Using the ME-30, measure the amplitude of the signal between AR1 terminal 3
and ground (see Figure 9). The normal reading will be .001 to .004 volt RMS. If the reading is
abnormal, you would replace transformer T1 and make the amplitude measurement again.
Perform the next step of the subtest.
Make the following equipment settings.
Remove audio signal.
DC POWER: OFF.
HOT MIKE: OFF.
Using the ME-26, measure the resistance between AR1-1 and AR1-2 (T2). The
normal reading should be 75 to 95 ohms.
A normal reading indicates that microphone amplifier assembly (AR1) be
An abnormal reading indicates that T2 (output transformer) needs replacing.
After the fault is corrected, perform the functional test.
Subtest 3. Fault code 1|0 indicates headset amplifier AR2 problem.
Equipment settings are as follows:
COMM CONT NUMBER 1 SELECTOR switch: ICS.
COMM CONT NUMBER 1 VOLUME CONTROL: Fully clockwise.
COMM CONT NUMBER 1 TEST: Position 7.
DC POWER: ON.
COMM CONT NUMBER 2 SELECTOR switch: ICS.
Disconnect headset H-101A/U from MK-994/AR HEADSET 2.
Set AN/URM-127 (audio oscillator) for 1000 Hz, 2.75 volts RMS output.