Garmin Fishfinder 240 Blue Manual

GMA 240
Pilot’s Guide

Copyright © 2008 Garmin Ltd. or its subsidiaries. All rights reserved.
This manual reflects the operation of GMA 240 units with mod level 0 or later.
Some differences in operation may be observed when comparing the information
in this manual to earlier or later Mod status levels.
Garmin International, Inc., 1200 East 151st Street, Olathe, Kansas 66062, U.S.A.
Tel: [phone] Fax: [phone]
Garmin AT, Inc., 2345 Turner Road SE, Salem, OR 97302, U.S.A.
Tel: [phone] Fax [phone]
Garmin (Europe) Ltd, Liberty House, Bulls Copse Road, Hounsdown Business Park,
Southampton, SO40 9RB, U.K.
Tel: [phone] Fax: [phone]
Garmin Corporation, No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
Tel: [phone] Fax: [phone]
Web Site Address: www.garmin.com
Except as expressly provided herein, no part of this manual may be reproduced,
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trademarks may not be used without the express permission of Garmin.
June, 2008 190-00917-00 Rev. A Printed in the U.S.A.

LIMITED WARRANTY
This Garmin product is warranted to be free from defects in materials or
workmanship for one year from the date of purchase. Within this period, Garmin
will, at its sole option, repair or replace any components that fail in normal use.
Such repairs or replacement will be made at no charge to the customer for parts
and labor, provided that the customer shall be responsible for any transportation
cost. This warranty does not cover failures due to abuse, misuse, accident, or
unauthorized alterations or repairs.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN
LIEUOFALLOTHERWARRANTIESEXPRESSORIMPLIED ORSTATUTORY,INCLUDING
ANY LIABILITY ARISING UNDER ANY WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE, STATUTORY OR OTHERWISE. THIS
WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, WHICH MAY VARY FROM STATE
TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FORANY INCIDENTAL,SPECIAL, INDIRECT
OR CONSEQUENTIAL DAMAGES, WHETHER RESULTING FROM THE USE, MISUSE,
OR INABILITY TO USE THIS PRODUCT OR FROM DEFECTS IN THE PRODUCT. Some
states do not allow the exclusion of incidental or consequential damages, so the
above limitations may not apply to you.
Garmin retains the exclusive right to repair or replace the unit or software, or to
offer a full refund of the purchase price, at its sole discretion. SUCH REMEDY SHALL
BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY BREACH OF WARRANTY.
To obtain warranty service, contact your local GarminAuthorized Service Center. For
assistance in locating a Service Center near you, visit the GarminWeb site at “http://
www.garmin.com” or contact Garmin Customer Service at 800-800-1020.
CAUTION: Incorrect aircraft wiring could short the left channel or
both channels to ground if a monaural headset is plugged into
the stereo jacks. If wired incorrectly, fail-safe operation will not
work.
CAUTION: If monaural headsets are plugged into stereo jacks,
power supply current increases, which may cause power supply
fuse damage.

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Garmin GMA 240 Pilot’s Guide
4
GMA 240 Audio Panel
Pilot’s
Squelch
Knob
Copilot/
Passenger/
Music Volume
Knob
Copilot/
Passenger
Squelch Knob
ON/OFF
and Pilot’s
Volume
Knob
Monitor Mute
Key
Music 1 or 2
Select Key Transceiver Selection Keys
Com Receiver
Keys Nav Receiver and AUX Audio Keys
Music On/
Off Key
Intercom
Mute Key and
Radio Mute
Key
Pilot ICS
Isolation
Key
Telephone
Key Music Audio
or Telephone
Input Jack
Volume/Squelch: Rotating the Pilot Volume Knob (left small
knob) controls the ON and OFF function (Full CCW detent is
OFF). The large left knob controls Pilot squelch.
Pulling the right volume knob (small knob) controls music
volume, pushing in controls Copilot and passenger volume.
The large right knob controls Copilot and passenger squelch.

