Read JBL L8400P (serv.man12) Service Manual online
TROUBLESHOOTING
If you used the high-level
(speaker) inputs and there
is no sound from any of the
speakers:
(speaker) inputs and there
is no sound from any of the
speakers:
• Check that the receiver/
amplifier is on and a source
is playing.
amplifier is on and a source
is playing.
• Check that the powered
subwoofer is plugged into
an active electrical outlet
and is switched on.
subwoofer is plugged into
an active electrical outlet
and is switched on.
• Check all wires and connec-
tions between the receiver/
amplifier and the speakers.
Make sure all wires are con-
nected. Make sure none of
the speaker wires are frayed,
cut or punctured, or touching
each other.
tions between the receiver/
amplifier and the speakers.
Make sure all wires are con-
nected. Make sure none of
the speaker wires are frayed,
cut or punctured, or touching
each other.
• Review proper operation
of your receiver/amplifier.
of your receiver/amplifier.
If there is low (or no) bass
output:
output:
• Make sure the connections
to the left and right “Speaker
Inputs” have the correct
polarity (+ and –).
to the left and right “Speaker
Inputs” have the correct
polarity (+ and –).
• Make sure that the sub-
woofer is plugged into an
active electrical outlet and
switched on.
woofer is plugged into an
active electrical outlet and
switched on.
• Adjust the crossover point.
• Flip the Phase Control switch
to the opposite position.
to the opposite position.
• If you are using a Dolby
Digital/DTS receiver or
processor, make sure that the
subwoofer and bass manage-
ment adjustments on the
receiver/processor are set up
correctly.
Digital/DTS receiver or
processor, make sure that the
subwoofer and bass manage-
ment adjustments on the
receiver/processor are set up
correctly.
• Slowly turn the Level Control
clockwise until you begin to
hear the desired amount of
bass.
clockwise until you begin to
hear the desired amount of
bass.
If you used the line-level
inputs and there is no sound
from the subwoofer:
inputs and there is no sound
from the subwoofer:
• Check that the receiver/
amplifier is on and a source is
playing.
amplifier is on and a source is
playing.
• Check that the powered
subwoofer is plugged into an
active electrical outlet and is
switched on.
subwoofer is plugged into an
active electrical outlet and is
switched on.
• Check all wires and
connections between the
receiver/amplifier and the
subwoofer. Make sure all
wires are connected. Make
sure none of the wires are
frayed, cut or punctured, or
touching each other.
connections between the
receiver/amplifier and the
subwoofer. Make sure all
wires are connected. Make
sure none of the wires are
frayed, cut or punctured, or
touching each other.
• Review proper operation of
your receiver/amplifier.
your receiver/amplifier.
• Slowly turn the Level
Control clockwise until you
begin to hear the desired
amount of bass.
Control clockwise until you
begin to hear the desired
amount of bass.
• Make sure that you have
configured your receiver/
processor so that the sub-
woofer/LFE output is on.
configured your receiver/
processor so that the sub-
woofer/LFE output is on.
Phase Control
The Phase Control
§ deter-
mines whether the sub-
woofer’s pistonlike action
moves in and out in phase
with the main speakers or
opposite the main speakers.
There is no correct or incor-
rect setting. Proper phase
adjustment depends on sev-
eral variables such as sub-
woofer placement and lis-
tener position. Adjust the
woofer’s pistonlike action
moves in and out in phase
with the main speakers or
opposite the main speakers.
There is no correct or incor-
rect setting. Proper phase
adjustment depends on sev-
eral variables such as sub-
woofer placement and lis-
tener position. Adjust the
Phase switch to maximize
bass output at the listening
position.
bass output at the listening
position.
Remember, every system,
room and listener is different.
There are no right or wrong
settings; this switch offers the
added flexibility to adjust your
subwoofer for optimum per-
formance for your specific
listening conditions without
room and listener is different.
There are no right or wrong
settings; this switch offers the
added flexibility to adjust your
subwoofer for optimum per-
formance for your specific
listening conditions without
having to move your speakers.
If at some time in the future
you happen to rearrange your
listening room and move your
speakers, you should experi-
ment with the Phase switch in
both positions, and leave it in
the position that maximizes
bass performance.
If at some time in the future
you happen to rearrange your
listening room and move your
speakers, you should experi-
ment with the Phase switch in
both positions, and leave it in
the position that maximizes
bass performance.
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L8400P OM 6/8/05 4:10 PM Page 9
L8400P
L
series
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