Well, it finally happened. A complete disaster involving cataract repair. I have a 1966 motorola console with its original 23EGP22 with very bad cataracts. The tube was mint too, 100% emission low hours. The set had an unbelieveable picture from what I could see through the cataracts. Yesterday I attempted the repair using the successful heatgun method with the heat lamp. The cataracts had the "mold" like appearance like the RCA's, so I figured this tube would be easy.
After preheating the lens for about 45 minutes, the CRT was ready. I removed the heat lamp and turned on my milwaukee heat gun. I started right in the center edge of the tube. I kid you not, it was only 10-15 seconds later "BLAM" the entire CRT imploded like a bomb and threw glass shards all over my shop. Phosphour dust was everywhere like someone threw ashes in the air. It happend right before my eyes and was so fast I couldn't believe it. I didnt even have enough time to react, I still had the heat gun in my hand holding it like i was still heating the lens. When the lens imploded the glass was rejected in a horizontal plane. Fortunately, the CRT was in a horizontal position and the safety lens did its job.
To my surprise, absolutely nothing happened to me. Not even a scratch.
Even though Im so dissapointed this happened, I can't be upset because this did not fail due to careless technique. Ive never attempted cataract repair on an NVC Motorola tube. Obviously, I will be no longer attempt the heat gun method to CRT's. The 23EGP22 is a mechanically weak and not capable of accepting the extreme heat. The frit seal is up much higher twards the face of the tube than RCA or Zenith tubes. I think what happened here is the glass expanded and with the smaller glass surface area on the side, it expanded down to the frit seal, which failed leading to the implosion.


So now Im out of a perfectly strong 23EGP22 (which is as rare as a good 15GP22 in my opinion) is gone, I need to find a replacement. I cannot sub any other tube unless I have a motorola CRT conversion kit as the support brackets would need to be changed as well as a modified CRT bezel. So finding a replacement EGP is my only hope to bring the set back to life. As of now, its a mint condition piece of scrap.

Im going to be experimenting with chemical reaction to PVA to see what can be done in the future to separate the lens for the tube. The heat gun method, while proven successful in the past has its dangers and should be stopped. What was always feared has finally turned into a reality.

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I'm not up on vintage Tv , so please explain what exactly is a cataract in a tv tube?

The cataract occurs because the clear PVA glue bonding the safety glass to the tube itself is chemically breaking down - usually due to air getting in. The result is the cataract you see.

Glad to hear you weren't hurt Doug. I've had a CRT go up in my face. If it weren't for the glasses I probably would have been blind or worse.

Reading of this makes me skiddish. I've got two 21FJP22 CRTs that both need surgery. I'd hate to have one of them go up in my face! At least the glass is stronger. I had no clue about the construction of the EGP

Simple to explain...See the first picture on Doug's post with the CRT still in the cabinet. The frosty appearence of the face of the CRT shows the condition..hence the dreaded cataract!
What is happening is that the bonding agent used to seal the safety glass face to the CRT itself is breaking down. This is most common on early color sets when the manufacturers went away from non-bonded glass fronts. Even on some early 70's sets this is still seen. RCA derived tubes/sealents are the worst! The Zenith type tubes create a greenish haze along the sides that may not take away from being able to view it under operation, as a different type of material was used.
On older sets dirt will accumilate between the two surfaces and affect the picture quality, and increased glare from sunlight/brightly lit rooms/reflections/etc. Bonding the face does make sense.
Come to think of it, black and white CRTS don't have this problem...hhmmm.

And Doug, I'm glad nothing happened to you! I've always thought of those 23EGP's to be nothing more than a black and white CRT with a color gun as Motorola's attempt to create a square crt!

Good thing you were okay!

Shame about the tube, but I'm sure another will come along.

OMG Doug, you are so lucky! Im glad to hear you are okay! It's good to see that the lens did its job!

YIKES!!

