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  #46  
Old 12-12-2010, 02:31 AM
eberts eberts is offline
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  #47  
Old 12-12-2010, 04:02 AM
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Whew, just got done breaking the lens off an FJP- back is killing me. Thankfully I did NOT have an implosion experience. lol
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  #48  
Old 12-12-2010, 07:00 AM
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Here's a edited fake video of a guy smashing his TV screen with a hammer and gets blown to the back of the room:
http://www.youtube.com/watch?v=5G0kA845GgM&NR=1
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  #49  
Old 12-12-2010, 01:04 PM
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I have intentionally imploded many CRTs but i also had one implode accidentally on me.

It was a mid 60s 23" B/W tabletop set with a bonded lens CRT i had when i was a kid, it was an European style set with a push-through screen so it was very front heavy, it toppled off my outdoor bench while i was unscrewing the back panel to fix it.
The shockwave was so loud it roared all over the neighborhood and scared the crap out of my parents.

Luckily the back panel was still on and the bonded safety lens did its job so the implosion remained 100% confined inside the set.
The set's speaker was totally shredded by the implosion!
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  #50  
Old 12-12-2010, 11:50 PM
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I just got back from my folk's house, where I soaked an FJP in methylene chloride for a day in an attempt to melt the PVA out. Yeah, didn't even budge. I ended up breaking the safety glass off, just like the last one.
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  #51  
Old 12-13-2010, 09:25 PM
ctc17 ctc17 is offline
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Im going to try the water trick. I have plenty of crts around here that need the glass removed. I just need to find a container and will let it soak for a month or so.
Its the RCA style that freaks me out. The Zenith green style cut off so easy with a hot wire I dont worry about those exploding.
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  #52  
Old 12-14-2010, 01:26 PM
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Yeah, for that one that imploded on me, we gathered up the PVA and I tested some common solvents to see how it would react. I forget what all I used, a short list would include: MEK, denatured alcohol, carb cleaner, brake cleaner. I sat the pva chunks in some sealed containers with the stuff for a week, and NONE of them really changed after that punishment. This was an RCA tube, btw.
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  #53  
Old 12-26-2010, 01:40 AM
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Some real life experiences/observations regarding this topic.

In another thread there was a short discussion regarding PVA vs PVB and a comment was made that auto glass uses PVB and that it doesn't suffer cataracts. Well I've run a car restoration shop and cataracts are actually fairly common, especially on vent windows (remember those?) and flat side glass. Have even seen them creep from the edges of some windshields.

Speaking of auto glass...had a first generation Mazda RX-7 that lost one of the spade connectors for the printed circuit defroster on the rear window (which was a hatchback). Removed the window and sat it upside down on some blankets. Using a soldering iron I was able to solder a replacement connector and left it to cool. Maybe 10-15 minutes later glass was raining down after the damn thing exploded. The interesting thing is that this was bonded safety glass AND had a metal frame around it...add to the equation that unlike a CRT there was no vacuum to contend with and I'm now even more ascared of working on picture tubes. Obviously I induced an incredible amount of localized stress. Mazdas may make you go "Hmmm" but in this case I went "WHATTHEHELLJUSTHAPPNED?!"

Regarding whether rebonding the safety glass is stronger (or not) then just sealing it around the periphery I vote that the original full face bond is stronger. Just stands to reason that the bond effectively doubles the thickness of the individual glass layers, plus it probably adds shear strength as well. Think of where plywood gets it strength from, layers of opposing grains of wood PLUS glue in between.

I could be completely wrong but that's my take on it.
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  #54  
Old 12-26-2010, 09:11 AM
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Quote:
Originally Posted by DaveWM View Post
"should" a band be added to a CRT that has the safty glass removed.

.
The band was just for the mounting lugs ?
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  #55  
Old 12-26-2010, 10:11 AM
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Quote:
Originally Posted by NewVista View Post
The band was just for the mounting lugs ?
Anybody correct me if I'm wrong here but yes, basically it's there for the mounting lugs to easily facilitate installation/replacement. Most tubes as we know had some sort of strapping set-up that mounted the tube to the bezel. There is the exception of some early Zenith Rectangular tubes that mounted in a "surround" then that was then bolted in, and was a PIA to unseat from the old tube during replacement.

Has anybody noticed any cateract conditions with the band/lug type tubes? With all that strapping and shielding was the use of bonding materials eliminated?

As for releasing tubes of vacuum, I remember a safe way was to drill a hole in the anode button after making sure it would remain discharged!
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  #56  
Old 12-26-2010, 10:52 AM
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Last edited by andy; 12-07-2021 at 01:30 PM.
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  #57  
Old 12-26-2010, 11:11 AM
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I think one way to reduce the chance of an implosion during a faceplate removal is to get the whole CRT as warm as possible before using the heat gun. The one time (so far) that I removed one, I put the CRT in the sun in my back yard for a few hours before starting the removal. It was quite hot, but since I was already wearing gloves for safety, I could pick it up and move it easily.
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  #58  
Old 01-14-2011, 09:57 PM
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Okay, folks, here is another one to add to our "collective experience".

Another VK member needed the safety glass off of a 21FJP22. Since I had a couple dud tubes in the attic I decided to pull one off. The crt in question is a used Philco-built tube that was gassy, from all I could tell. Certainly beyond anything a rejuvanator could do. I took it took work and let it sit in the shop for a few days before deciding to work on it today. I started warming it up with the heat gun-I've done 4 or 5 of these before using this method but after reading a couple implosion stories, I found myself unerved this time. I decided it really made more sense to air down this tube. I used my usual method for tubes I'm going to junk-I used an awl to poke a small hole in the ultor. No drama, it went to air in a minute like they usually do. I then flipped the tube back over. I decided instead of using the heat gun I would use a bank of infared lights I have at work. After setting them up it took some time before I started seeing results, maybe 45 minutes or so. I rotated it 30 degrees or so every time I walked by. At one point I looked and saw cracks, which made me think the safety glass had broken, but on further inspection I saw it to be the PVA. It was not until later, when the glass loosened enough to pull off, that I realized that, in fact, the face of the crt had cracked! (see photos) I can only assume this would have also happened had I not aired the tube, in which case I would have woke everybody in the shop up!

Lesson for me: from now on, it will be water only. I just don't trust heat anymore.
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File Type: jpg January 150.jpg (117.5 KB, 111 views)
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  #59  
Old 01-14-2011, 10:27 PM
ctc17 ctc17 is offline
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I agree, water only, These round tubes are to scarce at this point to risk it. Leave it or soak it.

I still feel good about wire slicing the green halo zenith style ones though.
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  #60  
Old 01-14-2011, 11:23 PM
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ohohyodafarted ohohyodafarted is offline
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PVA solvents from the internet

PVA is soluble in a number of organic solvents. Solubility of PVA is directly related to the volatility of the solvent; the more volatile the solvent, the more soluble the PVA. Some of the most common solvents, ranked in order from the most volatile to the least, are listed below.



1. diethyl ether (very volatile, water miscible) 2. acetone (best solvent that is commonly used) 3. benzene (very toxic) 4. ethylene dichloride (very toxic, non-water miscible) 5. methanol (toxic, cumulative poison) 6. methyl ethyl ketone (MEK) (toxic) 7. ethanol (denatured alcohols may be toxic) 8. toluene (slightly toxic) 9. xylene (slightly toxic) 10. amyl acetate (slightly water miscible).


This site indicates that PVB should be soluable in Toluene or Ethanol
http://www.ferro.com/NR/rdonlyres/0A...1/0/B75702.pdf
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Last edited by ohohyodafarted; 01-14-2011 at 11:46 PM.
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