Audio Systems: Sound is gone, output transistors, volt inputs

Question
Hi Tom.  I have a Pioneer DEH-P7500MP stereo in my car that worked fine until 2 days ago.  I cut the amp to the subwoofers off from the head unit like i always do when I'm sitting in a line somewhere, but when I went to cut it back on it didn't work.  I got to checking connections and fuses to rule that out and while testing it, the sound to all the speakers went out, there's not even any noise.  The fuse for the amp nearest to the battery is blown, and after replacing it with a known working one I still get no sound.  When i cut the car on, the power light to the amp flashes on the goes off.  I have checked all the connections, harnesses, and fuses, but I am totally stumped.  What do you think the problem is?
Thanks.

Answer
Mark,
It's possible that one or more of the output transistors has failed. If the main fuse for the power to the amp had blown out, it tells me that some kind of a surge may have damaged the amp. You can try using a 12volt test lamp and check the 12 volt inputs to the amp, the main feed and the remote on lead. When you yurn on the head unit and the power light on the amp turns on and then goes off or the protect light comes on, it signals a problem with the amp.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net