ground loop question

**yonu** · 09-30-2009, 10:03 AM

ok question about groundloops my issue is this with the pc bolted into the car it i turn it on with it hooked up to the battery it sounds like someone running there fingers over a mic if i touch any metal on the car you hear that as well, now it i leave it mounted and plug it into my bench supply it sounds perfect no noise or anything. All my grounds are tight i have the power run straight from the battery using a 8ga wire. I have yet to pickup a groundloop isolator i figured i would pickup one this evening but thought I would ask first to see if anyone had an idea first.

Thanks,
yonu

**yonu** · 09-30-2009, 02:44 PM

well I have been unable to find a Groundloop isolator so I will have to wait on that. just to see what happend I connected mt bench supply to my 200watt inverter and there is noise but not as bad as straight from the battery but I am a bit confused as I was thinking it may have been my m2 causing the noise but i have feeding it 12v whether it is from the battery the bench supply or the inverter so i don't think the m2 is the problem I have tryed 3 sets of rca cables and that doesn't help so any advice would be great

**thewizard** · 09-30-2009, 05:51 PM

The symptoms that you describe are pretty much unmistakable and I don't think that a ground loop isolator will help you, in fact more than likely if you hook a set up you will loose all audio all together because they will shield the RCA's from being able to loop the ground back. The reason is that you are clearly pulling your RCA ground from your power ground rather than from the RCA's ground. What are you using for a sound card? You could try grounding your RCA's and see if that helps, but sometimes in doing so can cause you pick up some alternator whine in the process. If you are using an external sound card then try using the onboard sound to see if the external unit is the source of the problem.

**yonu** · 09-30-2009, 06:32 PM

I am using onboard sound I have tried grounding the rcas and it has no effect is there anyway this could be caused by the m2-atx?

**yonu** · 09-30-2009, 06:41 PM

i just thought of something that may help my case is a metal box the rcas, power in and power out for monitor are all metal connectors panel mounted into the side of the box so with no power if you take a volt meter all the shells read as connected could this be causing this problem? and also I tryed a separate 3.5mm to rca adapter that plugged straight to the HU and motherboard and it is still there. if it helps the HU aux in is a homemade pioneer cd changer adapter

**yonu** · 09-30-2009, 09:28 PM

well I may have found the problem I think it may have been the motherboard as the board died about 20min after my last post so I am back to square one as I have to go motherboard shopping

Thanks,
yonu

**yonu** · 10-01-2009, 12:11 PM

question i figure while I am dealing with getting a new MB and PSU I want to find out do I need to find a way to insulate the connectors from the metal case or is it ok like that?