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Main => Monitor/Video Forum => Topic started by: Mauzy on March 07, 2008, 11:51:29 pm

Title: How thick is the glass on the front of a CRT?
Post by: Mauzy on March 07, 2008, 11:51:29 pm

I have a 26" Phillips Magnavox TV that I was thinking of MAME-ing, but it has a couple chips in the screen. I've used this TV on a daily basis for 4 years with the chips in it, but it got me to thinking: How thick is the front part of the glass on a CRT? How deep of a chip can it have before being deemed unsafe?

Title: Re: How thick is the glass on the front of a CRT?
Post by: brandon on March 08, 2008, 12:29:08 pm

its VERY thick!  I tried like hell to break a CRT in a dumpster once and didnt have much luck.  I would guess its at least 1-3"thick in places. That's why they're so darn heavy.  I dont think a chip would make a CRT unsafe.  Its not going to leak out nerve gas or anything like that :)

Title: Re: How thick is the glass on the front of a CRT?
Post by: Mauzy on March 08, 2008, 04:03:53 pm

Ha. Wow. I figured it would be thick, but not that thick.  Thats rather handy to know...

Title: Re: How thick is the glass on the front of a CRT?
Post by: Ummon on March 08, 2008, 06:28:15 pm

Notice when you put your hand on the glass and the image seems a bit away? Because it actually is.

Title: Re: How thick is the glass on the front of a CRT?
Post by: qrz on March 08, 2008, 10:04:22 pm

 as the screen size increases , thicker glass is required due to atmospheric pressure on surface area.
thats also why the neck can be so thin .  smaller surface area ......

qrz

Title: Re: How thick is the glass on the front of a CRT?
Post by: Rickn on March 09, 2008, 03:32:49 pm

The glass is about 3/4" thick. During the manufacture of the tube various tests are done to insure it meats UL requirements. These tests are not done on evert tube, just a sampling.

- first off the tube is positioned in a jig so that it is upright, it has a 7 Joule impact test. what this meams is a solid metal object shaped like a bulllet weighing 7 pounds is suspended on a rope like a pendulum, pulled back in a 7 foot arc and then let go so that it hits the center of the tube.... it cannot break or it fails.
- next the glass is frozen with nitrogen and the glass is scribed, the test is repeated and this time it will break, the glass cannot fall outside a line that is about 5 feet form the tube.

Bottom line your tube is probably safe, if it had chips around the "Frit seal" ( this is the white/grey seal that joins the faceplate to the tube) then it is a different story.

Hope this helps

Rick

Title: Re: How thick is the glass on the front of a CRT?
Post by: Mauzy on March 09, 2008, 04:49:32 pm

Thanks everybody. The chips are in the center of the viewing screen, so I guess Im safe.