This Week's Video: CRT Cataract removal

[Electronic M]

So I did a video showing my methods on RCA and Zenith style cataract removal with a surprise twist.
Just what we all need mid winter: something to make us look forward to our summer TV repair work. It will go live in 30 minutes from this post.

https://youtu.be/F8Wfg1I1Z8Y

[iong]

Excellent. Thank you,
Perry, Brooklyn, NY,

[LukeSimon]

We need more content like this. I have a few questions though: Is there a risk of scratching the safety panel or CRT glass? I see the RCA has a metal tension band and fastening lugs. Why does it need a safety panel? I thought a metal tension band was enough for implosion safety.

[old_tv_nut]

Originally Posted by LukeSimon

We need more content like this. I have a few questions though: Is there a risk of scratching the safety panel or CRT glass? I see the RCA has a metal tension band and fastening lugs. Why does it need a safety panel? I thought a metal tension band was enough for implosion safety.

A mounting band and ears is not the same as a tension band.

for example:

United States Patent 4415932


Abstract:
Improved mounting and implosion-protection means and method are disclosed for use in a cathode ray tube having a substantially rectangular glass face panel with a rearwardly extending skirt. A first tension band has a predetermined relatively wide width for compressively inwardly loading the panel at a tension level completely effective to protect against implosion. Four mounting brackets, one at each corner of the panel for mounting the tube, have a rearwardly extending foot. A second tension band substantially narrower than the first band circumscribes and overlays the first band. The second band is tensioned at a level 55 to 78 percent of the tension level of the first band for capturing and compressively holding each bracket foot against the first band. The effect according to the invention is such that the tension level of the second band is effective to retain the mounting brackets, but ineffective to deleteriously interfere with the implosion protective tension exerted on the panel by the first band.

[Electronic M]

Originally Posted by LukeSimon

We need more content like this. I have a few questions though: Is there a risk of scratching the safety panel or CRT glass? I see the RCA has a metal tension band and fastening lugs. Why does it need a safety panel? I thought a metal tension band was enough for implosion safety.

I assume you are worried about the Zenith method scratching. I use single strand steel guitar string both for tensile strength and because it should not be sharp. I've done somewhere in the neighborhood of 20-30 Zenith cataracts with wire and have not caused scratches.
I've seen some factory defects in the face glass especially on the normally mask hidden top and bottom of roundy tubes, but never any damage from my work.
Some have suggested the ribbed multistranded guitar string (not sure what the right word for it is) for better sawing action but I haven't tried it because I worry that might be able to scratch.

I forget if it was a true tension band or not. Many RCAs with safety glass used an adjustable metal strap (not a tension band) to hold the metal corner brackets that bolt the tube into the cabinet....I think that tube had an adjustable strap not a true tension band.
I probably could have loosened it and removed it, but it wasn't in my way and was an extra step.

There may have been some tubes with safety glass and a tension band. Either as a test to see if it was safe to remove the band or as a CRT rebuilding quirk....Many rebuilders would mix up straight (aluminized CRT) and bent (ion-trap CRT) guns. I'm sure there were some that put a safety glass and tension band on because they could.

EDIT I see OldTVnut hammered out a very good response between when I read what we were responding to and when I posted.

[maxhifi]

I used the wound guitar string on a zenith style CRT, and it did help to saw through the cataract without any scratches. It can't however be over stated how horrible the remaining silicone was to remove. What a mess!

[Electronic M]

Originally Posted by maxhifi

I used the wound guitar string on a zenith style CRT, and it did help to saw through the cataract without any scratches. It can't however be over stated how horrible the remaining silicone was to remove. What a mess!

From what I understand it's PVA not silicone that was the original glue. I can imagine it being more annoying to remove the glue from the separated glass if it has been effectively sawed.

It's usually time consuming and not super fun to do on tubes cut with a non-wound string...It's a much bigger headache than the RCA hard PVA to remove.

I understand why people don't like dealing with that aspect of Zenith tubes, but with something like 10 RCA safety glasses and 2 complete RCA CRTs I've lost (not to mention the hellish process of chiseling off a cracked safety glass that can no longer be wedged) in the process of figuring out and getting good at an RCA removal method that (while still an implosion risk) seems to work consistently well on every tube tried so far. I still prefer the Zenith method because while tedious, I've never had a failure on a Zenith tube cost me a tube or safety glass and I have never had to stress a Zenith tube in a way that made me worried it could spontaneously pop on me. Whenever I do an RCA tube I'm always somewhat scared something is going to go wrong.

Hastle and time don't bother me as much in a cataract removal as damage or loss of a tube and or real/precieved danger of glass cutting me do.

[maxhifi]

Originally Posted by Electronic M

From what I understand it's PVA not silicone that was the original glue. I can imagine it being more annoying to remove the glue from the separated glass if it has been effectively sawed.

It's usually time consuming and not super fun to do on tubes cut with a non-wound string...It's a much bigger headache than the RCA hard PVA to remove.

I understand why people don't like dealing with that aspect of Zenith tubes, but with something like 10 RCA safety glasses and 2 complete RCA CRTs I've lost (not to mention the hellish process of chiseling off a cracked safety glass that can no longer be wedged) in the process of figuring out and getting good at an RCA removal method that (while still an implosion risk) seems to work consistently well on every tube tried so far. I still prefer the Zenith method because while tedious, I've never had a failure on a Zenith tube cost me a tube or safety glass and I have never had to stress a Zenith tube in a way that made me worried it could spontaneously pop on me. Whenever I do an RCA tube I'm always somewhat scared something is going to go wrong.

Hastle and time don't bother me as much in a cataract removal as damage or loss of a tube and or real/precieved danger of glass cutting me do.

Right, PVA. I couldn't find a solvent which melted it effectively, it was more or less just elbow grease to get it off. It certainly does completely change the appearance of a TV to get rid of the nasty degraded cataract!

I haven't bothered on my RCA just yet, the cataract is just a slight tinge around the edge at this point, which is completely not visible on 16x9 program material.

[Electronic M]

Goof Off is a mild solvent for PVA. It won't break down the full original thickness layer, but thinner stubborn residue it will soften and or dissolve.

If it wasn't $6 per 16floz and fast to evaporate I'd probably try soaking RCA tubes in it...

[Tube TV]

Very good video Electronic M.

Has anyone ever tried running some lubricant (IE. goof off, terpintine, paint thinner) down along the guitar string and into the cut areas to prevent binding of the guitar string?

[maxhifi]

When I've done it, binding was never a concern... Zenith PVA is soft, you can cut right through it with enough persistence. Warming the tube up in the sun is probably the critical step here.

I did use goof off to get the final residue off. And acetone. And paint thinner. And alcohol and even gasoline. Nothing worked as well as scraping and polishing with a cloth. It did eventually come clean though. I wouldn't want to do cataract surgery for a living, but it also is straightforward enough.

[Electronic M]

I've done Zenith cataract removals on 45f fall nights with only dim distant fluorescent lighting and not noticed significant difference in cutting effort. I don't think heat is necessary for Zenith removals.

[bhegges]

Tom, thank you for posting this great video. I have a prime zenith candidate that you previously commented on how to fix. Seeing you walk through helps inspire some confidence to try it.