Test Procedures; Power Checks; Front Panel Assembly Tests - Garmin GMA 347 Maintenance Manual

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3.2 TEST PROCEDURES
3.2.1 Power Checks
Buss Power
This test will verify the Audio Panel can be powered by Buss 1 and Buss 2. Buss 1 and Buss 2 are
"ored" internally by diodes.
Aircraft Power Buss 1―J3472 Pins 53 and 55
Aircraft Power Buss 2―J3472 Pins 30 and 32
1. Power the Audio Panel via Aircraft Power Buss 1.
2. Verify proper operation.
3. Power the Audio Panel via Aircraft Power Buss 2.
4. Verify proper operation.
Unit Current
With the Audio Panel subjected to the following conditions, the unit current should not exceed
the values listed in the table below.
Note: current is to be measured as the total current going through both aircraft power 1 inputs
(J3472 Pins 53 and 55).
Audio Panel powered by Aircraft Power 1
•
All annunciators active
•
Audio Panel in PA mode with a sufficient MIC signal applied to achieve 10W into 4Ω
•
Backlighting set to maximum
•
Middle Marker Lamp output active into a 56 Ω load
•
UNIT STATUS
OFF
ON
ON
3.2.2 Front Panel Assembly Tests
Replace the Front Panel Board If any of the following tests fail.
Switch Power
Turn the unit ON and OFF and verify proper operation. To verify that the audio panel turned off
properly, verify that unit current (at Vin = 27.5Vdc) is < 0.015 A.
Key Response
Press each key (pushbutton) to verify proper operation.
Page 3‐6
Rev. A
MAX AMPS AT 27.5 VOLTS
0.015
1.75
1.75
MAX VOLTS AT 13.75
VOLTS
0.030
3.75
3.75
GMA 347 Maintenance Manual
190‐00325‐02