Actually 4

I think I would have had a rethink after one, two at the most!
Max.

 

One of my remaining brain cells is firing saying that it remembers that the band is holding the glass in compression -- and is needed. I wish I knew why that connection still exists yet is missing context.

On a (somewhat) related note... a CRT design must be tested for safety by dropping a 2" diameter steel ball onto the upwardly pointing face from something like three feet. The CRT is allowed to implode but no pieces, such as the electron gun, are allowed to come out of the face. I once bought the required ball bearing but, alas, never got to do the test.

 

From here:

The surface of the screen you see is most often part of the CRT envelope. In this case, there should be a tensioned steel band - a rimband - around the edge of the CRT near the front. The rimband is essential to assure the structural integrety of the CRT envelope against the emmense forces due to the air pressure attempting to crush it. In the event of a catastrophic event, the rimband will also reduce the range and velocity of any debrie. This is called 'integral implosion protection' by some manufacturers.

Warning: A CRT that is supposed to have a rimband but where it is missing or damaged is a serious hazard since the possibility of implosion is greatly increased and the effects of such an implosion will be more severe. However, such a situation is virtually impossible to occur on its own since the rimband is part of the mounting bracket assembly. Don't be tempted to remove the rimband for any reason unless the vacuum has been let out (in, whatever one does with a vacuum) of the CRT! Spontaneous implosion is even possible. See below for an example.
...
Anyway, a friend of mine decided to cut the rimband off a picture tube. I wasn't there, he told me about it. This was a 25" RCA tube he wanted to fit into a Zenith TV (don't ask me why). What happened in the next few seconds after he cut the rimband, the picture tube imploded in his face, embedding the neck and yoke assembly in the ceiling, he came out with a cut about half an inch above his right eye that needed 6 stitches to close. Had that shard of glass been half an inch lower, he would be wearing an eye patch or have a glass eye for the rest of his life.

Wow.

 

The only way I can see this done safely is to release the vacuum in the tube, and after rework of the metal work, restore the vacuum. I am sure there are still a lot of dusty color CRT rebuilding machines in basements! All of this must be done in a clinically clean environment!
If the cabinet is worth it, replace the whole inside with a modern TV (hinge the TV and have a hidden liquor cabinet behind!). Soon enough there will no longer be any analog TV signal to be had anyway.
Boy, all that without a single big word, italics, bolding, change of typeset or font size. But I am working on a small program to add "Phonetic Punctuation", invented by Victor Borge, to accommodate my dissertations! E

 

The only way I can see this done safely is to release the vacuum in the tube, and after rework of the metal work, restore the vacuum. I am sure there are still a lot of dusty color CRT rebuilding machines in basements! All of this must be done in a clinically clean environment!

This part is off target. HP merely wants to fit a large CRT in a cabinet that is too small, not rebuild the CRT.

Boy, all that without a single big word, italics, bolding, change of typeset or font size. But I am working on a small program to add "Phonetic Punctuation", invented by Victor Borge, to accommodate my dissertations! E

This part is properly on target.

 

I think I would have had a rethink after one, two at the most!
Max.

Oh! I thought and rethought alright! - and, unfortunately, reached four wildly different albeit equally wrong conclusions -- The irony is that when I began to suspect the truth I feared my 'hypothesis' that the band might be structurally important was 'grasping at straws' and liable to ridicule (go figure) --- To render yet another famous quote:

Truth is stranger than fiction, but it is because Fiction is obliged to stick to possibilities; Truth isn't

Spot on!!!

Chastened and rebuked (well, rebuked anyway...)
HP

 

From here:

Wow

"The surface of the screen you see is most often part of the CRT envelope. In this case, there should be a tensioned steel band - a rimband - around the edge of the CRT near the front. The rimband is essential to assure the structural integrety of the CRT envelope against the emmense forces due to the air pressure attempting to crush it. In the event of a catastrophic event, the rimband will also reduce the range and velocity of any debrie. This is called 'integral implosion protection' by some manufacturers.

Warning: A CRT that is supposed to have a rimband but where it is missing or damaged is a serious hazard since the possibility of implosion is greatly increased and the effects of such an implosion will be more severe. However, such a situation is virtually impossible to occur on its own since the rimband is part of the mounting bracket assembly. Don't be tempted to remove the rimband for any reason unless the vacuum has been let out (in, whatever one does with a vacuum) of the CRT! Spontaneous implosion is even possible. See below for an example.
...
Anyway, a friend of mine decided to cut the rimband off a picture tube. I wasn't there, he told me about it. This was a 25" RCA tube he wanted to fit into a Zenith TV (don't ask me why). What happened in the next few seconds after he cut the rimband, the picture tube imploded in his face, embedding the neck and yoke assembly in the ceiling, he came out with a cut about half an inch above his right eye that needed 6 stitches to close. Had that shard of glass been half an inch lower, he would be wearing an eye patch or have a glass eye for the rest of his life.."

...sure wish I'd seen that 24 Hours ago!

