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Monitor Repair Log and Database. **Arcade and Gaming** => LCD and CRT Monitor Repair Tech Support => Topic started by: shortrackskater on February 18, 2017, 05:32:18 PM

Title: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 18, 2017, 05:32:18 PM
I know enough on monitors to re-cap them. I've done a few and did this on recently. It looked great, still does but I've noticed this red blotch in the lower right corner. I don't think it's a cap issue but a matter of degaussing?
There's not degauss setting I can see on this relic.
I've seen some odd looking manual ways to degauss a CRT: using a soldering gun, a magnet on a drill motor, and using a transformer from a power supply.
Any ideas for Mark, the CRT novice?
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: rokgpsman on February 18, 2017, 05:50:10 PM
That may be a magnetized area on the crt, so if you have a degaussing coil it is an easy thing to try to fix. With the monitor powered on you hold the degaussing coil close to the monitor screen, then switch on the degausser and start moving it in circles. As you move the degausser you will see the screen colors change and shift around, that is normal. Keep the coil moving as you gradually move it away from the monitor screen. You can concentrate the degausser in the problem area of the screen but still need to make your circles large enough to cover the entire screen, otherwise you may cause another problem in a different place on the screen. Be several feet away from the screen before you switch the degausser off.

Most crt's have a degaussing coil built in, it is switched on when you first turn on the monitor, then after a few seconds it switches itself off. Yours may not be working. It is a wire cable that has several feet of wire inside it, runs around the backside of the crt near the 4 corners, then connects to the monitor circuit board. It is usually wrapped in some type of black tape or plastic sleeving to keep its wires tightly bound together to create a strong magnetic field.

Those large Weller soldering guns may have enough magnetism to work.

Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 18, 2017, 06:43:30 PM
I had a nice big old Weller... it  sat for so long that I finally put it in the goodwill box!
 I'll try one of my little DC adapters and see if that works. Thanks!
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 18, 2017, 07:24:12 PM
I pulled it out and there doesn't seem to be any degaussing wires at all. No degaussing sound on power up. I tried a D.C. Adapter but it's not powerful enough.
I've got a big magnet ...
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 18, 2017, 09:44:56 PM
Ahhh yes - I found a highly  complex and technical device. It was my electric trimmer. I just carefully moved it to the right in small circles until I "swept the red" away. I repeated that about five times and it's not too bad looking now!
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: rokgpsman on February 18, 2017, 10:37:17 PM
It does look better, that was a clever solution.   :odie:
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: oldgeiser1 on February 19, 2017, 12:01:57 PM
I use an electric hand mixer, works great.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 20, 2017, 09:50:45 AM
 :agreepost:

I'm still wondering how these monitors "degaussed" then? Mine has no setting, and I don't hear any noise on start up and there's no wire wrapped around the tube.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 27, 2017, 05:54:30 PM
I'm STILL wondering how these were degaussed in 1985? There's a very small red area on my monitor,  but it's nearly covered now by the plastic screen frame. 
I gauss... oops... guess I need to learn a little more on CRT's.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: rokgpsman on February 27, 2017, 08:27:41 PM
I don't know about that particular model of monitor you have but if it does not have a degaussing coil built in then I guess they figured back then years ago that any decent tech shop in those days that serviced slot machines would have one or more degaussing coils. Since the machines stay powered up all the time once they were working they stayed working for a long time, unless some yo-yo stuck a magnet to the screen. And by leaving the degaussing coil circuit out the monitor mfr could save a few bucks. Before flat panel LCD screens came out crt displays were king, so hand-operated degaussing coils were all over the place in any tv/computer monitor repair place.


Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: Badbaud on February 27, 2017, 09:24:05 PM
IGT never bothered with degaussing the tube with a coil.
Bally, on the other hand, has coils on their tubes going back to the V55500 poker.
We have always instructed our customers to use a plug in AC electric drill.
Hold it sideways against the screen, turn it on, rotate it and pull away from the screen slowly.
One customer complained that the drill bit kept slipping off of the glass, had to explain to her what sideways meant.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 27, 2017, 09:44:27 PM
Did she have a drill bit in the motor?  :24:

I'll give it a try right now, without the bit 😬
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 27, 2017, 10:17:13 PM
That worked better. The red is nearly gone now. It seems to just  be a matter of technique with using the drill. I tried it sideways and then  just moved it slightly until I was able to follow the red off the screen.
 It's definitely better with my drill motor then my hair trimmer!
Thanks to both of you.   :applause:
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: rokgpsman on February 28, 2017, 07:35:49 AM
yep, the bigger the electric motor the stronger the magnetic field. If you could hold your 12 amp vacuum cleaner up to the screen and make circles with it you'd really be operating!   :garfield:

My father-in-law had a furniture & appliance business for many years, and he was a GE appliance distributor. So he dealt with those large tv consoles that were made as attractive wooden furniture cabinets with a big crt tv set inside that were popular in the 1970's and 80's. Since the crt was only a few inches off the floor GE put a warning in the owner's manual to the customer to not switch on or off a vacuum cleaner when it was close to the tv because that could affect the purity, you'd get color blotches on the screen. When you turn on or off an electric motor you get a big jump or change to its magnetic field, that's when it can have a strong effect on the crt screen.



 
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: Badbaud on February 28, 2017, 09:27:29 AM
Reminding me of a old 3 Stooges show where Curley is ironing and he keeps trying to remove this one spot that keeps coming back only to discover it was the sun putting a spot on the shirt when he moved.

Have you ever degaused a tube only to see the blotch come back when you close the door?
Running the degausing tool around the door's metal THEN doing the tube gets rid of that effect.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: rokgpsman on February 28, 2017, 09:47:05 AM
I can see where that would happen, the metal door frame getting partly magnetized would affect the crt screen when the door got close to it. I wonder how long before it will be difficult to even get certain size crt tubes anymore, or get them at a reasonable cost. There is a lot of equip still in use by the government and military that uses crt tubes so I guess that will keep them getting made for the time being.



Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 28, 2017, 10:40:01 AM
Reminding me of a old 3 Stooges show where Curley is ironing and he keeps trying to remove this one spot that keeps coming back only to discover it was the sun putting a spot on the shirt when he moved.

 :3stooges:

Finally a use for that emoji!
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on February 28, 2017, 10:42:49 AM
I remember our neighbors had a HUGE ass color TV. And I remember the first time seeing Star Trek IN COLOR! It was breathtaking!

I wondering: Would it be better to run a smaller motor around the frame, rather than the big drill motor? I'm thinking the electric hair trimmer might work as a fine-tuning degausser, so to speak.

UPDATE: I repeated the process with the drill motor and the red is completely gone.

UPDATE: I repeated the process with the drill motor and the red is completely gone.   :propeller:
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: knagl on April 16, 2017, 10:08:26 PM
I've got one of these laying around which works well -- an old bulk tape eraser from Radio Shack.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on April 16, 2017, 11:21:41 PM
I had one of those! Of course, I stick it in the goodwill box thinking I'd never have a use for it again. :duh:
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: Badbaud on April 17, 2017, 07:07:58 AM
Fits much easier in my service call tool box than the big round horse collar one I use in the shop.
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: cowboygames on April 17, 2017, 08:57:36 AM
The magnets they put in cow's stomachs work really well too
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: rokgpsman on April 17, 2017, 10:25:01 AM
Do those magnets get reused on other cows if the cow dies or goes to slaughterhouse?
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: cowboygames on April 17, 2017, 12:33:02 PM
Every cow gets one, not sure if the slaughterhouse recovers them. Probably depends on what they do with the guts. We never got any back, but you'd never know if the one you got had been used probably. They use them to pick up small bits of metal before they get to far into the digestive system
Title: Re: CRT "red blotch" on IGT F2 monitor.
Post by: shortrackskater on April 17, 2017, 12:34:14 PM
Maybe they ask more $$$ for those cows since they're high in iron!  :rotfl:
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