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GMA 240 - Garmin
GMA 240
Installation Manual
190-00917-01
September, 2015
Revision E
© 2015
Garmin Ltd. or its subsidiaries
All Rights Reserved
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Garmin International, Inc.
1200 E. 151st Street
Olathe, KS 66062 USA
Telephone: 913.397.8200
Aviation Panel-Mount Technical Support Line (Toll Free) 1.888.606.5482
www.garmin.com
Garmin (Europe) Ltd.
Liberty House, Hounsdown Business Park
Southampton, Hampshire SO40 9LR U.K.
+44/ (0) 23 8052 4000
Garmin AT, Inc.
2345 Turner Rd., SE
Salem, OR 97302 USA
Telephone: 503.581.8101
RECORD OF REVISIONS
Revision
Revision Date
Description
A
06/09/08
Initial Release
B
01/18/11
Clarified backlighting info
C
04/13/11
Clarified mono/stereo headset switch info
D
06/16/12
Corrected temperature range spec
E
09/29/15
Updated lighting bus info and interconnect drawings
AVIATION LIMITED WARRANTY
GMA 240 warranty information is available at garmin.com/aviationwarranty.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page A
INFORMATION SUBJECT TO EXPORT CONTROL LAWS
This document may contain information which is subject to the Export Administration Regulations
("EAR") issued by the United States Department of Commerce (15 CFR, Chapter VII, Subchapter C) and
which may not be exported, released, or disclosed to foreign nationals inside or outside of the United States
without first obtaining an export license. The preceding statement is required to be included on any and all
reproductions in whole or in part of this manual.
DEFINITIONS OF WARNINGS, CAUTIONS, AND NOTES
WARNING
Warnings are used to bring to the installer’s immediate attention that not only
damage to the equipment but personal injury may occur if the instruction is
disregarded.
CAUTION
Cautions are used to alert the individual that damage to equipment may
result if the procedural step is not followed to the letter.
NOTE
Notes are used to expand and explain the preceding step and provide further
understanding of the reason for the particular operation.
WARNING
This product, its packaging, and its components contain chemicals known to the State of
California to cause cancer, birth defects, or reproductive harm. This Notice is being
provided in accordance with California's Proposition 65. If you have any questions or
would like additional information, please refer to our web site at www.garmin.com/prop65.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page i
CURRENT REVISION DESCRIPTION
Revision
E
Page
Number
Section
Number
2-3, 2-4
2.3.2
Updated/added volume/mute adjustments info
4-5
4.3.2
Updated lighting bus info
B-1–B-3
Appdx B
Description of Change
Updated interconnect drawing to show both J & P
connectors
GMA 240 HARDWARE MOD LEVEL HISTORY
The following table identifies hardware modification (Mod) Levels for the GMA 240 Audio
Panel. Mod Levels are listed with the associated service bulletin number, service bulletin date, and the
purpose of the modification. The table is current at the time of publication of this manual (see date on front
cover) and is subject to change without notice. Authorized Garmin Sales and Service Centers are
encouraged to access the most up-to-date bulletin and advisory information on the Garmin Dealer
Resource web site at www.garmin.com using their Garmin-provided user name and password.
Mod
Level
190-00917-01
Rev. E
Service
Bulletin
Number
Service
Bulletin Date
Purpose Of Modification
GMA 240 Installation Manual
Page ii
TABLE OF CONTENTS
PARAGRAPH
PAGE
Section 1 GENERAL DESCRIPTION .............................................................1-1
1.1 Introduction...................................................................................................................... 1-1
1.2 Equipment Description .................................................................................................... 1-1
1.3 Technical Specifications .................................................................................................. 1-2
1.4 Reference Documents ...................................................................................................... 1-4
Section 2 INSTALLATION OVERVIEW........................................................2-1
2.1 Introduction...................................................................................................................... 2-1
2.2 Installation Materials ....................................................................................................... 2-1
2.3 GMA 240 Wiring, Configuration, and Adjustment Options ........................................... 2-1
2.4 Noise ................................................................................................................................ 2-5
2.5 GMA 240 Mounting ........................................................................................................ 2-6
Section 3 INSTALLATION PROCEDURE .....................................................3-1
3.1 Unpacking Unit................................................................................................................ 3-1
3.2 Electrical Connections ..................................................................................................... 3-1
3.3 Audio Shield Termination ............................................................................................... 3-2
3.4 GMA 240 Installation ...................................................................................................... 3-2
3.5 Post Installation Checkout .............................................................................................. 3-3
3.6 Configuration Adjustments.............................................................................................. 3-4
3.7 Continued Airworthiness ................................................................................................. 3-4
Section 4 SYSTEM INTERCONNECTS..........................................................4-1
4.1 Connector Description ..................................................................................................... 4-1
4.2 Pin List ............................................................................................................................. 4-1
4.3 Aircraft Power and Lighting ............................................................................................ 4-4
4.4 Configuration Pins ........................................................................................................... 4-5
4.5 Audio Inputs/Outputs and Mic Keys ............................................................................... 4-6
Appendix A Outline and Installation Drawings .............................................A-1
Appendix B Interconnect Drawings.................................................................B-1
Appendix C Configuration Jumpers Drawing................................................C-1
190-00917-01
Rev. E
GMA 240 Installation Manual
Page iii
LIST OF FIGURES
FIGURE
PAGE
Section 1 GENERAL DESCRIPTION .............................................................1-1
Figure 1-1. GMA 240 Unit View.......................................................................................... 1-1
Section 2 INSTALLATION OVERVIEW........................................................2-1
Figure 2-1 ESD Caution Logo .............................................................................................. 2-2
Figure 2-2 Access Hole Locations (Top View) .................................................................... 2-4
Figure 2-3 GMA 340 (used for GMA 240) Unit Rack (115-00262-00)............................... 2-6
Section 3 INSTALLATION PROCEDURE .....................................................3-1
Figure 3-1 Audio Shield Termination................................................................................... 3-2
Section 4 SYSTEM INTERCONNECTS..........................................................4-1
Figure 4-1
Figure 4-2
Figure 4-3
Figure 4-4
Rear View of Backplate and Rack ...................................................................... 4-1
Rear Connectors J2401 & J2402, Viewed from Back of Unit............................ 4-1
2.5 mm Plug Used with J2403 ............................................................................ 4-4
Audio Jack Wiring ............................................................................................ 4-10
Appendix A Outline and Installation Drawings .............................................A-1
Figure A-1 GMA 240 Outline Drawing .............................................................................. A-1
Figure A-2 GMA 240 Connector/Rack Assembly Drawing ............................................... A-2
Figure A-3 GMA 240 Recommended Panel Cutout Dimensions........................................ A-3
Appendix B Interconnect Drawings ................................................................B-1
Figure B-1
