noise investigation

**Bravellir** · 09-22-2004, 10:28 PM

Originally Posted by MrPerfectionest

^ Did you read the thread at all? I already mentioned that and he said he tried it and it didn't help.

Yes I did, and just to be sure, I read it all again. He never said that he had the av switcher and the pc powered by the same source.

Originally Posted by lookinco

One opus feed power to the computer, and the other OPUS feed power to the AV switcher,

One in each OPUS

Originally Posted by lookinco

I don't think it is the OPUS. At first I only used one OPUS for the computer and the car's power for other video components. It created the same noise with the AV box and none without it.

One in the Opus and other directly to bat.

Originally Posted by MrPerfectionest

... He also mentioned a ground loop iso between the PC and AV fixed it.

Yes, but he also said:

Originally Posted by lookinco

Right now I have a ground loop isolator between the computer and AV box, which eliminated ALL the noise.

What might cause the problem? Is it my computer actaully making noise? But there are no noise from compute to headunit. I am really confused here. I have tried everything I read on the forum such as grounding the case, psu, motherboard, sound card,,etc etc etc etc and still no use.

Witch I presume means that he is curious enough to try to find the real problem.

My sugestion is that till now, is PC had two grounds. One from the rca connector on the AV Switcher and other from the Opus. Thats why the ground loop isolator only solved the problem when between the computer and AV box.

**antimatter** · 09-22-2004, 11:40 PM

Do you have another AV unit that you could use to test to see if it is AV Switcher. I know that you said that other componants work the AV Box but it is worth a try.

Try grounding things in a different location.

Try unplugging all inputs from the AV box and take the RCA from the computer and touch the chassis of the AV Box. If you hear the noise then it is comming from your computer.

Check the ground on your computer. Is the computer in a metal case. Ground the computer to your PS if not. The best ground location on the via is the screw hole next to the PS/2 connectors.

**lookinco** · 09-23-2004, 01:54 AM

Thanks for everyone's input. Everything has the same ground point. The two OPUS, computer case, AV switcher, inverter, all the screens. I rewired everything to the same ground point and 12v source. One OPUS for the computer, one OPUS for AV parts. Both OPUS get the same 12v source, same trigger, and same ground.

I tried to plug sources into the headunit and into the AV switcher, they all make NO noise at all. The only time I have noise is when I have my computer go through the AV switch into the headunit. If I bypass the AV switch then there is no noise also.

Like I said right now I have ground loop isolator in between the PC and AV switcher which eliminated all the noise. So my guess is the noise IS coming from the computer.

I will try to ground more things to see if it eliminates the problem. My system is a Shuttle in a shuttle case with a OPUS for shuttle and another OPUS secured on top of the shuttle case. I have tried grounding the case by attaching a groun wire to one of the case screw, but that didn't help.

Still confused...

**Motorcity** · 09-23-2004, 02:24 AM

It is possible that your AV switch is actually picking up the noise comming from another source through the ground wire attached to the AV switch. You say that when you bypass the AV switch, you get no noise, right? I would check your vehicle for loose ground straps. You van will have several. They usually attach from the engine/trans. to the body and frame, and also from frame to body. 1 of them may be loose, have fallen off, or has corrosion and making poor contact. Another thing to think about is the length of the ground wires you currently have. Shorter, the better. If you have too many ground wires running all over just to tie them together, this could cause problems too. Each electrical device you add to your vehicle should have it's own ground wire, of a decent gauge size, and be as short as possible (under 24" is prefered).

**lookinco** · 09-23-2004, 02:41 AM

I have tried the AV switch with just the computer plugged in. Before I rewired everything, there actaully was noise coming from other sourceand some static on the video. However after I rewired everything that problem was gone.

The AV switcher is right beside my computer which is right beside my ground point. The ground wires is 8 gauge and is less then 2 feet long.

I will check the ground strap tomorrow.