CRT scratch repair - Videokarma.org TV - Video

RetroHacker · #1 03-30-2006, 10:30 AM

I've come across a few sets recently that have scratched tubes. One has pretty good size gouges in the glass. I see this most on newer, 'black bubble' type sets, where the set is very front-heavy and the tube doesn't have bezel that sticks out farther than the center of the tube (like older sets). It looks like they fell on some gravel or something. I also see it sometimes on computer terminals, etc - but not as bad as I've got it here. Anyone come up with a way of fixing scratches like this? I remember seeing ads for scratch-fixing compound for eyeglasses - is there something similar that might work to repair or help hide scratches in a CRT? I know it's pobably not worth trying to fix, but I thought it might be interesting to try.

Any ideas?

-Ian

kerozene · #2 03-30-2006, 12:38 PM

I remember reading something about this...

http://www.encyclopedia.com/html/C/Canadaba.asp

http://www.merck.de/servlet/PB/menu/1115710/index.html

David Roper · #3 03-30-2006, 12:55 PM

I remember a letter to TV Guide's technical Q&A man David Lachenbruch from a lady whose son had thrown a toy which struck the TV screen, leaving a gouge in the face of the tube. Lachenbruch's response went something like: "Unplug the set, turn it toward the wall, then run--don't walk--to your local TV repairman." I think he went on to briefly touch on the dangers of implosion...you're familiar with the dangers of implosion when the structural integrity of the tube is threatened, yes? Those deep scratches and gouges are really bright flashing signs that say "REPLACE ME...VERY CAREFULLY...NOW!!" Don't hide them, heed them.

RetroHacker · #4 03-30-2006, 01:15 PM

I can't imagine that a few scratches on the tube's face could heighten implosion risk. The glass on a modern color television picture tube is like 1/2 to 3/4 of an inch thick on the face - a few 1/32" deep scratches shouldn't make it any less safe. Now, if it was a huge chunk or large deep gouge, then yeah, that makes sense. And one of these is a 32" set - the glass should be much thicker. These scratches are pretty large, but they're not deep gouges. It's just that those scratches on the screen are really, really annoying.

For the most part though, the scratches I run into are tiny, hair-thin ones on monitors or terminals. Tiny scratches won't be noticed on a large TV, but if you're staring into a terminal all day with a scratch in it, it gets annoying.

I'll look into some of that optical resin stuff. Where would one buy something like that? Hardware store, or maybe LensCrafter's or similar eyeglass chain?

-Ian

Sandy G · #5 03-30-2006, 01:43 PM

I dunno, Ian, I'd be careful. I've watched guys at a glass works just barely scratch glass-score it-& it breaks very easily. Whatever you do, PLEASE be carefull...this stuff is VERY unforgiving & doesn't take prisoners...

old_tv_nut · #6 03-30-2006, 02:31 PM

The problem with a scratch is that it concentrates the forces, so a scratch is a good starting point for a crack. I just would not risk it. Best to take the tube to air and dispose of it. Someone else here can probably tell you how to do that safely.

Grainger49 · #7 03-30-2006, 03:05 PM

Windshield places polish scratches out using something like jeweler's rouge and a felt buffing pad.

But you will have to press pretty hard on the face to do this.

Your choice.

kerozene · #8 03-30-2006, 03:41 PM

Don't TV tubes have a protective glass laminated/glued on top of the tube's glass?

andy · #9 03-30-2006, 05:06 PM

Quote:

Originally Posted by kerozene

Don't TV tubes have a protective glass laminated/glued on top of the tube's glass?

They used to, but no one has done this for 30 years.

Some modern TVs and monitors have a plastic anti glare film glued to the screen. Sony is particularly fond of this. It can be removed, but will leave the screen lacking any tint, or anti glare. I see a lot of these with scratches because plastic is much easier to scratch than glass.

The risk is minimal or nonexistent. CRT screen glass is not only very thick, it's very tough glass. You can't cut this type of glass as easily as ordinary window glass. Also, since the air pressure is pushing in on the screen, any scratches on the outside are on the wrong side for glass cutting.

I've seen lots an lots of TVs with scratched screens, but I've never seen one with an imploded screen (other than when someone was obviously bashing it with a hammer). Even when bare CRTs are thrown in a dumpster, the screen almost always survives without a crack.