TM 55-4920-428-13
4-34. Adjustment of 13 Volt Ac Power Supply PS3. (CRC)
a. Remove the panel (para 4-18).
b. Ensure the power switch is at OFF.
c. Connect power cable 145GS278-4 to POWER receptacle and output receptacle of the autotransformer.
Connect the autotransformer to 115 volts ac 60 Hz power source.
d. Adjust the output of the autotransformer to 115 volts ac.
e. Set the multimeter to measure ac volts. Connect it to terminals TB4-7 (line) and TB4-1.
f. Remove the cover from the ADJ POT opening in top of power supply PS3 (fig. 4-1).
g. Set the power switch to ON,
h. Adjust the variable resistor directly below the ADJ POT opening until the multimeter indicates 13 volts ac.
i. Install the cover.
j. Set the power switch to OFF.
k. Disconnect the multimeter and the power cable from the autotransformer,
l. Perform the power supply and DVM tests (para 4-40).
m. Install the panel (para 4-41).
n. Perform the final test (para 4-42).
4-35. Adjustment of Undervoltage Detector Circuit. (CRC)
a. Remove the panel (para 4-18).
b. Ensure the power switch is at OFF (fig. 4-1).
c. Connect power cable 145GS278-4 to POWER receptacle and output receptacle of the autotransformer.
Connect the autotransformer to 115 volts ac 60 Hz power source.
d. Adjust the output of the autotransformer to 115 volts ac.
e. Set the power switch to ON.
f. Reduce the output of the autotransformer to 105 volts ac.
g. On circuit board TB6B (fig. 4-l), adjust variable resistor (potentiometer) R10 until the WARNING indica-
tor just changes from on to off or from off to on. Turn variable resistor R10 in the other direction until the
WARNING indicator changes to its original state. Then set resistor R10 midway between the two positions,
h. Turn off the power switch.
i. Disconnect the power cable from the autotransformer.
j. Perform the power supply and DVM tests (para 4-40).
k. Install the panel (para 4-41).
1. Perform the final test (para 4-42).
4-36. Adjustment of – 12 Volt Dc Power Supply PSI. (CRC)
a. Remove the panel (para 4-18).
b. Ensure the power switch is at OFF.
4-10
Change 3
