Blurry video on a HP nc4200

My boss has an HP nc4200 notebook he wants to use for presentations.
Unfortunately, we found the video output is quite unstable, i.e. there
is something like an interference wave running down the picture, every
display line seems to jiggle left and right by about 2-3 pixels. Another
nc4200 shows the same pattern, so it's probably a software problem. Both
machines are running Gentoo Linux with X.org 4.8.99.15. We haven't tried
either under Windows yet as it would mean a complete reinstallation. Any
experiences with this misbehavior? Maybe something to do with the two
different rendering pipes in the gfx adaptor? I never quite got what
they are meant for anyway, Pipe A seems to be unused here and the CRT
uses the same one as the internal display.

regards
Matthias
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In comp.sys.laptops Matthias Bethke <> wrote:
> My boss has an HP nc4200 notebook he wants to use for presentations.
> Unfortunately, we found the video output is quite unstable, i.e. there

Well, lower the pixel frequency to something it can handle.

> is something like an interference wave running down the picture, every
> display line seems to jiggle left and right by about 2-3 pixels. Another
> nc4200 shows the same pattern, so it's probably a software problem. Both
> machines are running Gentoo Linux with X.org 4.8.99.15. We haven't tried
> either under Windows yet as it would mean a complete reinstallation. Any
> experiences with this misbehavior? Maybe something to do with the two

What makes you think it's not your configuration at fault? Have you
tried other configurations? What Modeline parameters are you using?
(pixel frequency, resolution). Are you using acceleration? What happens
when you don't?

What you describe sounds exactly like the card being over-driven at a
higher frequency than the components can take (badly shielded, etc.).
It may simply be your video cable that is the component at fault! But
you won't find out unless you experiment!

> different rendering pipes in the gfx adaptor? I never quite got what
> they are meant for anyway, Pipe A seems to be unused here and the CRT
> uses the same one as the internal display.

Well, switch the internal display off and see if that helps. Fiddle!

And read the driver notes for your release at Xorg. Contact the authors
too.

Peter

Matthias Bethke schrieb:

> My boss has an HP nc4200 notebook he wants to use for presentations.
> Unfortunately, we found the video output is quite unstable, i.e. there
> is something like an interference wave running down the picture, every
> display line seems to jiggle left and right by about 2-3 pixels. Another
> nc4200 shows the same pattern, so it's probably a software problem.

It's highly likely to be a software problem. As Peter already wrote the
symptoms are the ones that are caused by operating the gfx outside it's
specifications. Besides the blurry video you experience you also can
damage your hardware with that.

> Both
> machines are running Gentoo Linux with X.org 4.8.99.15. We haven't tried
> either under Windows yet as it would mean a complete reinstallation.

Well, the nc4200 is sold with Windows so that should be the first thing
to try. Shouldn't be a problem to make a HD image of the Linux install,
save it over the network, and install Windows on it. It should work as
expected, at least if you haven't already fried the gfx...

> Any
> experiences with this misbehavior?

We have several nc4200 at work, and all of them work fine as source for
presentations on different beamers.

Benjamin

"Matthias Bethke" <> wrote in message
news:...
> My boss has an HP nc4200 notebook he wants to use for presentations.
> Unfortunately, we found the video output is quite unstable, i.e. there
> is something like an interference wave running down the picture, every
> display line seems to jiggle left and right by about 2-3 pixels. Another
> nc4200 shows the same pattern, so it's probably a software problem. Both
> machines are running Gentoo Linux with X.org 4.8.99.15. We haven't tried
> either under Windows yet as it would mean a complete reinstallation. Any
> experiences with this misbehavior? Maybe something to do with the two
> different rendering pipes in the gfx adaptor? I never quite got what
> they are meant for anyway, Pipe A seems to be unused here and the CRT
> uses the same one as the internal display.
>

It is most likely that the refresh rate of the output from the laptop does
not match the optimum for the projector (it should probably be 60Hz - but
check the book of instructions).

It is also just possible that you have an earth loop, if both the projector
and the laptop are earthed. Does the problem disappear if you run the
laptop on the battery?