First try at repairing an amp.

[goose5741 10+ year member]

So I'm trying to repair an amp for the first time. Its and older Lanzar 1200rms@1ohm amp, thats all i know about it, don't know model or anything. It broke a few years ago, still worked but started blowing fuses (30 amp ones on the amp itself) whenever it tried to draw any significant amount of power, gains were set properly with a DMM (well I guess thats not neccesarily properly, who knows if it clipped or not at the 1200wrms i had it set for, never scoped it).

Anyways, i opened it up today, nothing is visibly burnt. And the only thing out of the ordinary was that 3 of the power MOSFETs clearly had been replaced and are not identical to the rest of them. Need to check data sheets if i can still read a part # off of them to see if they are equivalent to the rest, but i'm guessing they are in some form becuase the amped worked perfect the first 6 months i had it.

Any ideas where to start? or what could be wrong with it?

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[goose5741 10+ year member]

Nevermind on the FET's being different, I was wrong, those are diodes that are supposed to be there, the TO-220 package tricked me into assuming that all of those were supposed to be FETs

 

[MakeshiftAudio 10+ year member]

A word of advice. These things can be lethal. Be sure to discharge the SMPS filter capacitors every time before you grab the board or components.

Good luck.

 

[goose5741 10+ year member]

A word of advice. These things can be lethal. Be sure to discharge the SMPS filter capacitors every time before you grab the board or components.
Good luck.

How do you do that?

 

[dumple 5,000+ posts]

if you dont know u shouldnt be fuxin with it

 

[Grinder1989 5,000+ posts]

Indeed. You are way too inexperienced. You need to learn from someone. I got shocked by a Memphis 4kw (while checking for a hot part) because I wasn't paying attention. Lucky for me, the amp was not running, but it still shocked me and it hurt bad. You need to send that amp to someone who works one them instead of playing around with something that will either hurt you, or blow up after you think you've fixed it.

 

[midnightg35x 10+ year member]

How do you do that?

Easy way is to hook up a ground, and put a voltage on the remote turn on lead (NOTHING ON THE +12V LEAD!). Let it sit for a couple seconds, and you should be fine. Use a DMM to check for voltage between the +12V line and GND. Once the voltage is below 2-3V, you should be fine.

 

[Mass Car Audio 10+ year member]

Easy way is to hook up a ground, and put a voltage on the remote turn on lead (NOTHING ON THE +12V LEAD!). Let it sit for a couple seconds, and you should be fine. Use a DMM to check for voltage between the +12V line and GND. Once the voltage is below 2-3V, you should be fine.

x2, that's exactly what I do.