Had that shard of glass been half an inch lower, he would be wearing an eye patch or have a glass eye for the rest of his life..

My PPE 'ensemble' (Re: the first tube) consisted merely of a safety visor --- Thus it seems, considering the glass shot that sprayed same -- 3mm of polycarbonate was all that stood between me and a 'new and exciting' life as a pencil vendor That said I was obliged to effect sundry minor bodily repairs prior to renewed pursuit of that particular 'rainbow'

Drollery aside -- I'm pleased I decided to post my inquiry!-- better an educated former fool than a confirmed lackwit...

Best Regards
HP

 

Never remove the tension band around the face of a CRT. It is there to assure that if the tube breaks, the glass with collapse into the tube rather than going flying out into the room. The bands were usually heated and shrunk in place, resulting in a huge amount of tension.

The band is absolutely essential for safety.

This thread is absolutely the scariest thread I've read on this website.

 

It is there to assure that if the tube breaks, the glass with collapse into the tube rather than going flying out into the room.

...And, as I discovered to my cost, a vital structural member thereof! -- Please rest assured I've learned my lesson --- To wit: as the 'West Country Folk' are fond of saying: "doan do daaat! jus le-hit be! -- t'wer put daare for a ree-son!!!"

Best regards
HP

 

HP this is not funny! You think as dumb as I type now are you proud of yourself? This is forum for discussion of electronics not fetish of self mutilation! I come here hoping for uplifting experience not account of your gristly death! Suicide is a terribly selfish act and I say negligence just as bad! Don't hate me because I care
PS I think you care more about 300 dollar tubes than your life!

 

I don't think so. If HP cared about $300 tubes she would have asked before she ruined 4 of them.

 

Generally failure presents as formation of opacities -- which require removal of the bonded safety glass and all traces of adhesive followed by either re-bonding or 'tacking' the glass into place... Indeed removal of the the safety lense is the most difficult and hazardous part of the job (requiring carefully applied heat -- and a suit of 'armor')...

Maybe you should borrow Henry VIII's suit of armour from the Tower of London.

 

HP this is not funny!

Who said it was?

You think as dumb as I type...

Speaking of which - better watch it! -- Seems being PO'ed brings you within a hair's breadth of literacy!

Suicide is a terribly selfish act and I say negligence just as bad!

Seriously, where's all that coming from?

I come here hoping for uplifting experience not account of your gristly death!

I take it you are aware that I somehow managed to survive?
Or, to paraphrase Rowan Atkinson: "I find your morbid fascination with my death quite disturbing!"

PS I think you care more about 300 dollar tubes than your life!

It's not the cost but, rather, the scarcity -- by 'modern tubes' I meant relative to the TV receiver -- I doubt I can find others at any price! --- As far as misplaced evaluation? What can I say? The tubes are in pieces in a drum - while I'm here typing a response to your post -- what does that tell you???

Don't hate me because I care

In all seriousness - Your friendship is obvious! For which I am both grateful and deeply appreciative!!!

This is forum for discussion of electronics

Indeed it is! So, on that note, if you feel there's any more to be said in this vein - lets move it to PM ...K?

Sincere thanks for your concern!
HP

 

@boatsman

Ah! "the days of yore" when even PPE was aesthetic!!! --- Imagine what an item such as that would bring at auction!!!

Best regards
HP

 

She wanted to introduce a large screen monitor into a small screen space. He figured out that it was going about it in the wrong way. ............ get more politically correct then that.

Thanks HP for making me hit the dictionary, life was getting dull.

 

Thanks HP for making me hit the dictionary, life was getting dull.

You mean in my response to Aleph on this thread? If there's a 'fifty cent word' in there -- danged if I can find it?
Well, anyway, pleased to have dispelled you ennui

Best regards
HP

 

You mean in my response to Aleph on this thread? If there's a 'fifty cent word' in there -- danged if I can find it?
Well, anyway, pleased to have dispelled you ennui

Best regards
HP

Not this post at this point in time.

I suppose it would be your cumulative input on the forum.

 

That's a new one on me? You mean a tube so constructed that adhesive functions as the frit seal!?!? --- I'm thinking an alkali silicate or some such...?

Best regards
HP

At the time, it gave the impression of having been glued. My reading about frit seals was relatively recently.

Back then there were commercially available glass adhesives that would have seemed plausible for that use.

The set had been returned to the tip by another trader, a gassy CRT would probably explain why.

The face plate separated from the flare so easily I assumed it couldn't have been anything better than glued.

 

On a (somewhat) related note... a CRT design must be tested for safety by dropping a 2" diameter steel ball onto the upwardly pointing face from something like three feet.

One of the big old CRT's I changed years ago, I fired a .22 dead centre from 40ft away, the >1/2" thick chunks of the face were thrown 30ft.!!
Max.

 

HP Sorry about flames you think right it's because I care! You know west country dialect so you recognize this? _There's no need to look down on us simple folks just we're close to the soil!_