Fluke 287/289 True-rms Digital Multimeters Calibration Manual

Introduction

This manual provides information on the Fluke Models 287 & 289 True-rms Digital Multimeters, including specifications, precautions, safety information, basic maintenance, performance test procedures, and calibration procedures.

Warning: To avoid shock or injury, do not perform verification or calibration tests unless qualified. Information is for qualified personnel only.

Caution: The multimeters contain parts sensitive to static discharge. Follow standard practices for handling static-sensitive devices.

For complete operating instructions, refer to the Model 287 & 289 Users Manual.

Contacting Fluke

For accessories, assistance, or to locate a distributor/service center, contact Fluke:

• USA: 1-888-99-FLUKE (1-888-993-5853)
• Canada: 1-800-36-FLUKE (1-800-363-5853)
• Europe: +31 402-678-200
• Japan: +81-3-3434-0181
• Singapore: +65-738-5655
• Anywhere in the world: +1-425-446-5500

Correspondence Address:

Fluke Corporation
P.O. Box 9090,
Everett, WA 98206-9090
USA

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

Visit Fluke online at: www.fluke.com

Precautions and Safety Information

Warning: To avoid electric shock or personal injury, use the Meter only as specified in this manual or the protection provided by the Meter might be impaired.

Read the "Safety Information" page before servicing.

Warning: Identifies conditions and actions that pose hazard(s) to the user.

Caution: Identifies conditions and actions that may damage the Meter or test instruments.

International Symbols

The Meter complies with:

• ANSI/ISA 82.02.01 (61010-1) 2004
• UL 61010B (2003)
• CAN/CSA-C22.2 No. 61010-1-04
• IEC/EN 61010-1 2nd Edition Pollution Degree 2
• EMC EN 61326-1
• Measurement Category III, 1000V, Pollution Degree 2
• Measurement Category IV, 600 V, Pollution Degree 2

Warning: To avoid possible electric shock or personal injury, follow these guidelines:

• Use this Meter only as specified in this manual or the protection provided by the Meter might be impaired.
• Do not use the Meter if it is damaged. Inspect the case for cracks or missing plastic, especially around connectors.
• Ensure the battery door is closed and latched before operating.
• Remove test leads before opening the battery door.
• Inspect test leads for damaged insulation or exposed metal. Check for continuity. Replace damaged leads.
• Do not apply more than the rated voltage between terminals or between any terminal and earth ground.
• Never operate the Meter with the cover removed or the case open.
• Use caution with voltages above 30 V ac rms, 42 V ac peak, or 60 V dc, as these pose a shock hazard.
• Use only specified replacement fuses.
• Use the proper terminals, function, and range for measurements.
• Avoid working alone.
• When measuring current, turn off circuit power before connecting the Meter in series.
• When making electrical connections, connect the common test lead first, then the live test lead. When disconnecting, disconnect the live test lead first, then the common test lead.
• Do not use the Meter if it operates abnormally.
• Do not operate the Meter around explosive gas, vapor, or dust.
• Use only 1.5 V AA batteries, properly installed.
• When servicing, use only specified replacement parts.
• Keep fingers behind finger guards on probes.
• Do not use the Low Pass Filter option to verify hazardous voltages; make a separate voltage measurement first.
• Only use test leads with the same voltage, category, and amperage ratings as the meter and approved by a safety agency.
• Use proper protective equipment in hazardous areas.
• Comply with local and national safety requirements in hazardous locations.

Caution: To avoid possible damage to the Meter or equipment under test, follow these guidelines:

• Disconnect circuit power and discharge all high-voltage capacitors before testing resistance, continuity, diodes, or capacitance.
• Use the proper terminals, function, and range for all measurements.
• Do not remove batteries while the Meter is turned on or a signal is applied.
• Before measuring current, check the Meter's fuses.
• Do not use the LoZ mode to measure voltages in circuits that could be damaged by this mode's low impedance (≈3 kΩ). (Model 289 only)

Hazardous Voltage: The ⚠ symbol is displayed when the Meter detects a voltage ≥30 V or an overload (OL).

