Oscilloscope CRT implosion  - Page 1
Forum section: electronics / general

author: adriansmith31
author_rank: Contributor
timestamp: March 11, 2024, 05:55:52 pm
content: I smashed an oscilloscope CRT to see how much of a bang it went with. Very stupid I know but I did bag it up to avoid glass going everywhere.Demonstrates how dangerous these are if handled incorrectly. Glass very thin and no implosion protection. It was gone in 3 frames so camera didn't quite capture the full boom.Long versionhttps://youtu.be/_sL1OY1ONiUShort versionhttps://twitter.com/adriansmith31/status/1766966799898198085?t=eVceijRWaMCEeEk3h-fx9Q&s=19

author: coppice
author_rank: Super Contributor
timestamp: March 11, 2024, 06:00:26 pm
content: Scope tubes aren't big enough to be all that exciting when broken. TV tubes are a lot more spectacular, but you need some serious protection to restrain those corners.

author: adriansmith31
author_rank: Contributor
timestamp: March 11, 2024, 06:02:04 pm
content: Yeah, I dare not smash a TV tube in my kitchen lol.

author: coppice
author_rank: Super Contributor
timestamp: March 11, 2024, 06:09:25 pm
content: Quote from: adriansmith31 on March 11, 2024, 06:02:04 pmAbsolutely don't. Once they introduced bonded screens they became very hard to break, unless you break the neck, which isn't very spectacular. However, if you take the strap off, and hit them the right way they can be explosive in a way that will embed chunks of glass deep in the walls. Not a good place to be standing.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: March 11, 2024, 06:24:59 pm
content: And try not to breath the cloud of dust released from the phosphor screen whilst you're breaking those CRTs. The lead Pb rich CRT glass is classed as a hazardous material, so the busted bits should not really go into the domestic waste bin.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: March 11, 2024, 06:50:24 pm
content: Fearing such, I got rid of all implosive equipment as soon as possible and replacement equipment costs permitting. TVs with tubes, CTRs and even light bulbs. Anything with a vacuum (and a high voltage) frightens me until today.I am a sissy in this respect.

author: Ranayna
author_rank: Super Contributor
timestamp: March 11, 2024, 09:05:11 pm
content: Quote from: Messtechniker on March 11, 2024, 06:50:24 pmWhile there are a lot of reasons to get rid of incandescent light bulbs since the advent of LEDs, implosion risk is not one of them.Light bulbs are not under vacuum, they would be way too flimsy for that. IIRC they were filled with nitrogen, or some other inert gas.

author: coppice
author_rank: Super Contributor
timestamp: March 11, 2024, 09:21:17 pm
content: Quote from: Ranayna on March 11, 2024, 09:05:11 pmI think most are filled with argon. That certainly seems to have been the preferred option.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: March 12, 2024, 06:26:19 am
content: I mean the really old incandescent light bulbs with the tungsten filament. They certainly go with a nice bang when hit hard.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 12, 2024, 08:41:34 am
content: Quote from: adriansmith31 on March 11, 2024, 05:55:52 pmA large Scientific flask at atmospheric pressure would smash nearly as "spectacularly".The very large RADAR PPI tubes that were widely available as WW2 surplus are another story, & much of the "implosion" mythology dates back to them.Early TV tubes were not much better, but anything produced since the early 1960s is quite difficult to cause to implode.

author: coppice
author_rank: Super Contributor
timestamp: March 12, 2024, 02:51:03 pm
content: Quote from: vk6zgo on March 12, 2024, 08:41:34 amEarly 60s TV still had a tube with a separate armoured glass sheet in front of them. You need to get to the mid 60s before the bonded face tubes, with a metal band around them, took over. That's the innovation that made them very hard to damage in a spectacular way.

author: andy2000
author_rank: Frequent Contributor
timestamp: March 12, 2024, 03:27:29 pm
content: Early CRTs had no implosion protection, and required a separate safety glass. In the 60's they started bonding the safety glass to the front of the CRT for a more modern look, and less glare. In the 70's they got rid of the bonded safety glass and went to the tensioned metal band around the edge to reduce cost and weight. This system was used up until the end of CRT production.I was disposing of some CRTs about 20 years ago, and thought it would be interesting to just toss them in a dumpster while still under vacuum. One was a modern tension band CRT, the other was a 60's CRT with no implosion protection. The one with the tension band broke with little drama. The one without went off like a bomb when it hit the bottom of the dumpster, and glass rained down all over the place.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 12, 2024, 11:23:44 pm
content: Quote from: coppice on March 12, 2024, 02:51:03 pmIn Australia, bonded face tubes were appearing in around 1962/3.---that is still "early 1960s" to me!The bonded face tubes didn't have a metal band, that was a later innovation which controlled the stresses so the tube was very unlikely to break catastrophically, whilst allowing the tube maker to do away with the heavy bonded face.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 12, 2024, 11:28:01 pm
content: I used to treasure the armor glass window from the front of a 1950s TV. It protected me from a number of the unsafe experiments I ran in my dumb teen years. And I guess since the glass kept any shards and liquids from my skin and eyes those experiments weren't really unsafe.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 12, 2024, 11:39:59 pm
content: Quote from: andy2000 on March 12, 2024, 03:27:29 pmFunny you should say that.When I worked at a TV studio, we regularly changed the picture tubes of Picture Monitors, disposing of the old ones in a large dumpster.Throwing them in rarely broke them in any way, so we normally poked the neck with a long piece of what in Oz is called a "star picket".On one occasion, we had to dispose of some smallish late 1950s CRTs.They did break, but not spectacularly.Before that, I remember throwing some TV tubes out at the local garbage dump.Even though they fell a fair distance, they didn't break, so concerned, I told the tip attendant.He replied that they seldom did, but that the big metal wheeled compactor made short work of them!

author: coppice
author_rank: Super Contributor
timestamp: March 12, 2024, 11:46:28 pm
content: Quote from: vk6zgo on March 12, 2024, 11:23:44 pmI can accurately date the TV my parents bought in 1964 in London, because it supported 625 and 405 line operation, and the first 625 line channel (BBC2) didn't start operation until April 1964. All those early 625 line TVs still had an armoured glass plate.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 13, 2024, 05:51:49 am
content: Quote from: coppice on March 12, 2024, 11:46:28 pmI can only go with my recollections of the time., & in this country.When I started my first 'proper" job in 1959, all the TVs had a separate armoured glass plate.By at the latest, 1963, bonded tubes appeared.

author: coppice
author_rank: Super Contributor
timestamp: March 13, 2024, 12:07:43 pm
content: Quote from: vk6zgo on March 13, 2024, 05:51:49 amLocal safety regulations, perhaps? They can really skew the release of safety critical changes.