190-01134-11
GMA 350/350c/350H/350Hc Installation Manual
Rev. J
Page 3-5
3.8 Post Installation Checkout
NOTE
The GMA 350/350H does not provide valid outputs until the aircraft post installation
configuration procedures are completed.
3.8.1
Verify Failsafe Operation with a Mono Headset
1. Remove power to the unit by pulling the audio breaker.
2. Connect a mono headset to the pilot’s headset output jack and pilot’s mic jack.
NOTE
Use of a true mono headset is required for this test to insure proper wiring even if a stereo
jack is provided in the installation. Wiring left channel (tip contact) and right channel
(ring contact) backwards will cause failsafe mode not to function with mono headsets. Use
of a true mono headset is required for this test (not a stereo headset with a mono/stereo
switch because headset manufactures differ on how they accomplish this switching). This
will guarantee the condition of the right channel (ring terminal) being shorted to the
return (sleeve terminal) by the mono headset’s plug. This short occurs because of the
physical design of the headset plug contacts and is an inevitable consequence of plugging
a mono headset into a stereo jack. During power-on operation, this short will not damage
the audio panel.
3. Verify that COM1 transceiver can be heard in the pilot’s headset.
4. Verify that COM1 can key and transmit the pilot’s mic audio by verifying received sidetone or
checking reception of the transmission with another radio tuned to receive this transmission (verify
Pilot PTT and mic operation is delivered to this transceiver).
5. Apply unit power by restoring the audio breaker to the normal operating position.
3.8.2
Verify Installed Transceivers (COMs) are able to Transmit and Receive
1. Connect a headset to the pilot’s headset output and mic input jack.
2. Verify each installed transceiver (COM) can be heard when selected.
NOTE
Depending on settings, the mic selected COM may mute audio from other COMs.
3. Verify that each installed transceiver keys for transmission and transmits clear audio from the
pilot’s mic when selected for transmission and the Pilot PTT key is pressed.
NOTE
The audio panel can be configured to simulate received sidetone internally, verifying
transmission with a separate radio not in the system is recommended.
4. Move the headset to the copilot’s headset jacks and verify that any one of the installed
transceivers (testing each is not necessary) receives and transmits copilot mic properly as above.
