CRT implosion experience?
 

Have any of you ever experienced a catastrophic implosion of a picture tube in the shop? When I first started working around them in the 60's I was scared-to-death that one might implode if I looked at it cross eyed. Over the years we had several break from various causes, but fortunately never had an instance where the shop was sprayed with glass or anyone was injured.

That is VERY scary!! WOW! I don't know how I missed that thread. I always considered myself lucky for not having experienced something like that. Now doubly so.

Our friend Douglas had a harrowing experience not too long ago...

Yep, he describes it in the thread David linked above. Mr. Harland has been amazing and inspiring me for awhile now, so reading that even he had such a disaster definitely makes me all the more fearful/respectful of my CRT.

I had intended to carefully remove mine to apply new aquadag and clean the safety glass. Besides not holding it by the neck, handling it like a stick of leaky dynamite, resting it on several folded blankets, etc., are there any other precautions I should take to keep it from rending me to shreds?

Shook the building
 

When I was service manager at Radio Distributing, an Rca parts distributor. One of the guys dropped a 21 inch round crt in the box and shook the entire building which was about 400 feet long. Luckily it was still in the box. He was trying to move it off of a stack of crt's piled three high.

Didnt see it happen, but was there for the aftermath:

Customer had aquired his own CRT for his set. I think it was from Sears. He installed it himself. Instead of buying the correct tube, with a bonded safety glass, he went with a less-expensive tube without the safety. I still dont know how he figured out how to get a tube minus the glass.

We went to his home, and there was glass shards allover his living room, and the front of his TV was literally blown out.

He told us that when reinstalling the tube, he had a rough time getting the strap on the bell tightened enough, but finally got it, as he could tell by the rust marks on the strap screw threads. I couldn't tell him about differences in CRT sizes at this point.

The new CRT was in the set less than 24 hours before the implosion. Luckily, the customer and HIS KIDS were not watching TV when it happened, or things would have been much worse... I know the kids sat real close to the screen. I do know that the set was turned on, and the family was in the next room eating dinner.

The customer replaced his living room furniture, and all the carpeting, since even after careful cleaning, there was still glass in everything.

After all this was over, we installed a new CRT in his set... I want to say it was a GE, with the right safety glass, and I still have him for a customer today.

For a hoot, about 25 yrs ago, I bought a forlorn old 23" B/W console, took it up to the local dump & shot it w/my Uzi...A buddy taped it...Still have the tape somewhere. Kinda made a Believer outta me...

I have to remove the glass on a tube here in the near future, this time I'll be sure to wear some protective clothing. last time I just broke the lens to pieces with a FLATHEAD SCREWDRIVER. Yikes.

Sandy, that might have been a real collectors item!! Were you drinking or doing some of that I-420 stuff???:smoke:

I shot at a 25" color Admiral with a .22 rifle one time. It had survived a house fire, sort of. One shot went through the center of the screen. Then, it whistled really loudly until all the vacuum escaped. I've always been a believer in CRT implosion possibilities.

Bruce

Ha! Drinking and 420 make me curious about doing stupid crap as well.

Needless to say, I have intentionally imploded many crt's. But, nothing collectible, and always as safely as possible. From about 2005-2008, I must have trashpicked over 100 tv's in my area. Yes, some met a sad fate.

I'm glad that link was posted, I somehow missed it this spring. Scary stuff!

The most impressive crt implosion I've seen: when I was a teenager my favorite way to dipose of junk sets was to set them on fire. I had this GE console from about '80, typical-no signs of life, beyond my limited ability. So, I drug it outside and threw some gasoline in the back. Poof! Now, when the heat is really getting to that crt the phosphors will start to darken, and that's a good time to stand back! With this particular set, just as this happened my highschool sweetheart walked around the corner. There wasn't time to tell her what to expect....WHOOMP! Glass went everywhere, proof that the safety of a modern tension band crt has its limits.

Back in the 70s, when I was in college, I had to dispose of a 20 or so inch B&W CRT in the TV cabinet. The town trash collectors wanted us to let the vacuum out of CRTs by breaking off the little evac seal at the socket. We put it at the curb. Well, this CRT had a bakelite base and the glass seal was not accessible. So I decided to stand back about 25 feet and toss rocks at the CRT neck to snap it off, and be at a safe distance. I missed the neck, but nailed the big part (like where the high voltage connects to). Kaboom! flying glass all over the street and front yard lawn. Good thing I was 25 feet away. I wonder if the CRT phosphors helped fertilize the grass any. Don't remember any brown grass afterwards.

My CTC-24 has a minor cataract, and it's gonna stay that way. I've only removed the safety glass from one set, a CTC-17, and that was because the safety glass was broken and it had a bad cataract which was easily taken care of.

This is an interesting thread! FWIW I will add my 2 cents worth.

WRT the implosions that occured during the removal of the bonded safety glass in an attempt to remove the cataracts. It is very likely that the implosions were caused not by anything physical. It is most likely that the tubes imploded due to the UNEVEN application of heat and cooling. The glass envelopes from shich tubes are constructed, are under a lot of stress from the vacuum inside them. Imagind 14.7 PSI pushing inward on every single square inch of the tubes envelope. We are talking about many many tons of force.

