Garmin G1000 Maintenance Manual page 121

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5.1.7.9 GMA 1347D
Symptom
Noise in Audio
Buttons Do Not Work.
COM Bleed over
Speaker Cuts Out
Mic Audio Heard in Speaker
G1000 System Maintenance Manual
190-00903-00
Recommended Actions
Most often the cause of the noise is external to the GMA 1347D.
Try the following to locate the source of the noise before replacing
the 1347D:
•
Try a different pair of headsets. Noise cancelling
headsets may pick up and/or generate more noise than
standard headsets from their own circuitry.
•
Check for noise with engines turned off.
•
If the noise is present only when the engines are
running, check the generator and/or ignition system as
possible sources of noise (see applicable airframe
maintenance manual).
•
Check for noise as all electrical equipment is turned on
and off (strobes, other radios, etc.).
•
If the noise is identified from one electrical system or
component refer to the applicable airframe specific
maintenance manual.
•
Ensure the NAV/COM squelch is not open.
•
Ensure the ADF and DME audio is not active.
•
Ensure the marker beacon audio is not active.
•
Ensure the ICS squelch is not open.
•
Master squelch level can be adjusted on the 1347D
CONFIGURATION page for higher noise
environments.
•
Replace unit only after all possible external sources of
noise are eliminated.
Some buttons are disabled in the GMA CONFIGURATION page by
default. This is to remove potential sources of audio noise for
inputs that are not used. If in doubt as to which buttons should be
disabled, reload GMA config files and other config files for optional
equipment installed in the aircraft (i.e. ADF, HF, etc.) from the
loader card.
Verify on the GMA CONFIGURATION page that "Disable Split
COM" has a green box. Due to the closeness of the COM
antennas and high power of the COM transceivers, Split COM
operation is not approved. If the box is black (indicating COM ½
button is active), highlight "Disable Split COM" with the cursor and
press the ENT key to turn the box green which will deactivate Split
COM mode.
Reduce volume level of the item that caused the speaker to cut out
when turned up. A speaker protection circuit disables the speaker
output if the volume is too high. If the volume is not sufficient,
replace aircraft cabin speaker, reference the Airframe Maintenance
Manual.
Reduce ICS Volume.
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Rev. A