This is the 2nd Ample Audio A 1100 DX car amp
I've gotten in for service this month with a "ghostly" protect
problem.

Get this; Amp instantly goes into protection upon power up.
Okay, that's not unusual but, NO shorted mosfets in power
supply or Audio section.( I even pulled the rectifiers out of
circuit to isolate the PS)

No pri/sec shorts in Xformer. No leaky or shorted "totum pole" trans.
Swapped out the TL494 pulse wave chip. (checked all transistors in PS)

The PS does try to gernerate square waves, I can see them appear briefly
at the gates of the PS mosfets and at the secondary of Xformer.

Admittedly, I am NOT a car amp Guru, but I have repaired enough of them
to know my way around in there and I'm scratching my head.

Hopfully, someone out there has seen this or has more ideas.

TIA, humbley,
RIck

Either the internal power supply, or inverter (if there is one), has a
short, or one of the stages, especialy the output stage, is pulling too
much current.

The only way to find this, is to isolate the various stages in the set,
and see which one is causing the fault. You will most likely have to
cut a few traces to do this.

Jerry G.
======

"Jerry G." wrote in message
ups.com...
Either the internal power supply, or inverter (if there is one), has a
short, or one of the stages, especialy the output stage, is pulling too
much current.

The only way to find this, is to isolate the various stages in the set,
and see which one is causing the fault. You will most likely have to
cut a few traces to do this.



Sounds like he's already isolated it and it's still shutting down so this
isn't particularly helpful.