video signal reflection

  • Thread starter Thread starter blushark
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blushark

hi,
recently i upgraded my system with a new MB/processor/RAM/graphic card/PSU.
after booting up, i noticed a ghosting effect on my CRT monitor which i
previously only encountered on TV (when due to poor reception or contact on
antenna cable, everything displayed has several shadows on its right).
this however occurs in windows and any application i run.

dark objects leave these ghost shadows on bright areas. for example, if I
was to type letter O in notepad, this is how it would be displayed:
O)))))
ghosts are very transparent, you wouldn't notice them at first glance, but
after some time it's driving me crazy.


first thing i did was check monitor cable and connection, but no luck
there. then i tried connecting monitor to gfx card via DVI->analog adapter.
same thing.
then i borrowed a laptop, connected it to my monitor and the picture was
fine. (i used the same test image)
that would eliminate monitor and it's cable as source of problems.

does anyone have any ideas what might be causing the problem?

it's obviously one of newly inserted components, but i'm at loss as to what
might be going on and why.

newly inserted components are:
gigabyte 965-DS3 motherboard
gigabyte GF 8400GS PCIE
Intel E4500, DDR2 RAM, SATA DVD, new PSU.
i also have a PCI TV-card, SATA and IDE HDDs, if it matters.

i'm pretty far away from place where i bought the upgrade, so i can't just
simply take it back, i'd need to at least first figure out the exact
problem.

any replies are appreciated!
 
blushark said:
hi,
recently i upgraded my system with a new MB/processor/RAM/graphic
card/PSU.
after booting up, i noticed a ghosting effect on my CRT monitor which i
previously only encountered on TV (when due to poor reception or contact
on
antenna cable, everything displayed has several shadows on its right).
this however occurs in windows and any application i run.

dark objects leave these ghost shadows on bright areas. for example, if I
was to type letter O in notepad, this is how it would be displayed:
O)))))
ghosts are very transparent, you wouldn't notice them at first glance, but
after some time it's driving me crazy.
Click to expand...

Did you happen to change video cables, add an extender
or video switch, or some such during your upgrade? Does
the monitor happen to have switchable termination at the
video inputs (it would have labels something like "75 ohms"
and "High-Z" as the options) that might have been switched
the wrong way?

There's also the possibility that the monitor never has
had very good termination, but the reflections from the
monitor inputs didn't result in visible ghosting simply because
the old graphics card DID terminate the line properly.
(For the "ghost" to be visible, the reflection - generated
at the monitor termination - has to make it back to another
impedance mismatch and be reflected back toward the
monitor.)

Bob M.
 
hello bob,
Did you happen to change video cables, add an extender
or video switch, or some such during your upgrade?
Click to expand...

i didn't. monitor and cable are the same, just new graphics card directly
connected to monitor. as i said, same happens when using DVI output with
analog converter.
the monitor happen to have switchable termination at the
video inputs (it would have labels something like "75 ohms"
and "High-Z" as the options) that might have been switched
the wrong way?
Click to expand...

i have inspected the monitor (which btw is a 19" iiyama MM904UT).
unfortunately it has no switchable termination, just power and signal
cables and nothing extra.
There's also the possibility that the monitor never has
had very good termination, but the reflections from the
monitor inputs didn't result in visible ghosting simply because
the old graphics card DID terminate the line properly.
(For the "ghost" to be visible, the reflection - generated
at the monitor termination - has to make it back to another
impedance mismatch and be reflected back toward the
monitor.)
Click to expand...

it might be possible, yet i'm not sure why would it manifest only now?
i've been using this iiyama monitor (a decent mid-range model) for years,
on 3 different graphic cards. (gigabyte radeon 9200, leadtek geforce 6600
and now gigabyte geforce 8400gs).
i don't know what is the probability that this new graphics card from
relatively reputable manufacturer would fail to terminate the line
properly?
any other ideas?


i really appreciate your reply, thank you!
 
hello bob,


i didn't. monitor and cable are the same, just new graphics card directly
connected to monitor. as i said, same happens when using DVI output with
analog converter.


i have inspected the monitor (which btw is a 19" iiyama MM904UT).
unfortunately it has no switchable termination, just power and signal
cables and nothing extra.


it might be possible, yet i'm not sure why would it manifest only now?
i've been using this iiyama monitor (a decent mid-range model) for years,
on 3 different graphic cards. (gigabyte radeon 9200, leadtek geforce 6600
and now gigabyte geforce 8400gs).
i don't know what is the probability that this new graphics card from
relatively reputable manufacturer would fail to terminate the line
properly?
any other ideas?
Click to expand...

