Same outputs shorting each time

RJohns777

Member
2011-03-15 8:54 pm
Hi, working on a Sound Stream PIC 1.1700D amp. Can someone shed some light on why a class D amp will short the same outputs each time? Gate resistors and Diodes check fine. Driver board checks fine. It shorts the same two outputs. One on the positive side and one on the negative. Thanks.
 

RJohns777

Member
2011-03-15 8:54 pm
Here's the pics.
 

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RJohns777

Member
2011-03-15 8:54 pm
Yes I looked at that. They are not touching. I can shine a light between them. I'll insulate it anyway to make sure it doesn't short in the future.

The bright spot looked like white paint. Cleaned off easily with solvent and brush. No burned area around it. Doesn't appear to be rubbing away the insulation on the wire.

Checked the diodes out of the circuit. They read equally with all the other diodes.

Curious why the same two outputs short.
 
"Has the output filter capacitor failed shorted ?" No, output filter caps check fine.

I was trying to get an idea before rebuilding the power supply again. Decided to go ahead and put the power supply FETs in anyway. Now what I am getting is low voltage DC on the speaker positive and a loud high pitch squeal in the output. I haven't put the two shorted outputs back in yet.