Alternator Whine

csmager · 7 May 2006 at 17:42

Hi,

I've got a standard VW Beta Radio and VW Single CD Player. Since I bought the car, the radio has always worked fine... but when i listen to a cd, there's an audible whining that increases with engine revs. I've finally decided to do something about it.

Does anyone have any specfic advice or experience with this? As far as I can see, there are two options: Noise filter on the power lines near the head unit, or a big noise filter as near as i can get to the alternator.

Thanks for any help!

Mickey_D · 7 May 2006 at 17:54

99% of all alternator whine in audio equipment is caused by a faulty earthing point.

Do yourself a favor and check all three earthing (negative) connections under the bonnet (battery post, engine block and chassis) and the stereo earthing lead.

Clean up and redo all those connections first before going looking for noise filters.

csmager · 7 May 2006 at 18:23

I did get the car new, and it's done it since then (as far as I remember). I've been browsing various forums all day, and it would seem that it's not an uncommon problem with the Mk4 Golf's.

I'd take it that as corrosion of any earthing point is unlikely, that means it's most likely to be the head unit/cd player's grounding that's the problem?

EDIT: Actually, thinking about it, sometimes if I get really irritated, I give the side of the centre console a bit of percussive maintenance (i.e. whack it bloody hard), and the noise stops for a while. Sound like crap grounding to you?

Mickey_D · 7 May 2006 at 18:30

Yup, definately a poor connection somewhere. Now, whether it's in the HU mounting or internal to the HU I couldn't say.

With the aforementioned problem of it not occuring during radio use but appearing during CD use, it could be internal.

Being an electronics technician myself I would pul the HU and dismantle the case and start resoldering connections inside, but I would most certainly not recommend it to someone who's never done it before.

But it certainly won't hurt anything to redo the external connections first to see if it corrects the problem.

csmager · 7 May 2006 at 18:35

I'll have a look later. I should be getting the tools needed to remove the head unit in a couple of days. It doesn't whine with the engine off, so it's definitely alternator-induced noise getting in somewhere.

I'm getting a CD Changer too, so i'll see if that has whine on it. I'm binning the HU/CD Player combo in a while anyway, so I'm not overly fussed about the problem if it's the HU at fault. But if it was power-line related, i didn't want it to affect its successor.

I do have a GCSE and A-Level in Electronics, and I'm currently doing Electronic Engineering at University... but you're right - i'm not actually that handy with a soldering iron!

csmager · 12 May 2006 at 16:40

csmager said:
I'm getting a CD Changer too, so i'll see if that has whine on it. I'm binning the HU/CD Player combo in a while anyway, so I'm not overly fussed about the problem if it's the HU at fault. But if it was power-line related, i didn't want it to affect its successor.

Got the changer yesterday and plugged it in. If it goes via the single CD player (so i can choose either single cd or changer), then it whines with the engine on.

If I completely bypass the single CD deck and plug the changer directly into the HU, it works fine. Considering it's done it since the car was new, and countless people seem to complain their VW Single CD player does the same (1 guy said he'd had 4 VWs that do it), I'm half inclined to think there's a design fault with it.

Still, problem solved it seems.