General Specifications

Detailed Specifications

Accuracy

Accuracy is specified for one year after calibration, at 18 °C to 28 °C (64 °F to 82 °F), with relative humidity to 90%. Specifications are ±(% of reading + number of least significant digits). Ambient temperature stability of ±1 °C is assumed. For ambient temperature changes of ±5 °C, rated accuracy applies after 2 hours. For full accuracy in DC mV, Temperature, Ohms and LoZ (50) Ohms, allow the meter to stabilize for 20 minutes after using LoZ.

True-rms

AC mV, AC V, AC µA, AC mA, and AC A specifications are ac-coupled, true rms, and specified from 2% to 100% of range (except 10 A range is 10% to 100% of range).

Crest Factor

Accuracy is specified with AC crest factor ≤ 3.0 at full-scale, increasing linearly to 5.0 at half-scale. For the 1000 V range, it is 1.5 at full scale, increasing linearly to 3.0 at half-scale. For 500 mV and 5000 µA ranges, it is ≤3.0 at 80% of full scale, increasing linearly to 5.0 at half-scale. For non-sinusoidal waveforms, add ±(0.3% of range + 0.1% of reading).

AC Floor

When input leads are shorted in AC functions, the Meter may display a residual reading up to 200 counts. A 200 count residual reading causes a 20 count change at 2% of range. Using REL to offset this may produce a larger constant error.

AC+DC

AC+DC is defined as √(Vac² + Vdc²)

AC Voltage Specifications

Notes:
[1] Below 5% of range, add 20 counts.
[2] Specification increases linearly from -2% at 200 Hz to -6% at 440 Hz. Range is limited to 440 Hz.
[3] dBm (600 Ω) is specified by adding +2.2 dB to the dBV range values.
[4] 289 only.
[5] 500 mV range specification between 64.000 kHz and 67.000 kHz is +(0.0% to -5% of reading); 50 mV range specification between 64.000 kHz and 67.000 kHz is +(0.0% to -6% of reading ±40 counts). Valid from -20 °C to <18 °C and >28 °C to +55 °C.
[6] Add 2.5% above 65 kHz.
[7] Range is limited to 440 Hz.

AC Current Specifications

Notes:
[1] 10 A range (10% to 100% of range).
[2] 20 A for 30 seconds on, 10 minutes off. >10 A not specified.
[3] 400 mA continuous; 550 mA for 2 minutes on, 1 minute off.
[4] Verified by design and type tests.

DC Voltage Specifications

Notes:
[1] Add 20 counts in dual display ac over dc, dc over ac or ac+dc.
[2] AC+DC ranges are specified from 2% to 140% of range, except 1000 V is specified from 2% to 100% of range.
[3] When using the relative mode (RELA) to compensate for offsets.
[4] Add 4 counts/10 mV AC in dual display ac over dc, dc over ac or ac + dc.
[5] Add 10 counts/100 mV AC in dual display ac over dc, dc over ac or ac + dc.

DC Current Specifications

Notes:
[1] AC+DC ranges are specified from 2% to 140% of range.
[2] 20 A for 30 seconds on, 10 minutes off. >10 A not specified.
[3] Add 20 counts in dual display ac over dc, dc over ac or ac+dc.
[4] 400 mA continuous; 550 mA for 2 minutes on, 1 minute off.
[5] Verified by design and type tests.
[6] Temperature coefficient: 0.1 X (specified accuracy)/ °C (<18 °C or > 28 °C)

Resistance Specifications

Notes:
[1] When using the relative mode (RELA) to compensate for offsets.
[2] Add 20 counts above 33 nS in 50 nS range.
[3] For relative humidity >70%, resistance accuracy is 0.5% > 1 MΩ and 2.5 % > 10 MΩ.
[4] 289 only.

Temperature Specifications

Notes:
[1] Does not include error of the thermocouple probe.
[2] Accuracy specification assumes ambient temperature stable to ±1 °C. For ambient temperature changes of ±5 °C, rated accuracy applies after 2 hours.

