SCS 138 TRIO (serv.man3) - JBL Audio User Guide / Operation Manual. Page 7

If there is no sound from 
any of the speakers:
• Check that receiver/amplifier
is on and a source is playing.
• Check all wires and connec-
tions between receiver/ampli-
fier and speakers. Make sure
all wires are connected. Make
sure none of the speaker wires
are frayed, cut or punctured.
• Review proper operation of
your receiver/amplifier.

If there is no sound coming
from one speaker:
• Check the “Balance” control
on your receiver/amplifier.
• Check all wires and connec-
tions between receiver/
amplifier and speakers. Make
sure all wires are connected.
Make sure none of the speaker
wires are frayed, cut or punc-
tured.
• In Dolby* Digital or DTS

®

modes, make sure that the
receiver/processor is config-
ured so that the speaker in
question is enabled.

If there is no sound from the
center speaker:
• Check all wires and connec-
tions between receiver/
amplifier and speaker. Make
sure all wires are connected.
Make sure none of the speaker
wires are frayed, cut or 
punctured.

• If your receiver/processor is
set in Dolby Pro Logic* mode,
make sure the center speaker
is not in phantom mode.
• If your receiver/processor 
is set in Dolby Digital or DTS
mode, make sure the receiver/
processor is con-figured so
that the center speaker is
enabled.

If the system plays at low vol-
umes but shuts off as volume
is increased:
• Check all wires and connec-
tions between receiver/ampli-
fier and speakers. Make sure
all wires are connected. Make
sure none of the speaker wires
are frayed, cut or punctured.
• If more than one pair of main
speakers is being used, check
the minimum impedance
requirements of your receiver/
amplifier.

If there is low (or no) bass 
output:
• Make sure the connections
to the left and right “Speaker
Inputs” have the correct 
polarity (+ and –).
• Consider adding a powered
subwoofer to your system. See
your JBL dealer for further
assistance.
• If you are using a powered
subwoofer, check your owner’s
manual to make sure it is cor-
rectly connected and is being
used according to the manu-
facturer’s instructions.

If there is no sound from the
surround speakers:
• Check all wires and connec-
tions between receiver/ampli-
fier and speakers. Make sure
all wires are connected. Make
sure none of the speaker wires
are frayed, cut or punctured.
• Review proper operation of
your receiver/processor and
its surround-sound features.
• Make sure the movie or TV
show you are watching is
recorded in a surround-sound
mode. If it is not, check to see
if your receiver/processor has
other surround modes you may
use.
• In Dolby Digital or DTS modes,
make sure your receiver/
processor is configured so that
the surround speakers are
enabled.
• Review the operation of your
DVD player and the jacket of
your DVD to make sure that the
DVD features the desired
Dolby Digital or DTS mode, and
that you have properly select-
ed that mode using both the
DVD player’s menu and the
DVD disc’s menu.