Rockford Fosgate PUNCH 4020 DSM - Manual (Page 23)

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Engine Noise on
the Speaker Out-
puts of the Ampli-
fier Disconnect existing speak-
ers and test with known
working speakers. If engine
noise is gone, check and
repair wiring and installa-
tion of speakers as neces-
sary.
Check connections, substi-
tute with known working
cables and repair or replace
as necessary.
Run the RCA cable on a
different route.
Disconnect antenna from
the source unit. If engine
noise is gone, check, and
repair wiring and installa-
tion or use an antenna
ground loop isolator.
Bypass all other equipment
(crossovers and equalizers)
by connecting the head unit
directly to the amp. If noise
is gone, reconnect equip-
ment one piece at a time
and test for noise after each
install.
Symptom Diagnosis Remedy
Speaker leads are
shorted to each other or
to the chassis of the ve-
hicle.
RCA input from source
unit is not connected or
not functioning prop-
erly.
RCA cable is picking up
radiated noise.
Ground loop in antenna
line.
Multiple grounding
paths in the signal chain.
• If noise persists, see your Authorized Rockford Fosgate Dealer.