Roundie cataracts

Sorry if this has been already beaten to death, but am curious about the procedure to fix cataracts.

My RCA CT-16 has a bad case of cataracts, and while I still haven't gotten around to checking out this set or picture tube am wondering if it's possible to repair the cataracts short of sending the tube out for rebuilding.

Wasn't there mention of someone doing this themselves? Something about using a heat gun or hair dryer? Once you have the safety delaminated how do you clean the surfaces? What do you re-glue them with? How are the optics when done?

As cheap as I am, I want the finished product to be right....I'd hate to spend all that effort only to end up with an amateurish result. Of course all of this assumes the tube is good, which I don't know at the moment....but that doesn't take away from the question as I'm sure this is useful info for all. Perhaps we need a FAQ for the forums? Thanks!

Anthony

[Kamakiri]

....and it was EASY!!!

See this thread:

http://www.audiokarma.org/forums/sho...?threadid=6740

[Charlie]

Here's what the surgeons had to say...

http://www.audiokarma.org/forums/sho...&threadid=6740

http://www.audiokarma.org/forums/sho...=2795#post2795

[andy]

...

Thanks for the outstanding links guys! Did Rob ever reveal what his secret solvent was? Am wondering if carb cleaner might work as it melts most plastics. Common brake fluid can be used as a paint stripper, even on fragile plastics (always test first). As a matter of fact, many model train nuts use brake fluid to strip the factory paint off their plastic models.

Guess I now need to test the picture tube!

Anthony

[Kamakiri]

Use a heat gun like I did, fast and painless.

[bgadow]

The one I pulled apart had spent 10+ years outside and when I took loose what was left of the tape it basically fell off. Lots of water had gotten behind there, so I wonder if you left the crt face down in a tub of water for awhile what would happen? I'd like to try that.

[Rob]

Bryan,

I wouldn't do that! Ever try to pull two plates apart in the kitchen sink with the water between them causing a seal? The hardest part of separating the faceplate from the safety glass is getting air to slip between the plastic filler and the glass to which it is bonded on both sides. The heat gun method works because it causes air bubbles to form between one of these interfaces.

[drh4683]

Just as a note to those who attempt the heat gun method, it works wonderful on the RCA tubes which the cataracts, or any tube that has the really severe looking cataracts (the "moldy" looking white perimeter). The "green halo" common to most zenith and sylvania tubes, I DO NOT recommend the heat gun method. You will not get air pockets to form. The pva expands and cracks the bonded lens. Your best bet with the cataract repair on green halo, is to use a hot wire, like 18 gauge wire connected across a car battery. It acts as a "hot knife" and slides right between the crt and lens, this also works well on rcas cataracts problem. The heat gun method is great, but has its limitations.

[drh4683]

Just yesterday, I did a cataracts repair on a 1968 magnavox RECTANGULAR set. The PVA (poly vinal acetate) is the bonding material. This magnavox set had a serious case of "cataracts", and I took pictures of the repairs/procedures. Basically round and rectangular sets are the same thing as far as pva goes. Since this set was a magnavox, it had tube similar to the RCA, in which the pva was "dryed" out making the heat gun technique the primary choice.

In the first picture, you see the lens sitting in front of the crt, this is after I heated up the lens to the point of seeing air pockets, while lightly prying on the lens to "pop" it off. Notice that basically all of the pva is still on the face of the crt, and just a small amount is on the lens.

[drh4683]

This is what the crt looks like with the bad pva, but no lens.

[drh4683]

Since the face of the crt itself is EXTREMELY hot after removing the lens, you need to pull the pva off asap, so it wont cool and bond back to the glass. It is very very difficult to remove when cold. It will tear when removing, but if handeled correctly, you can basically peel it all of like sheet.

[drh4683]

Notice how the crt looks with part of the pva removed. Also note the center of the crt looks different. These are air pockets that were formed. I didnt get the face of the crt hot enough, so the air pockets didnt "merge" together, which is what they should do.

[drh4683]

When removing the pva, some if it will stick, and become very difficult to remove. It is a very tedious procedure. Just as a note, carborater cleaner DOES NOT remove pva, nor does "goof off" or "goo gone" What works best is gasoline with a scrubbing pad. Gasoline has its limitations, as the pva must be scraped off as much as possible, leaving only a thin film on the glass. Thin enough in which the gasoline will break it down.

After cleaning, use windex with newspaper to clean the glass. Obviously keeping dirt and lint to a minimum as the lens will DIRECTLY fit over the crt itself. I use packaging tape to secure the lens to the crt, it bonds excellent, just like the original tape used. After you are complete, your crt will look like brand new. The PVA does not effect picture quality, as the PVA is clear and has no effect on the color or focus. The lens is what gives the crt the dark look.
Here is the complete 25AFP22

[drh4683]

Here is the 1968 magnavox (remote set!!) fully serviced CRT. Sorry you cant see the "before" pictures as I didnt get the idea to take pictures untill I removed the crt.