Figure B-1
Figure B-1
Figure B-2
GMA 240 Interconnect Drawing (page 1 of 3) ..................................................B-1
GMA 240 Interconnect Drawing (page 2 of 3) ..................................................B-2
GMA 240 Interconnect Drawing (page 3 of 3) ..................................................B-3
GMA 240, J2401 & J2402 Connector Layout Drawing ....................................B-4
Appendix C Configuration Jumpers Drawing................................................C-1
Figure C-1 GMA 240 Internal Configuration Jumper Layout Drawing...............................C-1
190-00917-01
Rev. E
GMA 240 Installation Manual
Page iv
LIST OF TABLES
TABLE
PAGE
Section 1 GENERAL DESCRIPTION .............................................................1-1
Table 1-1
Table 1-2
Table 1-3
Table 1-4
Physical Characteristics........................................................................................ 1-2
Electrical Characteristics ...................................................................................... 1-3
Power Requirements............................................................................................. 1-4
Reference Documents........................................................................................... 1-4
Section 2 INSTALLATION OVERVIEW........................................................2-1
Table 2-1 .............................................................................................................................. 2-1
Section 3 INSTALLATION PROCEDURE .....................................................3-1
Table 3-1 Pin Contact Part Numbers .................................................................................... 3-1
Table 3-2 Recommended Crimp Tools................................................................................. 3-1
Section 4 SYSTEM INTERCONNECTS..........................................................4-1
Table 4-1 J2401 Pin Assignments ........................................................................................ 4-1
Table 4-2 J2402 Pin Assignments ........................................................................................ 4-3
Table 4-3 J2403 Connector................................................................................................... 4-4
Table 4-4 Aircraft Power ...................................................................................................... 4-4
Table 4-5 Lighting Bus ......................................................................................................... 4-5
Table 4-6 External Configuration Pins ................................................................................. 4-5
Table 4-7 Mic Audio Inputs and Mic Keys .......................................................................... 4-6
Table 4-8 Intercom Key Inputs ............................................................................................. 4-6
Table 4-9 COM Audio and Mic Keys .................................................................................. 4-7
Table 4-10 Alert Audio I/O .................................................................................................. 4-7
Table 4-11 AUX and NAV Audio Inputs ............................................................................. 4-7
Table 4-12 Failsafe Warning Audio ..................................................................................... 4-8
Table 4-13 Music Inputs ....................................................................................................... 4-8
Table 4-14 Tel Audio I/O ..................................................................................................... 4-8
Table 4-15 Headset Outputs ................................................................................................. 4-9
Table 4-16 COM Swap ....................................................................................................... 4-10
190-00917-01
Rev. E
GMA 240 Installation Manual
Page v
1 GENERAL DESCRIPTION
1.1 Introduction
This manual provides the installation instructions for the Garmin GMA 240 Audio Panel. References to
GMA 240 throughout this manual refer 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 deemphasis, 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
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 1-1
1.2.1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Features Summary
User-friendly, intuitive front panel layout
LEDs indicate selected function
Four position intercom: pilot, copilot, two passengers
Two stereo headset amplifiers: one for pilot, one for copilot/passengers
Two differential stereo music source inputs
Front panel music volume control, source selection, and master music on/off switch
Front panel controls for music muting by intercom and selected radios
Two selectable intercom operational modes
Selectable aural pushbutton annunciation (beep)
Independent pilot, copilot/passenger intercom volume and squelch controls
Individual VOX circuits for each of four (4) mic inputs
Automatic selection of COM audio source when corresponding mic is selected
Memory of explicitly selected COM audio source(s) when changing COM mic selection
MASQ™ Processing with configurable mute threshold
COM swap function
PTT indication
Power-off fail-safe to connect Pilot PTT, mic, and Headset to COM 1 if unit is turned off
Power-off fail-safe warning audio input
Full duplex Telephone interface
Front Panel Mini-Jack (MP3 player, cellular phone, etc.)
1.3 Technical Specifications
1.3.1
Physical Characteristics
Table 1-1 Physical Characteristics
Characteristic
Specification
Bezel Height
1.30 inches (33 mm)
Bezel Width
6.29 inches (159.77 mm)
Rack Height (Dimple to Dimple)
1.33 inches (34 mm)
Rack Width
6.30 inches (160.02 mm)
Depth Behind Panel with Connectors (measured from face of aircraft
panel to rear of connector backshells)
7.12 inches (181 mm)
GMA 240 Weight (Unit Only)
15.5 oz (440 g)
GMA 240 Weight (Installed with rack and connectors)
24 oz (680 g)
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 1-2
1.3.2
Electrical Characteristics
Table 1-2 Electrical Characteristics
Characteristic
Specification
Temperature
Range
-20 C to +55 C (operation)
-55 C to +85 C (storage)
Altitude
55,000 Feet
Dedicated Transceiver inputs: 3 (including TEL)
Dedicated Receiver inputs: 4 (all independently selectable)
Alert (unswitched) inputs: 3 (each with configurable volume)
Audio Panel
Functions
Input impedance: 500 Ω
Input isolation: 60 dB minimum
Alert/Receiver/Transceiver bandwidth: 100 Hz to 6.5 kHz
Special functions: Fail-safe operation
MASQ™ processing (Master Avionics Squelch)
Configurable button push aural annunciation
Positions: 4 (pilot, copilot, 2 passengers)
Volume controls: 3 (pilot, copilot/passengers, music)
VOX level controls: 2 (pilot, copilot/passengers)
VOX circuits: 4 (one per mic input)
Intercom Functions
Microphone input impedance: 450 Ω (compatible with 150 to 600 Ω mics)
Microphone bias voltage: about 10 Vdc delivered through 450 Ω
Microphone response: 9-pole characteristic cabin noise de-emphasis
Intercom isolation modes: 2 - all, pilot (or configure for all, crew)
Telephone interfaces: 1 full-duplex (use LRU pins or front jack)
Output amplifiers: 2 stereo (pilot, copilot/passengers)
Fidelity:
Headphone
Outputs
Load
Power
Distortion (typ.)
150 Ω
50 mW
<0.03% THD+N
150 Ω
100 mW
<0.07% THD+N
50 Ω
150 mW
<0.07% THD+N
50 Ω
300 mW
<0.10% THD+N
Compatible with higher headphone impedances, those shown are for worst-case
distortion and bandwidth
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 1-3
Table 1-2 Electrical Characteristics
Characteristic
Specification
Music inputs (stereo): 2
Music input impedance: 600 Ω (differential)
Music gain: -20dB @ min volume, +26dB @ max. volume (typ.)
Music input level:<200 mVrms for full power* output @ max music volume knob
position (typ.)
3.5 Vrms max music input level
Music bandwidth: 20 Hz to 20 kHz @ full power output
Music Functions
Music distortion: <0.1% THD+N (typ.) @ full power, full bandwidth
Special Functions: Front panel selection and volume control
Front panel control for muting by radios and ICS
Muting by alerts configurable
*Full power output refers to 300 mW into 50 Ω (three 150 Ω headsets in parallel
each driven to 100 mW)
Input Impedance: 5.1 kΩ
Music Input: Auto detection of music source will use jack as Music 1
Front Panel MiniJack Functions
1.3.3
Telephone Input: Auto detection of TEL source will use jack for TEL Telephone
ring signal is heard without TEL selected
Power Requirements
Table 1-3 Power Requirements
Characteristic
Specification
Input Voltage Range
11 to 33 Vdc
Power Input
4.3 W normal operation (310mA @ 13.8 V)
7.5 W max. operation (540 mA @ 13.8 V)
1.4 Reference Documents
The following publications are sources of additional information for installing the GMA 240. Before
installing the unit, the technician should read all referenced materials along with this manual.
