Cataracts repair gone wrong........

[drh4683]

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.

[andy]

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[steerpike2]

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

[jpdylon]

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

[marty59]

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!

[zenith2134]

Good thing you were okay!

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

[freakaftr8]

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

[MRX37]

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.

[colorfixer]

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

[N9ZQA]

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.

[Sandy G]

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...

[radiotvnut]

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.

[Carmine]

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.

[Robert Grant]

"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

[andy]

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