I found this article on TweakHardware.com. It will walk you through adjusting the focus on that old computer monitor. It will also help you adjust the color and brightness of your monitor.
Many monitors display an unnecessarily bad picture quality. Several older monitors suffer from showing a very dark and blurry image. But it doesn’t have to be this way! With a little knowledge and a couple of screwdrivers, we can make adjustments to achieve a sharper and/or brighter image.
The process is quite simple, but requires you to take the back cover off of your monitor. This is usually very simple and requires only a small screw driver. The guide on Tweak Hardware will walk you through the complete process.
Warning: This tweak, if not done properly, can cause serious injury and possibly death to you and your monitor. Use at your own risk
I have done this to my old Magitronic monitor and it worked great. My monitor went from a blurry piece of garbage to a monitor that looked almost brand new. The process was a bit different on my monitor, the focus and brightness potentiometers were located in different positions, but worked exactly the same. I would not recommend playing with the color potentiometers unless it’s really screwed up.
After fixing my monitor, I thought I would try it on my old TV, and it worked the same way. My TV was really screwed up and the colors were way off, so I adjusted the color potentiometers and finally got it to work. It takes very long to get the color right, since there’s three adjustments, red, green and blue, so expect to take some time if you plan on adjusting the color. And also try many source for testing the color. ie. DVD, Video Game, VHS, Satellite, Regular TV, etc.
To just adjust the focus and brightness it took me about 20 minutes, after I figured everything out, so why not fix your broken computer monitor or TV for free.