Table 1-4 Reference Documents
Part Number
190-00917-01
Rev. E
Document
190-00917-00
GMA 240 Pilot's Guide
190-00917-02
GMA 240 Maintenance Manual
GMA 240 Installation Manual
Page 1-4
2 INSTALLATION OVERVIEW
2.1 Introduction
This section provides the necessary information for the installation and checkout of the GMA 240 Audio
Panel. Installation of the GMA 240 will differ according to equipment location and other factors. Cabling
will be fabricated by the installing agency to fit these various requirements. The appendices contain
interconnect wiring diagrams, mounting dimensions, and information pertaining to installation.
2.2 Installation Materials
2.2.1
Equipment Available
GMA 240 Audio Panel, Ship Level Assembly, P/N 010-00735-() includes the following, depending on
part number:
Table 2-1
Item
2.2.2
•
•
•
Garmin P/N
Connector Kit, GMA 340
011-00652-00
Rack Backplate, GMA 340
011-00678-00
Unit Assembly, GMA 240
011-01988-00
Audio Cables, 2.5 mm RA Stereo Plug
011-02079-00
Install Rack, GMA 340 (used for GMA 240)
115-00262-00
Additional Equipment Required
Cables: The installer will fabricate and supply all system cables. Interconnect wiring diagrams are
detailed in Appendix B.
Hardware: #6-32 100° flat head screw (6 ea.) and #6-32 self-locking nut (6 ea.). Hardware
required to mount the installation rack is not provided.
Stereo headphone jacks (up to 4), microphone jacks (up to 4), 3.5mm stereo jacks (up to 2).
Insulating type jacks or insulating washers should be used for all jacks to isolate them from aircraft
chassis.
2.3 GMA 240 Wiring, Configuration, and Adjustment Options
The GMA 240 has several configuration/adjustment options, consideration of these options should be
discussed with the end user(s) of the aircraft before wiring begins. These configuration/adjustments are
described in the following sections:
•
•
•
Wiring options - Section 2.3.1 and Section 4.4.1
Internal configuration jumpers - Section 2.3.1
Volume/Mute adjustments - Section 2.3.2
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 2-1
2.3.1
Internal Configuration Jumpers
The following internal configuration adjustments may be made by removing or replacing jumpers on the
PCB. The jumper positions are designed to accept a 0Ω resistor of 0603 size. Refer to Appendix C for
component location.
This service should only be performed by a qualified technician. Garmin is not responsible for damage
caused during adjustment of these internal configuration jumper settings. Refer to the GMA 240
Maintenance Manual for disassembly/reassembly instructions.
Figure 2-1 ESD Caution Logo
NOTE
The GMA 240 contains static sensitive components. Observe proper anti-static
procedures when performing any solder procedures on the unit.
Table 2-1 Configuration Jumpers
Component
Name
R0303
Alert Mutes
Music
Populated
R0304
COM1
Internal
Sidetone
Empty
R0305
COM2
Internal
Sidetone
Empty
R0308
R0315
190-00917-01
Rev. E
TEL
Internal
Sidetone
TEL jack
detect
bypass
Default
Description
If this jumper is removed, music will not be interrupted by
alert audio. Default operation is recommended.
If a jumper is supplied in these positions, internal sidetone
will be heard during PTT to simulate received sidetone
from a radio that does not provide one during
transmission. This should only be used if a radio does not
perform this function already.
Populated
If this jumper is removed, intercom audio and intercom
sidetone will not be heard when the TEL button is
selected. Many phones supply sidetone when a call is in
session. This causes a noticeable change in intercom
sound quality but it is usually not disruptive. Default
operation is recommended unless the effect of sidetone
from the telephone is disruptive to intercom operation.
Empty
If a jumper is supplied in this position, when TEL is
selected the audio panel will assume a telephone is in use
in the front jack regardless of phone detection. This
should be used only if the audio panel is not capable of
properly detecting the telephone that will be used in the
installation.
GMA 240 Installation Manual
Page 2-2
Table 2-1 Configuration Jumpers
Component
R0314
Name
Only
Primary
COM
mutes
MUSIC
Default
Description
Empty
If a jumper is supplied in this position, the RADIO button
will mute music only when the Primary COM (the COM
selected for transmission) is receiving audio. Default
RADIO mutes music operation occurs when any selected
COM / NAV / AUX radio is receiving audio.
R0313
Enable
KEYED
ICS
Empty
If a jumper is supplied in this position, the intercom system
(ICS) will only allow intercom MIC audio to be heard when
the corresponding ICS KEY for the MIC position is
pressed. When this configuration is used, the VOX knobs
should be set fully CCW (live MIC). See Section 4.5.2 for
information on wiring intercom keys.
R0312
Reserved
Empty
Reserved
R0309
Reserved
Empty
Reserved
R0302
Reserved
Empty
Reserved
R0301
Reserved
Empty
Reserved
R0300
Reserved
Empty
Reserved
2.3.2
VOLUME/MUTE Configuration Adjustments
There are six access holes in the GMA 240 top cover (Figure 2-2) that allow access to potentiometers
which can be used to make adjustments to input volume levels and the MASQ (Master Avionics SQuelch)
mute level. The specific adjustments and their associated label on the back cover are:
•
•
•
•
•
•
Alert 1 Volume. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alert 2 Volume. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alert 3 Volume. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear connector TEL input volume . . . . . . . . . . . .
Front panel jack TEL input volume. . . . . . . . . . . .
MASQ (Master Avionics SQuelch) mute level . . .
ALRT 1 VOL
ALRT 2 VOL
ALRT 3 VOL
REAR TEL VOL
FRONT TEL VOL
MUTE LVL
NOTE
Adjusting these levels is not generally needed or recommended for most installations.
For Alert 1, 2, & 3 volume inputs, rear conn TEL input, and front panel jack TEL inputs, a CW (clockwise)
adjustment increases the levels for volume inputs.
For MASQ mute level, a CW (clockwise) adjustment increases the level for the mute threshold for radio
inputs. MASQ circuitry functions to prevent low level noise from being passed to the headset ear speakers,
this is known as “squelching” or muting the audio. To “break” or “open” squelch means that enough audio
signal is present that the signal is passed through the audio circuitry and can be heard. Increasing (CW
adjustment) this setting increases the signal level required to break/open squelch. If needed, adjust the
MASQ SQ level so the audio background noise is muted.
2.3.2.1 MASQ/ICS Squelch Descriptions
The Master Avionics Squelch (MASQ) mute level adjustment is a different/separate function from the ICS
squelch that is controlled by the pilot/copilot squelch knobs on the unit’s front panel. MASQ is a squelch
or noise threshold adjustment that applies to the radio/alert type inputs.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 2-3
The ICS (intercom) squelch (sound level that opens the mic audio for pilot/copilot/passengers) is manually
adjusted by the pilot and copilot with dedicated front panel knobs, and is totally separate from MASQ.
