Alternator whine HELP ME!

[PowerHouse407]

This can be one of the most difficult problems to track down and eliminate. Keep in mind, your RCA cables are likely run along the body of the car under the carpet . . . the body being the return path for all things electrical. The fact that they are on the opposite side that the power wire is run could either be helping or counting against you.

Really obnoxious noise is usually quite easy to eliminate. That typically indicates a problem with a component. Your explanation above is somewhat unclear. Did you say that you unplugged the RCA cables from the INPUT of the amplifier AT the amplifier and plugged your iPod directly into the amplifier and still had noise? Or, did you mean that you plugged your iPod into the RCA cables at the front of the vehicle near the deck?

Be careful unplugging and plugging RCA cables with the amplifier powered up. In some cases, the input section of the amplifier can begin to oscillate with nothing plugged into it. Bad things can happen as a result . . .

yeah well i plugged in the ipod directly into the amp not using the rcas and there was no alt whine witch makes me believe that there is no issues with the amp or speakers. so my only 2 things past that is the rcas or the head unit itself. so to rule out where my reas were ran my friend had a brand new set of top end rcas. so i ran those just over the seats not under the side trim ( just a 1 min test because he wanted them back) and the alt whine was still there. witch makes me believe that the rcas are ok. so now i'm at the head unit.

[PowerHouse407]

Upon re-reading your posts, is it possible that you did not ground the amplifier properly before powering it up? If so, the amp may have sought ground via the shield of the RCA cables and damaged the preamp section of your source unit.

Well i have a 2nd battery and i hooked the amp up directly to the 2nd battery pos to pos neg to neg. i am not sure if this is a bad thing or not. and i hope i did not mess up my new head unit :/

[snafu]

Ain't iPods great? In the old days, we had to use a source unit on a bench powered via a power supply to do that.

There are three possibilities here:

1. The source unit is indeed the source of the noise, via it's connection to the vehicle's wiring. If that is the case, the amplifier will simplify amplify this noise.

2. The connection between the source unit and the amplifier is the source of the noise. In this case, the source unit will have no audible noise out of the preamp outputs with all RCA cables disconnected. The act of connecting the source unit and amplifier is creating a "ground loop" which is caused by a difference in ground potential of the source unit and amplifier - IE, when these two ground points are tied together, voltage flows from one to the other.

3. The preamp section of the source unit is damaged - IE, the shield of the RCA is no longer connected to ground. This is easy to determine if you have a DMM. Simply power down the source unit, disconnect all RCAs from it, and measure continuity between the shield of one of the RCAs in question and the chassis of the source unit. If you get no reading, then this is the case.

If #3 is your problem, then the fix is to replace the source unit as well as determining what caused this damage to begin with. If #1 or #2 is your problem, then you may choose to seek the help of a professional fluent in the art of troubleshooting engine noise.