Sharp 172G-B TFT odd DVI issue

P

Philip

Hi

I have come across a strange problem using a Sharp 172G-B TFT monitor, and
wondering if anyone has any ideas. Graphics card is a XFX GeForce 5200,
using latest Nvidia drivers and problem present on older drivers.

I noticed one bright white flickering pixel, I thought it was a failing
pixel, but it wasn't as it moved when I dragged the image. The pixel always
manifests
itself in the same place in the same image. Moving the mouse pointer close
to it and the pixel becomes
normal (i.e. takes up its correct colour and stops flickering). I opened
the image in Paint Shop Pro and was able to cut and paste the section with
the bright pixel to a new image and that had it too. Zooming into the image
the white pixel grew to become a vertical green line (around 10 pixels high)
that flickered, looking like some form of interference. Changing the colour
depth of the image in Paint Shop Pro and the problem moved to a different
part of the image. Changing from 32bit to 16bit on the graphics card and the
problem seemed to go completely.

So I did some troubleshooting, and completely baffled as to where the
problem might be:

1) Swapping the Sharp monitor with a Philips 17" TFT with the same DVI cable
on
the same computer showed no flickering pixel problem on the Philips. This
made me think it was the Sharp monitor at fault as the Philips was fine.
2) Putting the Sharp TFT on a different computer (different graphics card
and cable), showed no flickering pixel problem when showing the same image.
So the Sharp monitor is okay?
3) Putting the Sharp back on the original computer and flickering pixel is
back so..
4) Swapping over the DVI cables and the flickering pixel is gone on the
Sharp, however I then noticed that it had moved to a different part of the
image and is now static bright, although this time disappears on zooming in
rather than becoming a horizontal green line. So sort of indicates a cable
problem as changing the cables results in a change to the symptoms?
5) Running the Sharp from the analogue connection shows no flickering pixel.
Indicating the panel is fine and it must be related to the DVI connection in
some way. Although I can't understand if it is a cable problem, how the
cable knows to effect the exact same pixel on every screen refresh, wouldn't
problems be more random?

I have ordered a new quality DVI cable to try as these current ones were
bundled with the monitors, but have given no problems before on other
monitors. It seems to
me that a particular combination of colours causes a data glitch on that
row, resulting in this phantom white pixel. I always get the problem in the
same image and saw it once while browsing a web page, but other than that
other pictures and graphics seem free from flickering rouge pixels at this
point in time.

If this is a problem with the graphics card, why doesn't it appear on
another monitor? If it is a problem with the Sharp monitor, why using a
different DVI cable results in a change to the problem, and the Sharp and
cable works fine on a different computer?

Any ideas as to what could be causing this?

Regards

Phil
 
Joined
Oct 3, 2005
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flickering pixels

I just had this exact same problem, i.e., flickering pixels (flashing white) on some photos but not others, always in the same spot on those photos, even as the photos are scrolled up and down (hence it's not bad pixels on my monitor). I am using a Samsung SyncMaster 930B on a WindowsXP machine with a NVIDIA GeForce FX 5500 w/DVI port. The video setting is at 1280x1024 and 32-bit color. The photos with flickering pixels had been clean only yesterday, this is a new phenomenon.
When I lowered the color depth to 16-bit the problem disappeared completely. And when I went back to 32-bit, it was still gone (so far). It seems to me the problem is rooted in the NVIDIA GeForce video card, especially since you are also using the same card type, albeit an earlier version.
If anyone is aware of such bugs in GeForce cards I would like to hear more about it. I already loaded the latest available driver for my card.
 

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