From ic.ac.uk!t.sippel-dau Thu Nov 26 12:12:46 1992 From: t.sippel-dau@ic.ac.uk Date: Thu, 26 Nov 1992 12:11:02 -0600 To: sgi-faq@archone.tamu.edu Subject: How to adjust a monitor root@sanger.chem.nd.edu (Doctor Math) asks: Where is the focus adjustment on the older 19" monitors? It seems to require taking the back of the monitor casing off. Is the control clearly labeled "focus"? Or does it just have a part number? I would gladly have RTFM if the monitor had a FM.. Response: Computer manufacturers are notoriously unhappy to document maintenance of monitors, because (a) they don't usually make them themselves, and (b) the high tension in a monitor can give you a VERY nasty shock SAFETY ====== To adjust monitors (other than by the user level controls reachable from outside) you have to run and adjust them while the casing is off. Make sure you have dry hands and shoes and that you cannot reach any metal part directly connected to the building, including steel or aluminum framed windows and doors as well as radiators and their pipes. Make sure that when you jump in reaction to a static discharge you will not hurt yourself. Also make sure that the monitor is standing firmly, a 19'' hunk of glass falling onto you is unpleasent even when not connected to the power mains. aHave a set of Colour TV adjuster tools - long plastic screwdriver like implements - you get them from Tandy or similar electronics shops. Monitors ======== The monitors on computers are usually bought in from other manufacturers, and will change internally even without the computer supplier knowing, Computer manufacturers also change their source of monitors from time to time, or have several concurrent suppliers. >From Silicon Graphics you could have (as far as I know) monitors from Hitachi, Mitsubishi, Philips or Sony, in both Tridot or Trinitron (tm) form. You need a magnifying glass to find out if you don't know which one you have, the Tridots have a Red, Blue and Green dot in an equilateral triangle, from which the picture is built up, the Trinitrons have vertical bars. Adjustments =========== Take the casing off, switch the monitor on and let it run until it is warmed up (ca 15 minutes). During this time you can study the any markings on the adjustment pots, usually there is a plan pasted somewhere, but on older monitors the adhesive goes and the label drops off. Ensure you can see the screen while adjusting, without compromising safety, use a mirror if nescessary. You can try wiggling pots if you are not sure what they are doing, but remeber where they were before you started. On the 5081 monitors I have seen about 20 pots, get more than a few out of a reasonable range and you have no hope of recovery - if the monitor survives, that is, because you can damage it beyond repair just by twiddling these pots. Bring up a monitor adjustment picture, on Silicon Graphics machines you find one under "Confidence tests" in the "System" section. Ensure that you get focus (which is what you asked for), convergence and a square picture with the right aspect ratio, h:v = 4:3 on 1024 point screens and 5:4 on 1280 point ones. Make your circles appear round. Also ensure you have a reasonable pixel density - somewhere near 75 or 100dpi on Silicon Graphics. This is important if you want to do true size previewing of text or drawings. You need to do this on a warmed up monitor, on cold ones the picture is a little bigger than normal. Many monitors here are delivered with the picture elongated and too small, I think this is because a full size picture on a cold tube is bigger than the active display area on the monitor, which makes people call out support. The techs seem to have given up explaining that that is what is right and just make the picture smaller, thus neatly transforming a 19'' monitor into a 17'' one. It also makes the picture appear a bit brighter since the output of the electron gun is concentrated on a smaller area. some people like that. Once you are happy, disconnect the monitor and put the casing on again. Do not use any metal tools before the monitor is switched off and has lost its static charge. You will find you have to degauss several times after adjusting the monitor. Brightness and Contrast ======================= Many monitors are just put to the highest brightness and contrast levels. This is not usually a good idea. With subdued lighting, set a low contrast level and look into a corner of the monitor. Usually the shadow mask allows the picture to be slightly bigger than is currently displayed. You should see a black frame (where there is no shadow mask) and a grey frame, the front and back porches of the display area. Reduce the brightness until until you see no difference between the black and the grey area. The correct setting varies slightly between daylight and artificial light. Then use the contrast adjuster to get the light areas to a brightness you like. You should not normally need to adjust brightness thereafter. Just remember: Brightness to make blacks blacker, Contrast to make whites whiter.