JBL GTQ240 - Manual (Page 10)

10
8. In Case of Difficulty
Power-on light does not come on
• Head unit not on; turn the head unit on.
• Ground wire is disconnected or defec-
tive; check for continuity with an ohm-
meter between the amplifier’s ground ter-
minal and a known chassis ground point.
• Battery wire is disconnected or defec-
tive; check for approximately
+ 12 volts
between the amplifier’s battery and
ground terminals.
• Blown fuse; check amplifier’s fuses
located on the end panel near the power
connector. If they are blown, replace them
with identical ones. If the new fuses blow
immediately, check all the wiring connec-
tions. If the source of the problem cannot
be determined, consult your JBL dealer.
• Remote-on wire between the head unit
and the amplifiers is disconnected or
defective; check for
+ 12 volts between
amplifier's remote-on input terminal and
the ground wire with the head unit on.
Power light is on, but no sound is heard
from some or all of the speakers
• Incorrect switch settings; make sure that
all switches (mode, input and crossover)
are in their correct positions for your sys-
tem configuration.
• Incorrectly connected or shorted speaker
wires; check for shorts in wiring.
• Defective or disconnected audio cables;
check for continuity and replace if
necessary.
• Incorrect gain adjustment; verify that the
amplifier gain controls are not turned
completely down. If they are, sound out-
put level may be very low and may give
the impression that the system (or part of
the system) is dead.
Power light is on, but no sound is heard
from some or all of the speakers
• Defective head unit or signal processor;
check each component for proper wiring
and operation.
• Defective GTQ amplifier; if there is audio
signal present at the inputs of the amplifi-
er and there is no output, the GTQ amplifi-
er may be defective.
Alternator whine through the audio sys-
tem with the engine running
• Ground loops; follow the wiring sugges-
tions in the section called “Solving Noise
Problems.” Also, verify that the chassis
grounding point you have chosen is true
ground by checking for continuity
between the chassis ground point and
battery ground.
Bass output from speakers too low
• Speaker wired out of phase; check for
proper polarity on all speaker wiring (
+
amp terminal to + speaker terminal and –
amp terminal to – speaker terminal).
Power light is blinking and no sound is
heard
• Incorrectly connected or shorted speaker
wires; check for shorts in wiring.
• Defective GTQ amplifier; if there is no
short on the speaker outputs, the GTQ
amplifier may be broken. Consult your
JBL dealer.
GTQ 360 new 7/17/98 10:44 AM Page 10