Capacitance and Diode Test Specifications

Note:
[1] With a film capacitor or better, using relative mode (REL A) to zero residual.

Frequency Counter Specifications

Notes:
[1] For 64.000 kHz to 67.000 kHz, accuracy = ±5 Hz, at -20 to +55 °C with R.H. 0% to 90% (0 °C to 37 °C), 0% to 65% (37 °C to 45 °C), 0% to 45% (45 °C to 55 °C).
[2] For rise times <1 µs. Signals centered around trigger levels.
[3] 0.5 to 200 kHz, pulse width >2 µs. Pulse width range is determined by the frequency of the signal.

Frequency Counter Sensitivity

Notes:
[1] Maximum input = 10 x range (1000 V maximum, 2 x 10⁷ V-Hz product maximum). Noise at low frequencies and amplitudes may affect accuracy.
[2] Typical frequency bandwidth with full scale (or maximum 2 x 10⁷ V-Hz product) rms sine wave.

MIN MAX, Recording, and Peak Specifications

Notes:
[1] For repetitive peaks; 2.5 ms for single events. Peak not specified for 500 µA DC, 50 mA DC, 5A DC.
[2] 200 counts in 500 mV AC, 500 µA AC, 50 mA AC, 5 A AC.
[3] 3% in 500 mV AC, 500 µA AC, 50 mA AC, 5 A AC.

Input Characteristics

Notes:
[1] Input is limited to the product of a V rms sinewave times frequency of 2 x 10⁷ V-Hz.
[2] For circuits <0.5 A short circuit. 660V for high energy circuits.

Burden Voltage (A, mA, µA)

Required Equipment

Required equipment is listed in Table 2. Equivalent specifications may be used if recommended models are unavailable. Repairs or servicing should be performed only by qualified personnel.

Basic Maintenance

Warning: To avoid electrical shock or personal injury, remove test leads and input signals before opening the case or replacing batteries/fuses. Install only specified batteries or fuses.

Opening the Meter Case

Caution: To avoid unintended circuit shorting, place the uncovered Meter assembly on a protective surface. When the case is open, circuit connections are exposed.

To open the Meter case:

1. Disconnect test leads from live source, turn Meter off, and remove test leads from input terminals.
2. Use a flat-blade screwdriver to turn the battery door fastener counterclockwise to unlock.
3. Lift the bottom of the battery pack and slide down to remove (see Figure 2).
4. Remove the six Phillips-head screws securing the case bottom to the case top.
5. Pull the two halves of the case apart.

Removing and Reinserting the Printed Circuit Assembly

The circuit board assembly (PCA) must be removed to access and replace the LCD. Refer to Figure 5.

Caution: The PCA is extremely susceptible to contamination. Handle by fuse clips or edges only. Use clean surgical gloves.

The LCD cable is delicate. Use extreme caution and do not exert excess force or strain on the cable or connector.

1. Set the Meter's rotary switch knob to the mvl position.
2. Refer to "Opening the Meter Case" and remove the case bottom.
3. Remove six Phillips-head screws securing the PCA to the case top and input terminals.
4. Remove the bottom shield.
5. Carefully remove the fragile LCD cable from the LCD connector without excessive bending. Remove the PCA.
6. Remove the top shield.
7. The LCD is now accessible and can be removed.

Reassembling the Meter Case

To reassemble:

1. Verify the rotary switch knob is in the mvl position.
2. Install the display bezel, LCD, and top shield into the top case.
3. Align the RSOB housing so the arrow matches the rotary switch knob orientation.
4. Place the PCA onto the top shield, ensuring alignment holes mate with detent studs.
5. Carefully insert the LCD cable stiffener vertically into the mating PCA connector.
6. Replace the bottom shield.
7. Caution: Do not over-torque the six Phillips-head screws when attaching the PCA and shields to the case top. Use 5 to 7 inch-lb of torque.
8. Carefully replace the six Phillips-head screws securing the PCA and shields to the case top and input terminals.
9. Hold the Meter face down and place the case bottom onto the case top. Ensure the LCD cable is not caught between the halves.
10. Caution: Do not over-torque the six Phillips-head case screws when attaching the case bottom. Use 5 to 7 inch-lb of torque.
11. Reinstall the six case screws and the battery door.
12. Secure the battery door by turning the fastener clockwise to the lock position.
13. Go to "Performance Test" and perform the procedures described.

