Mysterious alternator whine

mnapoles · 01-15-2007, 12:55 AM

Ok Ok, I know what people are going to say with "search the forums" and "learn to run wire" and "learn to ground" but this problem is a little different...

Ok so i have the RCAs going from a Female rca to male headphone jack... that plugs into my sound card. from there it goes to the Soundgate honda adapter then to my head unit. Since installation i have been getting an alternator whine and today i had enough.... i ripped out all my seats my center console and my carpet and RE-ran the RCAs as far from any power cables as i could... problem.... NOT solved... I literally clipped the rcas to the head board of my car and came down to the soundgate and still got a whine...
I tried plugging headphones straight to the soundcard and.... NO WHINE! so by method of deduction i have counted out the computer (due to no whine with the headphones) i have counted out the rcas (by using THREE different rcas and running them all different places) the only thing i havne tried going around is the soundgate... now... if you havnt used a soundgate they dont use power and thus no ground so i cant imagine how that is causing the feedback.... any ideas before i drive the car into a wall?!@

3rotorFD · 01-15-2007, 01:24 AM

try this : Ground the negative side of the RCA's and put a thicker ground on the soundgate unit....

3rotorFD · 01-15-2007, 01:33 AM

oh yah and i 4got. mount the unit as far AWAY from the ABS control module as possible.
i remember those picking up noise even from the A/C motor :ugh2:
JUST MY 2 CENTS

Rob Withey · 01-15-2007, 02:14 AM

99.9% sure it's a ground loop. Try a ground loop isolator to prove this point. Then solve it by fixing your grounds, or keeping the ground loop isolator.

mnapoles · 01-15-2007, 03:21 AM

Unfortunately there is no ground on the soundgate its power-less... there is no ground involved thats where im stuck with a solution?!

its rcas straight to the soundgate then the soundgate plugs into the stock h/u. ive tried moving things all around as much as possible in the car and to no avail. like i said the only fix i have been able to find is if i plug headphones in to the soundcard i get no feedback in the headphones. i used multiple rcas and 2 different rca to headphone connections... soundgate seems to be the only thing i havnt tried replacing but its not powered so i cant imagine that being the problem?

Rob Withey · 01-15-2007, 03:54 AM

If the soundgate passes the audio signal through, the audio ground will be grounded in the headunit. There MUST be a ground somewhere, otherwise there is no reference against which the audio signal means anything.

2k1Toaster · 01-15-2007, 06:20 AM

mnapoles · 01-15-2007, 05:04 PM

But i only get the alternator feedback when i have the h/u switch to AUX when its on FM/AM or CD theres no whine... when i plug headphones into the computer theres no whine so its somewhere between the computer and the H/U but as i stated it doesnt matter where i run the RCAs the whine stays the same no change in pitch or anything?

Rob Withey · 01-15-2007, 05:17 PM

Quote: Originally Posted by mnapoles

it doesnt matter where i run the RCAs the whine stays the same no change in pitch or anything?

No change in pitch? Doesn't vary with the engine speed? Then it is not alternator whine, and your title is very misleading.

mnapoles · 01-15-2007, 05:49 PM

it seems everyone approaches the forums and replying to threads as if the person posting the question doesnt know what they are talking about? it IS alternator whine. the pitch changes when you push the gas. what i meant is that the pitch doesnt change when the rcas are moved around the car leading me to discount the rcas as being the source of the problem. rather the rcas running too close to a power cable as being the source of the problem...

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