JBL GTO-1001EZ, GTO-501EZ, GTO-751EZ owner manual Troubleshooting, Problem Causes and solutions

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Troubleshooting

If your amplifier isn’t performing the way you think it should, check to see if the problem is covered in this section before calling your dealer or contacting JBL customer service.

Problem	Causes and solutions
No sound (the amplifier’s	• Check that the amplifier’s +12V and GND connections have been properly
Power/ Protection LED is off):	made.
	• Check if the fuse on the +12V wire located near the battery is blown; if so,
	replace it with an identical fuse.
	• Check all amplifier fuses; if any are blown, replace them with identical fuses.
	• If you are using the amplifier’s REM connection for turn-on, check that the
	wire is properly connected to the audio system’s remote turn-on wire or to the
	vehicle’s ACC power terminal.
	• If you are using the amplifier’s Auto Turn-On circuit for turn-on, check that the
	amplifier’s Auto Turn-On switch (on the amplifier’s bottom panel) is set in the
	“On” position.
No sound (the amplifier’s	• Check that all amplifier input and speaker connections have been properly
Power/ Protection LED is	made.
orange):	• Check that the amplifier’s Gain control is not turned all the way down.
	• Check that the vehicle audio system’s source unit’s volume control is not
	turned all the way down.
	• If you have connected an optional Remote Bass Control (sold separately)
	to the amplifier, check that it is not turned all the way down (fully
	counterclockwise).
No sound (the amplifier’s	• Confirm that the vehicle’s electrical system is supplying between 9V and 16V
Power/ Protection LED is red):	DC to the amplifier. If the supply voltage is outside of this range, correct the
	condition before attempting to use the amplifier.
	• If the amplifier has overheated, wait until it has cooled down before attempting
	to use it again.
	• Disconnect all speakers from the amplifier and attempt to turn it on again:
	– If the amplifier turns on (the Power/Protect LED is orange), there is a short
	circuit in one or more of the speaker wires. Correct all short circuits before
	reconnecting the speakers to the amplifier.
	– If the amplifier does not turn on (the Power/Protect LED is still red), contact
	your authorized JBL dealer for assistance.
	• If the optional Sub Channel Level control is connected to the amplifier, check
	that it is not turned all the way down (fully counterclockwise).
Sound is too quiet, even with the	• Check the amplifier’s Input Level switch. If it is set to “Hi1,” turn the amplifier’s
vehicle audio system’s head unit	Gain controls all the way down and re-set the Input Level switch to “Low.”
volume turned all the way up:	Then perform the Set the Gain procedure, on page 7, again.
Sound in the subwoofer is	• If the Input Level switch is set in the “Low” position, change the setting to “Hi1”
distorted:	and perform the Set the Gain procedure, on page 7, again for those channels.
	• While listening to bass-heavy music, turn the Bass Boost control all the way
	down, and then gradually increase it until the distortion begins to return.
	Reduce the Bass Boost control setting slightly to eliminate the distortion and
	leave it set there.
	• Check that the distortion is not originating from the vehicle audio system’s
	source unit.
The amplifier’s Gain LEDs	• Set the amplifier’s Gain LEDs switch in the “Off” position.
constantly illuminate red while
the amplifier is operating:

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