CW rotation of the ICS adjustment knobs increases the amount of mic audio (VOX level) required to break
squelch, see the GMA 240 Pilot’s Guide (190-00917-00) for details.
The MASQ affects the noise threshold for the COM, NAV, AUX, TEL, and Alert 1/2/3 audio inputs. It is
factory adjusted to a level that works well for most installations, so it seldom needs to be adjusted by
installers. When necessary, the MASQ is adjusted using a small screwdriver (see following note) through
the MUTE LVL top access hole in the cover. For example, if one of the alert inputs has some background
noise that is sometimes or always heard in the headset and causes music to be undesirably muted, raising
the MASQ threshold may eliminate this issue. Anytime the MASQ is adjusted, it is very important to
verify that all audio inputs, including alerts, still function correctly.
Figure 2-2 Access Hole Locations (Top View)
NOTE
Adjusting the MASQ mute level to a high level may squelch the desired audio.
NOTE
Exercise care when inserting adjustment tools through the top cover. Damage to the unit
may occur if an adjustment tool is accidentally forced against unintended components or
circuit board paths. Use a 2 mm (max blade width) flat-blade non-conductive screw
driver or adjustment tool.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 2-4
2.3.3
Hardwire Configuration Option
The following configuration options are available by externally wiring pins to aircraft chassis. When
change of operation is desired during flight, these can optionally be wired to chassis through a suitable
switch mounted in reach of the operator. See Section 4.4.1 for connector and pin details for implementing
these configuration options.
MASQ™ INHIBIT: The Master Avionics SQuelch inhibit configuration option allows selected avionics
audio inputs (COM, NAV, AUX) and alerts to be heard even if they do not exceed the MASQ threshold.
This increases background noise during otherwise quiet operation because noise from these inputs is not
squelched. This option is most useful as a troubleshooting tool.
CREW ISO: This input configures the audio panel for crew intercom isolation in place of pilot isolation.
When the PILOT ISO key is selected, the pilot and copilot will hear each other but will be isolated from
the passengers. When the CREW ISO configuration is selected, the copilot's headphone jack must be
wired in parallel with the pilot headset output. Microphones are wired as normal.
PILOT ISO MUSIC: This input configures music to be heard by the pilot during PILOT ISO mode (or by
the pilot and copilot if crew isolate mode is configured). Normally, the isolated ICS positions do not hear
music.
BUTTON PRESS TONE ENABLE: This input enables an audible tone to be heard when a button press is
detected.
MUTE ON COM TX: This input configures the audio panel to mute all selected radios (COM, NAV,
AUX) except the mic selected COM (COM selected for transmission) when a PTT key is activated for
COM transmit.
2.4 Noise
Because the audio panel is a point in the aircraft where signals from many pieces of equipment are brought
together, care must be taken to minimize effects from coupled interference and ground loops.
Coupled interference can sneak into audio system interconnecting cables when they are routed near large
AC electric fields, AC voltage sources, and pulse equipment (strobes, spark plugs, magnetos, EL displays,
CRTs, etc). Interference can also couple into audio system interconnecting cables by magnetic induction
when they are routed near large AC current-carrying conductors or switched DC equipment (heaters,
solenoids, fans, autopilot servos, etc).
Ground loops are created when there is more than one path in which return currents can flow, or when
signal returns share the same path as large currents from other equipment. These large currents create
differences in ground potential between the various equipment operating in the aircraft. These differences
in potential can produce an additive effect at an audio panel signal input.
The audio panel may "see" the desired input signal plus an unwanted component injected by ground
differentials, a common cause of alternator-related noise. This is the main reason why all audio jacks
should be isolated from ground. Terminating audio shields just at one end eliminates another potential
ground loop injection point.
Single-point grounding cannot be overstressed for the various avionics producing and processing audio
signals. Single-point, in this context, means that the various pieces of equipment share a single common
ground connection back to the airframe. Good aircraft electrical/charging system ground bonding is also
important.
The wiring diagrams and accompanying notes in this manual should be followed closely to minimize noise
effects.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 2-5
2.5 GMA 240 Mounting
The GMA 240 mounting surface must be capable of providing structural support and electrical bond to the
aircraft to minimize radiated EMI and provide protection from High-Intensity Radiation Fields (HIRF).
The GMA 240 is mounted using a GMA 340 unit rack. Figure 2-3 shows the GMA 340 unit rack. See
Section 3.4 for installation instructions.
NOTE
Rear support is recommended to ensure a sturdy mount.
Figure 2-3 GMA 340 (used for GMA 240) Unit Rack (115-00262-00)
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 2-6
3 INSTALLATION PROCEDURE
3.1 Unpacking Unit
Carefully unpack the equipment and make a visual inspection of the unit for evidence of damage incurred
during shipment. If the unit is damaged, notify the carrier and file a claim. To justify a claim, save the
original shipping container and all packing materials. Do not return the unit to Garmin until the carrier has
authorized the claim.
Retain the original shipping containers for storage. If the original containers are not available, a separate
cardboard container should be prepared that is large enough to accommodate sufficient packing material to
prevent movement.
3.2 Electrical Connections
All electrical connections to the GMA 240 are made through two 44-pin D-subminiature connectors (see
Figure 3-1). Section 4 defines the electrical characteristics of all input and output signals. Required
connector and associated hardware are supplied in the connector kit (P/N 011-00652-00). See Appendix B
for interconnect wiring diagrams.
Check wiring connections for errors before inserting the GMA 240 into the rack. Incorrect wiring could
cause internal component damage.
Table 3-1 Pin Contact Part Numbers
Manufacturer
22-28 AWG
Garmin P/N
336-00021-00
Military P/N
M39029/58-360
Table 3-2 Recommended Crimp Tools
High Density 22-28 AWG
Manufacturer
Hand
Crimping Tool
Positioner
Insertion/Extraction Tool
Military P/N
M22520/2-01
M22520/2-09
M81969/1-04
NOTE
Non-Garmin part numbers shown are not maintained by Garmin and consequently are
subject to change without notice.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 3-1
3.3 Audio Shield Termination
The audio shield wires should be terminated at the rear of the unit to the screws between J2401 and J2402
as shown in Figure 3-1.
Rear View of backplate and rack
J2402
J2401
Audio shields daisy chained and
terminated using a lug attached to
either of these screws.
Figure 3-1 Audio Shield Termination
3.4 GMA 240 Installation
NOTE
Avoid installing the unit near heat sources. If this is not possible, ensure that additional
cooling is provided. Allow adequate space for installation of cables and connectors. The
installer will supply and fabricate all of the cables.
1. Assemble the connector/rack kit according to Table 4-1, Table 4-2; and Figure B-1 and Figure B-1.
Install the rack assembly according to the dimensions given in Figure A-1 and Figure A-3.
Mounting brackets are not supplied due to the wide range of mounting configurations available.
Suitable mounting brackets may be fabricated from sheet metal or angle stock. To ensure a sturdy
mount, rear support for the unit should be provided.