Testing Fuses (F1 and F2)

Warning: To avoid electrical shock or personal injury, remove test leads and input signals before replacing batteries or fuses. Install only specified replacement fuses.

With the Meter in the Ω function, insert a test lead into the V/Ω jack and place the probe tip at the other end of the test lead against the metal at the top of the current input jack. If "Leads Connected Incorrectly" appears, the probe tip is inserted too far. The resistance value should be between 0.00 and 0.50 Ω for the A jack and 10.00 ±0.05 kΩ for the mA/µA jack. If readings differ, have the Meter serviced.

Figure 1 shows fuse testing. Replace F1 if reading is OL (Open Line) for the A jack. Replace F2 if reading is OL for the mA/µA jack.

Replacing Fuses

To replace fuses, refer to Figure 2:

1. Turn the meter off and remove test leads.
2. Remove the battery door fastener.
3. Gently pry one end of the fuse loose and lift it out.
4. Install only Fluke specified replacement fuses with the correct amperage, voltage, and interrupt ratings.
5. Replace the battery door and secure the fastener.

Replacing the Batteries

The Meter is powered by 6 AA batteries (NEDA 15A or IEC LR6).

Caution: Observe proper polarity when replacing batteries. Incorrect polarity may damage the Meter.

To replace batteries, refer to Figure 2:

1. Turn the meter off and remove test leads.
2. Remove the battery door fastener.
3. Replace batteries, observing proper polarity. Replace the battery door and secure the fastener.

Cleaning

Periodically wipe the case with a damp cloth and mild detergent. Do not use abrasives, isopropyl alcohol, or solvents.

Warning: To avoid electrical shock or damage, never allow water inside the case. Never apply solvents to the Meter housing.

Dirt or moisture in input terminals can affect readings and activate the Input Alert feature. Clean terminals as follows:

1. Turn the Meter off and remove all test leads.
2. Shake out any dirt from the terminals.
3. Swab terminals with a clean swab dipped in mild detergent and water. Dry with canned air.

Performance Tests

Performance tests ensure the Meter is operating correctly and check accuracy against specifications. A Fluke 5520A Calibrator or equivalent equipment is needed. Allow the Meter to stabilize to room temperature (several hours) before accuracy tests.

If the Meter fails tests, it needs calibration adjustment or repair.

Factory Default

To reset the Meter to factory defaults before performance tests:

1. Power on the Meter in any function.
2. Press F4 (Setup), select Reset using arrow keys.
3. Press F3 (Meter).
4. Press F1 (OK). The Meter will power up.

Power LED Test

The power button has an LED backlight. Power on the meter; the backlight should light for approximately 4 seconds, then extinguish.

Backlight Test

Press the backlight button twice. The backlight should come on at two different intensity levels.

Current Terminal Sensing Test

This test verifies the Input Alert™ function.

Note: Ensure the beeper is not disabled in setup before conducting this test.

1. Turn the Meter on.
2. Install a test lead in the mA/µA input terminal.
3. Turn the rotary switch to all functions except current. The beeper should chirp continuously, and the LCD should display a warning.
4. Turn the rotary switch to the A/mA position. The beeper should not chirp, and the leads warning should not be displayed.
5. Remove the test lead and install it into the A terminal. Repeat steps 3 and 4.

Keypad Test

Note: Ensure the beeper is not disabled in setup mode.

To test keypad buttons: Turn the Meter on and push each button separately. Each button push should cause the Meter to beep.

