If you have tried your monitor on another computer, or a 'known good' monitor on your computer and definately know it is your monitor that is blurry, then you can take it to someone who knows how to make internal adjustments in monitors (or a TV shop, in some cases, will do it), and get the problem fixed. Sometimes the blurriness is not fixable by an adjustment due to a bad component. Anymore, it's not usually worth it to have a part replaced in a monitor.
Monitors vary greatly between manufacturers, but typically you should find a black box, (about 2" x 4" x 1") inside the monitor, close to the back end of tube. It should have an adjustment knob that can be turned with a screwdriver - this will focus the monitor.
This knob is a 'fine' adjustment, the gross adjustment of focus is too complex to describe here, but it can be done. It's a bit more tricky and considering the inherent electric shock danger of CRT monitors, should be left for someone experienced.
In addition to the focus, there are typically adjustments for other aspects of the display, again depending on the brand of monitor. As a rule of thumb, you should have at least as many adjustment inside the monitor as you have on the outside or in the on-screen adjustment panel. What follows is a post I use whenever I find a place that talks about opening up a monitor without a strong enough warning about the dangers. It is about on-board adjustments for color, geometry, etc than focus, but it is still relevant.
I've been tweaking monitors for many years; I have a friend who used to have a monitor repair shop, and I learned a lot from him. I'm completely inept when it comes to board level circuit repair, so I wasn't able to pick up any repair info, but I learned how to 'tune' monitors and used to tune them for Bruce when I was hangin' out at his shop.
A CRT, (cathode ray tube), monitor is a VERY, VERY high voltage device. If the high voltage caps are not bled correctly, and you touch them with a screwdriver, you'll find after get up from the floor, (IF you wake up), that you have a ruined screwdriver lying on the floor somewhere. I saw Bruce pop himself a few times, and it was not pretty. One time, I was just about to thump his chest, and give him CPR since he wasn't coming to quick enough.
So, unlike many warnings you see on electronic devices, the warning on tube monitors is NOT overstating the danger.
With that said, there is an easy way to protect yourself, and as long as you aren't stupid and touch something with your hand, or dangle a long neck chain or necklace into the monitor's workings, you'll be OK.
If you go to a 'real' electronics store; the place where the board repair geeks go, you'll find plastic, non-conducting screwdrivers made for adjusting monitors. BUY SOME or don't open the damn monitor.
Alternatively, if you want to save some money, you can buy 1/8" fiberglass rod and make your own non-conducting screwdrivers. I've had mine so long I can't remember where I bought the stuff. As I remember, I stumbled on the rod somewhere when I was shopping for something else - it might have been a plastics store, like TAP Plastics. You want fiberglass rod as it is stiffer & stronger than a plain plastic rod.
Cut yourself several different lengths. Nothing shorter than 12-14". Adjusting monitors is something you want to do from a comfortable distance since you are reaching into the back to adjust and needing to see the display at the same time. A mirror can help, if your eyes are still good. (the mirror doubles the distance from your eyes to the screen.)
After you cut the lengths of rod, grab a file and turn both ends of the rod into a screwdriver tip. Nothing fancy, just taper both sides. Then wrap some duct tape around the middle of the rod to make a 'handle'. This is more important that you might think. Other than easier 'grippage', the more you increase the diameter of the rod with the tape, the more precise a tuning instrument it becomes.
It's simple physics, a larger circumference travels farther in distance around a center point than a smaller circumference. When you turn the tool 90', you have to move your fingers further with the larger diameter handle than you would with a smaller diameter handle. A larger handle makes it much easier to make 1/16 of a turn adjustments.
Something you can do after you figure out which 'pots' do what on the boards, is drill access holes in the monitor case, (if they can line up directly). Then you can do a quick tune without taking apart the monitor! Mark the spot with a felt-tip pen and drill the holes with the case off of the monitor; you don't want the drill to jump through the case, hit something electrically hot and kill yourself, let alone killing your monitor.
Internal adjustments will vary from monitor brand to monitor brand, some have a lot, some have few. Generally, the more on-screen adjustments you have, the more internal adjustments you'll find. While learning, I'd take a look at the position of the slot for later reference, then turn it one way to see what it did to the display, then I'd turn it the other way. This gave me an idea of the range of adjustment and what it effected. Then I looked for the 'sweet' spot - turning the adjustment while looking at the display.
BTW, if your monitor has knobs, or buttons, physically 'center' them before you make your actual tuning adjustments. When you're experimenting to discover which pots do what, it's easier if you do it with the monitor adjusted as well as you can get it. After you know what does what, then center the knobs and make the display perfect.
Infrequently, an adjustment won't do anything, if so, just put it back to it's original position.
FYI, 'pots' are little square boxes directly mounted on the boards in the monitor. They're about 3/16-1/4" square with a small slotted screw head in the middle of the square.
I've always looked at the theory of monitor adjustments this way: The internal adjustments are 'gross' adjustments, while the on-screen display, (or knobs on the monitor front), are 'fine' adjustments. If the on-screen or knob has a plus and minus adjustment, you want to do internal adjustments until you 'center' the knob - in other words, you want to create the most plus or minus adjustment you can have after you close up the monitor. The exception to this is if the monitor is weak in one area. Most often, it's the brightness, as that diminishes as the phosphor in the CRT diminishes with age. Then you want to crank the internal adjustment up until you have more plus adjustment than minus. Still, I never go more than a 3:1, plus:minus ratio.
I have found monitors in dumpsters, abandoned in parking garages, in a lot of places - I've brought them home, and with 15-20 minutes of tuning, I've had a great monitor to use, well or give away. For some reason, these free monitors are always the filthiest monitors ever seen - I've never found a clean monitor that only needed a 'tune'!
If your monitor needs some help, then be safe, get or make some plastic screwdrivers, and have some fun extending the life of your monitor- but I can't say it strong enough, be VERY, VERY respectful of the innards of the monitor. It CAN kill you.
GeoD
GeoNOregon
February 2010
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