Repaired Kx1200.1 Cutting Out At High Volume?

[rusty959]

Anyways, quick background, I have a kicker kx1200.1. which fried when my hatch unexpectedly leaked on it. I got it apart, seemed like only two fets blew, so I got the parts I needed and replaced them. I matched them as far as I know I had the ability to, and replaced that entire bank of 4.

I installed it again, with a single 4 ohm 12" so 300 watts rms, and it seemed to work fine, except it would occasionally cut out after higher volumes, especially over a couple minutes. Though my electrical isn't perfect, I know it wasn't dropping low enough to kill it that way when I measured it, (11's I believe) and besides, I had for a time had 2 12's in there so double the power, and it was fine before it fried. After a few days, it began working fine, just as it had previously. Then, I took the sub out and put it in a new box over the time of a couple days. Since I have put it back in, I am now having the same problem again, just slightly worse. Now if it cuts out, it likely won't turn back on until a few hours of sitting. I have waited a couple weeks to see if it would fix itself as it did before, and though it seems slightly better, it still is cutting out.

So Ive opened it up again, and checked all the fets etc, and everything looks good visually. Before I break out the multimeter and begin checking every single component, any suggestions on what it could be? Ive looked around on bcae1.com's repair section etc, but can't really find anything leading toward what it could be.

Any help is greatly appreciated.

[rusty959]

I guess ill just start testing everything I can find out how to test then...

[Boon]

Probably bad gate resistors in the power section, which have now (likely) damaged the FETs.

It's the little resistor, usually on the left leg of the FET. They're often fireproof so don't show damage when they're bad.

Really you need to remove all the FETs to check the resistances but if you do that you may as well replace them all.

Also inspect the power drive section but if you don't have an oscilloscope that could be hard.

[rusty959]

Thanks for the help boon.

So started again checking everything I could without completely taking the fets off again (as little as that might be) and got the idea to put the thing in the car one more time to do some testing to see what was really happening with the voltage etc. Turns out when it was cutting out, the voltage at the amp was going down to about 2 volts. This intrigued me as I didn't see that happen the other times it had cut out, or so I thought I guess. Anyways, realizing my fuse wasnt blowing, which it should if something was shorting out in the amp enough to drop it down to 2 volts (and it is a 25 amp fuse) there was a problem in my wiring somewhere. Anyways, in the end, I figured out there was a problem in a fuse holder I had bypassed in the 8 gauge wiring that was in the car due to the fact I had put a better fuse holder in. kinda pisses me off that it was something so simple all along that I thought was fine and dandy, but atleast it wasn't a problem in the amp and it is fixxed now.

Once again thanks for all the help boon, im happy to report that it now seems like the amp was well repaired, as it did quite well on my 4 hour trip I just took.

[Boon]

Once again thanks for all the help boon, im happy to report that it now seems like the amp was well repaired, as it did quite well on my 4 hour trip I just took.

Good to hear it

Sounds like they use pretty solid gate resistors and drive components then Most amps, if you pop the power supply FETs all the little related bits smoke as well...

[rusty959]

Yea, guess so. Remember it was blown due to water... so I don't know if that would cause any difference on what all would blow. On the other hand, Ive only had it hooked up at 4 ohms. The true test on whether it is all matched and stuff and good to go will be when I get it down to 1 I guess.