> From: Jun Qian <[log in to unmask]>
>
> I believe the problem is called "ghost affect", it usually caused by bad
> cable/switch box, or if you are using long vga cable, make sure to use
> "high
> resolution" cable and the conncetors are good. The other issue is the
> location, is there any reason that the location is unsuitable for
> (I've seen this problem in some offices), can you move the monitor
> around see
> if any better?
>
> Do you have same problem with ATI card?
>
> J Qian
>
> Earl Truss wrote:
>
> > I've just replaced an ATI Xpert 98 video card with a Creative Banshee.
> > Graphics displays appear fine but when displaying text, especially black
> > lettering on a white background, I can see ghosts of the letters to the
> > right of each letter and the text appears blurred and hard to focus on.
> > I've upgraded to the latest drivers, but not latest BIOS. I've played
> > around with cables, other equipment in the area and monitor settings and
> > nothing seems to have an effect. What kinds of things should I check for
> > or could this just be a defective card?
>
> ------------------------------
Back in the "old days", when everybody received their TV "off air"
instead of by cable, "ghosting" was a common problem - caused by a reflected
signal that took a longer path to the antenna than the direct signal.
I suspect that the distance the reflected signal is to the right of the
original signal on your monitor corresponds to twice the length of your cable
divided by the speed of light. Just as floppy drives, SCSI devices, etc.
need terminating resistors to absorb the signal when it gets to the end
of the cable to prevent the signal from reflecting back and forth in the
cable, the monitor should have terminating resistors. The video card
doesn't need them, as it doesn't receive any signal (other than monitor type
indicated by some grounded pins). Some monitors have switched inputs with
different input load resistances (say, 50 Ohms and 150 Ohms) to match
different types of cables. If so, switching to a higher value should help.
If not, you might try installing, say, 300 Ohm resistors between the video
signal lines and ground at the monitor end of the cable (inside the cable
connector). This would avoid exposing yourself to the hazards inside the
monitor.
Note that the lower these resistances, the harder your video card has to
work. An accidental short circuit could kill it.
A simpler, perhaps less effective (but maybe effective enough) solution
would be to install a ferrite toroid ("doughnut") at the monitor end of the
cable. Something like a RF transformer core with an area roughly 3/8 in.
(9 mm) square should do. If it is split in two halves, this will save
having to remove and replace the connector. In a pinch, a large steel
nut may be "good enough".
Use something like heat shrink tubing to hold it in place.
Hope this helps
Boyd Ramsay
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