Payment made for the answer

**ApoloV** · 11-03-2004, 01:57 PM

Ok well I had HD noise, alt. whine (changin pitch w/ engine RPMs) even noise as I used my touchscreen...

I got rid of most of it by making sure my soundcard (SB Live) was grounded to my HD and motherboard.
I got the rest of it out by using a ground loop isolator like this one
http://www.davidnavone.com/detail.asp?PRODUCT_ID=N-25
or
http://www.radioshack.com/product.as...t%5Fid=270-054

a few things to check out.. make sure your power lines are not crossnig your audio lines, try to have them at least 12" apart. Ideally you want your grounds to be as short as possible.
(Might consider checking your factory ground, some people will replace the stock 4awg ground w/ a 0awg ground, or just supplement with an additional grounding point from your batt. to alt, and batt. to stock ground and cyl head to batt.)

something else to check is if you run a temp power line directly from the Batt to your PC does the sound go away? This could show that your not getting a good enough ground. ?

Those are my thoughts.... Let me know if any of it helps

Apolo

**antimatter** · 11-03-2004, 02:13 PM

It could be your battery or your alternator.

Explain the noise and how it sounds

**dragonBTV** · 11-03-2004, 02:59 PM

OK,let everything to the end!

do'nt complain your sound card, they are fine

the noice come from your POWER of PC

sollution:

1.never think about DC to AC converter to normal PC power mode
2.use DC to DC power for PC, there are a few choice on mp3car store
3.do NOT use single ground methord on car wireing, it is for AC FCC control
4.instead trist every pair of your 12V line each pair anythere and ANY inch
5.the length of the wire in each pair should be exzactly same
6.dim of the 12v wire should larger than 0.1mmx10

**dragonBTV** · 11-03-2004, 03:03 PM

a picture or photo of your installing would show us more information on solving it.

**Matthew230** · 11-03-2004, 03:11 PM

Originally Posted by dragonBTV

OK,let everything to the end!

do'nt complain your sound card, they are fine

the noice come from your POWER of PC

sollution:

1.never think about DC to AC converter to normal PC power mode
2.use DC to DC power for PC, there are a few choice on mp3car store
3.do NOT use single ground methord on car wireing, it is for AC FCC control
4.instead trist every pair of your 12V line each pair anythere and ANY inch
5.the length of the wire in each pair should be exzactly same
6.dim of the 12v wire should larger than 0.1mmx10

Ok - I have an Opus 150w. I have tried using an external power supply, but I get the same result

I don't really understand points 3 to 6

The noise is definitely related to the engine, but I also hear a constant high pitched tone when just the ignition is on, and you can also hear mouse and HDD noise.

How can I test if my gorund is good with a multimeter ??

**Zac** · 11-03-2004, 03:20 PM

have you tested for the noise with individual components (basically just the screen :-P) off and unplugged from any power source?

**BiohazrD** · 11-03-2004, 03:24 PM

I had this exact same problem. How many amplifiers do you have? Do you have one for your midrange speakers? Does the any +12v wire from your battery at any point come within a foot of speaker cable. Your alt. is a big spinning magnet. Therefore it creates EMF, so, the higher the RPM's, the faster the magnet is spinning, the higher the flux. I guarantee this is your problem.

**Matthew230** · 11-03-2004, 03:25 PM

Originally Posted by ksmyarse

have you tested for the noise with individual components (basically just the screen :-P) off and unplugged from any power source?

Yes, I have managed to take everything out piece by piece, even HDD and DVDrom without success.

**Matthew230** · 11-03-2004, 03:28 PM

Originally Posted by BiohazrD

I had this exact same problem. How many amplifiers do you have? Do you have one for your midrange speakers? Does the any +12v wire from your battery at any point come within a foot of speaker cable. Your alt. is a big spinning magnet. Therefore it creates EMF, so, the higher the RPM's, the faster the magnet is spinning, the higher the flux. I guarantee this is your problem.

The HU is the amplifier. The only place the speaker wire would be close to 12v is at the back of the stereo. I get no noise if I use the radio or plug the CD changer back in. Also would that create Ignition/Mouse/HDD noise ??

**MatrixPC** · 11-03-2004, 03:32 PM

How did you "modded" the CD changer audio signal?
- Did you find the audio ground from the changer to the HU (normally it doesn't matter that much)?
- Are you using relay to switch between the CD changer and the computer for sound?

I did a little the "aux" audio in for my HU a little differnt from your but the same concept "jamp the audio from the cd player to the HU amplifier".
I used a DPDT relay to to switch the audio signal between the CD player module of the HU and the car PC. After I check for the audio ground from the CD player to the case, well they are the same.

So I just tap the audio from the CD to the HU case, nope doesn't work, I have engine whining.
I have to solder the audio from the ground to the PCB ground point. The noise is basically gone (well still there but you have to really listen to it to hear. Road noise and wind noise is much lounder than the engine whine.