190-00917-00 Rev. A Garmin GMA 240 Pilot’s Guide 5
GMA 240 Audio Panel
COM receiver keys. Pressing a COM receiver key selects the receiver,
which is heard in addition to the selected transceiver. Pressing again
deselects the receiver.
Transceiver selection keys. Pressing a COM transceiver key selects the
COM transmitter and associated receiver. One of the transceivers is
always selected as active.
Monitor Mute key. Mutes all other monitored receivers when the active
transceiver receives audio.
Telephone key. Pressing the TEL Key selects the Telephone interface.
Pressing again deselects the telephone.
NAV receiver and AUX keys. Pressing a key selects the Nav receiver or
AUX audio input. Pressing again deselects the audio.
Master Music key. Pressing the MUSIC Key allows the selected music
input to be heard. Pressing again deselects music.
Music Source 1 or 2 selection key and Music Source Annunciators.
Selects Music input 1 or 2. LED 1 or 2 iluminates to indicate which input
is selected.
Music 1/TEL jack. External music device or telephone input.
ICS Key. When selected, music is muted during Intercom operation.
RADIO Key. When selected, music is muted during reception of selected
aircraft radios.

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Garmin GMA 240 Pilot’s Guide
6
GMA 240 Audio Panel
FEATURES AND OPERATION
The Garmin GMA 240 is a headphones only audio control panel. Pushbutton
keys control audio selection of COM, NAV, telephone (TEL), and intercom.
Two AUX inputs are available for additional avionics or audio devices.
LED annunciators indicate when a key function is selected. Annunciator
brightness is adjusted automatically by photocell dimming. LED-illuminated
key brightness is adjusted by the radio dimming bus control.
In case power is interrupted or the unit is turned off, a fail-safe circuit
connects the Pilot’s headset, microphone, and PTT directly to COM 1 and the
fail-safe alert audio, such as an autopilot disconnect tone.
In addition to radio squelch circuitry, MASQ
TM
(Master Avionics Squelch)
processing further reduces ambient noise from the avionics inputs.
Upon installation, the unit may be configured in various ways depending
on the aircraft type and the needs of the Pilot. See the configuration list at the
end of this manual. Contact a Garmin-authorized service center for details
and assistance in altering the configuration settings.
MICROPHONES
The GMA 240 Audio Panel can accept up to four (4) microphone inputs,
allowing for a two-person crew and up to two (2) passenger intercom
stations in the aircraft. A push-to-talk (PTT) switch must be pressed to
transmit on a selected Transceiver. The passengers cannot transmit over the
active COM radio, even if equipped with a PTT switch.
Each microphone input has a dedicated VOX circuit to ensure that only
the active microphone is heard when squelch is broken.

190-00917-00 Rev. A Garmin GMA 240 Pilot’s Guide 7
GMA 240 Audio Panel
MONO/STEREO HEADSETS
The unit can accommodate up to four (4) headsets (Pilot, Copilot and up
to two (2) passengers). The use of stereo headsets is highly recommended.
If monaural headsets are plugged into stereo jacks, power supply fuses may
be damaged.
When wired correctly, the use of a monaural headset in a stereo jack
shorts the right headset channel to ground. Anyone listening on a monaural
headset hears only the left channel in both ears. If a monaural headset is
used at one of the passenger positions, anyone else listening on a stereo
headset hears audio in the left ear only, unless their headset has a mono/
stereo switch set to mono.
POWER ON/OFF
The GMA 240 may be powered ON and OFF with the avionics master
switch. The unit may also be turned ON and OFF with the Pilot ICS Volume
Knob. Rotate the knob clockwise out of the detent to turn ON. Rotate the
knob counterclockwise into the detent to turn OFF.
During power-up, the unit undergoes a self-test, illuminating all panel
annunciator lights for about two (2) seconds. Once the self-test is complete,
the unit is ready for use with the same keys selected as when the system was
last powered OFF.
TRANSCEIVERS
Pressing COM1 MIC or COM2 MIC Key selects the transmitter and receiver
audio for the selected transceiver source. The active COM audio is always
heard on the Pilot headphones. Audio level is controlled by the selected
COM radio volume control.
Either audio source can be selected independently by pressing the COM1
or COM2 receiver keys. When selected this way, they remain active as audio
sources regardless of which transceiver has been selected for microphone
use.

