JL Audio 500/5

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RockfordFIx

Member
2012-12-03 11:56 am
I have a JL Audio that has came in for repair. The sub channel plays clean audio but the rear speaker are distorted and front speaker have no audio. With panel removed I see 4 driver boards. The 2 front boards have additional LEDS lit. There are no visible burn marks and amp is not in shutdown. Do these LEDS not being indicate driver board fault.
 

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Perry Babin

Member
Paid Member
2003-11-20 11:01 am
Louisiana
www.bcae1.com
Yes. It's likely the most common problem that don't involve blown outputs. You can see the crack that develops in the attached image.

There are other problems but this is the first thing to do.

If you don't desolder be fore resoldering, the problem will often reoccur because the oxide layer isn't completely removed.

If you have ChipQuik, use it to remove the driver boards if you remove them to do the work.
 

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RockfordFIx

Member
2012-12-03 11:56 am
I removed the resistors one driver board resistors pads were coming off, so I installed some 1/4 watt resistors. The driver board to the left was okay I cleaned the pad and reinstalled them. When I powered the amp up all 4 driver boards were on and then the right back board started flickering
 

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RockfordFIx

Member
2012-12-03 11:56 am
Yes the driver board is working correctly now. I did however short the outputs one channel. It over heated checking signal with no load and FETs weren’t clamped. I just repacked them and bias those outputs. During disassemble 2 of the FET clamps broke at the bend. I am assuming because it was 5c in my garage during disassemble. Do you know when I can flirt these at?
 
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