Gma 1347 Related Alerts And Problems - Garmin G1000 Maintenance Manual

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5.5

GMA 1347 RELATED ALERTS AND PROBLEMS

5.5.1 Common Problems
Symptom
Noise in Audio
Buttons Do Not Work.
Page 5-40
Rev. B
Recommended Action
Most often the cause of the noise is external to the GMA 1347. Try
the following to locate the source of the noise before replacing the
1347:
•
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 engine off.
−
If the noise is present only when the engine is running, check
the generator and/or ignition system as possible sources of
noise (see OEM 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 OEM airframe 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
GMA CONFIGURATION page for higher noise environments.
•
Check resistors in line with Music 1 and Music 2 wiring at the
GMA 347 in accordance with system wiring diagrams
•
Verify Mic and Phone jacks are insulated from airframe ground
and that Music 1 and Music 2 jacks are not insulated from
airframe ground in console.
•
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 (ADF, DME) from the
loader card.
G1000 System Maintenance Manual
190-00907-00