AC/DC VOLTMETER Adjustment (CRC).

TM 55-4920-430-13

a. Connect plug P1 of power cable W7 to test set POWER receptacle J7. Connect plug P2 to a 115-

volt ac power source. Connect plug P3 to a 28-volt dc power source.

b. Set the 115V 400 Hz and +28 VDC TESTER POWER switches to ON. Allow 2 minutes for

warmup.

c. Adjust the digital multi meter to the 20 volt dc range. Connect the test leads of the multimeter to

EXT METER jacks HI and LO.

d. Adjust power supply PS1 for +5 volt output as follows:

(1) Set the METER switch to DC. Set the METER RANGE switch to 20V.

(2) Set SELF TEST CIRCUIT SELECT switches to 00,5.

(3) Turn the screwdriver adjustment on power supply PS1 until the digital multimeter reads +5

volts.

e. Adjust power supply PS2 for +15 volt output as follows.

(1) Set the METER RANGE switch to 20V.

(2) Set the METER switch to DC.

(3) Set the SELF TEST CIRCUIT SELECT switches to 00,3.

(4) Turn the screwdriver adjustment on power supply PS2 until the digital multimeter reads +15

volts.

f. Adjust power supply PS3 for +15 volt dc output as follows.

(1) Set the METER RANGE switch to 20V.

(2) Set the METER switch to DC.

(3) Set the SELF TEST CIRCUIT SELECT switches to 00,4.

(4) Turn the screwdriver adjustments on power supply PS3, until the digital multimeter reads

-15 volts.

4-37. AC/DC VOLTMETER Adjustment (CRC).

NOTE

Insure that Para. 4-36 has been complied with prior to start of AC/DC

VOLTMETER adjustments.

These adjustments set the AC/DC VOLTMETER input offset null, zero-width adjust, and gain. (See

a. Connect plug P1 of power cable W7 to test set POWER receptacle J7. Connect plug P2 to a 115-

volt ac power source. Connect plug P3 to a 28-volt dc power source.

b. Set the 115V 400HZ and +28VDC TESTER POWER switches to ON. Allow 2 minutes for

warmup.

c. Remove the AC/DC VOLTMETER lens.

d. Adjust input offset null and zero width as follows (fig. 4-2).

(1) Set the AC/DC VOLTMETER CIRCUIT SELECT switches to 00,0, B, 0.

(2) Set the SELF TEST CIRCUIT SELECT switches to 00,0.