Amp board blown on pbxa3000D?


2008-06-29 3:44 pm
I think the Ic may have blown on my Class D powerbass xa 3000d.

I say this as i can trace the input all the way to the pin input on the IC, it goes through all the input side fine. Voltages onto the ic are as spec'd.
However there is no output. I have had the scope across the relay and the relay comes on but no voltage/wave is present on the speak outputs.

How can i test the board for sure?
I have 3 'outputs' which lead to the fets. They are H-S, L-S (and V-S maybe?).

How should i test these outputs? Is it a crazy high frequency which my scope wont pick up?

Perry Babin

Paid Member
2003-11-20 11:01 am
The frequency isn't too high for your scope but the rail voltage may be very high so the rail voltage and the tops/bottoms of the waveforms may go off of the display if you don't have it set to the highest vertical amp setting.

Is there any DC on the speaker terminals?

With the scope set to 50v/div and the timebase set to 5 or 10uS, do you see any DC on the outputs?

Do you see a square wave?


2008-06-29 3:44 pm
I get no DC on speaker outputs except for a turn on and turn off thump. A -ve DC quickly resolving to 0v on turn on and a +ve on turn off. Just a flash of +ve and -ve.

On all 3 H-S VS and L-S I get nothing except a very small amount of static, nothing all the way down until .2v divs, then just symettrical peaks spaced equally.

All I have left on the board 'untested' is FB and APT now.

Second edit:

Just to make it clear. There is no protect light illuminated and there is voltage to everythign on the board as far as I can see.
I just can't see anything from the IC board.
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2008-06-29 3:44 pm
That's great.

Thanks for your help. I'll keep in touch. I do have another 3000d here suitable as a 'donor', exact same model, but with a destroyed power supply side. I could desolder the Ic out and replace it, but would that be a good idea, or are they very specific to the board?