Amp Repair ppl..Little help.

[edzy 10+ year member]

Thanks for the response.

I have a link above to the replacement fet.

Also I check the output fets with a dmm and had 12 volts in/out.

So at this point I am just gonna go ahead and get the replacement ones and go from there.

If anyone thinks there is something else that is prone to failure, jump on in.

Thanks.

 

[edzy 10+ year member]

bump?

 

[edzy 10+ year member]

"the gate resistors have to be changed also"

"I'd check the output stage if I was you. Something caused the FETs to fail. Could have just been the PSU, but, an output may have shorted which took out the PSU too."

And these things are located where?

I checked all the other fets and they have 12 volts in/out.

Also that single fet thing on its own? I assume thats some sort of temp thing? It also had 12 volts in/out.

 

[edzy 10+ year member]

so...no more input?

 

[edzy 10+ year member]

"the gate resistors have to be changed also"

"I'd check the output stage if I was you. Something caused the FETs to fail. Could have just been the PSU, but, an output may have shorted which took out the PSU too."

And these things are located where?

last bump.

 

[groundpound4200 5,000+ posts]

I think the gate resistors are located right in fron of the transistors on most boards. test those and make sure they are within spec. The usually burn with the transistor

 

[PioneerSPL1990 10+ year member]

make sure you clean that flux and burnt material out of they way when your done or before power up. I have got a couple amps used that had been sitting, they got in sun or heat, dust built up on the flux and it ran enough to cause a short it sucks.

 

[edzy 10+ year member]

So what are those large single fet things?

Top fest and bottom middle?

Also the PS has 12v on all legs. All the top fets have 12 on each outer leg.

 

[snoopdan 5,000+ posts]

Did you check those large diodes on the power input stage?

 

[edzy 10+ year member]

yep, 12 v on both sides

 

[dB-r 10+ year member]

Meh.

I don't think you should have 12V in so many places as you have indicated... sounds like transformer winding short and / or bad diodes in Power supply (big black ones). I would replace those FETs with IRF3205.

 

[edzy 10+ year member]

What is the benifit over those?

 

[edzy 10+ year member]

So why wouldnt I go with the exact replacement? but the IRF3205?

Ordering now... but the 80NF06

Unless their is reason to go with the other ones..

 

[edzy 10+ year member]

IRF3205-- minumun order 250 //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

went with the originals.

But thanks anyway.

 

[dB-r 10+ year member]

I could have sold you some IRF3205's for $0.50 each + $10 shipping.... IRF3205=110A factory parts = 80A.

Should not be repairing amps if you don't know the difference from looking at the datasheets... sorry, just being honest.

The Diodes I mentioned (and snoopdan mentioned) are likely bad. Pay attention....

And you may have a bad PWM IC, probably a SG3525. Some of the mmats amps i think had a MIC4424 driver (I think that's the part number) but looks like yours doesn't so the SG3525 must drive the power supply FETs directly.... good luck with it, but honestly with you limited experience here (it's obvious) you are likely to have trouble as this is a oddball design amp.