Page 2-8
GMA 340 Installation Manual
Rev. L
190-00149-01
2.6.5
Aircraft Receivers Check
1. Select the audio source corresponding to each installed avionics unit and check for audio over the
headsets.
2. Check for Pilot/Copilot audio isolation when pressing the COM 1/2 button (15). (Not applicable to Dual
ADF)
3. Press the SPKR button (12) and verify that any selected audio is heard over the speaker.
2.6.6
Music System Check
NOTE
Unit Mods 2 and 5 provide times ten gain for volume control of the entertainment
music system. Unit Mod 5 provides either switching this function between unity gain
(0 dB) and times ten gain (20 dB) or hard wiring J2 pin 15 to ground for times ten gain.
When audio levels applied to Music 1 and Music 2 inputs are increased by 20 dB, the
amplification may also increase unwanted audio noise. See note 17 in figures B5 and
B7 and refer to Garmin Service Bulletins 0113 and 0210.
1. Set the intercom to the ALL mode [Crew (9) and Pilot (10) LEDs off.]
2. Connect a stereo audio source to MUSIC 1. Verify that stereo audio is heard over all headset positions.
3. Select an audio source to COM 1 (13) and verify that the sound is muted by active Com 1 audio (break
squelch if necessary).
4. Connect a stereo music source to MUSIC 2. (NA to Dual ADF). Press the CREW button (9) to set the
ICS to the crew mode. Verify that stereo audio is heard in the passenger headsets only.
CAUTION
Be sure to check all aircraft control movements before flight is attempted to
insure that the wiring harness does not touch any moving part. Verify proper
operation of the marker beacon during a flight test under VFR conditions.
This completes the in-aircraft post installation checkout. Perform a flight test after installing the unit to ensure
satisfactory performance of the audio and marker beacon receiver functions. Verify proper operation of the
marker lamps and marker audio, including the marker audio mute function. Check proper operation of the
sensitivity selection [using the SENS button (4)] by flying towards the outer marker position initially using HI
sensitivity. When the COM audio is just barely audible in the headset, switching to LO sensitivity should reduce
or eliminate the audio.
