Samsung Syncmaster 204B [R] on DVI - don't try that at home!

Published: 2007-01-03 01:08 UTC. Tags: hardware linux syncmaster_204b

Note: This instruction is valid for the ATI driver included with Ubuntu Feisty Fawn (7.04). There's another entry on how to get it working in Ubuntu Gutsy (7.10).

I recently decided that it was time to replace my old trustworthy Nokia Multigraph 446XPro CRT display with a flatscreen. The 446XPro has server me well at various computers at home since 1998 (that's eight years!) but it was time for something less space-consuming on my desk. Also, I like the feeling of not sitting in front of an electron beam several hours a day.

My list of specifications for the replacement was rather short:

  • Must handle a resolution of 1600x1200 (I've been working with this resolution for many hours a day for the past 8 years, so I'm quite used to it)
  • Adjustable height
  • Reasonable price
After some research, I bought a Samsung Syncmaster 204B which seemed to be a reasonable fit given my specifications. As we'll see, the word Syncmaster is somewhat ironic in the name of the product... Also, it turned out that I got a Samsung Syncmaster 204B [R], which turned out to be very significant..

I got the screen just a few days after ordering it, and connected it to my graphics card, a ATI Radeon 9200SE, via analog VGA. After adjusting the vertical refresh to the recommended 60Hz, I got the display working, but with some distortions which made it hard to work with given the high resolution and the small font I use for displaying information. This was a disappointment. Obviously, the VGA decoder in the screen is not good enough to handle the recommended solution.

As a colleague of mine had similar trouble at work and solved them by switching to a graphics card with DVI output, I decided to go the easy way and buy a new graphics card, as the graphics card I had lacked DVI output. It turned out that the 9200SE was the very last card in the series that only had analog VGA output. My usual luck with hardware..

I bought a ATI Radeon 9250 as replacement and installed it. This gave me a sharp image. Yay! Or so I thought, because now, the screen started to go blank now and then with irregular intervals. It went completely black and then came back after half a second or so. Boy, that's irritating!

After many attempts, I managed to find the right words that made Google lead me right. This forum article led me to this forum article which describes the problem - it's a bug in the DVI implementation of Syncmaster 204B [R]. It can't handle the bandwidth. Gah! My usual luck with hardware..

The forum articles says this bug appears only on Syncmaster 204B [R], and only on models made in China. The latter seems not to be true, as mine is made in Slovakia.

There's a workaround - by lowering the vertical refresh to 56Hz, the problem goes away.

I'll do what I can to get a new screen without this bug anyway.

Here's my xorg.conf I use with the Radeon 9250 and the Syncmaster.
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Comment by Dom Layfield

Created Mon, 15 Jan 2007 20:01:52 +0000

I ran into the same problem. I have a dual-head 204B [R] setup (one DVI, one analog) and the DVI-connected 204B keeps blanking when running at 1600x1200 @ 60 Hz.

Like you, I eventually solved the problem by lowering the pixel clock so that the screen refreshes at 56 Hz. However, I needed to do a couple of other things to get everything working properly in dual-head.

Firstly, I had to add a line to the "Monitor" section to override the DDC/BIOS modes. (I think this only applies if you are using the 'radeon' Xorg driver.)

Option "PanelSize" "1600x1200"

Secondly, I found that if I added a modeline to one monitor, it appeared (surpringsly) to automatically be used for both screens, so that my second screen (driven with analog connection) was also running at 56 Hz. That part is fine, but I found that the modified modeline gave a display so far off center that the 'auto-adjust' feature of the 204B could not compensate. Consequently, I had to change the horizontal timings to center the display.

ModeLine "1600x1200@55" 150.0 1600 1804 1996 2160 1200 1201 1204 1250 +hsync +vsync

Comment by Mike Jones

Created Sat, 3 Feb 2007 10:45:12 +0000

Hi there, I just bought my Samsung 204b that is also made in Slovakia and have exactly the same problem! I am really pissed since I want to use the optimal resolution which is 1600x1200 and use DVI connnection. However that is now impossible thanks to the problem described above. My question to the author, Erik Forsberg, how exactly did you lower your vertical refresh rate? I saw the attached file but didn't really get the scheme? I have a Radeon 9250 as well and would really appreciate your help!

PS. Erik Forsberg - kan du möjligen vara från Sverige? Hoppas man får ett svar, då problemet är väldigt irriterande. Om man sänker uppdateringsfrekvensen till 56Hz, blir bilden sämre då? Jag menar rent kvalitetsmässigt? Annars kan jag ju lämna tillbaks skärmen, men om bilden har samma kvalitet så kan jag behålla den. Skulle verkligen uppskatta din feedback.
Tack på förhand!

Comment by Erik Forsberg

Created Wed, 7 Feb 2007 20:51:24 +0000

The idea is to replace your /etc/X11/xorg.conf with the file attached to this blog entry, and then restart the X server.

Btw, there will be another blog entry really soon on the same issue, as I had to struggle a bit to get it to work after upgrade of Ubuntu to edgy eft. This time, I had to use the ati driver and the modeline from Dom Layfield.

To answer your questions in swedish - yes, I'm swedish :-). No, the image quality is not affected.

Comment by Erik Forsberg

Created Wed, 7 Feb 2007 20:54:53 +0000

Thanks for the modeline! After upgrade to Ubuntu edgy eft, my old configuration didn't work anymore. Switching to the ati driver, using your modeline, made the trick!

Will update this blog entry with more information later.

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