190-00917-00 Rev. A
Garmin GMA 240 Pilot’s Guide
8
GMA 240 Audio Panel
When a microphone is keyed, the active transceiver’s MIC key LED blinks
approximately once per second indicating the PTT is pressed.
RECEIVERS
Pressing the NAV1 , NAV2 , AUX1 , or AUX2 Key selects the receiver audio
for the selected source. Each audio source can be selected independently by
pressing the appropriate receiver keys. They remain active as audio sources
until deselected.
Press the MON MUTE Key to mute all monitored receiver audio when
the active transceiver is receiving audio.
INTERCOM
The GMA 240 includes a four-position intercom system (ICS) with
electronic cabin noise de-emphasis and two stereo music inputs. Two
volume controls, one for the Pilot and one for a combined Copilot/passenger
control, set intercom audio level. Music volume is controlled by pulling
the right side (Copilot/passenger) volume control knob and turning it for
the desired audio level.
ICS squelch is adjusted by turning the Pilot side and Copilot/passenger
side SQ knob. Turning either knob clockwise increases the squelch threshold
level, turning counterclockwise decreases the level.
The intercom system provides two modes of isolation, PILOT and ALL,
controlled by pressing the PILOT ISO Key. In Pilot mode, (PILOT ISO
annunciator is illuminated) the Pilot is isolated from all other occupants of
the aircraft. In ALL mode, (PILOT ISO annunciator is off) everyone hears
all occupants of the aircraft.
The unit can also be configured for Crew Isolation in place of Pilot
Isolation. When configured for Crew Isolation, the Pilot and Copilot can
communicate with each other while the passengers are able to communicate
only with each other. In ALL mode, there is no isolation and every occupant
can communicate with every other occupant.

190-00917-00 Rev. A Garmin GMA 240 Pilot’s Guide 9
GMA 240 Audio Panel
Press the ICS Key to mute the music during intercom operation.
Press the PILOT ISO Key for Pilot or Crew isolation, depending on
configuration.
Mode Pilot Hears Copilot Hears Passenger Hears
ALL
(PILOT ISO not
Selected)
Selected Radios,
Alerts, Telephone,
Pilot, Copilot,
Passengers, Music
Selected Radios,
Alerts, Telephone,
Copilot, Pilot,
Passengers, Music
Selected Radios,
Alerts, Telephone,
Pilot, Copilot,
Passengers, Music
PILOT (PILOT
ISO Selected)
Selected Radios,
Alerts, Telephone,
Pilot, Music*
Copilot,
Passengers,
Music
Copilot,
Passengers,
Music
CREW (When
Crew Isolation
is configured
and PILOT ISO
is selected)
Selected Radios,
Alerts, Telephone,
Pilot, Copilot,
Music*
Selected Radios,
Alerts, Telephone,
Copilot, Pilot,
Music*
Passengers,
Music
*A configuration option can allow music for these positions.
ICS Isolation Modes & Telephone Distribution
TELEPHONE
The GMA 240 provides a full-duplex telephone interface. Press the
TEL Key to activate telephone operation. When the telephone is active,
operation depends on the ICS mode. See the ICS Isolation Modes &
Telephone Distribution table. Telephone communication is much like using
the intercom, allowing both parties to talk at once.

