190-01007-A1
System Maintenance Manual GTN 6XX/7XX Part 23 AML STC
Rev. 5
Page 7-9
7.2.2.6 Receiver Audio Check
If there are receiver audio sources connected to the GMA 35, the interface should be verified as described
below. Ensure the GMA 35 as well as each interfaced receiver (DME, ADF, etc) is powered on.
1. Plug in a headset at pilot and copilot position.
2. Tune the installed receiver to a valid station.
3. Ensure audio is being received over the crew headsets.
4. Ensure the audio volume is sufficient for all anticipated cockpit noise conditions. Adjust the audio
output level as needed at the receiver.
Repeat steps 2 through 4 for each installed receiver.
7.2.2.7 Intercom System (ICS) Check
NOTE
If a monaural headset is plugged into any stereo phone jack position, no damage will
occur to the GMA 35. In the case of plugging a monaural headset into any passenger
position, any stereo listener will lose one channel when another passenger plugs in a
monaural headset.
1. Place the audio panel into ALL ICS mode (refer to the GTN 725/750 Pilot’s Guide, P/N 190-
01007-03) so that all ICS positions hear all others.
2. Deselect or turn off other audio sources (MKR, transceivers, receivers, alerts). Some
configurations may mute passenger intercom audio to crew when aircraft audio is present.
3. From the pilot headset position, verify the pilot, copilot, and all passenger mic inputs can be heard
in the pilot’s headset when speaking into the mic input under test (adjust pilot ICS volume if
necessary).
4. Speak into the pilot’s mic and verify that pilot mic audio is heard in the copilot headset (adjust
copilot ICS volume if necessary) and in each passenger headset (adjust passenger ICS volume if
necessary).
7.2.2.8 Music System Check (if installed)
1. Set the intercom to the ALL mode.
2. Connect a stereo audio source to MUSIC 1 or MUSIC 2. Verify that stereo audio is heard over the
Pilot headset position.
3. Tune a station on COM 1 and verify that the sound is muted by active COM 1 audio (break squelch
on COM 1 if necessary).
4. Verify that stereo audio is also heard in the passenger headsets.
