Question scratches CRT TV - Page 1
Forum section: electronics / general

author: micksmelanie
author_rank: Regular Contributor
timestamp: July 08, 2020, 06:51:53 pm
content: Is there a product to remove scratches on the glass of the CRT TV screen?

author: wraper
author_rank: Unknown
timestamp: July 08, 2020, 07:02:01 pm
content: If there ever was something marketed particularly for this, it was discontinued a long time ago. IMHO process should be the same as doing so on car windshields.

author: edpalmer42
author_rank: Super Contributor
timestamp: July 08, 2020, 07:20:39 pm
content: Depending on how long and how deep the scratch is, that CRT could be a ticking time bomb! If you want to scare yourself, go to youtube and search for <CRT implosion>.

author: wraper
author_rank: Unknown
timestamp: July 08, 2020, 07:44:33 pm
content: Quote from: edpalmer42 on July 08, 2020, 07:20:39 pmNonsense, to crack a 10mm+ thick screen you need a sledgehammer, not some scratch.EDIT: BTW I smashed a few CRTs, not that scary IMHO.

author: james_s
author_rank: Super Contributor
timestamp: July 08, 2020, 08:02:55 pm
content: The screen is very strong. The bell of the tube is vulnerable though, I had a close call once about 20 years ago. I had replaced a worn out tube in an arcade game monitor and went to toss the old one in the dumpster at my apartment complex. It fell short and the funnel hit the hinge of the dumpster, there was an enormous BOOM and fragments of glass sprayed around about a 10 foot radius. Somehow I was unscathed but my ears were ringing.A light scratch on the face is nothing to worry about safety-wise. If it isn't too deep you may be able to polish it out with some buffing compound.

author: tggzzz
author_rank: Super Contributor
timestamp: July 08, 2020, 08:04:22 pm
content: Before spending too much time answering the OP, contributors may find it useful to be aware of:https://www.eevblog.com/forum/chat/question-remove-battery-smartphone/msg3121008/#msg3121008https://www.eevblog.com/forum/chat/moisture-and-electronics/msg3117256/#msg3117256https://www.eevblog.com/forum/chat/question-hygrometer/msg3117688/#msg3117688

author: edpalmer42
author_rank: Super Contributor
timestamp: July 08, 2020, 09:39:13 pm
content: Yes, I've heard where a little kid was banging on the CRT with a hammer and no problems. I've also heard of an electron gun assembly shooting out through the face of the tube. YMMV.

author: Nusa
author_rank: Super Contributor
timestamp: July 08, 2020, 10:01:55 pm
content: The correct answer is going to depend on the CRT involved and the degree of damage. Some injuries are beyond fixing.If there's an anti-glare coating (often found in professional equipment, and sometimes in consumer stuff), the CRT itself may be fine -- the fix is to disassemble/remove/replace that plastic filter.

author: amyk
author_rank: Super Contributor
timestamp: July 09, 2020, 12:10:13 am
content: Quote from: edpalmer42 on July 08, 2020, 09:39:13 pmThat's likely because of an implosion that started around the funnel. The face is curved to withstand atmosphere from the outside, so pressure from the inside will burst it far more easily.

author: james_s
author_rank: Super Contributor
timestamp: July 09, 2020, 05:46:42 am
content: I remember knocking the neck off dead tubes prior to disposing of them and I've had the gun impact the face of the tube but I don't think it's going to shoot through it unless the whole tube implodes causing cracks to propagate through the face. As long as the funnel is protected it's virtually impossible for a "modern" tube to implode.

author: micksmelanie
author_rank: Regular Contributor
timestamp: July 09, 2020, 12:21:32 pm
content: shallow scratches

author: free_electron
author_rank: Super Contributor
timestamp: July 09, 2020, 12:57:33 pm
content: in the early days of tv they put special plastic sheets in front of them to protect you if they went kablooie ... good riddance of those vacuum horrors...

author: wraper
author_rank: Unknown
timestamp: July 09, 2020, 02:11:37 pm
content: Quote from: free_electron on July 09, 2020, 12:57:33 pmLikely because early CRT did not have implosion protection band and other features preventing implosion.

author: Gyro
author_rank: Super Contributor
timestamp: July 09, 2020, 08:29:29 pm
content: Yes, the front screen went with the introduction of the external implosion band (and colour) - which also provided the mounting points necessary for the more modern 'pushed through' appearance.

