NeutralAxis

The screen resolution problem that had stymied my MythTV experiments is solved.  One website in particular provided the means to get the problem fixed and now I can run at resolutions up to 1600×1200.

The information that helped me solve the problem is at UbuntuForums.org.  HOWTO: Screen Resolution in Hoary 5.04.  That article described what edits needed to be made to the /etc/X11/xorg.conf file to add resolutions that the standard installation fails to recognize. In this case, my monitor is an old 19″ Gateway EV910 which supports resolutions up to 1600×1200 at 75hz and nVidia FX5200 graphics card.  The process wasn’t without hiccups though, probably because I’m using Intrepid 8.10, so I’ll walk through what worked and what didn’t.  You’ll have to open a Terminal window to do this, so brace yourself for a command line.

Step 1: Backing up xorg.conf in case of big errors is simple.

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup

Step 2: Edit xorg.conf file using the text editor of your choice. I use nano.

sudo nano /etc/X11/xorg.conf

Step 3: Look up supported resolutions, horizontal sync range and vertical refresh range capabilities of the monitor and jot the figures down.  In my case, I no longer had the monitor manual and went to Gateway’s website to find that information.  I decided as a first try, I wouldn’t push things and just go for the 1024×768 resolution.  I found that my monitor had a horizontal sync range from 31.5kHz to 93.72kHz.  The vertical refresh range was 60hz to 75hz.

Step 4: In the xorg.conf file, erase everything between Section “Monitor”  and EndSection.  And replace it with the data you’ve just determined like this:

Section "Monitor"
    Identifier    "Gateway EV910"
    HorizSync     31.5-93.72
    VertRefresh    60-75
EndSection

Step 5: Keep your current Terminal window open and open a new one and execute this command to generate a couple of lines of code that apparently mean something to the machine.  The code apparently tells the machine how to generate the specified resolution.

gtf horizontalresolution verticalresolution refreshrate
for example if you want the code for 1024x768 @ 75hz use:
gtf 1024 768 75

This will generate a couple of lines that you need to copy and paste into the “Monitor” section.  You’ll get something like this:

# 1024x768 @ 75.00 Hz (GTF) hsync: 60.15 kHz; pclk: 81.80 MHz
  Modeline "1024x768_75.00"  81.80  1024 1080 1192 1360  768 769 772 802  -HSync +Vsync

Which you’ll put into the Monitor section.

Section "Monitor"
    Identifier    "Gateway EV910"
    HorizSync     31.5-93.72
    VertRefresh    60-75
# 1024x768 @ 75.00 Hz (GTF) hsync: 60.15 kHz; pclk: 81.80 MHz
  Modeline "1024x768_75.00"  81.80  1024 1080 1192 1360  768 769 772 802  -HSync +Vsync
EndSection

Step 6: Not done yet, but we’re getting there.  Edit the “Screen” section of the xorg.conf file.  You need to change the monitor name to match whatever you used in the “Monitor” section.  Also add the DefaultDepth line and the SubSection “Display” lines.  NOTE:  This step is where I had to diverge from the HOWTO link.  Use the following as your guide:

Section "Screen"
    Identifier    "Default Screen"
    Device        "Configured Video Device"
    Monitor        "Gateway EV910"
    DefaultDepth    24
    SubSection "Display"
        Depth        24
        Modes      "1024x768" "1600x1200"
    EndSubSection
EndSection

Depth and DefaultDepth need to match and refer to the color depth.  16 yields 65536 colors, or 24 yields 16 million colors.  The modes line is still a little unclear to me, because even with only those two modes listed, the screen resolution setting under the Preferences menu shows about 12 choices.  What I DO know though is that the first resolution on the Modes line is the default, and will be used for Ubuntu’s login screen.

NOTE:  This step is where I had to diverge from the HOWTO link.  Their procedure shows a colon “:” at the end of the SubSection “Display” line.  In my Intrepid installation that caused an error on my first attempt to make my changes take affect.  I thought perhaps I misread it and changed it to a semicolon, but that failed too.  Finally, I removed the colon entirely, and it worked.

Step 7: Save your work on the xorg.conf file and exit the terminal windows you had opened.  Restart X (the display subsystem) by issuing CTRL+ALT+BKSPACE and cross your fingers that it comes back.  [Update 6/16/09:  Ubuntu 9.04 has removed this key combination from the default installation.  The best option is probably to log off and back on ] As I mentioned, I had two failures at this point because of that colon and semicolon that were apparently wrong for Intrepid.  Fortunately, the system went into a diagnostic mode that made it simple to identify and fix the errors.

Step 8: When mine came back on, I was still at 800×600 and thought it hadn’t worked.  But then I went to System>Administration>Screen Resolution and found that I had a whole range of new resolutions available to me with the highest being the 1600×1200 I had added.  Success!  If you’d like, you can now delete the backup you made in step 1.