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laptop to lcd tv issue

Discussion in 'Electronic Repair' started by [email protected], Sep 8, 2007.

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  1. Guest

    Hi

    The problem is that when connected laptop to lcd tv, while laptop
    running on ac power, the tv screen flickers. When switched to battery,
    screen looks smooth without any issues. Plug in powerd cord again and
    the screen starts flickering again.

    Any idea what could be a problem. Tried all resolutions, refresh rates
    and nothing improves the quality. The problem only occurs while laptop
    connected to ac power. Thought that maybe could it be that processor
    speed interferes, but while running on battery set up all to max speed
    and everything seems fine, screen looks smooth. While on ac power,
    even when reduced processor speed to minimum, I could say that it
    improves the quiality a little, but still visible noise on the screen.

    Please help
     
  2. Peter K

    Peter K Guest

    Possibly smoothing cap in Powersupply faulty,
    causing interference to go through the laptop to the tv?
    Perhaps try another PSU (if u have one)
    P
     
  3. If processor speed really does affect this, then could be bad
    or inadequate filtering in the powre supply as suggested below.

    Long shot but make sure the laptop is plugged into the same AC circuit
    and try reversing the laptop or TV plug if they aren't polarized.

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  4. Guest

    It might be a ground loop. I had this problem several twice (using
    Desktop PC and laptop) (in Germany...) and both times it was a ground
    loop. A solution may be to use a _STRONG_ wire to link the grounds of
    the devices to avoid the current flowing through the thin Ground lead
    of the cable.
    If you have one, you could try an isolation transformer before the
    power supply, but du NOT connect the laptop's ground!
     
  5. JANA

    JANA Guest

    There is a ground loop occurring between the AC mains and the signal ground
    coming from the laptop to the TV. They both use different field rates
    internally.

    If you can find a way to isolate either the power supply in the laptop, or
    the power supply in the TV, this will fix the problem.

    One thing you can try, is if the laptop has a ground pin on its AC cord,
    invest in a ground lift adaptor at the hardware store, or if you safely know
    how, buy the pieces and make on one up your self.

    If the laptop uses no dedicated AC mains ground, and is using a polarized AC
    mains connector only, then you will have to research out how to do an
    isolation on it. This may mean opening the power supply and working out some
    design changes, which I do not advise, unless you are skilled in designing
    power supplies.

    --

    JANA
    _____


    Hi

    The problem is that when connected laptop to lcd tv, while laptop
    running on ac power, the tv screen flickers. When switched to battery,
    screen looks smooth without any issues. Plug in powerd cord again and
    the screen starts flickering again.

    Any idea what could be a problem. Tried all resolutions, refresh rates
    and nothing improves the quality. The problem only occurs while laptop
    connected to ac power. Thought that maybe could it be that processor
    speed interferes, but while running on battery set up all to max speed
    and everything seems fine, screen looks smooth. While on ac power,
    even when reduced processor speed to minimum, I could say that it
    improves the quiality a little, but still visible noise on the screen.

    Please help
     
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