes low.

If this sequence does not occur, communication to the Main Processor is held off

with the DISRX signal high. If DISRX stays high but is not shorted to VCC, A2U1

must be faulty.

Verify activity for both the DISTX and DSCLK signals. These signals are driven by

the Main Processor and must be transitioning for the Display Controller to receive

commands from the Main Processor.

If all segments of a particular digit do not turn on at power-up, the grid drive from

A2U1 may not be connected properly to A2DS1. Grids are numbered from 0 to 10

(left to right as the display is viewed). For a digit to be enabled, the respective grid

drive signals (GRID(0:10)) must be at approximately VCC (4.85 to 5.35 V dc.) For a

digit to be disabled, the drive must be at VLOAD (-28.5 to -32.0 V dc.)

If a segment under each of several (or all) grids fails to be turned on (or off)

properly, one of the anode drive signals may not be connected properly from A2U1

to A2DS1. When an anode signal is at VCC, and a grid signal is at VCC, then the

corresponding segment on the display is illuminated.

If the Main Processor has difficulty recognizing front-panel button presses, the

switch scanning signals (SWR1 through SWR6, A1U6-21 through -26, respectively)

should be checked. When no switch contacts are being closed, the switch scanning

lines should have about 20 kΩ of resistance between each other (through two 10 kΩ

pullup resistors to VCC). None of the switch scanning lines should be shorted

directly to GND at any time, unless one of the switches is closed.

5-16. Calibration Failures

5-17. Introduction

Calibration processes for both front panel and computer interface operation are described

in Chapter 4 of this manual. Generally, a calibration failure is noted with an error beep

5-19

Service Manual

and a displayed ’Error’ at the front panel and a device dependent error over the computer

interface. These indications occur if the input varies from what the meter expects to see

by more than ±15%. After one second, the meter reverts to normal operation in

calibration mode.

Before suspecting a fault with the Fluke 45, verify that the calibration is being conducted

properly.

• Check the connections between the source and the meter. Are all the connections in

place.

• Check the output of the calibration source. Does it equal the value called for by this

calibration step?

• Check the calibration source. Is it in operate mode? Has it reverted to standby?

If the calibration setup is correct, a faulty component within the Fluke 45 may be causing

the failure. Each measurement function depends on a combination of components in and

around the Analog Measurement Processor (A1U1). Basic dc measurements depend on

the zener reference (A1VR1), reference divider network (A1Z3), and integrate resistors

(A1Z3). Resistance measurements and dc measurements above three volts additionally

depend on the resistors in the dc divider network (A1Z1). AC measurements depend on

the ac divider network (A1Z2), ac buffer (A1AR1), and rms converter (A1A1), as well

as the basic dc measurement components.

Note

The Fluke 45 utilizes three measurement rates: slow, medium, and fast.

Two sets of measurement ranges are used: one for the medium and fast

rates and one for the slow rate. Whenever the meter is powered-up or put

in calibration mode, the medium rate is selected. During calibration, the

slow rate is selected automatically as required by the calibration step.

5-18.

Calibration-Related Components

Measurement function calibration depends on various combinations of components in

and around the Analog Measurement Processor. The major components are:

• Rms Converter A1A1

• AC Buffer A1AR1

• Shunt Resistors A1R2, A1R3

• Zener Reference A1VR1

• Divider Network (DC/Ohms) A1Z1

• Integrate Resistors, Reference Divider A1Z3

• AC Divider Network A1Z2

• Rms Converter Network A1Z4

Calibration of the Fluke 45 utilizes a building block approach; individual components

are calibrated separately and the appropriate calibration building blocks are assembled

later for correction of any particular measurement function, range, and rate. Calibration

steps are grouped by function, with dc volts being first.

Therefore, the calibration constants are partitioned to allow for some independence in

the correction of the various measurement functions. For example, if the zener reference

and divider needed replacing, it would be necessary to recalibrate dc volts only; ac volts

would not be affected. Table 5-6 identifies components that are unique to each

5-20

Diagnostic Testing and Troubleshooting

Calibration Failures

calibration step. Table 5-7 provides a different approach, relating components that are

common to a group of calibration steps.

5-19.

Calibration Interrelationships

If you suspect calibration errors, but the meter does not exhibit the symptoms mentioned

above, verify that you are observing the following calibration rules:

• Stored dc volts calibration constants influence constants for several other functions.

If dc volts is recalibrated, these other functions must be recalibrated. This

interrelationship is explained in Table 5-8.

• Independent calibration of any function except dc volts results in the storage of

correcting calibration constants for that function only.

• Once calibration is begun, all steps for that function must be completed before the

calibration constants are stored. If all steps are not completed and the procedure is

terminated, only calibration constants for previously completed functions are stored.

5-20.

Retrieving Calibration Constants

If a calibration error is suspected, the stored constant can be retrieved and verified over

the computer interface. This information can be specified by the number of the constant.

Table 5-9 lists the calibration constant numbers. Use the following format:

CALCONST? xx (where xx denotes the calibration constant number)

Except for constants 9, 11, 21, and 32, the response format is:

±1.XXXXXXor ±0.XXXXXXX

5-21.

Replacing the EEROM A1U5

The EEROM provides non-volatile storage for the serial number of the meter, meter

configuration and calibration information. If the EEROM is replaced during repair, the

new EEROM should be programmed with the 7-digit serial number, found on the rear

panel of the meter. Use the following command to program the serial number into the

EEROM:

SERIAL XXXXXXX

(xxxxxxx denotes the 7-digit serial number. Note:

once entered, the serial number cannot be changed.)