LCD Test

The 28X uses a dot matrix LCD. To test LCD pixels:

1. Turn the rotary switch knob to mvl and turn the Meter on.
2. Push F4 for Setup and select contrast.
3. Push the Backlight button twice for maximum brightness. Use F1 and F2 softkeys to adjust contrast for the brightest display.
4. Push the “i Info” button and scroll text with F1 and F2. Inspect the LCD for missing pixels or unreadable areas due to pixel defects.

IR Port Verification

Note: If using MET/CAL for testing via the IR port, this verification is not necessary.

1. Connect the Infrared Serial Cable to a PC's USB port (Windows 98 or later) and the Meter's IR port.
2. Turn the Meter on and set the rotary switch to any function.
3. On the PC, go to Start > Programs > Accessories > HyperTerminal.
4. Setup HyperTerminal: Name: 289, 287 IR Port Test; Connect using: ComX; Bits per second: 115200; Data bits: 8; Parity: None; Stop bits: 1; Flow control: None.
5. Click the Properties ICON on the toolbar.
6. Click the "Settings" tab and leave default settings.
7. Select "ASCII Setup:".
8. Set the following: Send line ends with line feed; Echo typed characters locally; Append line feeds to incoming line ends; Wrap lines that exceed terminal width.
9. Enter the identification command <ID> followed by carriage return (Enter).
10. The Meter should respond: FLUKE 289, VX.XX, X (model, software version, serial number).

Note: If the PC indicates no connection, ensure the COM port is correct and the IR Serial Cable is properly connected to the Meter's IR window.

Temperature Accuracy Test

Note: Allow the meter to stabilize to within ±1°C of ambient temperature before performing tests. This may take several hours.

1. Connect a K-type thermocouple and Fluke 80AK to the Meter's temperature input.
2. Connect the other end to the 5520A TC output. Allow connections to stabilize for two minutes.
3. Turn the Meter on and set the rotary switch to mvl. Select the temperature function and degrees C key.
4. On the Meter, select Offset. Adjust the offset to 000.0 using keypad edit buttons.
5. Close the Offset window.
6. Set the 5520A for K-type thermocouple and an output of 0 °C.
7. Perform measurement steps in Table 3.

Accuracy Tests for Volts, Current, Ω, 艹, and 艹 Test Functions

To verify accuracy:

1. Connect the Calibrator Normal terminals to the Meter's V and COM input terminals.
2. Turn on the Meter.
3. Turn the rotary switch to mvl.

Note: DC mV measurements in Table 4 are subject to offsets from thermal gradients. After connecting the calibrator, allow time (several minutes) for thermals to dissipate. When readings stabilize, perform a REL and record the reading.

4. Apply the Input Level and frequency for step 1 of Table 4.
5. Compare the Meter's display reading with the Display Limits in Table 4.
6. If the display reading falls outside the limits, the Meter needs adjustment or repair.
7. Complete remaining test steps for each function listed in Table 4.

Put Meter's rotary switch to Capacitance function

Remove Test Leads from 5520A and REL offset

Reconnect Test Leads to 5520A

Connect 5520A Normal Output to Meter's V Input Terminal

Notes:
[1] Must allow for source and Meter setting before receiving reading.
[2] When using the relative mode (RELA) to compensate for offsets.
[3] The Meter accuracy is not specified at this frequency with Low-pass filter on. The display reading limits shown in table 4, checks that the Low-pass filter is active and follows an expected roll-off curve.
[4] With a film capacitor or better, using relative mode (REL A) to zero residual.
[5] Test limits are mathematically guard banded to ensure performance, at 20 kHz and lower.
[6] To obtain full accuracy in DC mV, Temperature, ohms, and LoZ, let the Meter stabilize for 20 minutes after using LoZ.
[7] To avoid calibrator overload/current limit condition, step the calibrator output to 60 V and then 120 V.

Calibration Adjustment

The Meter features closed-case calibration adjustment using known reference sources. The Meter measures the applied reference source, calculates correction factors, and stores them in nonvolatile memory.

The following sections present features and Meter pushbutton functions used during calibration.

Before beginning, allow the Meter to reach ambient temperature (several hours depending on gradient).

