JL Audio 1000/1 Amplifier Low-Pass Filter Problem

[SQ ABSOLUTE]

The mode/slope switch no longer works in the 12-dB or 24-dB position. In those positions there is no output from the amp. However, when I change the switch position to "off" there is output from the amp. What could be the cause of this? A sticky switch maybe?

I am the original owner. I have had the amplifier in storage for quite some time, and all was well when I had it installed before.

[Perry Babin]

Pull the bottom cover. You'll see that there are several connectors between the main and preamp board. Pull the preamp board up VERY slightly and push it back down. Only pull it up about 1/16". Do this a couple of times for each connector. Does the amp work properly now?

If not, you'll have to check a few other things. Do you have a scope?

[SQ ABSOLUTE]

Thanks for your response, Perry. After posting the above, I went outside and used a can of air and blew air thru a nozzle thru several of the switch positions. Tried the system sometime afterwards and it worked up to last night.

Tried again this morning and the original problem manifested itself. I just came from playing with the switch in several of its positions, off, 12-dB and 24-dB. It worked, then tried several positions again and it stopped working again. Again played with the switch positions several times again and got it to work again. Just came inside to give you a progress report. Amplifier still works in the crossover off position.

In response to your question above yes, I do have an oscilloscope.

[Perry Babin]

Did you try what I suggested?

[SQ ABSOLUTE]

Sorry, no I did not. I was assuming that what I did had mimicked what you suggested above. I guess it was NOT a substitute.

However, I will do as you suggested and report back.

[SQ ABSOLUTE]

Originally Posted by Perry Babin

Did you try what I suggested?

Yes, and the amp works perfectly now on all crossover settings....BUT it did work prior to me removing the bottom cover.

[Perry Babin]

Sometimes, the connectors between the boards get slightly oxidized and moving them as I suggested cleans the contacts.

[SQ ABSOLUTE]

Originally Posted by Perry Babin

Sometimes, the connectors between the boards get slightly oxidized and moving them as I suggested cleans the contacts.

I understand. I am not sure whether I performed the procedure correctly as the very long pre amp board is within a groove on either side of the amplifier and there are two allen screw hold-down screws on the left and right of the preamp board, so I am not sure whether I was able to move the board sufficiently enough to make and break the connector contacts, as the board is held in its place very solidly. (no play in it).

[Perry Babin]

You need to move it no more than 1/16". That should be easy to do without removing the end plates.

[SQ ABSOLUTE]

Then I guess I applied sufficiently enough pressure to the board where the connectgors are located.

I will now take the car out for a test drive to see whether the problem has gone away.