Glass is a very britle material. apply heat to only one area of the tube and you will cause the glass to expand enough that the huge forces on the tube due to atmospheric presssure, are enough to cause the envelope to crack. IF the tube was not vacuum, the envelope might not even crack, but due to the forces on the outside of the tube from the pressure of atmospheric pressure, you are asking for big trouble if you heat the tube unevenly.

Another point. Several years ago somebody posted about a 21fjp22 he had sitting in his garage for some years. Often the tube was sitting with the fase of the tube submerged in water. When he went to move the tube, the safety glass just fell off.

On my lst trip to Hawkeye I asked Scotty about his method of safety glass removal. He said that they placed the tubes in the warming oven. (presumably after the vacuum relieved and the gun was removed. Then whent he tube was warm, they would pop off the safety glass.

Scotty said in the old days, they had a tank which contained water and detergent, and they would place the safety glasses that had been removed into the tank and let them soak for a week. The soaking softened the bonding agent and made for easy cleaning.

From all of the above one might reasonabley expect that it is not necessary to remove the safety glass using heat, provided you are in no hurry. I suspect that simply soaking the front of the tube in soapy water for a long period of time will cause the safety glass to loosen and the PVA to soften so you can remove it easily.

I have a number of color crt's with bonded safety glass. I am going to experiment to see if the safety glass can be removed by just soaking in soapy water for a long time. I will let the group know the results. This may take a month or more so don't hold your breath.

As a novice to this forum when I read the cataracts thread I foolishly :o argued that they wouldn't have used PVA to bond the safety glass because PVA is water soluble which would cause problems.

Since they really did use PVA the water bath removal makes sense.

If you dig through the old threads you will read my experience with water. It was positive. I tried it with the "green" type used by Zenith and others, the one that does not respond well to heat. I bought a cheap blow-up kiddie pool at the dollar store and let the crt sit face down in water. It took about 5 days, as I recall. I think the longer you wait the easier it will go. I tried it later with the RCA style PVA and it didn't respond at all even after a week. If you have an outbuilding with some spare room, I say just get such a pool and let it soak. Detergent couldn't hurt. Some have suggested kerosene or other solvents-the trouble I see there is that you then have to deal with this vat of flammable, smelly stuff. There is a product called Bean-a-Doo which is sold as a soaking agent to remove adhesives from automotive trim, and perhaps it would work. Made from soybean oil. But, very expensive. Even plain vegatable oil would be expensive if you bought enough to soak a tube.

I have removed several faceplates with heat, with good results, but I am nervous after reading some of these experiences. I may be removing one this week but I don't think that one has any adhesion left at all. I may stick with water from here on out.

I've posted this before, but here it is again:
My only "serious" experience occurred the summer when I was 17. I was helping my Dad swap CRTs (25AXP22's) between two sets at his TV shop. I pulled the bad CRT out of the set and set it on the dump pile outside, then busted the "tit" to let it go to air, no problem. Dad, meanwhile, left to go get a new blue lateral assembly at the parts place a mile away. I was alone and with the vigor of youth, decided to pull the "good" tube to have it ready when Dad got back. I unbolted it just fine, and I lifted it from the set (by the neck) and set it on the edge of the cabinet to reposition it. I then hoisted it up by the sides (face down), only to have the 2nd anode button come in contact with my abdomen and now-sweaty t-shirt. WHAM!! - I got the residual charge. I reacted by pushing it away from me, into the corner of a workbench, imploding the CRT about 6-8" from me. I was shaking, and alone, and uninjured. My only scare was what was I going to tell Dad when he returned. Thankfully, he laughed it off after ensuring I wasn't hurt. Glass shards were everywhere, and we even found some 6 months later when we moved some equipment around in the shop.

Cheers,

Have you considered trying biodiesel? B100 should cost around $3.50 a gallon, and is not that flammable or smelly. It dissolves rubber fuel lines, it might work well on this. The only trouble would be finding it as very few fuel stations sell 100% biodiesel, moreso this time of year.

-J

Well, there's brake fluid, which is widely known to dissolve paint. maybe it would do a CRT. My brother uses brake fluid to remove the paint off of his plastic model train models.

If the bonding material on a particular tube is a type of polyester resin (I believe that some were ... PPG 5252 or something like that), methylene chloride will do the job. Very nasty, however. :yuck:

jr

Dow Chemical's formula is in Patent 3007833:

33 parts by weight diglycidyl etherr of bisphenol A, 67 parts diglycidyl ether of polyoxypropylene glycol having a molecular weight of 400 and 5.5 parts of monoethanolamine and 1 part of diethylenetriamine.

What that means, I dunno. The patent is for the use of a Saran wrap band around the tube and safety plate while filling the gap with the above mix.

US Patent 3265234 from Union Carbide lists a number of other chemicals that were used to bond the safety plates - about 4 or 5 formulations are compared.

I guess not all CRT's used the same bonding materials....


