Car Amp Repairs

[kmanian 5,000+ posts]

its the exact same fet that keeps shorting out?

same set

 

[Timmothy Web 10+ year member]

i would say the driver might be at fault.

 

[2Dcore 10+ year member]

Zach i sent you a pm about 2 amps i need repaired. Haven't got a response? Are you not taking any work now?

 

[zach90z 10+ year member]

Zach i sent you a pm about 2 amps i need repaired. Haven't got a response? Are you not taking any work now?

Yes im not taking anything at the moment im to busy with school.

And to everyone that is sending me pm's I haven't had time to respond. Im very sorry.

 

[envisionelec]

I hate working these mega amps....

That said - there is a good chance that the Curie point of the transformer in question has been affected. This means that the magnetic properties of the transformer have been degraded by excessive heat and that the core must be replaced. What then happens is that the magnetic flux in a push-pull power supply "walks away" from being centered and a DC offset will result. This DC offset saturates the core and causes the FETs to excessively heat - usually just one bank of them - and only past a certain current draw. By the way, this can also be caused by an open rectifier on the secondary side. If you 'scope the transformer's primary, you'll see a huge negative voltage spike that will take out the FETs in short order.

Good luck. You are amazingly brave to have worked on this amp.

 

[Timmothy Web 10+ year member]

yea i know right... i dont touch them.