Garmin G1000 NAV III Line Maintenance Manual page 68

2.3.2 Common Problems
Symptom
Noise in Audio
Buttons Do Not Work.
COM Bleedover
Speaker Cuts Out
Page 2-40
Rev. L
Recommended Action
•
Remove GMA and check for MOD 1 marking if below S/N 47100641. If
MOD 1 is not marked, unit may be returned to Garmin for installation of
Service Bulletin 0410.
•
On the MFD AUX – SYSTEM STATUS page, see if GIA63's are under
S/N 46902653. If so, remove GIA63's from rack and check if MOD 1
has been installed. If not, units may be returned to Garmin for
installation of Service Bulletin 0416.
Most often the cause of the noise is external to the GMA. Try the following
to locate the source of the noise before replacing the GMA:
•
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 turned off.
If the noise is present only when the engine is running, check the
o
alternator and/or ignition system as possible sources of noise (see
applicable airframe specific 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
o
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 GMA
o
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 file and other config files for optional equipment
installed in the aircraft (i.e. ADF, DME) 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 deactive Split COM mode.
•
On the MFD AUX – SYSTEM STATUS page, see if GIA's are under
S/N 46905099. If so, remove GIA's from rack and check if MOD 3 has
been installed. If not, units may be returned to Garmin for installation of
Service Bulletin 0505.
•
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.
G1000 Nav III Line Maintenance Manual
190-00352-00