Cheers,

YES! I think that is the reason for some frustration on this board... methods for dealing with one type of bonding material may not be effective, and perhaps even dangerous to use to remove another type.
Dow Corning 184 for example, was sometimes used on smaller special purpose tubes where high optical quality was desired... I suspect that heat alone would not be effective to remove a faceplate bonded with 184.
jr

Really nasty and dangerous. It has a high vapor pressure and will evaporate very quickly. It would have to be a very valuable tube before I'd try it.

I'm not sure how you'd do that either. I still have a scar from trying to remove a PMT from a light guide that we wanted to save that had been bonded with Dow 184. Have you ever seen a cataract or similar form with 184? I'd expect it to last nearly forever. Rebuilding a CRT bonded with it would be a real bear. A long term soak in trichloroethylene would swell the 184 and loosen the bond, but is also hazardous.

Dow 184 is nearly ideal for the purpose, but would break the bank for a large CRT.

Yes, I have observed partial de-lamination on some tubes using 184.... sort of looked like "worm tracks" in the material.

I see that Amazon has the material listed, wonder how many 21" crts could be bonded with an 3.9kg "kit" for $336 ?:eek:

jr

Guess it would depend on the bond line. If it was 1/8" you could do about five 21" CRTs.

John

Used to put old CRTs in a 55 gal trash barrel & chuck a rock in from about 20' away. Always got an impressive geyser of glass out of the barrel.

Furniture Blanket
 

My Dad owned a TV shop ,we wrapped a furniture moving blanket around the tube: Then , put it in a METAL trashed can and then broke the neck off with a LONG pipe.
Now working at NASA with huge vacuum chambers on night-shift..............
Put it this way........... I don't fall asleep at work !!!
I'm always ready for the unexpected !!!!!!!!!!!!!!!!!:scratch2::smoke::nono:

And the neighbors might think that you have set up a meth lab... :D

Working in a tube rebuilding facility in the '60's, the only time we had a tube implode was in the ovens. Years ago, I had a TV repair shop in our local flea market where I would repair TV's while you wait. There was another guy who started up on the other side of the market which we called "Brand X". A good guy but more of a piddler. One day I heard a tube go off (I knew that sound!) and ran to the other side of the market where he was sitting down on the floor in bewilderment beside the TV. I was for sure at that point that he was seriously hurt as there were chunks of glass shards all over the place and a few customers running. What he had done was cut the pressure band off of a live 25" tube to make it fit into the cabinet. DON'T YOU EVER CUT A PRESSURE BAND OFF OF A LIVE TUBE!!! EVER!!!

The theory is before a tube can implode, the faceplate has to be forced inward and it cannot if there is a band on the tube. For rebuilding, we took the band off after the tube was let down to atmosphere pressure.

that story reminds me of my post about "hillbilly frank".he cut the band of a magnavox crt to use in something else.he fired the set up and after a few minutes,i heard a blast like a grenade.the set exploded in his living room.he was on the phone with me when it happened.i have cut off the ears on a magnavox crt but never cut the pressure band.though it didnt pull the nails from the walls,it did leave pieces everywhere.

Why was the band cut off during rebuilding-heat expansion issues?

Yes, when the tube goes into the over the band has to come off because it has to expand or it definitely will go off in the oven.

nver understood how the band prevented implosion, thats for that explantion.

so I guess the follow up question would be, if a bonded glass CRT has the cataract removed, then why would the CRT not implode upon removal of the bonded glass? Can a band be added to a tube that had the bonded glass (guess before the removal takes place) to be safe again? if so is there a procedure/tools/tension mearuring device that should be used?

Because the glass is just glued to the front of the CRT, it does not impart any tension on the face at all like a band does.

besides the band or safty glass is there a difference in the contsrution of the two?

What I am getting at is "should" a band be added to a CRT that has the safty glass removed.

If they are the same basic CRT just one uses bonded glass and the other has a band, then it would seem that a band should be added if the bonded glass is removed.

As far as I know, they would NOT be "the same basic CRT," as I don't think you will find the same part number with a safety glass OR a band - it will be one or the other. Note the danger of implosion of a banded tube when the band is removed. This tells me the banded and unbanded tubes must be basically different. The engineers may have determined that a particular glass kit could be used either way, but I don't know if that has ever been done, unless someone who knows tells us.

when i was about 11 years old me and some of my friends were playing around in a house that had burnt down months before we went in it..
the roof had collapsed in several of the rooms. and there was a large tv in the living room. the case was real wood and i remember the screen looking grey and not black like moden screens..
the tv was atleast 32inches..

we were throwing rocks at it trying to break it.. after all we were kids and the tv was glass...
i was throwing big rocks or chunks of cement at it.. it was only scratching the screen..
my friend threw a small rock at the screen and BOOOOOMMMMM!!!
it was a amazing sound.. it felt like sombody hit me in the chest.
i actually moved alittle from the sound it made..
it was louder than the artilary shell fireworks..

it was definetly something i didnt expect to happen.

A couple of scary implosions on YT...

http://www.youtube.com/watch?v=NnZ39EL-wF0

http://www.youtube.com/watch?v=zKvyGt7xhGw