Red Red Whine....

Matthew230 · 10-25-2004, 02:03 PM

Everything installed and, but speakers are buzzing and whining, some of it is clearly related to when the hard drive working, and some of it is related to the engine revs.

The setup -

Micro Atx board 2.4 celeron, with onboard sound, the speaker line is connected with RCA's to the CD changer, where I have cut the left and right audio feed and attached female RCA's (I hope this is clear)

The car is powered via cigarette lighter. Opus 150w.

I have tried lots of different grounding points, nothing makes a difference. I have tried powering it direct from the battery, still no difference, I have tried grounding the case, and the opus chassis, still whining and buzzing.

It doesn't matter if the ignition is off or not, but if the PC is shut down then there is no noise.

I have tried plugging the headphone jack that goes into the PC into a portable CD player and everything is fine, no noise.

I have plugged external speakers into the PC and there is also noise on them.

Can anyone tell me what to try next, and likely causes given the symptons and test results above.

Many thanks,

Matt

Tidder · 10-25-2004, 02:35 PM

Have you tried grounding your audio ground?

Matthew230 · 10-25-2004, 03:16 PM

Quote: Originally Posted by Tidder

Have you tried grounding your audio ground?

Apologies for my ignorance, but how do I do that ??

Thanks,

Matt

MatrixPC · 10-25-2004, 03:29 PM

Try not to power the Opus via the cig lighter. Wire it directly to the battery and use the cig light wire for turn on the Opus (IGN).

Matthew230 · 10-25-2004, 04:16 PM

Quote: Originally Posted by MatrixPC

Try not to power the Opus via the cig lighter. Wire it directly to the battery and use the cig light wire for turn on the Opus (IGN).

Cigarette lighter is permanently on. So can't do that. Tried hardwiring it to the battery and there was no improvement.

Do you know how to ground the audio?

Thanks,

Matt

Grayscale · 10-25-2004, 04:23 PM

try grounding the motherboard to the case of the opus?

Matthew230 · 10-25-2004, 04:32 PM

Quote: Originally Posted by Grayscale

try grounding the motherboard to the case of the opus?

Surely the motherboard should already be grounded to the case which is grounded to the opus which I tried grounding independently to no avail.

Can anyone tell me how to ground the audio, or offer any other suggestions ??

Thanks,

Matthew

Tidder · 10-25-2004, 08:10 PM

You ground the audio by splicing into your audio wire, and using it's ground to connect to chassy ground. Fixed some major audio whining in my car.

Huflungdung5342 · 10-25-2004, 10:41 PM

ground it by exposing a section of the chassis' metal, sand off some of the paint, and attach the ground wire to it

coachreed · 10-25-2004, 11:07 PM

You should have your grounds for amps and source (headunit and/or computer) grounded to the SAME point on the vehicle chassis... if that means you have to run an extra ground wire from the front to the rear of the vehicle, you should do it... just keeps from having ground-loop problems where you will most likely pick up noise due to a potential voltage difference. If that made ANY sense.

Later!

jjh221 · 10-25-2004, 11:18 PM

I had the same problem . I had my lilliput powered by my psu, and i found when i turned off the lilliput most of the idle noise went away, but still having the harddrive and engine reve noise. So what i did next was solder the lillput to the cig lighter. Work, well for that much. I still had the harddrive noise and engine rev noise. So what i did next was ground the mobo to the same ground, on the cig lighter, as the lilliput. My problem was solved.

Matthew230 · 10-26-2004, 08:29 AM

Ok,

I'm going to ground everything to one point, and see what that fixes.

Though I'm not clear on how to ground a motherboard.

Can anyone help with this ?

Cheers,

Matt

EBFoxbat · 10-26-2004, 08:33 AM

The ATX power (from the OPUS) should take care of your motherboard ground.

Matthew230 · 10-26-2004, 09:11 AM

I'm still a little unclear about grounding audio.

I have a headphone jack line out that goes into RCA left and right.

Am i cutting into each of these wires and making a ground, or am I using the shield wire aroud them and grounding that ??

Cheers,

Matt

jjh221 · 10-26-2004, 11:01 AM

My mobo is not in a case, but screwed to some plexy glass. Your ground on the mobo is where the screws go to hold it to what ever it is attached to. If ya notice the holes are circled in metal or whatever.
If your audio is to your head unit i would think that that is already grouned.

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