____________________________________________________________________
Page 5-60
Cirrus Perspective™ Line Maintenance Manual
Rev. E
190-00920-00
5.7
GMA
347
RELATED
ALERTS
AND
PROBLEMS
5.7.1
Common
Problems
Symptom
Recommended
Action
Noise
in
Audio
Most
often
the
cause
of
the
noise
is
external
to
the
GMA
347.
Try
the
following
to
locate
the
source
of
the
noise
before
replacing
the
347:
•
Try
a
different
pair
of
headsets.
Noise
cancelling
headsets
may
pick
up
and/or
generate
more
noise
than
standard
headsets
from
their
own
circuitry.
•
Check
for
noise
with
engine
turned
off.
−
If
the
noise
is
present
only
when
the
engine
is
running,
check
the
generator
and/or
ignition
system
as
possible
sources
of
noise
(see
Cirrus
Maintenance
Manual).
•
Check
for
noise
as
all
electrical
equipment
is
turned
on
and
off
(strobes,
other
radios,
etc.).
−
If
the
noise
is
identified
from
one
electrical
system
or
component
refer
to
the
Cirrus
airframe
maintenance
manual.
•
Make
sure
the
NAV/COM
squelch
is
not
open.
•
Make
sure
the
ADF
and
DME
audio
is
not
active.
•
Make
sure
the
marker
beacon
audio
is
not
active.
•
Make
sure
the
ICS
squelch
is
not
open.
Master
squelch
level
can
be
adjusted
on
the
GMA
CONFIGURATION
page
for
higher
noise
environments.
•
Check
resistors
in
line
with
Music
1
and
Music
2
wiring
at
the
GMA
347
in
accordance
with
system
wiring
diagrams
•
Make
sure
the
Mic
and
Phone
jacks
are
insulated
from
airframe
ground
and
that
Music
1
and
Music
2
jacks
are
not
insulated
from
airframe
ground
in
console.
•
Replace
unit
only
after
all
possible
external
sources
of
noise
are
eliminated.
Buttons
Do
Not
Work.
•
Some
buttons
are
disabled
in
the
GMA
CONFIGURATION
page
by
default.
This
is
to
remove
potential
sources
of
audio
noise
for
inputs
that
are
not
used.
If
in
doubt
as
to
which
buttons
should
be
disabled,
reload
GMA
config
files
and
other
config
files
for
optional
equipment
installed
in
the
aircraft
(ADF,
DME)
from
the
SD
loader
card.
Summary of Contents for Cirrus Perspective SR20
Page 2: ......