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Garmin GMA 240 Pilot’s Guide
10
GMA 240 Audio Panel
ENTERTAINMENT INPUTS
The GMA 240 provides two stereo entertainment inputs; MUSIC 1 and
MUSIC 2. A MUSIC 1/TEL jack is also located on the GMA 240 front panel.
The MUSIC 1/TEL jack can accept music or telephone sources.
The MUSIC 1 and MUSIC 2 rear inputs may be wired to either a stereo
phone jack in a convenient place, or to an audio device in a fixed mount
(e.g. a GPSMAP 396 dock or a CD player). These inputs are compatible
with popular portable entertainment devices such as MP3 and CD players.
The headphone outputs of these devices are plugged into the MUSIC 1 or
MUSIC 2 jacks.
Press the MUSIC Key to enable the selected music input to be heard.
Press again to disable music audio.
Press the MUSIC 1-2 Key to select either the MUSIC 1 or MUSIC 2 input.
Annunciators above the key indicate which music source is selected.
Either music source may be selected. The selected source is heard by
all unless intercom isolation removes the audio. A music source plugged
into the GMA 240 front panel MUSIC 1 jack will bypass the MUSIC 1 rear
input.
MUSIC is soft-muted under certain conditions. Soft-muting refers to the
temporary reduction of music volume and a gradual return to its original
level. This muting occurs during alerts (unless configured otherwise),
during selected radio reception if the RADIO Key is selected, during
intercom operation if the ICS Key is selected, and any time the TEL Key is
selected.

190-00917-00 Rev. A Garmin GMA 240 Pilot’s Guide 11
GMA 240 Audio Panel
GMA 240 PROGRAMMING OPTIONS
Programming options include variable configurations that can be
arranged by a Garmin authorized service center. Some options include a
Pilot operable pushbutton or toggle switch or might be fixed configurations
that are unchangeable. Configurations include the following:
•COM Swap - A remote mounted pushbutton is used to transfer the active
microphone between COM1 MIC and COM2 MIC.
•COM muting on transmit - Audio on the other selected radios is muted
while the active transceiver is transmitting.
•Deactivate MASQ
TM
(master avionics squelch). Enables/disables master
squelch. The threshold level of MASQ
TM
is also adjustable.
•Internal Sidetone - Enables/disables internal sidetone for radios that
do not provide sidetone during transmission. This can be selected
independently for COM1, COM2, and TEL.
•Crew Isolation - ICS isolation for the crew in place of Pilot isolation.
•PILOT ISO Music - Enable music audio to be heard by the Pilot during
PILOT ISO mode.
•Button Press Tone - Enable beep tone annunciation of button presses.
•Alert Music Mute - Disable music interruption by alert audio. Default
operation is recommended.
•Jack TEL detect - Phone detection is bypassed. Audio panel assumes a
telephone is plugged into the jack whenever the TEL Key is selected.
•Music mute by primary COM only - When RADIO Key is selected,
music is muted only when active COM is receiving audio.
•Enable Keyed ICS - Intercom MIC audio heard only when the
corresponding ICS Key for the MIC position is pressed.
•Individual volume controls - The volume can be adjusted individually
for each alert input, the rear connector pin TEL audio input, and the front
accessory jack TEL audio input.

Garmin International, Inc.
1200 East 151st Street
Olathe, KS 66062, U.S.A.
p: 913.397.8200
f: 913.397.8282
Garmin AT, Inc.
2345 Turner Road SE
Salem, OR 97302, U.S.A.
p: 503.391.3411
f: 503.364.2138
Garmin (Europe) Ltd
Liberty House, Bulls Copse Road
Hounsdown Business Park
Southampton, SO40 9RB, U.K.
p: 44/0870.8501241
f: 44/0870.8501251
Garmin Corporation
No. 68, Jangshu 2nd Road
Shijr, Taipei County, Taiwan
p: 886/2.2642.9199
f: 886/2.2642.9099
www.garmin.com
190-00917-00 Rev. A
© 2008 Garmin Ltd. or its subsidiaries