GTQ 190 - English 06/03/98 11:50 Side 13
In Case of DifficultySolving Noise Problems
portables, works well for this. Listen to
see if the noise is present in the signal
Power-on light does not come on
System Noisefrom the source unit. If so, consult the
Y Head unit not on; turn the head unit on.
System noise, generally appearing asmanufacturer of the source unit, or your
Y Ground wire is disconnected or defective;
hiss, is usually the result of improperJBL dealer, for help in reducing this
check for continuity with an ohmmeter
Power light is on, but no sound is heardinput gain (sensitivity) adjustment. Withnoise. If there is no noise in this signal, it
between the amplifierOs ground terminal and
from some or all of the speakersthe proper setting, your JBL amplifier willcan be eliminated as the source of your
a known chassis ground point.
not create this noise, but will amplify any
Y Battery wire is disconnected or defective;Y Defective head unit or signal processor;problems.
noise generated ahead of it as part of the
check for approximately +12 volts betweencheck each component for proper wiring andGround Loops � The vast major-ity of
signal. Refer to OAdjusting the Gain�
noise problems are caused by
the amplifierOs battery and ground terminals.operation.section on page 11 for instructions on
inadequate or improper grounding. The
Y Blown fuse; check amplifierOs fuses locatedY Defective GTQ amplifier; if there is audio
how to minimize this noise.head unit, the amplifier, and any other
on the end panel near the power connector.signal present at the inputs of the amplifier
If they are blown, replace them withand there is no output, the GTQ amplifiercomponents must be grounded to a
identical ones. If the new fuses blowmay be defective.Vehicle Noisemajor metal member of the vehicleOs
Every vehicle has some electrical noiseframe. Make sure to choose a solid metal
immediately, check all the wiringAlternator whine through the audio system
that is generated by the ignition system,ground point, as some new vehicles
connections. If the source of the problemwith the engine running
the alternator, the accessories, and theircontain structural elements made of
cannot be determined, consult your JBL
Y Ground loops; follow the wiring sugges-wiring. High-performance audioplastic.
dealer.
tions in the section called OSolving Noiseequipment is more likely to pick up suchMost often the noise level in the system
Y Remote-on wire between the head unit andProblems.� Also, verify that the chassisnoise than conventional equipmentwill be lower if amplifiers and signal
the amplifier is disconnected or defective;
grounding point you have chosen is true
check for +12 volts between amplifier'sbecause it has wide-frequency bandwidthprocessors that do not have isolated
ground by checking for continuity betweenand high-gain (amplification) circuits.supplies are all grounded to the same
remote-on input terminal and the ground
the chassis ground point and battery ground.GTQ amplifiers have two built-in powerpoint on the chassis. Amplifiers, such as
wire with the head unit on.
Bass output from speakers too lowsupply filters to help prevent noisethe GTQs, which internally isolate the
Power light is on, but no sound is heardproblems. If noise occurs it is probablysignal ground connection from the power
Y Speaker wired out of phase; check for
from some or all of the speakersthe result of improper installation. Theground connection, generally do not
proper polarity on all speaker wiring (+ amp
Y Incorrect switch settings; make sure that allfollowing suggestions will help youbenefit from this. Usually the head unit
terminal to + speaker terminal and � amp
switches (mode, input and crossover) are ineliminate most noise problems.does not need to be grounded to the
terminal to � speaker terminal).
their correct positions for your systemSource Noise � Often noise in a systemsame point as the rest of the system, but
configuration.Power light is blinking and no sound isis picked up by the signal source. Beforein some instances, depending on the
Y Incorrectly connected or shorted speakerheardattempting to eliminate noise from thedesign of the signal processors involved,s Manual
wires; check for shorts in wiring.Y Incorrectly connected or shorted speakeramp, be sure it is not being picked up bygrounding signal processors to the same
Y Defective or disconnected audio cables;wires; check for shorts in wiring.the signal source and then passed on topoint as the head unit will also help. If
check for continuity and replace if necessary.Y Defective GTQ amplifier; if there is no shortother components. To do this, connectthis does not adequately reduce the
Y Incorrect gain adjustment; verify that theon the speaker outputs, the GTQ amplifierthe signal source output to an externalnoise level, try another ground point on
amplifier gain controls are not turnedmay be broken. Consult your JBL dealer.amplifier which has no other connectionthe car frame. Because of current flow
completely down. If they are, sound outputto the vehicle except for the audio signalpatterns within the vehicle chassis, some
level may be very low and may give theIf you want to talk to us about any problems,leads. A battery-powered amplifiedground points are noisier than others. As
impression that the system (or part of thecall JBL Customer Service at 1-800-336-4JBLportable speaker, such as those sold fora general rule, try to keep grounds awayOwnerO
system) is dead.between 9AM and 5PM Eastern time.use with com-puters or Walkman-typefrom the main flow of current between
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ACEC
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