RCA cataract removal

[DavGoodlin]

Originally Posted by Electronic M

IIRC the government put the viewable area law in place in 1968.

I've put that tube in for the longest time I'd heard used. It belonged to a client so I could only wait so long.

Zenith CRTs can be done cool, safe, and reliably by cutting the soft glue with a guitar string....I'll take a dozen Zenith cat removal jobs over one RCA any day.

Tom, Do I recall you passing some controlled current thru that guitar string to speed the process, like from a car battery

[Electronic M]

Originally Posted by DavGoodlin

Tom, Do I recall you passing some controlled current thru that guitar string to speed the process, like from a car battery

I initially* designed my rig to be capable of that, but did not pass any current when I did my successful Zenith type cataract removals. I initially experimented with current, but found the wire would develop hot spots, loose tensile strength and snap well before any significant progress would be made.
I've found it works best with NO current running through the wire and the wire at ambient air temp. I've also found it unnecessary for the tube to be warm...Back in fall when it was something like 45-65 F outside at night I did a guitar string zenith cat removal with the tube at ambient temp and the wire at ambient temp and it worked fine.

Make sure you attach the wire solidly to your pull handles, and to use something more sturdy than paint stir sticks. The glue will try and hold the wire/provide a good amount of resistance to pulling so it takes a good bit of arm strength.



*I've long since removed the current supply from the early guitar string cataract removal rig in my video.

The guitar string method is meant for the green halo Zenith style cataracts, the white moldy RCA style is unlikely to respond well to the guitar string method.

[DavGoodlin]

Great, I have two Zenith 25's that will need done. That yellow tint around the edge really makes the color look awful on those. Not Acceptable!

[DaveWM]

Pretty sure how rebuilder did it has come up before. that have industrial size ovens that can heat up the entire tube very evenly, to the point where the glass just lifts off. The issue with the heat gun is presumably un uneven heat causing stress for un equal expansion of the glass. I think the roundies are generally safter than the rectangles. Later rectangles had safety banding that would compress the perimeter. I the perimeter cant expand, then the tube can not explode along the perimeter, just inward from the implosion. After having one go off on me I tend to not mess with it anymore. just look for a decent CRT and live with it. Oh one more thing, if you are using heat clearly do not use a damp cloth to cool it down, again rapid uneven heat and cool is not what you want.

https://www.youtube.com/watch?v=lRJ0otqgmYs

check out the burnt shadow mask..

[Findm-Keepm]

Originally Posted by DaveWM

Pretty sure how rebuilder did it has come up before. that have industrial size ovens that can heat up the entire tube very evenly, to the point where the glass just lifts off.

Sony even patented the process. Rauland had been using it for years, but never sought a patent. I don't know if there was ever a patent fight, but both of them used the same process - heat it up.

PVB used in the first rectangular tubes is impervious to water. I'm sure that if someone knew the exact brand of PVB, a solvent is readily available - whether it be ammonia, acetic acid, some alcohol based solvent, or some hydrocarbon solvent.

The same PVB is used with early automobile windshields where they bonded the safety glass to the oven glass and needed an optically clear adhesive.

https://en.wikipedia.org/wiki/Polyvinyl_butyral

[Findm-Keepm]

BLASTED! Here's RCA's method...

[MadMan]

Originally Posted by Findm-Keepm

BLASTED! Here's RCA's method...

The tube is seated in the masking box so that only the glass cap is exposed. Abrasive particles are then blown from the nozzle and upon the cap... To erode the cap by pulverization thereof, the nozzle is moved back and forth...

So basically they sandblast the safety glass until it doesn't exist anymore?

[TUD1]

The water soak method is already showing sure signs of progress. Looked at it again today, and I was able to easily remove two huge chunks from the corners. I gently put some clothes pins in, and I could see where it was starting to come apart more.

[DaveWM]

leave it soak for a couple weeks (or months since its still cold out). Summer time is best for doing the removal, you put it out in the sun, put clips all around the perimeter, just a little bit of pressure from the clips bearing on the glass with as much contact area as possible. Slowly the glass will begin to let go, you can see the de-lamination progress as shadow lines will form on the face of the crt. As this happens the clips will get loose, tapping them in gently until just firm and walk away. The process can take hours. Best to do when its at least 90f outside in full sun. the most important thing is not to get impatient.

[TUD1]

Had a good idea today while I was burying the mouse I finally caught. I dug a hole in the ground, put a tire on top for safety, and voila, poor man's cataract removal studio. I'm going to get a heat gun one of these days and start doing cataract surgeries that way. Water is taking too long.

[Electronic M]

Originally Posted by TUD1

Had a good idea today while I was burying the mouse I finally caught. I dug a hole in the ground, put a tire on top for safety, and voila, poor man's cataract removal studio. I'm going to get a heat gun one of these days and start doing cataract surgeries that way. Water is taking too long.

That looks like a Zenith type cataract. Better to get some #18 steel guitar string (type that has a smooth surface), screws, and small pieces of wood to use as handles. Using the guitar string method (which I linked a video demonstrating above) is about 10X safer/more likely to completely succeed than using a heat gun, and bit faster.

[TUD1]

That tube is an RCA Colorama that is graveyard dead. It's my guinea pig CRT. At 8 volts, it has no emmision.

[mrjukebox160]

I have never seen an RCA tube turn green. Strange.

[Electronic M]

It is possible RCA had a shortage and re-labeled another makers' tube or used Zenith type PVA. Peel the tape on the edge and poke the glue...If it is soft and springy like chewing gum when you first get it soft, then it is Zenith type glue (which was not used exclusively on Zenith tubes), but if it is hard as tire tread rubber then it is RCA type glue (which was not used exclusively by RCA). Neither Zenith nor RCA were the exclusive maker using that glue, and IIRC both makers used other types of glue occasionally (very rare to find).

I've also seen smaller makes use something in between or outside of the two types normally encountered and thought of as Being either RCA or Zenith....Those can be a bitch.

Regardless of make/label the yellow/green springy stuff is what we call Zenith type, and the hard stuff that turns white/black and moldy is RCA type. Ignore the makers mark and look at the glue!

[TUD1]

Went to Lowe's and got a heat gun today. It's kind of a piece of crap, but I'm sure it will at least last for two cataract removals.