2. Slide the unit into the rack until the jackscrew makes contact with the receptacle located in the
back plate.
3. Insert a 3/32" Allen wrench into the jackscrew access hole on the faceplate.
4. Turn the Allen wrench clockwise until the unit is secured in the rack. Continue turning until tight,
but do not over-tighten.
CAUTION
Do not use excessive force when inserting the GMA 240 into the rack. This may
damage the connectors, unit, and/or unit rack. If heavy resistance is felt during
installation, stop, and remove the GMA 240 and identify the source of resistance.
5. To remove the unit from the rack, turn the Allen wrench counterclockwise until it disengages from
the rack.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 3-2
3.5
Post Installation Checkout
CAUTION
Check wiring connections for errors before inserting the GMA 240 into the rack.
Incorrect wiring could cause internal component damage.
An in-aircraft checkout may be performed in the aircraft on the ramp with known good microphone,
headset, and avionics receivers.
3.5.1
Lamp Test
1. Apply power to the unit by rotating the pilot intercom knob clockwise.
2. Verify that all annunciators on the front panel are illuminated during initial power up.
3.5.2
Failsafe Operation Check
1. Turn the unit off by rotating the pilot intercom knob fully counter clockwise.
2. Check the failsafe operation by exercising the COM 1 microphone, microphone key, and
monitoring received COM 1 audio over the pilot headphone's left earpiece.
3. If installed, check that the failsafe warning is heard in the pilot headphone's left earpiece.
4. Turn the unit back on to continue testing.
3.5.3
Transceiver Operational Check
1. Perform a ramp test radio check by exercising the installed transceivers, microphone, microphone
key, and audio over the headphone.
2. Verify that communications are loud and clear and PTT operation is correct.
3.5.4
Intercom System (ICS) Check
NOTE
Stereo headsets are recommended if stereo jacks are installed. Alternatively, the
installation should employ stereo jacks with a mono/stereo switch that disconnects the
audio panel's right channel output from the jack's ring contact when in mono mode. If a
monaural headset is used in a stereo jack, the audio panel's right channel output is
shorted to ground by the mono headset's plug. This causes excess power supply current to
be drawn. While this does not damage the unit's output circuitry, prolonged periods
(especially at high volume) may cause the internal power input fuse to open. This is
because the unit is optimized for low-power operation in systems with limited power
budgets. In the case of copilot/passenger positions wired in parallel, any stereo listener
will lose right channel audio when another passenger plugs in a mono headset.
1. Set the intercom to the ALL mode [Pilot ISO LED off.]
2. Plug in headsets at each ICS position.
NOTE
For helicopter operation using a two-stage Intercom/PTT switch, prior to using the keyedintercom mode, the VOX level should be set by adjusting the VOX knob while the first
detent is actuated and held.
3. Check Pilot and Copilot ICS positions for isolation and proper operation of volume and squelch
controls.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 3-3
3.5.5
Aircraft Receivers Check
1. Select the audio source corresponding to each installed avionics unit and check for audio over the
headsets.
3.5.6
Music System Check
1. Set the intercom to the ALL mode [Pilot ISO LED off.]
2. Connect a stereo audio source to MUSIC 1 (ensure the front panel jack is empty and the music
volume knob is not set to minimum). Verify that stereo audio is heard over all headset positions
when MUSIC 1 is selected as the music source and MUSIC LED is on. Pull out on the right side
small knob and verify that music volume adjustment is working properly.
3. Select an audio source to COM 1 and verify that the sound is muted by active COM 1 audio when
RADIO music mute is selected and by intercom audio when ICS music mute is selected.
4. Connect a stereo music source to MUSIC 2. Verify that stereo audio is heard when MUSIC 2 is
selected as the music source and MUSIC LED is on.
5. Connect a stereo audio source to the front panel jack. Verify that stereo audio is heard when
MUSIC 1 is selected as the music source and MUSIC LED is on.
CAUTION
Be sure to check all aircraft control movements before flight is attempted to
ensure that the wiring harness does not touch any moving part.
This completes the in-aircraft post installation checkout. Perform a flight test after installing the unit to
ensure satisfactory performance of the audio functions.
3.6 Configuration Adjustments
Adjustment to the Volume and Squelch settings can be made to the GMA 240 through access holes in the
unit's top cover. Refer to Section 2.3 for details.
3.7 Continued Airworthiness
Maintenance of the GMA 240 is "on condition" only. Refer to the GMA 240 Maintenance Manual
(Garmin P/N 190-00917-02) as needed. Periodic maintenance of the GMA 240 is not required.
Instructions for Continued Airworthiness (ICA) are not required for this product under 14 CFR Part 21
since the GMA 240 has received no FAA approval or endorsement.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 3-4
4 SYSTEM INTERCONNECTS
4.1 Connector Description
The GMA 240 has two 44-pin connectors located at the rear of the unit designated J2401 and J2402 which
are oriented as shown in Figure 4-1.
J2402
J2401
Figure 4-1 Rear View of Backplate and Rack
4.2 Pin List
Figure 4-2 Rear Connectors J2401 & J2402, Viewed from Back of Unit
J2401 and J2402 pins are configured as shown in Figure 4-2. J2401 and J2402 pin assignments are given
in Table 4-1, Table 4-2, and Appendix B.
Following the pin assignment tables (Table 4-1 & Table 4-2), additional tables group pin connections by
function.
An asterisk (*) following a signal name denotes that the signal is active low logic. Active low inputs are
connected to ground to activate. Active low outputs sink current to ground when active.
