Installation Instructions

190-01007-A3 GTN 6XX/7XX AML STC Installation Manual
Rev. 4 Page 5-93
5.7.6.2 Failsafe Operation Check
1. Power the GMA 35 off by pulling the GMA 35 circuit breaker.
2. Check the failsafe operation by exercising the COM1 microphone, microphone key and audio
over the pilot’s headphones.
NOTE
Use of a true mono headset is required for this test to ensure 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. During
power-on operation, this short will not damage the audio panel.
3. 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).
4. Turn the unit back on to continue testing.
NOTE
If the configuration setting ‘COM 1 is connected as COM 2’ is set to True (described
in Section 5.5.4.8.2.1), then the COM 2 microphone should be exercised rather than
COM 1.
5.7.6.3 COM Transceiver Operational Check
1. Connect a headset to the pilot’s headset output and mic input jack.
2. Verify that each installed transceiver (COM) can be heard when selected.
NOTE
Depending on configuration 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. (Because the audio
panel can be configured to simulate received sidetone internally, verifying transmission with a
separate radio not in the system is recommended.)
NOTE