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Old 08-15-2008, 09:54 PM   #1
Odyssey1942
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Resolution issue with older of two same model monitors


I have been using Ubuntu 7.04 on a 1 to 1-1/2 year old 19" Sceptre lcd monitor for some time and want to move that computer to another location and use it alongside a Windoze machine with a KVM also with an (older) Sceptre 19" lcd monitor allowing me to switch between the two. It works OK except for one thing.

The natural resolution for each screen is 1024 x 768. Ubuntu comes up just fine in that resolution on the newer monitor I had been using. But it only comes up in 800 x 600 on the older monitor in the new setup using the KVM. I went to the System/Preference/Screen Resolution, but it only offers a lower resolution (640 X 480), not the 1024 x 768 that I want and need.

Is this likely because the monitor that I want to use is older than the one that works correctly or because of the KVM?

Any ideas welcome. TIA
 
Old 08-16-2008, 04:20 AM   #2
GlennsPref
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Hi, I think it is because of the kvm, not allowing the edid from the lcd monitor.

If you set a static config (in /etc/X11/xorg.conf) instead while the monitor is plugged in bypassing the kvm switch, you should be able to make it stick.

Then make sure edid is turned off. IMHO, edid is being sought by X, but the kvm won't allow it.

I hope this gives you something to look for, regards, Glenn
 
Old 08-16-2008, 03:53 PM   #3
Odyssey1942
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Glenn, Thanks for yours.

Just to be sure that this doesn't pre-empt the proposed solution. The Windoze machine is getting the desired resolution onto the monitor. Is Ubuntu unique in that it cannot get through while Windoze can. Or does the fact that Windoze can accomplish it indicate a different solution path than the one proposed?

If not, I am very much a linux noob, so don't know how to implement your suggestion. Don't understand how to:

"set a static config (in /etc/X11/xorg.conf)" or "turn off edid"

Can you refer me to a tutorial of some sort that will help me through it?
 
Old 08-16-2008, 09:16 PM   #4
GlennsPref
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To turn off edid, and see if it actually is the problem, check this post, it has directions...

http://www.linuxquestions.org/questi...t-edid-624959/
 
Old 08-18-2008, 05:19 PM   #5
Odyssey1942
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Solution found:

The following articles are helpful:

1. https://help.ubuntu.com/community/Fi...esolutionHowto

and

2. HOWTO: YES! There IS an easy, safe way of reloading Xorg.conf without shutting down X - Ubuntu Forums

A combination of the two results in a changed xorg.conf file and when a second session is started, the screen still comes up in the lower resolution.

However, clicking on System/Preferences/Screen Resolution shows that the desired resolution choice is now available. Choosing the desired resolution implements properly.

Thanks for your help.
 
Old 08-18-2008, 06:49 PM   #6
GlennsPref
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To save me reading those links, did you use 2 drivers?

Can you post your new xorg.conf for interference?

Thank you, I'm interested in how it is implemented.

I thought, like my kvm switch, the switch blocks the dmps signal from passing through,

regards, Glenn
 
Old 08-18-2008, 09:54 PM   #7
Odyssey1942
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Glenn, I think you are exactly right about the KVM blocking EDID. The solution was three part:

1. editing xorg.conf to add the necessary parameters that Ubuntu was not receiving through EDID. The monitor lines in xorg looked like this before editing:

Code:
Section "Monitor"
	Identifier	"Sceptre"
	Option		"DPMS"
and like this after:

Code:
Section "Monitor"
	Identifier	"Sceptre"
	Option		"DPMS"
        HorizSync          24-80
        VertRefresh        50-75
2. finding the parameters for HorizSynch and VertRefresh to insert in the above. After an exhaustive search, I finally found the CD that came with the monitor which had a user manual with specifications.

3. the third part had to do with my trepidation in restarting X in case I had not got the editing right. You appear to be very capable, unlike myself, in editing without concern for things going pear shaped. If I got this right you can ignore this point. Otherwise, I suggest you read the article. But in a word, it was simply to click through on System/Preferences/Screen Resolution and choosing the now available correct resolution.

If I have missed anything you wanted to know, sing out.
 
Old 08-19-2008, 01:41 AM   #8
GlennsPref
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That's great, I glad you got it worked out.

See you 'round the posts, Glenn
 
  


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