4.2.1
J2401 Connector
Table 4-1 J2401 Pin Assignments
Pin
Pin Name
I/O
1
RESERVED
--
2
RESERVED
--
3
TEL AUDIO IN HI
IN
4
TEL AUDIO LO
--
5
TEL MIC AUDIO OUT HI
6
RESERVED
--
7
AUX2 AUDIO IN HI
IN
190-00917-01
Rev. E
OUT
GMA 240 Installation Manual
Page 4-1
Table 4-1 J2401 Pin Assignments
Pin
Pin Name
I/O
8
AUX2 AUDIO IN LO
--
9
COM 1 AUDIO IN HI
IN
10
COM 1 AUDIO LO
--
11
COM 1 MIC AUDIO OUT HI
OUT
12
COM 1 MIC KEY* OUT
OUT
13
COM 2 AUDIO IN HI
IN
14
COM 2 AUDIO LO
--
15
COM 2 MIC AUDIO OUT HI
16
MASQ INHIBIT* IN
IN
17
NAV 1 AUDIO IN HI
IN
18
NAV 1 AUDIO IN LO
--
19
NAV 2 AUDIO IN HI
IN
20
NAV 2 AUDIO IN LO
--
21
AUX1 AUDIO IN HI
IN
22
AUX1 AUDIO IN LO
--
23
RESERVED
--
24
RESERVED
--
25
RESERVED
--
26
RESERVED
--
27
RESERVED
--
28
RESERVED
--
29
CREW ISO* IN
IN
30
COM 2 MIC KEY* OUT
OUT
31
ALERT 1 AUDIO IN HI
IN
32
ALERT 1 AUDIO IN LO
--
33
PILOT MIC AUDIO IN HI
IN
34
PILOT MIC KEY* IN
IN
35
PILOT MIC AUDIO IN LO
--
36
RESERVED
--
37
RESERVED
--
38
RESERVED
--
39
RESERVED
--
40
PASS HEADSET AUDIO OUT LEFT
OUT
41
PASS HEADSET AUDIO OUT RIGHT
OUT
42
PASS HEADSET AUDIO OUT LO
--
43
ALERT 2,3 AUDIO IN LO
--
44
ALERT 2 AUDIO IN HI
IN
OUT
*Denotes Active Low (Inputs: ground to activate; Outputs: grounded when active)
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 4-2
4.2.2
J2402 Connector
Table 4-2 J2402 Pin Assignments
Pin
Pin Name
I/O
1
PILOT HEADSET AUDIO OUT LO
--
2
COPILOT HEADSET AUDIO OUT LO
--
3
COPILOT HEADSET AUDIO OUT LEFT
OUT
4
COPILOT HEADSET AUDIO OUT RIGHT
OUT
5
LIGHTING BUS 14V LO/28V LO
--
6
LIGHTING BUS 14V HI/28V LO
IN
7
LIGHTING BUS 14V HI/28V HI
IN
8
AIRCRAFT POWER
IN
9
AIRCRAFT POWER
IN
10
AIRCRAFT GROUND
--
11
AIRCRAFT GROUND
--
12
RESERVED
--
13
PILOT ISO MUSIC* IN
IN
14
PILOT ISO MUSIC* RETURN
--
15
ALERT 3 AUDIO IN HI
IN
16
PILOT HEADSET AUDIO OUT LEFT
17
RESERVED
--
18
RESERVED
--
19
BUTTON PRESS TONE ENABLE* IN
IN
20
COM SWAP* IN
IN
21
COM SWAP* IN RETURN
--
22
RESERVED
--
23
MUSIC 1 IN LEFT
IN
24
MUSIC 1 IN RIGHT
IN
25
MUSIC 1 IN LO
--
26
MUSIC 2 IN LEFT
IN
27
MUSIC 2 IN RIGHT
IN
28
MUSIC 2 IN LO
--
29
FAILSAFE WARN AUDIO IN HI
IN
30
MUTE ON COM TX* IN
IN
31
PILOT HEADSET AUDIO OUT RIGHT
32
COPILOT MIC AUDIO IN HI
IN
33
COPILOT MIC KEY* IN
IN
34
COPILOT MIC AUDIO IN LO
--
35
PASS 1 MIC AUDIO IN HI
IN
OUT
OUT
*Denotes Active Low (Inputs: ground to activate; Outputs: grounded when active)
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 4-3
Table 4-2 J2402 Pin Assignments
Pin
Pin Name
I/O
36
PASS 1 MIC AUDIO IN LO
--
37
PASS 2 MIC AUDIO IN HI
IN
38
PASS 2 MIC AUDIO IN LO
--
39
RESERVED
--
40
RESERVED
--
41
RESERVED
--
42
RESERVED
--
43
RESERVED
--
44
RESERVED
--
* Denotes Active Low (Inputs: ground to activate; Outputs: grounded when active)
4.2.3
J2403 Connector (front panel 2.5 mm mini-jack)
Figure 4-3 2.5 mm Plug Used with J2403
Table 4-3 J2403 Connector
Pin
Pin Name
TIP
RING
SLEEVE
I/O
MUSIC 1 LEFT IN/TEL MIC OUT HI
I/O
MUSIC 1 RIGHT IN/TEL AUDIO IN HI
IN
MUSIC 1 LO IN/TEL AUDIO LO
--
4.3 Aircraft Power and Lighting
4.3.1
Aircraft Power
The GMA 240 has four inputs for aircraft power bus inputs of 14/28Vdc.
Table 4-4 Aircraft Power
Pin
Connector
8
J2402
AIRCRAFT POWER
IN
9
J2402
AIRCRAFT POWER
IN
10
J2402
POWER GROUND
--
11
J2402
POWER GROUND
--
190-00917-01
Rev. E
Pin Name
I/O
GMA 240 Installation Manual
Page 4-4
4.3.2
Lighting Bus
The GMA 240 photocell controls the brightness of the LEDs (annunciators) that show selection of
functions (e.g. rectangular LEDs in the buttons).
The external lighting bus (if used) input on pins 5, 6, & 7 (P2402), should be connected as shown in
Figure B-1 (page 3 of 3) to control the brightness of the text on the buttons (e.g. “COM1”) and the text in
the background of the button fields (e.g. “MUTE MUSIC”). The lighting bus must be capable of
supplying 160 mA at 14 V or 100 mA at 28 V to provide backlight power to these pins at full brightness. If
pins 5, 6, & 7 are not connected, the text labeling will not be backlit.
Table 4-5 Lighting Bus
Pin
Connector
Pin Name
I/O
5
J2402
LIGHTING BUS 14V LO/28V LO
--
6
J2402
LIGHTING BUS 14V HI/28V LO
IN
7
J2402
LIGHTING BUS 14V HI/28V HI
IN
4.4 Configuration Pins
4.4.1
External Configuration Pins
The following pins may be used to change the configuration of the installation as described.
Table 4-6 External Configuration Pins
Pin
16
Connector
J2401
Pin Name
Description
MASQ
INHIBIT* IN
Ground to disable Master Avionics Squelch circuitry. This will
cause alerts and selected radios to be heard at all times
without needing to exceed the mute threshold. This causes
an increase in background noise from the inputs during quiet
output.
29
J2401
CREW ISO*
IN
Ground to configure the unit for CREW ICS isolation. In this
configuration, the copilot headset jack should be wired in
parallel with the pilot headset output. The mics are wired as
normal. In this mode, when the PILOT ISO button is selected,
the pilot and copilot will hear each other, but will be intercom
isolated from the passengers.
13
J2402
PILOT ISO
MUSIC* IN
Ground to allow Music audio to be heard by the pilot during
pilot isolate mode.
19
J2402
BUTTON
PRESS
TONE
ENABLE* IN
Ground to enable beep tone annunciation of button presses
30
J2402
MUTE ON
COM TX* IN
Ground to enable muting of other selected radios during mic
selected COM transmission (mic-selected COM is still heard,
but not other selected radios)
*Denotes Active Low (Ground to activate)
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 4-5
4.5 Audio Inputs/Outputs and Mic Keys
4.5.1
Mic Audio Inputs and Mic Keys
Table 4-7 Mic Audio Inputs and Mic Keys
Pin
Connector
Pin Name
34
J2401
PILOT MIC KEY* IN
33
J2402
COPILOT MIC KEY* IN
33
J2401
PILOT MIC AUDIO IN HI
35
J2401
PILOT MIC IN LO
32
J2402
COPILOT MIC AUDIO IN HI
34
J2402
COPILOT MIC IN LO
35
J2402
PASS 1 MIC AUDIO IN HI
36
J2402
PASS 1 MIC AUDIO IN LO
37
J2402
PASS 2 MIC AUDIO IN HI
38
J2402
PASS 2 MIC AUDIO IN LO
Description
I/O
Enables respective MIC audio into
the selected transceiver unit
IN
Pilot Mic audio input and ground
reference
IN
Copilot Mic audio input and ground
reference
IN
Passenger 1 Mic audio and ground
reference
IN
Passenger 2 Mic audio and ground
reference
IN
IN
--
--
--
--
*Denotes Active Low (Ground to activate)
4.5.2
Intercom Key Inputs (if configured)
These inputs only perform the described ICS KEY function if the audio panel has been configured for
KEYED ICS by configuration jumper settings (Section 2.3.1). For this configuration, intercom squelch
levels should be set fully CCW (live MIC) because the MIC signal must also break the VOX threshold to
be heard.
