Blown amp

[andrew018018]

Well i sold my old amp about a week ago to a friend and he's already blown it, i'm not exactly sure what he did but it's shorted out.

Basically when you put a multimeter on the positive and negative terminals it reads 0 ohms, i tested all the mosfets and they seem fine, but when i came to test the transformer i run into a problem because the power supply is shorted i cant read the resistance across it since it reads 0 ohm everywhere... unless i pull it off the board i dont know what to do

Anyway, what are the main causes of a shorted amp and what testing methods can i use

thank you

[andrew018018]

I pulled off all the mosfets from the power supply, just to make sure that they weren't shorting the amp out, but as I concluded before the mosfets are fine and the amp is still shorting out...

So does this mean the amp has a blown transformer? or could it be something else?

[andrew018018]

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here is a photo, it a kenwood 8104D