Zenith Halo Cataract Removal, How I Did
 

First, let me stress safety. Cover yourself and ware a face shield.

This is a mod on Dougs How to repair CRT cataracts RCA removal how to. Watch these videos first. http://www.youtube.com/user/drh4683#p/u/78/5l1EoMmmOcQ

The Zenith style is a soft glue, almost like wet silicone.

http://justsmog.com/Clay/halo1.jpg
This is the Zenith style crt with green halo.

http://justsmog.com/Clay/halo2.jpg
First remove the tape.

http://justsmog.com/Clay/halo3.jpg
Pile of removed tape.

http://justsmog.com/Clay/halo4.jpg
Just as in the video, I warmed the lens up a bit to soften the glue.

http://justsmog.com/Clay/halo5.jpg
This is what Im using as a hot wire to cut though the glue. I got a 5 pack of these guitar strings for $6.

http://justsmog.com/Clay/halo6.jpg
You could use an old filament transformer for this. Something fairly high current. Im not sure what this transformer is out of but the secondary output is about 10volts at 20 amps. Im using my variac to regulate the output so the guitar string doesnt just turn red and burn.

http://justsmog.com/Clay/halo7.jpg
Size the guitar string up to be just about an inch longer than the small width of the crt face. Screw it down to to blocks of wood wrapping the string around the screws. It has to be fastened to the wood well.

http://justsmog.com/Clay/halo8.jpg
Turn the vairac up to where the wire gets good and hot but not to the point it weakens. This takes some experimenting. Start at the corner working through the glue.

http://justsmog.com/Clay/halo9.jpg
Work your way through....

http://justsmog.com/Clay/halo10.jpg
Keep going....pulling back and forth a little....

http://justsmog.com/Clay/halo11.jpg
Getting there. This really went very fast. Less than a minute to cut the safety lens loose.

http://justsmog.com/Clay/halo12.jpg
Lift lens off.

From here follow the cleaning and re installation steps in Dougs (drh4683) Videos.

This was much easier than I thought. When the lens and wire are warm the wire cuts right through the glue with ease.

Hot wire! Good idea. this is a great post thanks!

nice work. I assume a petro based solvent? let me know what you use.

Not sure what its made of. You can just kinda roll it off with you fingers. Its almost like jello.
It smells nasty, this is an outside project for sure.

:drool:This is amazing! On pieces of glass!!! And how they think always You do something like this? :scratch2::smoke:

I know a guy who did it that way. Thanks for posting this. That is very fast.

Very nice! Looks like it worked great for you! Look forward to seeing the finished product.

This was a junk crt I brought home form SC. All the guns are shorted and red is totally dead. I wanted to test this method out on a junk crt before destroying a good one.
That Zenith goo stinks bad! Acetone takes it right off.

I just finished removing the glass using your method off a junk rca roudie. Look at this! I couldnt even tell it was this bad before getting it apart.
http://justsmog.com/Clay/rca101.jpg

I'm gonna have to try this sometime. I was kinda scared of this method, dealing with that hot wire and all, but you made this look easy!

Man that is awesome!! Kinda makes me want to perform this on my Heath Kit! That goo is really nasty!!

P.S sorry guys I was gone for a while, work sends me on some freak trips for a month every year (and no internet access).... Waaaahh

this is Very Interesting!! Yes, I have seen cateracts on the so-called gel-coupled crt's. The gel or "the glue" whatever you called it. as it ages that how its happened when the sets are getting old. so, I WOULD be interested in seeing those cleaned-up crt's. I have seen a rebuilt crt with separated safety glass - Only one!! upon installiing onto the television set.

Cheers!!

Caution - Do not bake the Color crt!!

OH, By The Way, when you guys are going to clean the cateracts of the Picture tube OR Rebuild a CRT. DO NOT BAKE THE CRT OR the Shadow mask inside of the color crt right behind the facescreen of crt will warp causing purity problems. I have watched the manufacturing process on youtube and THEY NEVER BAKE the CRT or the aperture mask will warp!!

The professional rebuilders put the whole thing in an oven so Im not sure about that. Also not much heat makes it though to the crt face. That goo on either type of crt is a great insulation.

And now a word from Squibb, makers of Pep-O-Mint Life Savers...

Great pictures, ctc17. I also really appreciate Doug's videos (drh4683). I followed his techniques this past weekend on my first cataract surgery and it went exactly as he described, on an RCA 21FJP22A. I didn't have halogen lamps to do the preheating, but I am in California, so I just let the CRT sit face up in the sun for a couple of hours first! :cool:

Yep, Chris's CTC-16's cataract proceedure was done using Dougs method. That CRT gel was nasty!!