5-21

Service Manual

Table 5-6. Calibration Steps and Related Components

Step

Range

Input

Related Components

VDC

100 mV

0.0000 V

A1VR1, A1Z3

100 mV

0.0900 V

A1VR1, A1Z3

100 mV

-0.0900 V

A1VR1, A1Z3

1000

0.9000 V

A1VR1

0.0900 V

A1VR1, A1Z3

100 mV

0.2900 V

A1VR1, A1Z3

300 mV

2.9000 V

A1VR1, A1Z3

3 V

29.000 V

A1VR1, A1Z1, A1Z3

30 V

290.00 V

A1VR1, A1Z1, A1Z3

300 V

1000.0 V

A1VR1, A1Z1, A1Z3

1000 V

VAC

300 mV

0.0290 V

A1A1 A1VR1, A1Z2, A1Z3, A1Z4

300 mV

0.2900 V

A1A1 A1VR1, A1Z2, A1Z3, A1Z4

3 V

0.2900 V

A1A1 A1VR1, A1Z2, A1Z3, A1Z4

3 V

2.9000 V

A1A1 A1VR1, A1Z2, A1Z3, A1Z4

30 V

29.000 V

A1A1 A1VR1, A1Z2, A1Z3, A1Z4

300 V

290.00 V

A1A1 A1Z1, A1Z2, A1Z3, A1Z4

750 V

750.00 V

A1A1 A1Z1, A1Z2, A1Z3, A1Z4

DC mA

30 mA

29.000 mA

A1R2, A1VR1, A1Z3, A1F1

100 mA

100.00 mA

A1R2, A1VR1, A1Z3, A1F1

AC mA

30 mA

29.000 mA

A1A1, A1R2, A1VR1, A1Z2, A1Z3, A1Z4, A1F1

100 mA

100.00 mA

A1A1, A1R2, A1VR1, A1Z2, A1Z3, A1Z4, A1F1

DC A

10 A

10.000 A

A1R3, A1VR1, A1Z3, A1F2

AC A

10 A

2.0000 A

A1A1, A1R3, A1Z4, A1F2

10 A

10.000 A

A1A1, A1R3, A1VR1, A1Z3, A1Z4, A1F2

Ohms

300 Ω

190.00 Ω

A1Z1, A1Z3

3 kΩ

1.9000 kΩ

A1Z1, A1Z3

30 kΩ

19.000 kΩ

A1Z1, A1Z3

300 kΩ

190.00 kΩ

A1Z1, A1Z3

3 MΩ

1.9000 MΩ

A1Z1, A1Z3

Continuity/Hysteresis Threshold

0.000 mV

A1U1

20.00 mV

A1U1

Frequency

2.000 V p-p 10 kHz

A1Y1

5-22

Diagnostic Testing and Troubleshooting

Calibration Failures

Table 5-7. Components Unique to Calibration Steps

Related Component (Main PCA)

Cal

A1A1

A1AR

A1R2

A1R3

A1U1

A1VR1

A1Y1

A1Z1

A1Z2

A1Z3

A1Z4

Step

VDC

VAC

DC mA

AC mA

DC A

AC A

OHMS

Continuity/Hysteresis Threshold

Frequency

5-23

Service Manual

Table 5-8. Calibration Hierarchy

Calibration Type

Prior Calibration Required

DC Volts

none

AC Volts

DC Volts

DC Amps

DC Volts

AC Amps

DC Volts

Ohms

DC Volts

Continuity/Hysteresis Threshold

none

Frequency

Continuity/Hysteresis Threshold

Table 5-9. Calibration Constants

Calconst?

Valid Range

Description

0.97025 to 1.03775

VDC, range 1

0.97025 to 1.03775

VDC, range 2

0.97267 to 1.04554

VDC, range 3

0.96782 to 1.04035

VDC, range 4

0.96792 to 1.04045

VDC, range 5

0.9975 to 1.0025

100 mV gain

0.9975 to 1.0025

320 mV gain

0.9975 to 1.0025

3.2 V gain

-100 to 100

VAC offset, range 1

0.9725 to 1.0275

VAC, range 1

-100 to 100

VAC offset, ranges 2 through 4

0.9725 to 1.0275

VAC, range 2

0.9725 to 1.0275

VAC, range 3

0.9725 to 1.0275

VAC, range 4

0.9725 to 1.0275

VAC, range 5

0.9500 to 1.0500

ADC, range 1

0.9500 to 1.0500

ADC, range 2

0.9500 to 1.0500

ADC, range 3

0.9225 to 1.0775

AAC, range 1

0.9225 to 1.0775

AAC, range 2

-100 to 100

AAC offset, range 3

0.9225 to 1.0775

AAC, range 3

0.9990 to 1.0090

OHMS, range 1

1.0000 to 1.0100

OHMS, range 2

1.0040 to 1.0140

OHMS, range 3

0.9990 to 1.0090

OHMS, range 4

0.9990 to 1.0090

OHMS, range 5

0.9990 to 1.0090

OHMS, range 6

0.9886 to 1.0035

Slow Siemens

0.9910 to 1.0010

Medium and Fast Siemens

0.9999 to 1.0001

Frequency calibration

-10.0 to 10.0

Slow offset

1.0000 to 1.0006

Slow negative gain

5-24

FLUKE 45 Dual Display Multimeter. Service Manual (For IEC 1010 Meters Only) - page 2