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Thread: How to ground when powering accessories off of pc supply?

  1. #1
    Low Bitrate willmeyer's Avatar
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    How to ground when powering accessories off of pc supply?

    Hi there. I am planning to run one each 5V and 12V power lines from my power supply (M2-ATX) int he trunk to my dash area, one for my lilliput and one for my SB hub. When doing this, I was planning on just running the power lines then grounding to a grounding point in the dash, given that the negative for the motherboard is actually coming off the body ground as well. I read in someone's post about using a DC-DC supply and not wanting to ground it that way, though.

    Is/was my original idea the right way to do this? Any reason I need to actually run the power supply negative/ground and use that?

    Thanks!

  2. #2
    Variable Bitrate
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    Not sure what others have done, but I made sure that I grounded everything back to the power supply, not to the body of the car.

    I think from memory, I tried to earth to the chassis to isolate some hum but around that time I blew a fuse on the power supply.
    RodW
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  3. #3
    FLAC
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    Yeah you need to ground back to the power supply in most cases. Most power supplies play with the power in such ways that it's almost as though the power supply and the cars electrical system are entirely independent circuits.

    Also think of it as... in a house, you wouldn't ground your hard drive back to a wall socket, would you?
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  4. #4
    Low Bitrate willmeyer's Avatar
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    thx

    Ok thanks guys. Yeah I suppose it makes sense, though I would have thought board ground was body ground etc etc. In any case, will keep the negative going from the supply to the accessories.

  5. #5
    FLAC
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    also, don't forget to use fuses on those lines. you don't want to blow a power supply and risk taking out other components too.
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