Small Red Marks on CRT Projection Screen

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Hulk701

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Hey Gang,

I purchased an Hitachi 46" UXB7/K Projection TV from a repair shop. It works fine but I noticed it has two small red marks close to the middle of the screen. The two marks are comet shaped, with a head and tail, and both head and tail seem to go in the same direction. One is about 3mm in length, the other is about 6mm. About 1-2 mm in width on each mark.

When I turn the TV off I can't see them. When I brush my fingernail against them I can't feel them. I wonder if they are what's called "burn marks" inside the CRT and just ignore them, or if they are something like pen or crayon marks that I can get rid of.

They seem to be red in color. When the screen switches to something darker than red they disappear. However sometimes they appear to be purple when the color of the screen changes. They are also semi-transparent.

I have tried using eyeglass cleaner and no joy. I'm afraid of using something more powerful because I have heard of people using Windex and getting some serious permanent streaks on their screens. Also the manual says not to use heavy chemicals.

The TV screen itself appears to be plastic and made with grooves in it. I can slide my fingernail through the grooves.

Does anyone have any experience with this sort of thing? :(

Thanks,
HULK! ;)
 
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Could be small imperfection or little bubble in the CRT glass right in front of the phosphor surface. Looks a bit like a burnt pixel that you might see on LCD/DLP units.

I have one of these in my red CRT, so that I see a very small greenish dot on the screen when I project an all white screen. It's so small that only *I* notice it from time to time when viewing DVD's - and that's because I'm anal and know what to look for. :)

I thought it was a spec of dust on the CRT glass surface, but removing the lens told me otherwise... It's hard to tell without removing the lens. Since I use a home theater PC, to pinpoint where it was exactly on the tube surface I had place my mouse pointer right next to it by looking at the screen, the I removed the lens and looked right at the CRT surface. There was a TINY little imperfection in the glass surface. I never would have seen by just removing the lens and looking at that glass CRT surface.

http://archive.avsforum.com/avs-vb/history/topic/111179-1.html
 

Hulk701

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So this sort of thing is quite common eh, well my education continues. I'd rather know this than try to spends hundreds of more dollars trying to fix it.

You just saved me a lot of time and trouble Barfly, thanx :D
 

Hulk701

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Another question. Would buying a screen protector do anything about the red marks already on the current screen or not?
 
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