Heathkit Model IM-5284

Multimeter

Calibration Procedure

· With the power supply off, the meter pointer should be over the zero indication on the meter face.  If it is not, adjust the mechanical zero-adjust screw at the bottom of the meter until the pointer is properly aligned.

· If using the unit as a portable instrument, install a fresh set of 9-volt batteries and set the SOURCE switch (on rear of unit) to the BATT position.

· If powered using the IPA-5280-1 AC Power Supply, set the SOURCE switch (on rear of unit) to the LINE position.

· Install a fresh C cell.

Ancillary Equipment Required

1-3/4” red wire

1” black wire

1” white wire

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INITIAL SETTINGS

Refer to Pictorial 17

Manual page 29

Front Panel Initial Settings

(    )         Set the FUNCTION switch to the OFF position.

(    )         Set the RANGE switch to the 1000 V position.

(    )         Set the ZERO ADJUST control to the center of rotation.

(    )         Set the OHMS ADJUST control to maximum counter-clockwise.

Circuit Board Initial Settings

(    )         Set the METER ADJ control to maximum counter-clockwise.

(    )         Set the DC CAL control to maximum clockwise.

(    )         Set the AC CAL control to maximum counter-clockwise.

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METER ADJUSTMENT

· Connect the following wires to the foil side of the circuit board

(    )         Solder a Black wire between hole AC (S-1) and hole Z (S-1).

(    )         Solder a Red wire between hole AF (S-1) and hole AE (S-1).

(    )         Solder a White wire to hole AD (S-1).

(    )         Set the FUNCTION switch to the DC+ position.

               Meter should indicate approximately 8 on the DC scale. (Note the meter reading.)

(    )         Set the FUNCTION switch to the OFF position.

(    )         Solder the White wire to foil pad AE (S-2).

(    )         Set the FUNCTION switch to the DC+ position.

(    )         Adjust the METER ADJ control [on the circuit board] until the meter indicates one-half the value noted above.

(    )         Set the FUNCTION switch to the OFF position.

(    )         De-solder the White wire and the Red wire from foil pad AE (D-2).

(    )         De-solder the White wire from hole AD (D-1).

(    )         De-solder the Black wire from hole Z (D-1).

(    )         Solder the Black wire to hole AE (S-2).

(    )         Solder the Red wire to hole AB (S-1).

(    )         Set the FUNCTION switch to the DC+ position.

(    )         Set the ZERO ADJUST control to maximum clockwise.

               This should cause an upscale reading.

(    )         Set the FUNCTION switch to the DC- position.

(    )         Set the ZERO ADJUST control to maximum counter-clockwise.

               This should cause an upscale reading.

(    )         Adjust the ZERO ADJUST control for a zero meter indication.

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DC CALIBRATION

(    )         Insert a pair of test probes into the input jacks.

(    )         Set the FUNCTION switch to the DC+ position.

(    )         Set the RANGE switch to the 10 V position.

(    )*       Touch the tip of the red input jack probe to the positive terminal of the 1.5-volt C-cell.

(    )*       Adjust the DC CAL [on the circuit board] for a 1.5-volt meter indication on the DC scale.

(    )*       Disconnect the probe from the 1.5-volt C-cell.

(    )*       Adjust the ZERO ADJUST control for a zero meter indication.

(    )         Repeat the above four marked steps* until no change in the meter readings.

* * * * * * *

AC CALIBRATION

Using the IPA-5280-1 AC Power Supply

· DO NOT use the common (black) input jack when measuring power line voltages if using the IPA-5280-1 AC Power Supply. The common lead is already connected to the circuit ground and to the power line ground. If the common lead should contact the “hot” side of the power outlet, the power line will be short circuited. Connect a probe only to the positive (red) input jack.

(    )         Disconnect the test probe from the black input jack.

(    )         Set the FUNCTION switch to the AC position.

(    )         Set the RANGE switch to the 1000 V position.

(    )         Connect the red input jack probe to the side of the AC line which gives the highest meter deflection.

(    )         Adjust the AC CAL [on the circuit board] until the meter indicates the known AC line voltage on the black (DC) scale.

(    )         Disconnect the probe from the AC line.

(    )         Connect a test probe to the black input jack.

Using 9-volt Batteries

Refer to Pictorial 8

Manual page 16

(    )         Set the RANGE switch to the 10 V position.

(    )         Set the FUNCTION switch to the AC position.

(    )         Connect the red input jack probe to the FUNCTION switch (SW1) rear wafer CR lug 1 (+9-volts).

(    )         Connect the black input jack probe to the RANGE switch (SW2) front wafer AF lug 12 (.047 uf capacitor).

(    )         Adjust the AC CAL [on the circuit board] for a meter indication of 7.4 on the black (DC) scale.

* * * * * * *

OHMS ADJUSTMENT

(    )         Set the RANGE switch to the R x 1MEG position.

(    )         Set the FUNCTION switch to the OHMS position.

               This should cause an upscale reading.

(    )*       Adjust the OHMS ADJUST control for a full scale indication (INF) on the green (OHMS) scale.

(    )*       Touch the tips of the test probes together.

               Meter indication should read zero.

(    )*       Adjust the ZERO ADJUST control for a zero meter indication.

(    )*       Disconnect the test probes.

               Meter indication should again read full scale.

(    )         Repeat the above four marked steps* until no change in the meter readings.

(    )         Set the RANGE switch to each of the other three OHMS positions and repeat the above four marked steps* until no change in the meter readings.

(    )         Set the RANGE switch to the 1000 V position.

(    )         Set the FUNCTION switch to the OFF position.

(    )         Disconnect the test probes from the input jacks.

(    )         Calibration procedure is complete.