CRT implosion

[sortedradio]

In many threads I have read about vintage televisions I have seen CRT implosion referred to. My main area of TV interest is post WW2 to 1960, and I am aware that there are dangers involved in handling these tubes, as well as the voltages, live chassis etc in the sets.
What precautions do other members take when handling these tubes, and working on chassis in the bench. I am only concerned here about the risk of implosion and have any members had the misfortune to experience it?

[peter_scott]

I have broken a few as a wayward school boy but without injury.

See: https://www.vintage-radio.net/forum/...ght=tube+floor

Peter

[Welsh Anorak]

My experience is later than your preferred time, but despite accidents when I've knocked the neck off or deliberately brought a tube down to air, I've never had a catastrophe, even when two sets have accidentally banged their faces together. However, these CRTs were modern by comparison, and I'm very wary of pre-1950 CRTs as implosion protection was rudimentary.

[Maarten]

The tension band implosion protection was introduced in the early 1960's. I think it's safe to say that sortedradio only has non-protected sets. While those also can go down to air peacefully when the neck cracks, the glass not being pretensioned to direct the forces inwards will usually fly everywhere with some force when it cracks. The chances of the glass cracking aren't higher, but the damage it can do is. Hence the presence of a separate safety glass, either attached to the cabinet or glued to the tube front.

[Alistair D]

I once watched a 0.22 bullet fired at the face of an old TV CRT from a safe distance. The result was a sight to behold, there pieces if 1inch thick glass flying feet in the air. Anyone close to the tube would have been shredded.

The tube was a 'rectangular' one but I do not remember which size

In case anyone is concerned, The gun was fired by the licence holder on the land he was permitted to shoot on and we did clean up after ourselves.

Al

[MrBungle]

I popped a 1950s set by accident when I was a kid. Someone had left it outside in the rain and the case had swelled up so took the opportunity to kick it off to get the yoke out as I couldn't afford that much copper wire new back then.

Guess who kicked the neck off by accident. What an explosion!

No injuries but I am wary of older sets (and scope tubes). The worst thing is all the tiny bits of glass you didn't notice on your clothes. Safety glasses, disposable long sleeve t-shirt are minimum for handling. I usually work over a towel as well to stop bits hitting the bench.

[sortedradio]

Thank you for your replies. I don't have any of the early Pyrex clear style tubes at the moment, but most lack a safety band and have separate safety glass in the cabinet. I have a pair of googles, but think I will buy a pair that include a visor for face protection. Laying a towel over the tube while working on the chassis seems like a good idea.

[Refugee]

I popped one or two back in the 1970s.
As it was for entertainment a safe distance was the order of the day.
With the hardware removed including the tension band they were rolled with the neck out to one side down a steep bank onto a pile of rubble.
They were loud and the dumped rubble gave us an excuse not to clear up afterwards.

[Nuvistor]

From the Television Engineers Pocketbook, editor JP Hawker,

Face and eye protection is required as you have noted, perhaps gloves as well.

[cheerfulcharlie]

As a youngster I was given an old TV set of the 50s, rather curiously I took it to pieces I had no idea what I was doing (still don't) and was left with the tube without the strap. I use to try and look in the clear glass edges to see if I could understand what was going on inside. We moved house and carried this tube along for some reason, it lay in an outbuilding for some time until while playing an elder chum spotted it and said something like "what the hell are you doing with this, have you seen one of these go off".We took it to some waste ground and he wacked a piece of rock at it..Wow! a "voom" and then it looked more like an explosion to me rather than an implosion but we were running for cover instantly. Great schoolboy fun when you smashed screens rather than sat all day looking at them LOL

[sortedradio]

Thanks Frank, that's very useful. I have worked on computer monitors and a few more recent TVs in the past, but now have a few 1950's I would like to restore. I have a face visor & gloves on order.

[TonyDuell]

My late father, who worked on high vacuum systems in his day job as a research chemist, was very worried about implosions. He wasn't the sort of person to take ridiculous precautions either, but he was very careful round a TV CRT.