That is why I do NOT mess with the CRT. If I find a TV, and the CRT is shot, I consider it unfixable.

Maybe there was a scratch or defect in the glass that was hidden by the PVA? This would account for the implosion during heating.

Doug -

Glad you're okay! That definitely looks like a spare pair of shorts moment... The first tube I removed a cataract on was a 23EGP22 using the heat gun technique. I was worried about the tube letting go but didn't have any problems and eventually did a 25SP22 with the same technique. After seeing your post, I've got reservations about ever doing that again.

There was some discussion here a while back about placing the CRT face-down in a tub of water, after which the PVA was supposed to dissolve and break loose in a couple days' time. Seems like it may be a safer, albeit slower process.

Damn, Doug, sorry to hear about that, but glad YOU'RE OK...We can get another CRT, but not another Doug...And we ALL need to remember that, yes, these things we play with, CAN & WILL bite back at times...

Doug, I hate to hear about your CRT disaster; but, I thank God you're OK! Like has already been said; we can get more TV's but we can't get another you! As much as we love our hobby, it's not worth risking injury or death over.

I have several tubes w/ cataracts in sets, including a Motorola 23EGP22. I've had mixed emotions concerning removing the cataracts; but, I think my mind is made up now. I'll either locate cataract-free CRT's for my sets or wait until a safer method can be found.

Doug, glad you're ok! Not only have I always found your posts interesting, I can now add the word "exciting"!

If I know you, you're most angry at losing the OEM CRT. What a shame.

Motorola is a pretty rich company nowadays... I smell lawyers ;)

You're gonna be finding glass shards until you're 50. I would try a soak in a shallow tub of lacquer thinner, or MEK. I can't imagine any glue those twop couldn't break down.

"A black and white CRT with color guns added" may be not too off the mark (of course, you also need shadow mask and color phospors on the front).

A repairman decades ago told me that the 23EGP22 was manufactured from used B&W CRTs.

Personally, I -did- see one Motorola color tv with a disclaimer on the cabinet, stating that used components were included in the receiver!

Rob

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I'm glad your Ok Doug, Picture tubes are replaceable you're not!

Glad you weren't hurt! I've had close calls, but never a full implosion in my face. I've seen tubes spontaneously implode in the middle of the night, so maybe yours had a weak spot or a tiny bubble in the glass next to the seal?

I've only done a couple of cataract jobs, and I need to do a 19EYP22 in a CTC-19 consolette soon. I have, in the past, done the job by sacrificing the safetly glass by smashing it from the edge, then carefully pulling it off piece by piece. Not recommended, though! I did that 25 years ago. When I did the HR21GVP22 (military 21FJP22) for my Zenith roundie a couple years ago, I used the heat gun method and it went fine, but the safety glass cracked. That was OK in that case, because I was replacing a 21FB with separate glass anyway. And I wore full motocross gear including helmet, chest protector & neck roll. I looked goofy, but would probably have been fine in an implosion.

Charles

Doug I’m thankful you were not injured I’ve had close calls as well but nothing like that. I have always treated CRT’s like a bomb. And as we know they can turn into one. In my case I have used this type of procedure on several tubes during the last 20 years or so. But only on 21FJP22’s. I have always been worried about too much heat on one side of the tube. The last one I did I let it sit in the sun all day before I started working on the front. This may be the reason the Motorola tube failed. Charles I was dressed similar to you except I was wearing welding gear. In the tube plants this type of thing would happen all the time. Lets all learn from this and use it as a reminder that any work around a CRT can be dangerous. Anytime the back is off you are exposed to this danger.

glad you weren t hurt doug.i saw a crt implode after the band and ears removed. it was a magnavox crt in a sylvania gt matic.did the same thing and blew the cabinet apart.it was frightening to say the least! as the set was playing,(approx15-20 minutes)the cabinet started to swell up and finally boom!!!!!ny buddy frank never attempted such a stunt agaim and i never was near his house when he was doing tv repair!!!!again,i am sooo glad you werent hurt!

