Appendix D: Troubleshooting - JL Audio HD900/5 Owner's Manual

aPPendix d: troublesHooting

"How do i properly set the input sensitivity on my amplifier"
"my amplifier doesn't turn on"
"i get a distorted / attenuated sound coming out of the speaker(s)"
"my amplifier's output fluctuates when i tap on it or hit a bump"
20 | JL Audio - HD900/5 Owner's Manual
Please refer to Appendix C (pages 18, 19) to set the input sensitivity
for maximum, low-distortion output.
Check the fuse(s), not just visually, but with a continuity meter. It
is possible for a fuse to have poor internal connections that
cannot be found by visual inspection. It is best to take the
fuse out of the holder for testing. If no problem is found with
the fuse, inspect the fuse-holder.
Check the integrity of the connections made to each of the
"+12VDC", "Ground", and "Remote" terminals. Ensure
that no wire insulation is pinched by the terminal set screw
and that each connection is tight.
Check to make sure there is +12V at the "Remote" connection of the
amplifier. In some cases, the turn-on lead from the source unit
is insufficient to turn on multiple devices and the use of a relay
is required. To test for this problem, jump the "+12VDC" wire
to the "Remote" terminal to see if the amplifier turns on.
Check the speaker wires for a possible short, either between the
positive and negative leads or between either speaker lead and
the vehicle's chassis ground. If a short is present, you
will experience distorted and/or attenuated output. The
"Status" LED will turn amber (yellow) in this situation. It may
be helpful to disconnect the speaker wires from the amplifier
and use a different set of wires connected to a test speaker.
Check the nominal load impedance to verify that each channel
of the amplifier is driving a load equal to or greater than
1.5 ohms in stereo mode (3 ohms bridged).
Check the input signal and input signal cables to make sure signal
is present at the "Amplifier Inputs" and the cables are not
pinched or loose. It may be helpful to try a different set of
cables and/or a different signal source to be sure.
Reset the amplifier by removing the power plug, then wait ten
seconds and reconnect the power plug.
Check the connections to the amplifier. Make sure that the
insulation for all wires has been stripped back far enough to
allow a good contact area inside the connector plugs.
Check the input connectors to ensure that they all are making good
contact with the input jacks on the amplifier.