190-00917-01
GMA 240 Installation Manual
Rev. D
Page 1-1
1 GENERAL DESCRIPTION
1.1 Introduction
This manual provides the installation instructions for the Garmin GMA 240 Audio Panel. Reference to
GMA 240 throughout this manual refers to all versions of the unit. Information pertaining to the
maintenance of the unit can be found in the GMA 240 Maintenance Manual, P/N 190-00917-02.
Information pertaining to the operation of the unit can be found in the GMA 240 Pilot's Guide, P/N
190-00917-00.
1.2 Equipment Description
The Garmin GMA 240 Audio Panel is not a TSO-certified product and has received no FAA approval or
endorsement.
The GMA 240 meets the needs of aircraft owners and operators who require reliability and versatility in
the essential audio switching function. LED-illuminated push-button simplicity and intuitive panel layout
allow audio selection of both NAV and COM audio. Large, single-button activation of the COM
microphone and audio for two COM transceivers simplifies cockpit workload. Photocell dimming
circuitry automatically adjusts the brightness of the annunciators to a level appropriate for ambient cockpit
light. The brightness of the backlighting is controlled by the aircraft lighting bus. A fail-safe circuit
connects the pilot's headset and microphone directly to COM1 and a fail-safe warning audio input in the
event that power is interrupted or the unit is turned off.
Additionally, the GMA 240 includes a four-position intercom (ICS) with electronic cabin noise de-
emphasis, two stereo music inputs, and independent pilot and copilot/passenger volume controls. To
further simplify the cockpit workload, the intercom provides for pilot isolation. One hundred percent solid
state circuitry and extensive use of surface mount technology are employed.
Figure 1-1. GMA 240 Unit View
PILO T
C OPILO T
MUTE
MON
SQ
OFF/
VOL
SQ
VOL
PULL
MUSIC
VOL
TE L
GMA 240
PILOT
IS O
MUTE MUS IC
MUS IC
IC S
RADIO
NAV1
NAV2
AUX1
AUX2
C OM1
MIC
C OM1
C OM2
C OM2
MIC
TEL
1
1-2
1
2