Thank God you're ok! THAT was close. You could have been killed man! So much for the heat gun method, especially on an EGP. Shawn has a tube for you, he probably has already contacted you.

There was somebody on here earlier this year who singled out the EGP and said they were weak and couldn't be trusted...I took what he said with a grain of salt. Maybe he knew what he was talking about after all!

I have done a number of tubes with the heat gun, and once I got the hang of it it worked very well. This is an important reminder to all of us about what can happen.

There were different variants of PVA, and not just the gray or green. I think there were at least a couple of the gray variety...or maybe I am just seeing them age differently. My tests showed that a Zenith (green) responds well to water but a green Motorola (a later 21" tube) was very slow to respond to it. I'd have to say that if I came across one of these tubes I would be VERY patient with it now.

That's so good you weren't hurt by the implosion. I was just fixing to try the heat gun technique on a 21FJP22, have never done it before but I will not chance it. What is the water method? just immerse the screen end in a bucket of water?

I am so glad this thread isn't what I expected from the title. I was afraid I would read about someone being blinded by their eye surgeon! I never look to see what forum something is in, I just scan through the recent posts for something that looks interesting.

Damn your lucky you didn't get hurt, the best thing to do in this situation is to figure out what went wrong, then see what you can do differently next time.

You should definitely add this story to your web site...

sorry gentlemen, I explained why the color TV SET Americans have double glass on kinescopes almost to form a tube? I think he saw only a sony kv 2000 with this type of double glazing. in color SET TV in Europe this double glass not exist.

That's so good you weren't hurt by the implosion. I was just fixing to try the heat gun technique on a 21FJP22, have never done it before but I will not chance it. What is the water method? just immerse the screen end in a bucket of water?

There is a old thread that details it. Basically you peel off the "packing tape" and then put the crt face down in water-I went to Dollar General and bought an inflatable kiddie pool for a few bucks. It could take some time...a "green" Zenith broke down in about a week, as I recall, but an RCA-type hadn't responded after about 2 weeks. If you have the space and the time, though, eventually it will work. The proof is to look at a crt that has been outdoors for a long time.

Wow, Doug - glad you're OK - that's one of those things you'd rather see from a safe distance by closed-circuit. ("Bring in the remote control robot!") Hope you can find a replacement.

Bryan,
So your saying the water method did work on the Zenith crt you were experimenting on? I remember your original post on it but didnt remember the outcome. I do remember that you said it didnt work well on the RCA tubes. If it did work on the Zenith, did the glass just fall off or did you still have to pop it off the crt?

Doug, i'm glad your ok and am glad you werent injured. Since i've had three crt's implode on me, i understand the situation completely. Two imploded by bringing them from a cold shed into a hot house in the middle of winter. The third imploded when i stupidly released the metal perma-band on an old b/w tube. I was young at the time and didnt know any better. One of the crt's imploded in my hands. Luckily, it only left me with two cuts to one hand, neither requiring stitches. Yes, i was extremely lucky. Today when i handle crts, i use leather gloves, goggles and a heavy coat.

The only thing i can think of that happened to Doug was that the Motorola must have had a weak spot in the glass envelope somewhere as he has did several of them with no problems, so it didnt happen because of lack of experience or technique. I believe the RCA type crt's can still be done safely with the heat gun method but all precautions need to be covered as far as safety ahead of time. Dougs mishap had to be a fluke with this particular crt as when he decribed this procedure in the past he took and stressed in great detail about the safety precautions that had to be taken to do this. I know there wasnt an error on his part.

