tension banding

[DaveWM]

http://www.google.com/patents/US4160510

finally I found something about how MUCH tension, 800-1000 lbs. Yikes, needless to say I will be very very protected before trying this.

I would like to try this on a dud I have, apply the tension band 1st then remove the bonded CRT. on a 23v

[Kevin Kuehn]

Yeah, just a little scary. I would think if you apply the band first, that it may create uneven tension(distortion) in the glass envelope upon removal of the faceplate. But possibly the faceplate adhesive will slip(or compress) first, when applying the tension band. I have no formal understanding of the forces at work.

[DaveWM]

I am assuming the bonding agent adds nothing to the stress on the tube (after all it is pliable), so applying the banding with it on or off would make no difference, BUT if anything goes wrong while applying the banding I would prefer it to have the bonded face plate to hopefully contain some of the carnage.

Maybe when ETF gets the CRT rebuilding going, Scotty (who I hope will stop by to help with the learning part) can advise. I know VDC rebuilds had a simple band with a crimp on clamp and no bonding. Some of the factory new CRTs had a much more elaborate affair (steel form fitting frame around the edge of the CRT with the banding out side of that) as part of I presume implosion protection.

I would prefer to have that molded steel part since it seems like it would make band slippage a non issue. With out that it seems like you would need to make sure the band slips some as the tension is applied to allow for a uniform compression force around the perimeter of the tube.

[old_tv_nut]

Originally Posted by DaveWM

http://www.google.com/patents/US4160510

finally I found something about how MUCH tension, 800-1000 lbs. Yikes, needless to say I will be very very protected before trying this.

I would like to try this on a dud I have, apply the tension band 1st then remove the bonded CRT. on a 23v

Explain more please?
Are you trying to apply a band to a CRT that normally didn't use one? This sounds very dangerous to me, as I expect the banded CRTs were designed specifically to take the compression forces evenly so as to be strengthened. If they took the force incorrectly, they could be MORE likely to implode.

[DaveWM]

I assume that CRT's (rectangle color 23v 25A 25X) seem to come in two flavors of implosion protection.

Bonded face or Tension band no face.

I see the common fix to bonding that is broken down is to remove the lens, and the bonding agent and re attach the lens around the perimeter, effectively removing the lamination which I assume is where the implosion protection comes from.

I have seen rebuilt CRT's with ONLY the band (and not the formed steel hardware that is often seen on this era CRT). I assume these rebuilts started as bonded and part of the rebuild was to use a band (no other steel frame). I do not know this as a fact but I think scotty used to rebuild rectangle and remove the lens and bonding agent and install only the steel band on his rebuilds.

I have seen rebuilts that also had a bonded face (the channel masters in the foam boxes), which I presume had been rebuilt with guns AND rebonded (but are failing again).

This is why I am hoping someone that actually did this for a leaving (rebuild crt's) like Scotty may address. I am in no hurry to do it with out hearing from someone that has done this professionally.

I would be all for rebonding if I knew how this was done, not sure of the bonding agent or if special equipment is used to install.

Of course could just do like many others and just remove the lens and reattach with no bonding many have done with no reports of spontaneous implosion.

[old_tv_nut]

Originally Posted by DaveWM

...I think scotty used to rebuild rectangle and remove the lens and bonding agent and install only the steel band on his rebuilds.

I agree it would be nice to have this verified. In the case of roundies posted here, after the faceplate bonding is removed it is not replaced, and no attempt is made to band the tube either. The protective plate may then be mounted spaced from the tube face by a tape gasket. It is questionable whether the bonded cover provided any strength increase, or just protected the face from a concentrated blow.

On the other hand, we have had examples posted here of Motorola rectangular bonded tubes not taking well to faceplate removal, so in some cases it may actually provide significant added strength.

Inquiring minds would like to know!

[DaveWM]

I have never seen a banded roundie so I assume its not a good idea on them.

I did have a CRT go off on me in the process of removing a lens (un banded bonded lens RCA type with the very hard bonding agent). I was lucky that happened when I had my back to it in the process. Since then I have been more actively trying to find out the best thing to do.

[StellarTV]

Shango066 on Youtube made a video of removing the tension band from a 90s era color CRT; 27 or 32" IIRC. It just fell off when he sliced through it.

[andy]

...

[philcophan]

HOLY C**P!!! I often removed the tension band to remove the mounting ears so the jug would be usable in a set that used a jug with no ears... guess I was lucky to not have an implosion. However, having shot out many dud tubes with a gun, I never had one "go"... just a small phhfftt... rather anticlimactic... we were expecting and prepared for a KABOOM... we didn't need the safety glasses after all.

[DaveWM]

Originally Posted by StellarTV

Shango066 on Youtube made a video of removing the tension band from a 90s era color CRT; 27 or 32" IIRC. It just fell off when he sliced through it.

yes I remember that. Just do not know the characteristics of tension band material. If its very hard (does not stretch) then it I suppose it could just fall off when cut as there is no stored energy.

if I ever get around to this I assure you I will be doing a lot of testing, including noting how much "stretch" is involved as it relates to tension.

[jstout66]

I threw out a 20" 90's era Sony with built in VCR.
I flung it in an empty dumpster. I heard the biggest boom and it blew the back of the set. I NEVER saw a CRT implode like that. Back in the repair shop days, we junked a ton of sets and only got a small pffttt when we necked the tube.

[StellarTV]

Originally Posted by jstout66

I threw out a 20" 90's era Sony with built in VCR.
I flung it in an empty dumpster. I heard the biggest boom and it blew the back of the set. I NEVER saw a CRT implode like that. Back in the repair shop days, we junked a ton of sets and only got a small pffttt when we necked the tube.

Ditto on that. As a (reckless) teen I hauled a 32" Color CRT from an early 90s Toshiba television, with the help of friends, down to a bridge nearby which golf carts would use to drive over the river and dropped it off onto the sand below. It was a good 20 foot drop. The implosion sounded like a cannon firing and shook that sturdy bridge pretty well. Of what remained there was a shadow mask, yoke, and gun inside of a good sized crater of debris.

The potential is definitely there.

[N2IXK]

The older tubes made before the various "integral implosion protection" schemes are certainly much more energetic as a rule.

Most of the modern tubes I have disposed of were pretty unspectacular. Just a quick hiss when the neck was broken off, even the big ones over 25". The most powerful bang I remember was a lowly 10BP4 that I chucked into an empty dumpster behind the shop I worked at. Sounded like an M-80 firecracker going off, and threw pieces of glass up higher than the building.

[Zenith26kc20]

Panasonic 32", I think it was called a "Tau". Put it in the garbage truck with the face down. They then compacted the load. It sounded like a bomb inside the truck. If you want to make them implode violently, hurl a brick at the angled side. They make quite a mess.