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Thread: Noise!! AARGH!

  1. #11
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    It's not just my VGA - it makes this sound even when only the power is hooked up.



    So I spent the last hour or so troubleshooting this some more. I experimented with adding a ground direct to the battery from a variety of locations. Still won't go away. It didn't even reduce slightly, this sound is just not budging. It's kind of like a static noise which matches the clickings from my engine ( = engine noise).

    So I'm really getting frustrated with this now.. I have no idea what is going on.

    One thing I noticed while poking around with my voltmeter.. When the computer is plugged in (note: NOT on just plugged in), I see ~5vAC (yes AC) between the chassis and the common ground points. I see the same on my amplifier's RCA cables (which makes sense since they are basically connected to my pc). But when I unplug my pc's power supply, it goes way up to like ~ +100vAC easily (I didn't really look how high it went).

    What is causing this?

    Where else can I test ground points to get rid of this noise? I tried my pc case (sanded a spot), my pc's psu ground lead, my sound card mounting screw, etc..

    Any ideas???

    HELP!!!!!!!!!!!!!!!!!!!!!!!


  2. #12
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    Put a 47.000 uF 25V (min.) capacity plus 10 capacity of 10 uF all togheter in parallel to your supply line.

    You should resolve the problem! ;o)

    Bye bye, paperinics!

  3. #13
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    That would basically be a separate battery for the PC, no?

    I have a feeling something is not right and that would just be putting a band-aid on the problem..

    If it is a ground issue, how can I tell if my grounds are "good" ??

  4. #14
    Clover Grayscale's Avatar
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    no, those Farrad values are way too low to be considered a seperate battery for the pc, however i am not so sure that doing that will fix your problem.

    what got rid of my noise problem was completely ungrounding my motherboard from the PC case...
    CarPC install is starting to come along again...

  5. #15
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    For me it worked well... all noise was killed! It was mainly introduced into the power line by the Lilliput 8" touch screen, when the engine was running...

    I'am quite sure that this capacity trick should remove or attenuate your noise.
    Putting a big capacity plus some minor capacity in parallel will decrease the internal resistance of the toal parallel capacity permitting a better filtering!

    Just try ) capacity doensn't cost too much!

    bye bye, Mauro.

  6. #16
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    Grayscale: That is a very interesting thought. Where is the motherboard typically grounded to the case, though? I do not recall running any wires to case ground.. Or maybe the PSU is grounded? I have a Morex Cubid 2799R case (the black one).

    Do the motherboard screw mounts ground the board to the case?? Maybe I need to add those red felt washers?

  7. #17
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    I could be wrong on this but I think the MOBO is grounded from one of the wires in the ATX power connection.

    But to do a better job. Slap another cable from one of the screws on the case to a ground point.

    I know I get whining when I first start my car. As soon as the computer boots the whining goes away. Its slightly annoying but it only lasts for maybe 10-15 seconds.

  8. #18
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    Hook up a Portable CD player or similar to the RCA inputs of your amp(s) and see if you get the same noise issue. Amp(s) may not be properly grounded.

    Try moving the power cables around... away from any signal type lines.

    Try a ground loop isolator on your signal leads.

  9. #19
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    Well I need to try again and remove the ITPS and also the distribution blocks to ensure I'm getting clean power inputs and outputs.

    I tried grounding the case, but that didn't help worth squat. Neither did grounding the screw to the sound card or the motherboard's ground, or the ITPS's ground.

  10. #20
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    What if I added a 2nd battery to power my PC/Amp? Would that get away from the ignition noise??

    But then I would need to charge the 2nd battery from the 1st/alternator -- would this then induce the engine noise again? I know you need some kind of battery isolator to do this dual-battery setup, but would that block the noise?

    HELP!!


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