Got the chassis out of the cabinet today. Broke the cap part of the brightness knob off its base but think it can be epoxyed back together. Bigger problem is the grey plastic ring that encircles the picture tube. It's broken at about 11:00 into many pieces and at the base, 600PM where the plastic mounts onto the chassis with two sheet metal screws. It would be a chore to glue all the pieces back together and not sure it would ultimately hold once reinstalled around the tube. Photos attached. Anyone have a good used one they want to sell?

My 16" porthole has a perfect and pliable CRT mask.
But my 19" porthole mask has some cracks.
Might be hard to find a replacement.
Save all the pieces as you probably will want to refurbish it.

Wonder if anyone here has repaired a CRT mask?

Carl

Got the chassis out of the cabinet today. Broke the cap part of the brightness knob off its base but think it can be epoxyed back together. Bigger problem is the grey plastic ring that encircles the picture tube. It's broken at about 11:00 into many pieces and at the base, 600PM where the plastic mounts onto the chassis with two sheet metal screws. It would be a chore to glue all the pieces back together and not sure it would ultimately hold once reinstalled around the tube. Photos attached. Anyone have a good used one they want to sell?

What model did it come off of and what is the diameter as best as you can determine? I have one that's 15 5/8" in Dia. good shape. measured as if you were looking at the set. The forward ring in other words.

(oh! I just looked at your other thread. You have a 19".. sorry don't have that one)

CW - No answers from others so far. Not only are there about 6-8 little pieces but it has some cracks around the perimeter that are in imminent danger of breaking all the way through. I hate to start cementing this old plastic until I gingerly clean it up a bit, especially the broken surfaces that need to be mated. So what to clean it with and what type of bonding agent to use? Steve

I bet poster Bandersen could come up with some suggestions.
If I remember correctly, my 16" mask was some sort of rigid hard rubber. Many cars have rubber bumpers and I saw an episode of the BBC show Wheeler Dealer where they repaired a rubber bumper using a special product. Unless someone comes up with a better idea, I would try that.

My 19" CRT mask has cracks from front to back and when I remove the chassis again, I'll probably have to deal with fixing it.

Also, I wonder if we can find a metal band that we can form around the mask -- but if we do we would have to ground it to the chassis to avoid possible HV shock.

Interesting problem that needs an answer.

Carl

This has got me to thinking.
Wonder if we can get make a mold out of say plaster paris. Then pour some liquid rubber to make a copy.

Here is an interesting video:
http://www.youtube.com/watch?v=b3eR89iGyio&feature=related

Carl

Thanks for the link. That's certainly one possibility. It will probably require some experimenting with different materials which can be kinda of expensive though :scratch2:

I've repaired rigid plastic with Loctite 2-part epoxy plastic binder in the past. It's strong, fills voids and can be sanded. I haven't tried it on a bezel yet.

Yah, I'd make an effort to repair it if you have enough of the pieces to make it structurally sound. Two-part epoxy would be my choice, too.

Once glued together, if there are some gaps, they can be filled with bondo. Then you can sand as needed and repaint.

Casting a reproduction is not rocket science, but it requires an intact original to make the mold. If you repair your ring well enough to serve as the model for making a mold, then presumably it's repaired well enough to use. An alternative would be to fabricate an entirely new model out of clay or whatever, which exactly matches the original, and use that as the model.

I have made simple one-piece molds in the past. This thing might require a two-piece mold. It's also a rather large object. Neither factor makes reproduction impossible, but they would make it more complicated.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Thanks for the suggestions guys. I like the two-part epoxy idea. So now I need to clean up the pieces that are to be bonded and do a little experimenting to see how/if this puzzle will hold. No real work to begin on the chassis until next month when friend Bob will help with that. Went over the chassis with a damp cloth and it looks excellent. Opened up the tuner and it looks clean. I'll be back with more later. Steve

It is really hard to find any of those plastic rings that don't have at least one crack in them. I think the exposure to ozone-generating HV accelerates the deterioration of the plastic.

I used JB Weld to fill in a crack on my 16" set, and in about a week, it fell apart again. I used Bond-O this time, and it seems to be holding up. I repainted the whole ring in primer grey, and it was a fine match.

Did you use any reinforcing like say fiberglass cloth in the Bondo?