Table 4-8 Intercom Key Inputs
Pin
Connector
Pin Name
17
J2402
PILOT ICS KEY* IN
36
J2401
COPILOT ICS KEY* IN
37
J2401
PASSENGER ICS KEY* IN
Description
Enables respective mic audio to be heard in the
intercom
*Denotes Active Low (Ground to activate)
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 4-6
4.5.3
COM Audio and Mic Keys
Table 4-9 COM Audio and Mic Keys
Pin
Connector
Pin Name
Description
I/O
12
J2401
COM 1 MIC KEY* OUT
30
J2401
COM 2 MIC KEY* OUT
Enables transmission on the
respective transceiver unit
9
J2401
COM 1 AUDIO IN HI
COM 1 Audio Input
11
J2401
COM 1 MIC AUDIO OUT HI
COM 1 Audio Output
10
J2401
COM 1 AUDIO LO
Ground Reference for COM 1
--
13
J2401
COM 2 AUDIO IN HI
COM 2 Audio Input
IN
15
J2401
COM 2 MIC AUDIO OUT HI
COM 2 Audio Output
14
J2401
COM 2 AUDIO LO
Ground Reference for COM 2
OUT
OUT
IN
OUT
OUT
--
*Denotes Active Low (Sinks current to ground when active)
4.5.4
Alert Audio I/O
Table 4-10 Alert Audio I/O
Pin
Connector
31
J2401
ALERT 1 AUDIO IN HI
Alert 1 Audio Input
IN
32
J2401
ALERT 1 AUDIO IN LO
Ground Reference for Alert 1
--
44
J2401
ALERT 2 AUDIO IN HI
Alert 2 Audio Input
IN
15
J2402
ALERT 3 AUDIO IN HI
Alert 3 Audio Input
IN
43
J2401
ALERT 2,3 AUDIO IN LO
Ground Reference for Alert 2 & 3
--
4.5.5
Pin Name
Description
I/O
AUX and NAV Audio Inputs
Table 4-11 AUX and NAV Audio Inputs
Pin
Connector
21
J2401
AUX1 AUDIO IN HI
AUX1 Audio Input
IN
22
J2401
AUX1 AUDIO IN LO
Ground Reference for AUX1 Input
--
7
J2401
AUX2 AUDIO IN HI
AUX2 Audio Input
IN
8
J2401
AUX2 AUDIO IN LO
Ground Reference for AUX2 Input
--
17
J2401
NAV 1 AUDIO IN HI
NAV 1 Audio Input
IN
18
J2401
NAV 1 AUDIO IN LO
NAV 1 Ground Reference
--
19
J2401
NAV 2 AUDIO IN HI
NAV 2 Audio Input
IN
20
J2401
NAV 2 AUDIO IN LO
NAV 2 Ground Reference
--
190-00917-01
Rev. E
Pin Name
Description
I/O
GMA 240 Installation Manual
Page 4-7
4.5.6
Failsafe Warning Audio
Table 4-12 Failsafe Warning Audio
Pin
Connector
29
J2402
4.5.7
Pin Name
FAILSAFE WARN AUDIO IN HI
Description
Failsafe Warning Audio Input
I/O
IN
Music Inputs
Table 4-13 Music Inputs
Pin
Connector
23
J2402
MUSIC 1 IN LEFT
24
J2402
MUSIC 1 IN RIGHT
25
J2402
MUSIC 1 IN LO
Ground Reference for Music 1
--
26
J2402
MUSIC 2 IN LEFT
Music 2 Input
IN
27
J2402
MUSIC 2 IN RIGHT
28
J2402
MUSIC 2 IN LO
4.5.8
Pin Name
Description
Music 1 Input
I/O
IN
IN
IN
Ground Reference for Music 2
--
Tel Audio I/O
Table 4-14 Tel Audio I/O
Pin
Connector
3
J2401
TEL AUDIO IN HI
Telephone Audio Input
IN
4
J2401
TEL AUDIO LO
Ground Reference for Telephone
--
5
J2401
TEL MIC AUDIO OUT HI
TEL MIC Audio Output
190-00917-01
Rev. E
Pin Name
Description
I/O
OUT
GMA 240 Installation Manual
Page 4-8
4.5.9
Headset Outputs
Table 4-15 Headset Outputs
Pin
Connector
Pin Name
Description
16
J2402
PILOT HEADSET AUDIO
OUT LEFT
31
J2402
PILOT HEADSET AUDIO
OUT RIGHT
OUT
1
J2402
PILOT HEADSET AUDIO
OUT LO
--
3
J2402
COPILOT HEADSET AUDIO
OUT LEFT
4
J2402
COPILOT HEADSET AUDIO
OUT RIGHT
OUT
2
J2402
COPILOT HEADSET AUDIO
OUT LO
--
40
J2401
PASS HEADSET AUDIO
OUT LEFT
41
J2401
PASS HEADSET AUDIO
OUT RIGHT
OUT
42
J2401
PASS HEADSET AUDIO
OUT LO
--
Pilot Headset Audio Output
Copilot Headset Audio Output
Passenger Headset Audio Output
I/O
OUT
OUT
OUT
NOTE
Copilot and Passenger headset outputs are internally the same connection. Separate
Passenger headset output pins are provided for wiring convenience and GMA 340 pin
compatibility.
NOTE
For CREW ISO configuration, the copilot's headphone jack should be wired in parallel
with the pilot jack to the Pilot headset output pins. Passengers may be connected to either
the copilot or passenger pins.
190-00917-01
Rev. E
GMA 240 Installation Manual
Page 4-9
NOTE
Using a mono headset with an audio jack wired for stereo may damage the GMA 240.
Installations using only mono headsets may use a stereo audio jack and leave the ring
contact unconnected or install a switch as shown in Figure 4-4. Also note that many
stereo headsets have a mono/stereo switch to be compatible with mono or stereo-wired
jacks.
