avic n3 feedback

Hey Guys, Ive got an avic-n3 and I was getting terrible feedback through my 4 channel and my 2 channel. Bad alternator wine, pulsating when I brake. It was BAD. I had this problem once before with a pioneer deck, I sent it out to service and it was fine when it came back. It has absolutely nothing to do with grounds on the amps, rca's or anything to do with the amps. I replaced and re-replaced every peice of wiring in the car. I replaced my battery and alternator. I replaced my factory ground. Does anybody have any idea what goes wrong inside these pioneer that causes them to give that feedback? Is there anything I can do to fix it? Pioneer wants $200 just to look at it. I am MECP Advanced certified, and it drives me crazy not to know what this is. Anyways, Im babbling. Thanks for any info.

There is a surface mount fuse in the shield path of the RCA cables.  As shown in the picture on the bottom of the page that Haem' posted.  The reason the fuse opens is from one of the following:  1.  A power wire touched the shield of the RCA cable.  2. Power and RCA was attached to an amp before the amp was grounded.   As soon as the power wire is connected to an amp, (or any electronic device for that matter) it begins looking for a path to ground.  When the RCA cable is plugged in, the amp says hey there is ground, you guys follow me.  They head down that path only to find out it is limited by the fuse.  So as stated above, disconnecting the battery before performing any work on your system, should prevent ths from happening.