Heathkit Model IT-5283

Signal Tracer

Calibration Procedure

· 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.

· Disconnect all external components from the front panel terminals.

Ancillary Equipment Needed

VTVM

Demodulation probe

Audio generator

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RESISTANCE CHECKS

Refer to Pictorial 3-3

Manual page 18

(    )         Temporarily remove the 9-volt batteries if installed.

(    )         Set the SOURCE switch [on rear of unit] to the BATT position if connected to an IPA-5280-1.

(    )         Set the FUNCTION switch to the OFF / SPKR SUB position.

(    )         Set the VTVM FUNCTION switch to the OHMS position.

(    )         Set the VTVM RANGE switch to the R x 100 position.

(    )         Connect the VTVM common lead to the chassis.

(    )         Set the FUNCTION switch to the AUDIBLE / V/W position.

(    )         Touch the ohmmeter probe to SW1 wafer 2 lug 1.

               [Red wire from switch to connection C on the circuit board]

(    )         Meter indication should be 50 W or higher.

(    )         Touch the ohmmeter probe to SW1 wafer 2 lug 3.

               [Green wire from switch to connection F on the circuit board]

(    )         Meter indication should be 100 W or higher.

(    )         Set the FUNCTION switch to the OFF / SPKR SUB position.

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HUM INJECTION TEST

Refer to Pictorial 6-4

Manual page 27

(    )         Install fresh batteries (if using them) and set the SOURCE switch to the BATT position.

(    )         If the unit is powered using a IPA-5280-1, set the SOURCE switch to the LINE position.

(    )         Set the LEVEL control to maximum counter-clockwise.

(    )         Connect the unit’s test probe (demodulation probe) to the input terminals.

(    )         Set the test probe’s tip to the DC position.

(    )         Set the FUNCTION switch to the SIGNAL TRACER position.

(    )         Wait a few seconds for the unit to stabilize.

(    )         Adjust the LEVEL control until a hum is heard from the speaker.

· Do not adjust the LEVEL control any higher than necessary to save battery life.

(    )         Touch the tip of the test probe to your fingers; the hum level should increase.

(    )         Set the probe tip to the diode (demodulation) position.

(    )         Touch the tip of the test probe to your fingers; the hum should change slightly in tone.

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OSCILLATOR TEST

Refer to Pictorial 6-5

Manual page 28

(    )         Set the FUNCTION switch to the AUDIBLE / V/W position.

(    )         Set the test probe’s tip to the DC position.

(    )         Touch the test probe to the chassis; a tone should be heard from the speaker.

(    )         Touch the test probe to SW1 wafer 2 lug 3; a tone higher in frequency should be heard from the speaker.

               [Green wire from switch to connection F on the circuit board]

(    )         Set the probe tip to the diode (demodulation) position.

(    )         Touch the tip of the test probe to the chassis; there should be no tone heard.

(    )         Disconnect the test probe from the input terminals.

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SPEAKER SUBSTITUTION TEST

Refer to Pictorial 6-6

Manual page 29

(    )         Set the FUNCTION switch to the OFF / SPKR SUB position.

(    )         Connect an audio generator to the SPKR terminals.

(    )         Set the generator frequency to 1000 Hz.

(    )         Adjust the audio generator output until a tone is heard from the speaker.

(    )         Disconnect the audio generator.

(    )         Calibration procedure is complete.