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Thread: Noise in VGA signal while laptop plugged in

  1. #1
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    Noise in VGA signal while laptop plugged in

    I have recently been getting noise in the form of horizontal light gray lines that bounce around and travel up and down my screen (Xenarc 700TSV).

    -I know it is not a screen issue because I plugged the screen and same cable into another laptop and it works fine.
    -I know its not a cable issue because I tried it on a CRT monitor with a built-in cable and the same thing happened.

    So it must be something with my laptop mobo. The interesting thing is when I unplug it from power and let it run on battery, the noise disappears altogether.

    If I let it run on battery and then plug it back after the battery has lost some charge, the noise is gone until the battery is recharged. So I know its an issue with interference from the power source and the charging circuit eliminates it.

    It happens both when plugged into the original a/c adapter as well as when hooked into the output of my CNX-P2140 which is very clean and stable.

    Does anyone know of a way I can reground or shield something to prevent this? The laptop is a compaq presario 2800t, p4 1.6ghz. Thanks!

  2. #2
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    anyone?

  3. #3
    Maximum Bitrate Borte's Avatar
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    Make sure that you use the SAME ground point for both the screen and the laptop.
    That helped for me.
    Failure is not an option...
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  4. #4
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    theyre both grounded directly back to my power supply.

  5. #5
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    Could this be a ground loop ? Check that there is no small voltage between your ground source to battery ground.

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