Scotty at Hawkeye said that when he rebuilt these type crts in the past that the faceplates fell off when they were put into the oven. Obviously the heat gun shouldnt have generated as much heat as Scotty's ovens do, so i dont think the heat was the real problem. So it seems logical that there was a defect in the glass envelope somewhere. I guess the thing to concider here is use the faceplate removal as a last resort when a good replacement cant be found and then only when a good precentage of the bond has already separated. If the water removal procedure works on Zenith crt's then half of the tubes like this out there can be done that way, which leaves only the RCA's to use the heat treatment with. I have heard stories from former tv techs mentioning that these 23EGP22 crt's being unstable. I heard several examples where these crt's would implode by moving the tv from one location to another so it seems the quality control was lacking in the construction along with the crappy guns they put in these.
-Tony

Glad you're OK, remember a picture tube is replaceable, you are not. That would be scary.

Tony, yes, the Zenith responded nicely. I did have to pry a bit. I inserted popsicle sticks in the gap which helped it along. Once water started getting behind the glass it didn't take long. The green pva Motorola I tried didn't respond so fast and, sadly I grew impatient. After floating in the drink for over a week I started tinkering with it, prying on it...and I broke the safety glass. I had a devil of a time getting it off, still. The lesson is to give it plenty of time. Other solvents may work better than water but then you'd have to deal with having a tub of something nasty sitting there in your garage.

I wonder if putting a farm water trough heater in the pool would help by warming the water?

I like Carmine's suggestion of using solvents like Lacquer thinner or MEK to dissolve the PVA goop. I would also give acetone a try. As I have never had to handle a CRT with a face like this, is the face plate itself made from glass, or is it plastic? If it is anything other than glass, those solvents may also dissolve it as well...

The 23EGP22 was the first mass produced rectangular tube made by a tube company called National Video.
The first ones were sulfide screens.
Later batches used rare earth.
It was the most dangerous and stupid tube designed, based on costs and profitability, with no regard to consumer safety.
At the time, just making a rect tube was like landing a man on the moon.
The tubes were very unstable. At the time, the technology just wasn't there, no computers, just draftsmen in a room, saying "Oh yea, that looks good."
Many engineers were very closed minded too.

Look at an old TV, You have a high wattage, high temperature, high voltage generating mess with a potential bomb all enclosed in a real wood highly combustible box. Almost like an automobile.

You guys should use an infra red heater to remove an RCA type safety glass, and use a piano wire to slice the gooey Zenith type plates off. You can clean up a Zenith mess with paste paint remover.

The tubes should be warm. Wear eye protection.

Never, ever remove a tensioned band.

Two things here, the tube itself was not banded and it had a scratch in it somewhere. The faceplate has to be heated uniformly and completely-not spotty with a heatgun. You got one area too hot and it couldn't expand uniformly. Also, NEVER EVER EVER remove a pressure band from a live tube either or the same result will happen.

We used a infrared heater that covered the entire faceplate. The tube should be a little warmer than room temperature to start with.

OK I'm curious; I've got to admit. Once the safety glass is off such a set, what is done? Is it re-sealed? Is the safety glass simply omitted? Is some sort of protector installed? I have a big RCA (currently waiting for a CTC-131 Chassis...) with a piece of plate glass over the tube, and I've seen other sets with this before. Is this a safety glass or is it just to protect the surface of the tube? Note that the flat glass panels I speak of are factory items.

Doug, the same exact thing happen to me . I was attempting to remove a safety glass from a color tube and the crt imploded right in front of me on my work bench . Lucky for me i was wearing safety glasses . I had a piece of glass fly into my arm and slightly cut me , but i was ok . It really scared the hell out of me and i never would attempt it again. Can be very dangerous . I either buy another crt or throw out the tv , wont dare to try the catarac removal procedure again .

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More likely to save one knowing they can be fixed!

I trashed many a crt with cataracts before reading the "how-to" here on AK!

I have a big RCA (currently waiting for a CTC-131 Chassis...) with a piece of plate glass over the tube, and I've seen other sets with this before. Is this a safety glass or is it just to protect the surface of the tube? Note that the flat glass panels I speak of are factory items.