My feeling is that a CRT with built-in implosion protection, such as a tension band, is relatively safe (although I am still careful, if only to avoid having to source another CRT). But I don't like working on older TVs at all.

The technical manual for one of my classic computers (Whitechapel MG1) has a rather amusingly worded comment in the the section on the monitor (which uses a tension-banded CRT). I will find the manual to get the exact wording if anyone cares but basically it suggests you wear a face sheild to BSnnnn, heavy duty gauntlets and 'A heavy apron to protect those other important parts'

[Chris55000]

Hi!

Towards the final end of the CRT era in the mid-2000s, I came across many poorly manufactured (Far Eastern!) so-called "Rim-band" CRTs where the CRT Rim-band could be removed easily with the hands & fingers, and to my mind these were just as dangerous as the first generations of post-war 1950s/early 1960s CRTs that had no implosion protection built in as standard!

My gaffer Mike Smith refused to accept delivery of any CRT in this condition, as he knew the dangers as much as all of us do on this Forum, and insisted on the CRT supplier taking it back by courier and supplying another!

Chris Williams

[TonyDuell]

I actually think CRTs with a defective rimband are MORE dangerous than the 1950's CRTs. The latter would be used in cabinets with a safety glass screen in front of the CRT, so at least the viewer/user would be protected. The former would, presumably, not be used with any other implosion protection.

[emeritus]

Inches the 1950's and 60's our neighbour used to dismantle old TVs and radios for the scrap metal. He used to let dad have the valves and other components, including the implosion screens. Dad did once dispose of the CRT of our first TV by lobbing it out of the back door into our concrete yard, and managed to appear as surprised as the surrounding neighbours who looked out of their windows to see what had caused the bang. The tube had shattered into tiny unrecognisable fragments.

I came across three different types of implosion screen: perspex about 1/4" thick , colourless or tinted grey or pink; laminated safety glass - two layers stuck together with a clear bonding medium; and armour plate glass, about 1/4" thick with "Armour Plate" etched in small letters in one corner.

[AC/HL]

Originally Posted by TonyDuell

My late father, who worked on high vacuum systems in his day job as a research chemist, was very worried about implosions. He wasn't the sort of person to take ridiculous precautions either, but he was very careful round a TV CRT.

Good point with very wide implications. Professionals don't take ridiculous precautions, they take wise ones because they know and understand the risk/consequence balance.

[Lloyd 1985]

I’ve been messing about with old TV’s since I was a kid, but only started working on 50’s sets around 2005, some of the 50’s CRT’s are scary! They don’t bother me normally, but recently I had to do a tube swap on a 50’s Ekco with a 10” Mazda tube in it, the glass is stupidly thin, and the tube feels so light, like handling a wine glass. The Mullard tube that replaced it was more substantially built, must have had thicker glass. I also had the CRT out of one of the 32” Samsung Slim-fit TVs once so I could clean the cabinet, that was a bit hair raising too, just because of the weight of the thing, I should have got help with it really, but managed it on my own without breaking anything (or giving myself a hernia!).

So far, I’ve not had a CRT go pop on me, or even damaged one. But there is still room for a first time, so I’m very careful when handling them, make sure you have room to work with the tube (something I don’t do quite often...) only handle it by the bowl and with both hands, not swinging it about by it’s neck, and also have a close look before even attempting removal of a CRT that it isn’t damaged in any way that could cause a safety issue, such as hairline cracks.

Regards
Lloyd

[sortedradio]

Thanks Lloyd, do you wear goggles & gloves when handling these CRTs, and when working on the chassis , complete with the tube on the bench. I'm just trying to get a balance between, sensible, practical and paranoia!

[HamishBoxer]

There was a time when you were advised to wear a leather apron.

[sortedradio]

Originally Posted by HamishBoxer

There was a time when you were advised to wear a leather apron.

Yes, I had wondered what is considered suitable clothing. I guess a bomb disposal suit would be safest, but I would imagine expensive and not very practical!