New Flat Panel Monitor "Flicker" Problem Under SuSE 8.1
Daniel Harper
I've got one that's troubling me. I'll keep it short and sweet.
Just bought an NEC MultiSync LCD1765 Flat Panel display, and it's giving
me problems with the frequency. Whenever I boot up the fonts display in
disjointed lettering, and whenever my window manager opens, I get a sort
of "flicker" effect on the gray standard background. Whenever KDE opens,
it puts a nice wallpaper _over_ the effect, and solves it insofar as the
system is usable, but I cannot use my console windows without having to
puzzle out partial commands.
I've been fiddling with frequency rates under YAST all day, and can't
quite figure out what the problem is. Whenever I ctrl-alt-F6 (or F1 or
whatever) over, the monitor displays a warning that I am currently outside
the operating frequency of the monitor, even though under YAST I have
deliberately set the display frequency to one that is usable with this
monitor. My guess is that the display under the console window is giving
me issues with resolution/frequency, but I have no idea how to change
those.
Any help you can give would be much appreciated. This problem did not
occur with my old 17" flat screen KDS monitor, or any other non-flat panel
that I installed on the system.
Thanks in advance.
--
In the Beginning, was the Command Line...
--Daniel Harper
(change terra to earth for email)
Ben McTee
moving, but then the welcome/login screen shows up and then it's fine. The
command line looks ok too, so I didn't worry about it that much. I'm booted
into windows right now or would tell you what my refresh rate is. I believe
it's at 72, but can't be for sure.
--
Ben McTee
---====---
"Daniel Harper" <daniel...@terralink.net> wrote in message
news:pan.2004.03.30...@terralink.net...
Valentín Guillén
> I've been fiddling with frequency rates under YAST all day, and can't
> quite figure out what the problem is. Whenever I ctrl-alt-F6 (or F1 or
> whatever) over, the monitor displays a warning that I am currently outside
> the operating frequency of the monitor, even though under YAST I have
> deliberately set the display frequency to one that is usable with this
> monitor. My guess is that the display under the console window is giving
> me issues with resolution/frequency, but I have no idea how to change
> those.
>
> Any help you can give would be much appreciated. This problem did not
> occur with my old 17" flat screen KDS monitor, or any other non-flat panel
> that I installed on the system.
On last-century old CRTs, the screens were drawn by a moving electron ray,
and the screens were drawn up at the rate of "so many" per second. Because
of the way the human eye "sees", the rate of assembly of these "screens"
had to be a certain minimum, or else the human eye would perceive
"flicker" on the screen. For most, but not all of us, the perception of
flicker disappears at about 70~72 'refreshes' per second. In old CRT
parlance, this was called the 'vertical refresh rate', and in
most-things-video, this is still the term.
Now with the advent of LCD and other newer technologies, the way
information is assembled or drawn up on these newer screens is all the way
different. However, XFree86 STILL uses files and parlance from the old
technology. Indeed, these video configuration utilities still need to deal with the
old technology, while accomodating those of us who can afford the newer
tech.
With the older technology (CRTs) we did our best to avoid vertical refresh
rates below 70Hz. But with LCDs, the vertical refresh rate is not
"non-ergonomical" at 60 Hz refresh rate. You can and should set your
vertical refresh rate at 60Hz.
The easiest way to do this is to drop out of a GUI, and edit your
XF86Config file, and in the appropriate section of the file, manually edit
and insert 60Hz as the vertical refresh rate. Fire up your X, and all
should be better.
It goes without saying that you should first consult the documentation
provided by NEC with the panel. And of course, you haven't mentioned if
your video display adapter is being used with, or whether it even provides a
DVI-D or other digital interconnector, or if you're using a VGA plug, and
display input.
Try that and see if there is a radical improvement!
Regards,
vg
Zurab Davitiani
> I know the regulars here probably get sick of answering questions, but
> I've got one that's troubling me. I'll keep it short and sweet.
>
> Just bought an NEC MultiSync LCD1765 Flat Panel display, and it's giving
> me problems with the frequency. Whenever I boot up the fonts display in
> disjointed lettering, and whenever my window manager opens, I get a sort
> of "flicker" effect on the gray standard background. Whenever KDE opens,
> it puts a nice wallpaper _over_ the effect, and solves it insofar as the
> system is usable, but I cannot use my console windows without having to
> puzzle out partial commands.
I think the "flicker" or "moving dots" on that screen when X starts is OK. I
have the same thing on slightly older Sony.
> I've been fiddling with frequency rates under YAST all day, and can't
> quite figure out what the problem is. Whenever I ctrl-alt-F6 (or F1 or
> whatever) over, the monitor displays a warning that I am currently outside
> the operating frequency of the monitor, even though under YAST I have
> deliberately set the display frequency to one that is usable with this
> monitor. My guess is that the display under the console window is giving
> me issues with resolution/frequency, but I have no idea how to change
> those.
I think you are correct in that YaST changes the X configuration options.