Ghosts are *only* caused by multiple versions of the signal arriving at the
receiver/monitor. Given the info you supplied and Bob's post, I'd be 98% sure
the problem is the new video card. (Your tests with the laptop source pretty
much confirm that.) The other 2% possibility is that the video cable to the
monitor has suffered some damage during your changeover.

If you still have the previous video card, try installing that onto the new
platform. That will very quickly verify whether the new v/c is the culprit.

Also check the new v/c for any switchable/jumper_selectable features.
 
blushark said:
i didn't. monitor and cable are the same, just new graphics card directly
connected to monitor. as i said, same happens when using DVI output with
analog converter.
Click to expand...

Not sure what you mean by "DVI output with analog
converter." Are you talking about an external box that
will convert a DVI-D output to analog, or do you have
a DVI-I output and are using a DVI-to-VGA cable?

Either way, though, it's sounding like you've possibly
got a problem within the monitor itself - can't imagine
why it would just have happened at the same time you're
changing everything else, but if it's an old CRT monitor
there's a good chance you've got a fair length of cabling
between the input connector and the video amp board
in the monitor. If so, the reflection could be bouncing
around solely within the monitor - between a bad
termination at the input to the video amp board and
the input connector on the rear.

Bob M.
 
Ghosts are *only* caused by multiple versions of the signal arriving at the
receiver/monitor. Given the info you supplied and Bob's post, I'd be 98% sure
the problem is the new video card. (Your tests with the laptop source pretty
much confirm that.) The other 2% possibility is that the video cable to the
monitor has suffered some damage during your changeover.
Click to expand...

it seems apparent to me too that it's probably due to new graphics card.
cable is probably out of the question because i switched to laptop twice,
checking and comparing in between.
If you still have the previous video card, try installing that onto the new
platform. That will very quickly verify whether the new v/c is the culprit.
Click to expand...

unfortunately old video card won't work (agp vs pcie), so i can't do that.
i was thinking of trying a different monitor, or trying the same card
somewhere else, but that is going to take some time as i have no idea who
to ask for help.
Also check the new v/c for any switchable/jumper_selectable features.
Click to expand...

i will, but i think it's just a regular budget card with no special
features.

thanks for replying!
 
Not sure what you mean by "DVI output with analog
converter." Are you talking about an external box that
will convert a DVI-D output to analog, or do you have
a DVI-I output and are using a DVI-to-VGA cable?
Click to expand...

i have VGA and DVI-I output on the video card, and i found somewhere a
little DVI-to-VGA converter, so i tried connecting the monitor via both VGA
and DVI output (to eliminate any possibility of having trouble on the VGA
port).
however, there was absolutely no difference.

Either way, though, it's sounding like you've possibly
got a problem within the monitor itself - can't imagine
why it would just have happened at the same time you're
changing everything else, but if it's an old CRT monitor
there's a good chance you've got a fair length of cabling
between the input connector and the video amp board
in the monitor. If so, the reflection could be bouncing
around solely within the monitor - between a bad
termination at the input to the video amp board and
the input connector on the rear.
Click to expand...

i imagine it could, yet i'm not sure why the monitor would work perfectly
on the laptop and old videocard?
monitor cable is average length, just like any other i've had experience
with, and trying to move/bend it to check for bad contact had no results.

well, i guess trying a different videocard and monitor is inevitable.

thanks again!
 
blushark said:
i have VGA and DVI-I output on the video card, and i found somewhere a
little DVI-to-VGA converter, so i tried connecting the monitor via both
VGA
and DVI output (to eliminate any possibility of having trouble on the VGA
port).
however, there was absolutely no difference.



i imagine it could, yet i'm not sure why the monitor would work perfectly
on the laptop and old videocard?
monitor cable is average length, just like any other i've had experience
with, and trying to move/bend it to check for bad contact had no results.

well, i guess trying a different videocard and monitor is inevitable.

thanks again!
Click to expand...

It could be that the new video card is putting out a different video
signal level. It might be too high for the monitor to adjust to, and
inducing ringing in the monitor's input circuits causing it to display
multiple object edges. The best way to determine is to try it with
another monitor. The newer video cards with DVI outputs are
better paired with LCD monitors with DVI in. No ghosting there as
there is a one to one pixel relationship between card memory and
monitor screen locations with exact timing.
 
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