Perform calibration adjustment if the Meter fails performance test steps in Table 4.

Operation

Calibration adjustment starts by pressing the F1 [Setup] softkey, then navigating to “Calibration” on the Setup menu.

Note: Calibration is not allowed with a low battery condition.

Entering the Password

A four-digit numeric password is required. The default is "1234".

When "Calibrate" [F1] is selected, a dialog box titled "Enter Password" appears. Use arrow keys to edit digits. Press F1 [OK] to enter. Press F4 [Cancel] to abort.

If an incorrect password is entered, "Incorrect password entered" is displayed. Press OK to return to the "Enter Password" screen.

Changing the Password

When F2 "Password" is selected, a dialog box titled "Enter Password" appears. Enter the current password as described above.

A "Enter New Password" dialog box appears. Enter the new password using the same method.

"Password changed" is displayed upon acceptance. Press F1 [OK] to return to measurement mode.

Restoring Factory Default Password

To restore the factory default password [1234]:

1. Remove the Meter's bottom case (see "Disassembly").
2. Locate PCA Battery Terminals (Figure 3). Apply 9 volts to the terminals (or TP8 and TP10) using an external lab supply or battery, observing correct polarity.
3. Power on the Meter using the front panel power button.
4. Locate the PCA CAL keypad (Figure 3).
5. Short the CAL keypad terminals to reset the password. The Meter beeps upon completion.

Adjustment Procedure Operation

The Meter guides the user through calibration steps, showing live reading, source value, and step number. Figure 4 shows the first step.

Screenshot Description

1. Live Reading: Primary display shows measurement using default calibration constants. It may differ slightly from the applied signal as it's uncalibrated.
2. Bolt icon: Shown at all times during calibration.
3. Source value: For Calibrator shown in the secondary measurement portion.
4. Calibration Step progress indicator.
5. Calibration status message: Usually blank, but can display:
   • "Calibrating"... while measurements are made after Next. Softkeys except ABORT are disabled.
   • Error message if rotary switch or source jacks are in incorrect positions.

Navigation Buttons

UP and DOWN Arrow buttons adjust display contrast. RIGHT and LEFT Arrow buttons are disabled.

Mode Buttons

HOLD, MIN MAX, RANGE, and i buttons are disabled during calibration.

Description of Calibration Adjustment Steps

General calibration procedure:

1. Move the rotary switch to the function being calibrated.
2. Apply the source value indicated by the secondary display.
3. Wait for the primary display measurement to settle.
4. Press the NEXT softkey to calculate calibration constants. "Calibrating..." is shown. Some measurements take up to 115 seconds. If within tolerance, the Meter records the constant(s) and proceeds, giving a single beep.

Note: Frequency values for AC functions are not validated.

If the measurement is not within calibration tolerance, an error message appears after pressing NEXT. The operator can adjust the input signal and try NEXT again.

If errors persist, the procedure may not proceed, and the meter may need service. Select Abort to exit; calculated constants will be discarded.

5. If more functions need calibration, move the rotary switch to the appropriate function and repeat from step 1.
6. Repeat steps 1-5 until "Cal Complete" message appears. New constants are saved. Select F1 [OK] and restart the Meter.

A counter records completed calibrations. Review in Setup "Meter Info" screen.

Power Cycle

If power is turned off during calibration, the procedure aborts, and calculated constants are discarded. Previously stored constants are used after power-on.

Calibration Adjustment Steps

Table 7 shows calibration steps and settling/calibrating times.

Note: Set the present time and date before starting for accurate calibration date tracking (found in Setup "Meter Info"). Allow the Meter to reach ambient temperature.

Connect the 5520A in a 4-Wire configuration and select COMP 2-Wire

To reduce settling time, apply 10 ohms to Meter before setting Rotary Switch to LoΩ

Notes:
[1] Meter is "Calibrating" after "Next" is pressed.
[2] For software version 1.00, the instrument display indicates 60 kHz. Use 65 kHz.

Parts

Table 8 lists available replacement parts shown in Figure 5.