[mythtv-users] OT: Optimising 50Hz over 60Hz VGA

Ben Lancaster lists at benlancaster.co.uk
Wed Apr 11 13:06:04 UTC 2007


ryan patterson wrote:
>
>
> On 4/11/07, *Flo* <flo at flobittner.de <mailto:flo at flobittner.de>> wrote:
>
>
>     There's only one thing left with my picture, sometimes there's
>     like a wave
>     moving downwards through the picture. I think there's a difference
>     in the
>     vertical sync of my lcd and the graphics card. But i'm not sure
>     because it's
>     hard to describe and to find anything about that...
>
>
> Sounds like a ground loop problem to me.  in short, the LCD and the 
> computer both have their power cords connected to ground.  But there 
> is a small voltage difference between the LCD's ground and the 
> computer's ground.  This causes a small current in the ground signal 
> of the video cable going between the LCD and computer.
Seconded. Are they both plugged in to the same socket/multigang? If so, 
then I guess it could be your PSU, or your graphics card misbehaving.


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