Sean, I still have the CTC-16 combo in your picture, plus a TV-only one that I picked up last summer in Reno.

I wonder if there is a solvent that would just soak in and breakdown the bonding agent? just thinking out loud with a 3rd way to remove the glass.

I just got a nos 25" RCA tube that has a bad cateract (was in the box) and it seems like the bonding agent is very thick at the edges and rock hard.

I don't think that alcohol, acetone or any of the more common solvents will touch it. IIRC, methylene chloride, or perhaps MEK was used back in the day to clean up the dispenser after CRTs were laminated.

jr

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I seem to recall someone tried soaking one in a wading pool full of plain water once with good results, took several days but no danger of implosion.

It may not work with some types of adhesive.

http://justsmog.com/Clay/halo8.jpg
You may want to use a full face shield, the sort welders use. Flying glass could get past the glasses. Besides, flying glass on bare face skin won't be a picnic even if it stayed out of the eyes.

That makes a lot of sense since PVA was used.


I second that. Where I work, full face shields over safety glasses are required when grinding. Flying glass would be worse. I'd worry about the neck area too.

well I have a swimming pool, I may just go set it face down in there and let it be for a week or two, just the face of course I dont want to rust the anode or pins.

a small wading pool is perfect.you dont have to fill it up all the way.enough water to submerge the safety glass only.i have used many methods.one effective was the use of wd 40 and a heat gun.spray it into a loose edge and watch it penetrate .use of the heat gun forces it to spread,loosening the glass.it speeds the progress tremendously.the hot wire,hammer and chisel,piano wire,etc.i think i have ran the gamut.the wading pool is the safest,but also the most time consuming!

ok I will will do the wading pool approach and report back, no hurry since I dont need this CRT right at the moment.

What would be a good gauge of wire for the Zenith cateract process? should one just pick one that heats well with whatever transformer is avalible or is a speciffic guage needed?

Will soaking work on Zenith cateracts too? Or is it only effective with RCA tubes?

The sun is so hot in the afternoon here that another tube I have with an RCA cateract was unbonding well before the sun started going down so preheating is not a problem.

Tom C.

with the zenith I used a .07 ss wire (think it was saftey wire used securing nuts and bolts). You don't even need a heat source if the tube is warm just from reg sun, the green stuff is gooey, you can just pull it through. I wrapped the wire on a couple of wood dowels for better hand holds and just pulled it no heat from power source required. this was on a zenith roundie. The goo was leaking out a small hole I poked in the tape that goes around the edge. the RCA stuff is rock hard.

So the hot wire method works on the RCA tubes as well then?

If so, that would make the problem a little less dangerous.

no the hot wire did not work at all on RCA tubes. for those soaking in water to get the adhesive pliable, them tug out the edges of the adhesive, put the tube in the sun on a hot day and use small wedges all around the perimeter. Tap them in just a bit and then leave it for 15 min, tap them in again (they will loosen up as the bond breaks down), go away for 10 min, keep doing this. you can see the bond breaking down in the bright sunlight, it will look like tiny fissues forming. The key is to just do it slowly and evenly around the rim. As it progresses the bond will break down into a nearly perfect circle and then just pop, and the whole lens will jump off the CRT. It also accerates the debonding as it goes (less bonded area, faster the remaining bond lets go).

the sun heat is key. the water soak makes it easier to get the wedges in.

I have one out in a pool for months and its still on there, so no telling how long it would take to just come off with out the heat and pressure.

I think the main thing is to avoid the heat gun approach as the heat is too concentrated, the sun is a more even approach.

If a wire is hot enough to melt thru 1/2" of RCA type glue in ten seconds (also the insulation on wires) will it be hot enough to work well on the Zenith glue?
photo of melted RCA PVA.
http://i1095.photobucket.com/albums/...y/DSCN0957.jpg

I like the idea of sun only, but having the hot wire to fall back on would be nice.

Tom C.

The sun/gentle pressure method is great.

Water method. http://www.youtube.com/watch?v=VeaiuHW0ges

Putting one together. http://www.youtube.com/watch?v=Y-gSjaYxw-0


This one is reinstalling the crt and setting it up. http://youtu.be/1AWG61TAIHg

on mine the wire melted before the glue on the RCA. No need on the zenith as its already soft (no water, no heated wire, just a thin wire and warm sun.