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Thread: Ground loop with carputer - not with my new laptop --- HELP!!!

  1. #1
    Variable Bitrate
    Join Date
    Aug 2006
    Central PA

    Ground loop with carputer - not with my new laptop --- HELP!!!

    So I've been dealing with a ground loop since December and I've just now gotten to figuring out just what is causing it.

    My carputer is a laptop with both built in sound jack and an external usb sound card. I have the ground loop with both. I also have the ground loop with the power hooked up to the laptop and without. There is no change.

    I've been reading about how everyone else has dealt with their ground loops and someone mentioned grounding the chassis of the laptop or grounding the external sound card.

    To test this theory I tried hooking up my new laptop which I thought would probably be better grounded. Sure enough when I hooked my new laptop up it sounded great.

    On a side note, I have a ground loop isolator as well. That helped with the ground loop a LOT.

    So my question is how should I go about fixing the grounding issue with my carputer? Is grounding the motherboard and then using the built in jack the solution? Ground the external usb sound card and use that? Or something else? I'm open to any ideas.

    I know there are a billion of these posts on the forums, I hope you guys won't mind helping me out with my individual issue!

  2. #2
    MySQL Error soundman98's Avatar
    Join Date
    Jan 2008
    on the border of northern IL/IN
    ground loops are really a install-by-install problem, you could have 2 identical cars with identical stereo installations, but installed by 2 different people-- and one could have a ground loop while the other doesn't.

    it might help to ground the computer, it might not, it is very hard to tell. the other idea that i have used in the past is to try to ground the negative lead of the headphone jack, sometimes it works, sometimes it doesn't.

  3. #3
    Raw Wave treetop777's Avatar
    Join Date
    Sep 2006
    War-Town, GA.
    I had a real bad one untill i grounded the PSU the same place the HU was grounded (since i use the HU AV-in); that reduced it to just a minor humm and a quality ground loop isolator eliminated it completely. Now it's dead quiet.
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  4. #4
    Low Bitrate jake789's Avatar
    Join Date
    Apr 2009
    Audio cables have a type of ground wire in them, in turn they connect your pc ground with your headunit ground. For some reason your laptop seems to like the headunits ground better than its own.

    The easiest way to try to fix it is what soundman98 suggested to ground the neg of the audio cable. You'll want to ground it as close to the laptop as possible. RCA's are easy cause you can just wrap a wire around the shielding part, but I'm not sure if a phono plug will be so simple.

    Otherwise the real way to try to fix it would be go ground a safe place on the mobo, but laptops aren't easy to disassemble and if you don't pick the right place you could mess something up.

    Try powering up the laptop with the batt removed. Maybe your batt is messed up?

  5. #5
    MySQL Error soundman98's Avatar
    Join Date
    Jan 2008
    on the border of northern IL/IN
    hw are you powering the laptop? inverters are notorious for extra noise...

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