190-01878-02
GMA 342/345 Installation Manual
Rev. 5
Page 4-9
4.6.5 Failsafe Warning Audio
Failsafe audio is audio from another device that is heard when the GMA 342/345 is in failsafe mode
(power off or unit failure) and is desired to be heard in addition to the COM audio.
CAUTION
During failsafe mode both FAILSAFE WARN AUDIO IN HI and COM 1 AUDIO INPUT
are connected to the PILOT HEADSET LEFT OUTPUT. When in failsafe the output of the
COM 1 radio and the output of the device connected to FAILSAFE WARN AUDIO IN HI
will become shorted together, potentially causing damage or interference. If the
FAILSAFE WARN AUDIO IN HI is used, it may be necessary to install summing resistors
in series between these sources and the inputs to the audio panel to protect the outputs
from damage.
4.6.6 Music Inputs
The MUSIC LO signals are not the same reference as other ground connections. The MUSIC LO signals
should be used as part of a differential pair (along with the MUSIC RIGHT and MUSIC LEFT signals). If
the MUSIC LO signal is tied to a ground connection, the music will contain noise, and the audio quality
will be degraded.
Table 4-11 Failsafe Warning Audio
Pin
Connector
Pin Name
Description
I/O
29
J3402
FAILSAFE WARN AUDIO
IN HI
In the event of power loss, if wired,
failsafe warning audio will be heard in the
Pilot’s Left headset in addition to the
COM1 Audio Input.
IN
14
J3402
ALERT 2 LO, FAILSAFE
AUDIO IN LO
Ground Reference for Failsafe Warning
Audio Input
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Table 4-12 Music Inputs
Pin
Connector
Pin Name
Description
I/O
23
J3402
MUSIC 1 IN LEFT
Music 1 Input
IN
24
J3402
MUSIC 1 IN RIGHT
25
J3402
MUSIC 1 IN LO
Differential Reference for Music 1
--
26
J3402
MUSIC 2 IN LEFT
Music 2 Input
IN
27
J3402
MUSIC 2 IN RIGHT
28
J3402
MUSIC 2 IN LO
Differential Reference for Music 2
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