When you switch out of X, or shut it down, those no longer apply. You said
when system was booting up you are seeing "disjointed lettering." Can you
see lilo/grub screens OK? Is there a way you can configure your monitor for
that text mode? When you go out of X, do you still see "disjointed letters"
or does it have another effect? What video card/driver do you have?
Daniel Harper
I edited the file by hand under a non-GUI interface, and got no change. I
checked the file a second ago, and under "Monitor" one of the entries is
"VertRefresh 60". Although I knew better, I even rebooted the system just
to make sure. No change.
> It goes without saying that you should first consult the documentation
> provided by NEC with the panel.
Done and doner. I checked the documentation to see what the Horizontal and
Vertical Rates should be, and set them by hand to the proper numbers. No
change.
> And of course, you haven't mentioned if
> your video display adapter is being used with, or whether it even provides
> a DVI-D or other digital interconnector, or if you're using a VGA plug,
> and display input.
Sorry. I'm using the standard VGA instead of a DVI connector. My video
card doesn't have a DVI connector.
>
> Try that and see if there is a radical improvement!
>
> Regards,
>
> vg
Thanks for the assistance so far, and it at least takes care of one more
"thing to try", but the problem remains as intractable as ever.
One noticeable issue is that even under non-GUI command-line interface, my
text is garbled. It's just barely legible, but it is definitely garbled.
The exact error message my monitor gives me when on one of the alternate
consoles (but not the KDE window manager) is such:
=======================BEGIN ERROR MESSAGE=======================
H. Frequency: 35kHz
V. Frequency: 43kHz
Pixelrate is over limitation.
Please choose suitable one.
======================END ERROR MESSAGE==========================
I also get that message (or something very similar) whenever booting my X
Server. Comments?
Valentín Guillén
> Thanks for the assistance so far, and it at least takes care of one more
> "thing to try", but the problem remains as intractable as ever.
>
> One noticeable issue is that even under non-GUI command-line interface, my
> text is garbled. It's just barely legible, but it is definitely garbled.
> The exact error message my monitor gives me when on one of the alternate
> consoles (but not the KDE window manager) is such:
>
> =======================BEGIN ERROR MESSAGE=======================
>
> H. Frequency: 35kHz
> V. Frequency: 43kHz
>
> Pixelrate is over limitation.
>
> Please choose suitable one.
>
> ======================END ERROR MESSAGE==========================
>
> I also get that message (or something very similar) whenever booting my X
> Server. Comments?
OK I think we're making progress.
When you boot the computer, at the POST section of booting, can you see
the text correctly when using the NEC?
When booting INTO Linux, what is the screen mode? In other words, when
you see the white letters on the black background, are the letters much
smaller than what they were upon power-up/POST?
IF you get a good reading (legible text) during post, examine your BIOS
settings to see what text mode the BIOS is using when displaying text. It
is probably VGA mode, but could be a VESA mode.....
Regarding the XF86Config file and editing it, when X is started, it begins
parsing the file. It will latch onto, and use the first valid modeline
entry which it finds, for whichever is the default resolution/colordepth
which is valid. BUT, you may have several otherwise valid modeline
entries for each resolution/colordepth.
You could save the present file, and then edit out all of the modeline
entries for the resolution you don't want. BUT when you edit out the
unnecessary ones, you can know which are the unnecessary ones by examining
the first entry on the line after the resolution. This is the "clock"
entry, or the "dotclock" entry, and this value must correspond to one of
the dot-clock rates which your video display adapter can support. This is
often called the pixel-rate.
Check to see if your distribution of XFree86 includes a file called
VideoModes.doc. This document is a database which contains information on
how to determine these values for each resolution which your monitor
supports.
If I recall correctly, this "clock-rate" must fall into the value which
the chosen vertical refresh rate dictates. Roughly speaking, the "clock
rate" is doubled, and must fall into the value which is called the
vertical refresh rate. Thus, if the modeline which X selects to use has a
clockrate of 25.175 Hz, for example, and this value gets doubled, then the
doubling is 50.347, which is NOT 60Hz, and therefore that modeline entry
would be invalid when used in a file which dictates Vertical Refresh Rate
of 60. Because the entry would be invalid, X would parse over the invalid
modeline entry and never use it.
More to come.......
vg
Valentín Guillén
> =======================BEGIN ERROR MESSAGE=======================
>
> H. Frequency: 35kHz
> V. Frequency: 43kHz
>
> Pixelrate is over limitation.
>
> Please choose suitable one.
>
> ======================END ERROR MESSAGE==========================
>
> I also get that message (or something very similar) whenever booting my X
> Server. Comments?
The Pixelrate is the "dot-clock rate" and the setting which it is
attempting to use is over the limit which is supposed to be used.
You'll need to be using a Pixelrate which the vid card and montitor combo
can use.
vg
Daniel Harper
No. My LILO and grub screen are disjointed in exactly the same way.
> Is there a way you can configure your monitor
> for that text mode? When you go out of X, do you still see "disjointed
> letters" or does it have another effect? What video card/driver do you
> have?
Under "Display" in YAST, it says I have a SIS6326 Video Accelerator.