author: james_s
author_rank: Super Contributor
timestamp: July 09, 2020, 10:49:04 pm
content: Quote from: Gyro on July 09, 2020, 08:29:29 pmThat "pushed through" appearance is bizarre to me, I've only ever seen it in pictures of some UK/European TVs. I've never, ever seen a CRT TV in North America that didn't have a bezel around the face of the tube.

author: Nusa
author_rank: Super Contributor
timestamp: July 10, 2020, 01:27:33 am
content: A bezel was sort of necessary to keep the tube in the set. But the Philco Predicta from the late 1950's came pretty close to no bezel.https://en.wikipedia.org/wiki/Predicta

author: 0culus
author_rank: Super Contributor
timestamp: July 10, 2020, 03:26:27 am
content: Quote from: Nusa on July 10, 2020, 01:27:33 amIsn't the tube usually held in by a strap of some kind? i.e. the bezel you see is cosmetic.

author: helius
author_rank: Super Contributor
timestamp: July 10, 2020, 04:24:50 am
content: Held into what?I have been inside several computer CRT monitors and they all bolt the CRT's band into the bezel. The bezel is then connected to the base where the stand is attached. You clearly can't support the tube from the bottom, you have to support it from the front.On older TV sets I have seen (1940s), there is frequently a support around the gun area. I have never seen anything like that in a 1970s or later display.To the OP, the antireflective coating is what generally picks up scratches. In some cases the glass may be scratched, but remember that it's barium-lead doped glass and ishardanddense. Either way, there is nothing you can do to remove the scratches. Don't under any circumstances try to polish the glass, it will absolutely ruin it. Get used to the scratches and you'll find they are not very visible after all.

author: 0culus
author_rank: Super Contributor
timestamp: July 10, 2020, 04:27:53 am
content: The chassis...obviously...BTW the OP was banned earlier for shilling an aliexpress store. He has left the building.

author: james_s
author_rank: Super Contributor
timestamp: July 12, 2020, 05:04:01 am
content: There are lots of open frame monitors that have no bezel. Most arcade monitors have the tube bolted to an open metal frame, the bezel is cosmetic and attaches to the cabinet, sometimes it's a vacuum molded plastic piece, other times it's just a cardboard thing.

author: classicsamus87
author_rank: Regular Contributor
timestamp: December 28, 2020, 11:10:00 am
content: my crt has some scratches and i need a product to apply with fabric on the glass and remove the scratch

author: S. Petrukhin
author_rank: Super Contributor
timestamp: December 28, 2020, 07:13:52 pm
content: Try an immersion gel - it fills in cracks and scratches, has the same refractive index as glass and therefore hides defects-no change in density. It is inexpensive, does not require any special application, if it does not help , it is not a pity.https://aliexpress.ru/item/4000972107338.html

author: james_s
author_rank: Super Contributor
timestamp: December 28, 2020, 07:20:59 pm
content: If that doesn't work (and the scratch is not deep) you can get abrasive polishing compound that will work on glass, but you will want a power tool to do it, a polishing wheel on an electric drill will work. It works by gently grinding away glass to smooth the surface so it takes a good deal of mechanical effort to accomplish.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 28, 2020, 07:37:46 pm
content: What's the stuff they used in microscope slides? Canada Balsam?https://en.wikipedia.org/wiki/Canada_balsamDo they still make it? Sounds harmless and cheap.

author: james_s
author_rank: Super Contributor
timestamp: December 28, 2020, 07:39:49 pm
content: The stuff I've used is called polishing rouge or jeweler's rouge, it comes as a bar that has a hard waxy consistency.

author: helius
author_rank: Super Contributor
timestamp: December 28, 2020, 11:49:33 pm
content: I have discovered that the antireflective treatment on some monitors is a plastic film that can be peeled off. Since scratches are probably in this (soft) film and not the (hard) doped glass, it would be smart to try removing it before doing crazy things like polishing.

author: HobGoblyn
author_rank: Unknown
timestamp: December 29, 2020, 12:09:56 am
content: I had an annoying light scratch on a crt years ago.I used duraglit/brassoIt removed the scratch, but it did also polished the surrounding area (removed coating).I then had this annoying bright bit, although in most uses it wasn’t as annoying as the original scratch was