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Page 2-2 GMA 240 Installation Manual
Rev. A 190-00917-01
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 0 Ω 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.
The GMA 240 contains static sensitive components. Observe proper anti-static
procedures when performing any solder procedures on the unit.
Component Name Default Description
R0303 Alert Mutes
Music
Populated If this jumper is removed, music will not be
interrupted by alert audio. Default operation
is recommended.
R0304 COM1 Internal
Sidetone
Empty
R0305 COM2 Internal
Sidetone
Empty
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.
R0308 TEL Internal
Sidetone
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.
R0315 TEL jack detect
bypass
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.