The old sets with flat plates of glass are tinted and tempered.
They were pretty strong and thick. I would throw some in a dumpster, they would not break unless smacked hard with a hammer.
The glass bonded to old tubes with resin are thin, crack easily, most are treated on the outside to be dull looking, not shine, most were tinted dark.
The next version used glass that was not tinted, designed to reduce x-ray exposure, and let more brightness through, mostly used on black matrix tubes.

Doug and Mike, glad to hear you're both OK! Wow, scary stuff! My condolences on the loss of the tubes, too. FedEx killed a client's double-boxed 7DP4 on its way to me last year, so the loss of a tube is bad enough in and of itself. I'm not equipped to do cataract surgery, so I haven't tried yet. Now, I'm wondering if I ever will. I'll probably just let the seasoned pros at that kind of work take care of any cataracts I encounter, although the kiddie pool idea sounds much safer than a heat gun. If I do attempt a cataract fix, I'd probably use the slow-and-steady water method with the setup locked safely in a garage.

This may be a obvious question, but I am a bit confused as to the tension band VS a mounting band.

I have replaced round and rectangular CRT's but have only experienced a band which holds the mounting ears on. This band was basically a huge clamp with a tightening screw on it. I never wanted to tighten it too much for fear of putting too much stress on the CRT. This is especially true of a
25AXP22.

I would appreciate it if someone could explain the difference between these type of bands. Wouldn't you have to remove this to transfer the mounts to a new CRT?

Thanks!

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I saved this off the web a while ago: I don't recall the original source.

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.

I've heard of at least a half-dozen instances of this happening. Plenty of folks tried it; not sure if anyone ever did it successfully. I did install a tension band tube in a set that used a bonded tube; it was a tight fit but it worked. As long as you leave it intact you are A.O.K.

I've said this before so at the risk of sounding like a broken record... :)

When you remove the PVA from a CRT and reattach it with a bit of tape or Silicone around the edges you are essentially using a tube with ZERO implosion protection.
In fact it might be more dangerous because in the event of an implosion you now have a thin safety glass that will shatter and fly about as well as the tube itself.

I realize of course there aren't really any options and the risk of a spontaneous implosion is slim but it could happen.

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A tension band is similar to a mounting band, but it's under much higher tension, and it's not removable without cutting it. The idea is that if the screen breaks, the band will compress the pieces together so they will stay in place. The mounting ears are usually welded to the tension band, or under the band. If you need to remove them, cut them off (very carefully) instead of cutting the tension band. If you cut off the tension band, you would have to use a separate safety glass since the band was what provided implosion protection.

I've never tried it, but I've heard that a CRT will shatter if the band is cut while it's still under vacuum.

A shop in my hometown (which, fortunately, closed years ago) was well known for its hack repairs. At some time, well over 20 years ago, one of their technicians cut a rimband to attempt to fit a tube with rimband-secured mounting lugs into a set where a different mounting scheme was required for the CRT. I heard about this from one of that shop's other former technicians. As the story goes, the tube began to make an ominous clinking sound, the tech bolted out of the room and shut the door. Moments later, KABOOM!!! I was told the noise sounded like a shotgun blast, and that large shards of glass had flown under such force as to have become lodged in the drywall. The purpose of the rimband is to exert a force around the perimeter of the faceplate which acts against atmospheric pressure upon the faceplate (by tending to bow the curved faceplate outward more) roughly like the strings of a guitar and neck truss rod produce opposing forces acting upon a guitar neck. The force of the rimband around the curved faceplate produces a component of force acting outward over the faceplate surface, opposing the inward force due to atmospheric pressure. Without the rimband, the action of the counter-force is lost, and the full force of atmospheric pressure acts with far less force counter-balancing it than the manufacturer's design team ever intended. If the tube does not implode immediately or within a matter of less than one minute, its structure is permanently weakened and extremely unsafe for use. NEVER cut a rimband under ANY circumnstances!!!