TIP
HEADSET LEFT OUTPUT
MONO
RING
HEADSET RIGHT OUTPUT
STEREO
SLEEVE
HEADSET LO OUTPUT
Figure 4-4 Audio Jack Wiring
4.5.10 COM Swap
Table 4-16 COM Swap
Pin
Connector
20
J2402
COM SWAP* IN
Ground Through a Momentary PB
Switch to Swap Active COM (COM 1
or COM 2)
IN
21
J2402
COM SWAP RETURN
Return Path for PB Switch
--
190-00917-01
Rev. E
Pin Name
Description
I/O
GMA 240 Installation Manual
Page 4-10
APPENDIX A Outline and Installation Drawings
P2401
P2402
Figure A-1 GMA 240 Outline Drawing
190-00917-01
Revision E
GMA 240 Installation Manual
Page A-1
APPENDIX A Outline and Installation Drawings
P2401
P2402
Figure A-2 GMA 240 Connector/Rack Assembly Drawing
190-00917-01
Revision E
GMA 240 Installation Manual
Page A-2
APPENDIX A Outline and Installation Drawings
Figure A-3 GMA 240 Recommended Panel Cutout Dimensions
190-00917-01
Revision E
GMA 240 Installation Manual
Page A-3
APPENDIX B Interconnect Drawings
Figure B-1 GMA 240 Interconnect Drawing (page 1 of 3)
190-00917-01
Revision E
GMA 240 Installation Manual
Page B-1
PLUGGING A MONAURAL HEADSET INTO A STEREO JACK SHORTS THE RIGHT CHANNEL OUTPUT TO GROUND. THIS CAUSES EXCESS CURRENT TO BE DRAWN AND MAY DAMAGE
THE GMA 240. STEREO HEADSETS ARE RECOMMENDED IF STEREO JACKS ARE INSTALLED. INSTALLATIONS USING ONLY MONO HEADSETS MAY USE A STEREO AUDIO JACK AND
LEAVE THE RING CONTACT UNCONNECTED OR INSTALL A SWITCH AS SHOWN BELOW. ALSO NOTE THAT MANY STEREO HEADSETS HAVE A MONO/STEREO SWITCH TO BE
COMPATIBLE WITH MONO OR STEREO-WIRED JACKS.
APPENDIX B Interconnect Drawings
Figure B-1 GMA 240 Interconnect Drawing (page 2 of 3)
190-00917-01
Revision E
GMA 240 Installation Manual
Page B-2
APPENDIX B Interconnect Drawings
10. THE PHOTOCELL CONTROLS THE BRIGHTNESS OF THE LEDs (ANNUNCIATORS) THAT SHOW SELECTION OF FUNCTIONS
(e.g. LEDs IN BUTTONS). THE EXTERNAL LIGHTING BUS INPUTS ON PINS 5, 6, & 7 (P2402) MUST BE CONNECTED TO CONTROL
THE BRIGHTNESS OF THE TEXT LABELING ON THE BUTTON FIELDS (e.g. “MUTE MUSIC”). A LIGHTING BUS MUST BE
CAPABLE OF SUPPLYING 160 mA AT 14 V OR 100 mA AT 28 V IF USED TO PROVIDE BACKLIGHT POWER FOR THESE PINS.
IF PINS 5, 6, & 7 ARE NOT CONNECTED, THE TEXT LABELING WILL NOT BE BACKLIT.
Figure B-1 GMA 240 Interconnect Drawing (page 3 of 3)
190-00917-01
Revision E
GMA 240 Installation Manual
Page B-3
APPENDIX B Interconnect Drawings
GMA240 J2401
14
15
13
11
12
COM 2 MIC COM 2 AUDIO COM 2 AUDIO
LO
IN HI
AUDIO OUT HI
COM 1 MIC COM 1 AUDIO COM 1 AUDIO
AUDIO OUT HI
LO
IN HI
COM 1 MIC
KEY* OUT
8
7
6
AUX2 AUDIO
IN LO
AUX2 AUDIO
IN HI
RESERVED
9
10
5
4
2
1
RESERVED
RESERVED
3
TEL MIC
TEL AUDIO LO TEL AUDIO IN
AUDIO OUT HI
HI
30
29
28
27
26
25
24
23
22
21
20
19
COM 2 MIC
KEY* OUT
CREW ISO* IN
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
AUX1 AUDIO
IN LO
AUX1 AUDIO
IN HI
NAV 2 AUDIO
IN LO
NAV 2 AUDIO
IN HI
18
16
17
NAV 1 AUDIO NAV 1 AUDIO
IN LO
IN HI
MASQ
INHIBIT* IN
44
43
42
41
40
39
38
37
36
35
34
33
32
31
ALERT 2
AUDIO IN HI
ALERT 2,3
AUDIO IN LO
PASS
HEADSET
AUDIO OUT
LO
PASS
HEADSET
AUDIO OUT
RIGHT
PASS
HEADSET
AUDIO OUT
LEFT
RESERVED
RESERVED
RESERVED
RESERVED
PILOT MIC
AUDIO IN LO
PILOT MIC
KEY* IN
PILOT MIC
AUDIO IN HI
ALERT 1
AUDIO IN LO
ALERT 1
AUDIO IN HI
6
LIGHTING
BUS 14V
HI/28V LO
5
LIGHTING
BUS 14V
LO/28V LO
2
COPILOT
HEADSET
AUDIO OUT
LO
1
PILOT
HEADSET
AUDIO OUT
LO
GMA240 J2402
14
PILOT ISO
MUSIC*
RETURN
15
ALERT 3
AUDIO IN HI
13
PILOT ISO
MUSIC* IN
29
30
MUTE* ON
COM TX IN
11
AIRCRAFT
GROUND
12
RESERVED
7
LIGHTING
BUS 14V
HI/28V HI
8
AIRCRAFT
POWER
9
AIRCRAFT
POWER
4
COPILOT
HEADSET
AUDIO OUT
RIGHT
3
COPILOT
HEADSET
AUDIO OUT
LEFT
27
26
25
24
23
22
21
20
19
18
MUSIC 2 IN
RIGHT
MUSIC 2 IN
LEFT
MUSIC 1 IN LO
MUSIC 1 IN
RIGHT
MUSIC 1 IN
LEFT
RESERVED
COM SWAP*
IN RETURN
COM SWAP*
IN
BUTTON
PRESS TONE
ENABLE* IN
RESERVED
28
MUSIC 2 IN LO
FAILSAFE
WARN AUDIO
IN HI
10
AIRCRAFT
GROUND
44
43
42
RESERVED
RESERVED
RESERVED
41
RESERVED
40
RESERVED
39
RESERVED
38
PASS 2 MIC
AUDIO IN LO
37
PASS 2 MIC
AUDIO IN HI
36
35
PASS 1 MIC
AUDIO IN LO
PASS 1 MIC
AUDIO IN HI
34
33
16
17
PILOT
HEADSET
AUDIO OUT
LEFT
RESERVED
32
COPILOT MIC COPILOT MIC COPILOT MIC
KEY* IN
AUDIO IN LO
AUDIO IN HI
31
PILOT
HEADSET
AUDIO OUT
RIGHT
Figure B-2 GMA 240, J2401 & J2402 Connector Layout Drawing
190-00917-01
Revision E
GMA 240 Installation Manual
Page B-4
APPENDIX C Configuration Jumpers Drawing
Top of Main Board
Bottom of Main Board
Figure C-1 GMA 240 Internal Configuration Jumper Layout Drawing
190-00917-01
Revision E
GMA 240 Installation Manual
Page C-1
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