I just switched out my OEM deck, that was running two Rockford amps and no noise problems, with a Sony that I bought from a member and now I have a constant whine. If I disconnect one pair RCA's it goes away. If I turn up the music it can barely be heard. If I turn the motor off it goes away. If I turn the music all the way down it is very noticable. I've tried several different grounds including the battery. No difference. I've turned down the gains, does not help. The whine does not go up or down with the rpms, just stay constant. Any ideas to what the problem is?

 

are you confident that you grounded the new head unit and the amp properly? If there is a ground isolation on either the head unit or the amp, you may have that result...also, did you run the power wire for the amp next to the rca cables? If so, that arrangement could cause problems too.

 

What is ground isolation? I used Lucid's harnass and plugged it into the Sony and tried a number of different grounds near the spare tire to ground the amp with the same result.

 

You can try Ground loop isolator type of noise filter on the RCA jacks going to the amps or maybe a noise filter on the power leads. The radio could also be a
problem.

 

since the whine went away when you disconnected the rca cables then it's either in the head or coming in via the rca-cables. the cables are obviously the easier one to debug, just try different cables and run them down the center of the car (or outside the car) to isolate them from any possible interference in the car.

if you have access to another head with preamps you could test that way too, but to test properly you'd need to plug it into the harness. it sounds like you're grounding through the harness? that might be a problem, but i would really look at the preamp cables first, my bet is the sound is coming in through them.

 

if the sound is not related to RPM then i would doubt that it is a bad ground...i would double check the path of your RCA cables or possibly replace them with a more shielded set of cables.

M

 

Ok, another two hours spent trying to get rid of the whine. No luck. Here is what I've found out. RCA's not even close to power wires. RCA down left side, power down the right. Tried better cables, only made the problem worse. If only one set of cables is plugged in to the HU, no problem. Add the second set of RCA's to either the sub or rear out put and it is there. I'm beginning to think I was sold a lemon. I bought a CDX-650 and the door won't flip, so I can't put in a cd and have to operate the radio by dash controls or remote. I thought I'd see if I could get that fixed if the seller paid part, but now that I can't get rid of the whine, I'm beginning to believe it may be getting to expensive to fix. Is there anything I might of overlooked?

 

you could try to flip flop the RCA's... plug the set that sound good into the rear or sub and see if the whine shows up and vice versa, try the set that sound bad into the fronts and see if they sound bad.

that might help you tell if it's the head or just that one set of RCA's.

 

[QUOTE]Originally posted by PJK3
[B]you could try to flip flop the RCA's...

 

Ground loop problem, for sure...