Help File Library: Configuring X Window for LCD Monitors

Introduction

This document will hopefully help you set up the newer flat-panel LCD displays so they will work properly in X Windows, with a rather stable display. You probably already have tried and found that your dispaly might be flickering a little, or have wavy lines going through the text, especially light text on dark background. The text might even be nearly unreadable in some instances. This is due to the monitor not having the correct settings.

You can do some of this in the XF86Config file when you run xf86config but you might also need to further adjust the settings. This information was tested with a computer that has an ATI Rage Pro Turbo AGP integrated video (built into the motherboard) and a SYS 15" Model 154UG LCD monitor. You also might have to have Windows installed and running, or a Windows machine you can hook the monitor up to, though you might be able to get away with just using the monitor manual if you have a monitor other than the one I used for this.

Step 1: Getting the Refresh Rates

Here is where you might want to get the monitor hooked up to a Windows machine or some machine where you can set the display modes, and then check them.

Most all newer monitors have a button on them that when pressed, will bring up a screen that will show on top of the screen the refresh rates and resolution the monitor is currently set to. Try and get the monitor into several modes and press that button (first one marked "1" in a square on the SYS 154UG), then write down the refresh rates for each mode.

Here are the modes for the SYS monitor. Note that the refresh rates are the same for 24-bit, 16-bit and 256 color modes. We don't need rates for 16-color modes because X Window doesn't use 16 color modes as a rule. At least, they don't show up in xf86config. Also, if you used to have your machine on Windows and used the 32-bit mode, X Window displays things the same in 24-bit mode. There's little difference in those two, just a matter of how the video is processed. But the display looks about the same, so don't worry about setting 32-bit modes. They also have the same refresh rates anyway.

Resolution	Horizontal (KHz)	Vertical (Hz)
640 x 480	37.5	75.2
800 x 600	46.8	74.9
1024 x 768	59.8	74.8

There are also higher modes possible, but the SYS 154UG will only do up to 1024 x 786. If your monitor does a higher mode, be sure to add that to your list of values.

Step 2: Setting Up X Window

First, it's very important that you log in as root. Now go to the /etc/X11 directory and look for XF86Config file. Copy it to another file, for safe keeping, like this:

cp XF86Config XF86Config.default

If you have one that is default already, then just copy it to another file.

Now we are ready to run xf86config. Go through and set up the mouse and keyboard to fit your system. Note here: I haven't figured out which one works to enable scrolling with the MS Optical Wheel Mouse so if anyone knows, please email me. In addition, most keyboards with the Windows Keys on them generally can use the #3 option (Generic 104-key) but choose what suits your system configuration. When you get to the monitor part, you will see an option #11, which allows you to add your own refresh rates. Choose this, and enter the lowest Horizontal rate, a dash, then the highest HOrizontal rate. For my example, it would look like this: 37.5-59.8

Next, you go on to the vertical rates, again, choose the option to enter your own and do like you did with the Horizontal rates, but using the Vertical rates instead. My example would look like this: 74.8-75.2

Next is your video card. Choose the appropriate one, if you find it in the list. If, like me, you do not find an exact match, it would be best to use option #0 (Generic VESA) because otherwise you might get a display that jumps up and down or something when in X Window.

Now finish off the configuration, and answer "y" to the first prompt. You should be ready to start and text X Window.

Step 3: Starting X Window And Tweaking The Display

Type startx at the prompt. When X starts, watch how it behaves. The display may be quite distored or "messy" when it first starts. Don't panic. This is normal as it's displaying contents that are in the Video Ram at the time, for some odd reason. The display should clear up to a plain white one (if you're using KDE, for example) or a black and white checker-like one (if you're using an older Window Manager).

If you find that these things don't happen, or the screen stays garbled for more than five seconds, or jumps up and down or side to side, hit CTRL+ALT+Backspace and wait while X Window abruptly shuts down. You'll want to go back and reconfigure your video card settings by running xf86config again, and be sure to enter the same monitor settings you used before, but choose another video card driver (like the Generic Vesa, which is a good one to start from anyway). If X Window loads properly, you may see the wavy lines in the text, especially in light colored text on dark backgrounds. To correct this, the monitor also has to set itself internally to remember that this mode takes new settings than it had before. Press the "2" button (last button) on the SYS 154UG monitor, or whatever button your LCD uses to auto-adjust the display. After the monitor jumps the display around a bit and stabilizes it, you should see the text and other things clear, stable and without wavy lines! If so, pat yourself on the back, cause you did it! :)

Step 4: Backup Your Configuration!

Wait! We're not done yet! Exit X Window (logout) and when it stops (kinda stalls) the display of spew that it does after leaving, just hit ENTER to get your prompt back (if you need to do this). Then go to the /etc/X11 directory and copy the XF86Config file to XF86Config.working so that you have a backup of a configuration you know worked. Now you're done. Go play. :D