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Monitor Repair Log and Database. **Arcade and Gaming** => LCD and CRT Monitor Repair Tech Support => Topic started by: Slots8168 on December 03, 2017, 11:01:37 AM
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Would anyone know why my Igt upright is very slow on warmup and dim after warmup?
This is 17jn Igt G/K U/R Kortek KT 0074
Thanks Kerry
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Has it always been this way since you got the machine, or has it just started doing this while you've had it? Overall brightness of the screen can be affected by a lowering of the high voltage section, as well as aging of the phosphor coating on the inside of the crt.
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No just started a while back , getting slower and dimmer on startup. After few hours after turning it on, you can see the game but dim.
Thanks Kerry
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I'm not a monitor/tv tech but if someone could check the high voltage (carefully) that might tell you if that's the problem. For a screen that size the high voltage may be around 15,000-20,000 volts. An informal thing some people do is to move the back of your hand across the crt screen (with it powered on). You can often feel the static electricity tingle from the high voltage if it is present. This isn't a very scientific way, depends on things like the humidity in the room, your skin's dryness, etc. If you have another similar sized working monitor you can do the same informal test and compare.
This may be one of those situations where replacing all the large value capacitors might help. Some places sell these "cap kits" for particular monitors. Do you know how old the monitor is? There might be a date on a sticker on the side of the crt. just an idea.....
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I had 2 17" GK machines with these monitor, and both were very dim. I did try to put new caps on one chassis, but it didn't help.. I just figured that the CRT was going bad and I replaced both with LCD screens. The monitors will do this with age. If you have a TV repair shop by you, they may be able to try a rejuvenate of your monitor.
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Was LCD plug and play or does it require new wiring?
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.....The monitors will do this with age. If you have a TV repair shop by you, they may be able to try a rejuvenate of your monitor.
or you can try it yourself by getting a low-cost crt rejuvenator and give your cathodes a blast:
https://www.ebay.com/itm/B-K-Manufacturing-Company-CRT-Model-440-Cathode-Rejuvenator-Tester/332437932368?hash=item4d66d84950:g:DsUAAOSw42JZBOVl (https://www.ebay.com/itm/B-K-Manufacturing-Company-CRT-Model-440-Cathode-Rejuvenator-Tester/332437932368?hash=item4d66d84950:g:DsUAAOSw42JZBOVl)
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The change over was just a plug and play operation. The only thing you really need to know is what size monitor plug you have.. There are 2 different versions, 19 pin and 25 pin. This is the number of pins and openings on your monitor and cabinet plug.. Not every hole in the plug will have a wire attached. Make sure that if you buy one, that it comes with a flat panel door bezel. The one from the older CRT can't be use.
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I just adjusted the screen to the right and it got bright, if I turn the dial back to the center it gets dim again.
Thanks for all the info on the lcd
Thanks Kerry
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Sounds like the color guns in your CRT have a carbon build up. A tube rejuvenation would get your monitor back to normal, or close to it.
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Sorry ! Can you please simplify on your notes.
Thanks Kerry
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The CRT has parts inside that emit electrons. These electrons move from the narrow end of the crt to the other end where they light up your screen. The more electrons you have and the faster they move the brighter the image will be on your screen. The part that makes the electrons is called the cathode, that's why the tube is called a Cathode Ray Tube (CRT). The cathode is heated very hot by a nearby heating element. The cathode is metal and it gets so hot that electrons are forced off of it, and other parts inside the crt and a very high positive voltage down at the bigger end attract the electrons and cause the electrons to move to the screen. The screen has a phosphor coating that lights when the electrons hit it. The parts that give off the electrons and bunch them into a beam are commonly called the "electron gun". Since your crt is a color type it has 3 of these electron guns, one each for Red, Green and Blue colors.
As the years go by the part that gives off the electrons (the cathode) gets weaker and produces less electrons, so the image on the screen gets dimmer. A crt rejuvenator is a machine that you attach to the crt, it applies a higher than normal burst of electricity to the crt elements like the cathode and causes it to once again give off more electrons. This will make your screen image brighter. The rejuvenator is a last resort type of thing, it can kill the crt or it can cause it to work much better. And when it does work the effect may not last for a long time, so the problem could return. If you have access to a rejuvenator and if your crt image is unusable you can try it, not much to lose. TV repair shops used to do this all the time, it saved the cost of a new crt (picture tube).
(https://s18.postimg.org/v3vgegb49/CRT-_Block-diagram.png)
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Wow ! Thanks for all the info
Thanks Again
Kerry
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Sounds like the color guns in your CRT have a carbon build up. A tube rejuvenation would get your monitor back to normal, or close to it.
Where does the carbon buildup in a CRT come from? Is it just static electricity that attracts airborne crud, or is the gun itself coming apart?
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The CRT is sealed, no outside air or dust can get into it. All of the air is removed from the inside when it is made, sort of like an ordinary incandescent light bulb (the ones with the filament wire). The cathode is the part inside the CRT that emits the electrons, they are "boiled" off the cathode by a heating element that is nearby to the cathode. This heating process takes it's toll on the cathode metal over time, and the cathode no longer gives off as many electrons. Sometimes this problem is described as a "coating" on the outer surface of the cathode. If you can remove this coating then the cathode will work better, it will give off more electrons like it used to and the screen image becomes brighter.
The CRT rejuvenator applies a larger than normal voltage to attempt to remove this coating on the cathode. This rejuvenator often works to give extra life to the CRT, but it can sometimes kill the CRT, so should be used as a last resort when the CRT isn't performing acceptably and it is worth taking the chance.