Strange ampli problem, pls help

[cosma]

Hi all,

I'm a newbie here, and I post to find some help about a problem with my ampli. Not sure if I'm posting in the right place, can anyone help?

It's a multi-channel car amplifier (Alpine MRP-F320, 5 channels), but the 2nd doesn't work (the others work fine). The strange thing is that, if I plug only the RCA signal, excluding the ground, the ch. works, with a much lower volume than other channels..

I get the same effect connecting the RCA signal from the cable to the RCA input ground.

Any ideas of the damage? Can be simple to repair? Thanks in advance for the help.

[djk]

Look for a burnt ground trace near the RCAs

When the main power ground goes open (from the car hitting a bump or whatever) the signal ground has to carry the power supply current.

This can also burn a trace in the head unit in the dash.

There may also be additional damage.

I always use a transformer to get rid of this and nasty ground loops.

http://www.edcorusa.com/sound/matchers/s2s10k_10k.htm

This product is vastly better than the car stereo ones.

[cosma]

Originally posted by djk
[B]Look for a burnt ground trace near the RCAs

When the main power ground goes open (from the car hitting a bump or whatever) the signal ground has to carry the power supply current.

Ok.. still a doubt: with a burnt trace there should be no current flow, right? if so, I would get the same result either with rca ground connected and not..

Originally posted by djk
[B]This can also burn a trace in the head unit in the dash.

There may also be additional damage.

I bought the ampli used, and it was already broken so I can't have other damage..