[mythtv-users] Refresh line being seen

[Allen Edwards]

On Sat, Feb 14, 2009 at 10:22 AM, Brian Wood <beww at beww.org> wrote:

> On Saturday 14 February 2009 11:02:41 MrVining wrote:
> > On Feb 14, 2009, at 9:26 AM, Paulin wrote:
> > > I'm having an old problem reappear after upgrading the NVidia
> > > driver and then downgrading.  Can't seem to figure it out.
> > >
> > > 1. Upgraded to 180.22 NVidia driver.
> > > 2. Eventually downgraded back to 180.16 driver.
> > > 3. Put the .nvidia-settingrc file back from before the upgrade
> > >
> > > Now whenever watching a recorded program there is a thin line
> > > scrolling down the screen every minute or so.
> > >
> > > Can anyone tell me what I should be looking at to correct this.  I
> > > thought it was caused by the Nvidia settings but since they are
> > > back to what they were before I updated/downgraded the driver I'm
> > > not sure why it's happening.
> > >
> > > Any help would be appreciated.
> > >
> > > Thanks,
> > > steve
> >
> > Is it possible that it is not driver related?  Has there been any
> > physical changes made to the system.  I hear line slowly scrolling
> > down the screen and I still jump right to grounding issue (retired
> > cable guy).
>
> With NTSC at least, a horizontal line scrolling slowly *up* the screen
> indicates 60 or 120 Hz. hum. The rate is the difference between the
> vertical
> rate being precisely 60Hz, and what it really is with NTSC color (in other
> words, if 3.579545 was in fact 3.600000, then the bar would be stationary).
>
> A grounding issue would thus create a moving up bar, unless the scan rate
> of
> the video was far enough from 60Hz. to create a downward motion of the bar.
>
> I tend to agree that the OP does not have a driver issue, more likely some
> sort of interference in the machine itself, the monitor, or the cabling, or
> some sort of common mode (ie: grounding) problem.
>
> --
> beww


By ground problem, likely it means that there is a difference between the
computer ground and the TV ground.  So, in this case you may not have done
anything to the computer but if you plugged the TV in to a different slot or
changed your antenna setup it could explain it.

If you have cable, it could even be that the cable guy came by while you
were not looking and grounded the feed.

I had to run power from my projector to my surround setup to get rid of a
line like that. Now everything is on the same circuit.  I also ground my
antenna to that same sub panel.

Allen
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