Two display anomalies (one FIXED, one left open)

Matthew Saltzman mjs at ces.clemson.edu
Thu Sep 8 00:16:23 UTC 2005


If you are following this thread, there are updates on both issues below.

Thanks for your suggestions so far.  Keep 'em coming!

On Wed, 7 Sep 2005, Matthew Saltzman wrote:

> On Wed, 7 Sep 2005, Bob Chiodini wrote:
>
>> On Tue, 2005-09-06 at 23:01 -0400, Matthew Saltzman wrote:
>>> On Tue, 6 Sep 2005, Bob Chiodini wrote:
>>> 
>>>> On Tue, 2005-09-06 at 20:58 -0400, Matthew Saltzman wrote:
>>>>> (1)
>>>>> Video card: NVIDIA GeForce 2 MX (generic)
>>>>> Monitor: Samsung SyncMaster 930B (flat panel)
>>>>> Driver: nvidia (the commercial one), but it happens as well with nv.
>>>>> Resolution: 1280x1024, 32-bit color or 16-bit color
>>>>> Sypmtom: Monitor flickers as if it's synching at very low rate.
>>>>> The monitor reports that it is syching at 75Hz, but I still see flicker.
>
> Strange, this morning, the monitor is perfect.  Even the auto-adjust works 
> (forgot to mention that it was aligning the image too far left).  And I 
> didn't touch anything.
>
> I'm almost afraid to try rebooting.  But I'll keep the synch advice handy in 
> case I see a recurrence.

Looks like this morning was just a case of the ambient light obscuring the 
flicker.  It was back this afternoon, and setting the vertical refresh 
rate to a max of 60 Hz seems to cure it.

Auto-adjust works if it's done after logging in.  If I do it at the login 
screen, it might display anomalies.

>
> That leaves this one:
>
>>>>> 
>>>>> (2)
>>>>> Video card: ATI Radeon Mobility 7500 in an IBM Thinkpad T41.
>>>>> Driver: radeon
>>>>> Kernel: kernel-2.6.12-1.1398_FC4
>>>>> Kernel option: video=radeonfb
>>>>> X: xorg-x11-6.8.2-37.FC4.45
>>>>> Symptom: When I use the VGA-out jack to connect to an overhead projector
>>>>> or external monitor, the projector image ripples slowly, as though (very
>>>>> narrow) waves are passing over it.
>>>>> 
>>>>> In FC3, this behavior varied with the kernel version.  In FC4, I need 
>>>>> this
>>>>> kernel in order to get proper ACPI behavior, so I haven't tested much. 
>>>>> In
>>>>> WinXP, the display is rock-solid.
>
> I'll check refresh rate in XP and Linux and test some cables and report back.

Haven't tested yet, but I did find out that the vert. refresh rate in XP 
is 60Hz.  It appears from the logs to also be 60Hz in X, but I changed 
xorg.conf anyway.  That does not appear to affect the problem on my 
externa monitor.  I will check the projector with a brand new cable 
tomorrow.

Forgot to note that the problem occurs in a virtual console as well as in 
X.


>
> Thanks for the help so far.
>
>>>>> 
>>>>> [...]
>>>>> 
>>>>> For (2), I'm pretty convinced it's a bug, but I' not sure what component
>>>>> to report it against.  In FC3, it varied with kernel version, with
>>>>> whatever XFree/xorg was installed.  So I'm sort-of thinking kernel.
>>>>> 
>>>>> Thanks for any suggestions.
>>>>> 
>>>> [...]
>> 
>> Matthew,
>> 
>> When I needed to switch from a tube to an LCD, I
>> edited /etc/X11/xorg.conf and changed the upper vertical refresh rate to
>> 60.
>> 
>> Bob...
>> 
>> 
>> 
>
>

-- 
 		Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs




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