JBL Control 23 - TROUBLESHOOTING TABLE; No Output.; Questionable or intermittent output such as crackling.; Constant noise such as buzzing, hissing, or the humming sound.

If none of the suggestions below solve your problem, contact your nearest JBL service center or JBL distributor.
Problem
1 . No Output.
2. Questionable or
intermittent output
such as crackling.
3. Constant noise such as
buzzing, hissing , or
the humming sound.
4. Poor low frequency
output.
Possible
Cause(s)
• Speaker
Cable(s)
• Amplifier
• A poor
connection
• A faulty
electronic
device in the
signal chain
• Poor system
grounding
·Out-of-Polarity
Hookup
between multiple
sp e akers
· - ~- ---
Action
• Replace the cable(s) con n ec t ing the loudspeaker system
and amplifier .
•
Make sure the amplifier channel is being fed an input
signal (preferably via a "signal input" indicator on the
amp).
• Check that the amplifier channel's volume control is
turned up.
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• Connect the speaker and cable which had no output to i
another amplifier channel, making sure an i np ut signal is ---~-
fed to the new amp channel. If you then get output, the l
problem was the amplifier channel. If not , then the ----r---
problem may be in the cable or speaker.
• Check all cabling for proper connector contact since a
bad connection can result in intermittent contact or
dramatically increased resistance which , in turn , can
cause reduced output or noises unrelated to the signal.
• Since loudspeakers cannot generate these sounds by
themselves, you may have a faulty electronic device in
the signal chain.
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• Check and correct the system grounding, as required.
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• When two speakers are hooked up out - of-polarity ("out-
of - phase"), the low frequenc i es cancel each other out. _
Try reversing the polarity of one of the speakers either
by turning around a dual - banana plug at the am plifier or
i
---
by reversing the tip/sleeve leads on the jack. Whichever _ ___, __
condition results in greater low-frequency output is the
. ! ' in-po , larity oonaition. - . ;
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