Carl


It is really hard to find any of those plastic rings that don't have at least one crack in them. I think the exposure to ozone-generating HV accelerates the deterioration of the plastic.

I used JB Weld to fill in a crack on my 16" set, and in about a week, it fell apart again. I used Bond-O this time, and it seems to be holding up. I repainted the whole ring in primer grey, and it was a fine match.

CW,
So you're saying to use bond-O exclusively by itself? Or use the expoxy for the initial gluing of the big pieces then fill in the cracks with bond-O?

CW,
So you're saying to use bond-O exclusively by itself? Or use the expoxy for the initial gluing of the big pieces then fill in the cracks with bond-O?

Bob, do you think that the epoxy by itself will hold?
Would using fiberglass cloth make it stronger?

I've never done this before.

Carl

I've used JB Weld with very good results sticking bakelite pieces back together on a radio cabinet. Strange it didn't work on that ring. As to reinforcement, you can use fiberglass cloth or scraps of plastic window screen.

After curing, JB Weld is stronger than most materials that you might glue with it.

With this and all other adhesives, the pieces to be glued must be clean. I remember one case where JB Weld didn't hold on a metal surface because it was somewhat greasy (as I discovered later).

Bondo is primarily a filler. I use it to fill in cracks after glueing with something that has greater sticking power.

Fiberglass cloth is helpful to fill in a big gap with bondo after glueing the main structure with epoxy.

Phil Nelson

I did not back the Bondo with anything. In small quantities, Bondo is about as flexible as the Zenith mask is. Basically, I forced a blob through the back of the mask, struck the excess level off of the face of the mask, and let it cure. I gave it the "twist test" and the Bondo stayed put. But to be safe, I pulled the whole piece out, and glued it back in with either gel superglue or gorilla glue (I forget which). Bondo tends to stay together in one piece (which is why auto restorers dislike it, as the whole fill piece will eventually fall out, making an ugly wound in the car) so it can be pretty easily be removed from the work piece as I did and still be a perfect fit later.

If it were me, I'd dry fit all the pieces making sure where they will fit. Then use Epoxy to carefully glue it back together. Smooth it down to the surface. Then let it cure. Then put down a bed of Epoxy and take some fiberglass cloth and press down into the glue. I would only use the fiberglass cloth on a non-visible area and make sure that it is low enough that the Mask will still fit in the TV cabinet.

If there are any voids from missing pieces, etc, I'd use some bondo and/or fiberglass cloth and carefully smooth it out before it dries. Then if it looks "patchy", paint the mask.

I bet you can make it look as good as new. Restoring these old TVs sometimes requires ingenuity that you didn't originally anticipate.

Hey, I've got a 19" Zenith Porthole and it has cracks in the mask that I am going to address when I pull the chassis again. When you get your Porthole playing, I think you will find that 19" CRT makes a pretty good size viewing surface. These Zenith Portholes make wonderful TVs and are very collectible.

Carl

CW, Phil and everyone that responded, Thanks for all the tips. I've copied them all and will print them out when I'm ready to tackle that darn'd ring. I want it to be right and I will take my time with it. Heck, it will be one of the last pieces back on anyway. I'm having fun every night piddling with her and haven't even started the real work yet! I look at the chassis and the cabinet every night and feel like a proud papa. :)

CW, Phil and everyone that responded, Thanks for all the tips. I've copied them all and will print them out when I'm ready to tackle that darn'd ring. I want it to be right and I will take my time with it. Heck, it will be one of the last pieces back on anyway. I'm having fun every night piddling with her and haven't even started the real work yet! I look at the chassis and the cabinet every night and feel like a proud papa. :)

Be sure and take lots of detailed pictures of your chassis for later referral. How about posting some here for us to see?

Carl

These are from the 23rd after I used a damp t-shirt to take off the dust and dirt. It was actually cleaner and easier to make it clean then my Predicta. The Predicta is so cramped for space I only used compressed air and a small paint brush.

That CRT is not supported, and could break like that. Remove it before you do
any more work.

That CRT is not supported, and could break like that. Remove it before you do
any more work.

Didn't notice that. I agree with John, remove that CRT and store it in a safe place. The CRT is very hard to find a replacement for.

Carl

I honestly do not know how to remove it safely and my friend Bob who will help with the resto won't be over for weeks. Is there something I can put under the tube to support it temporarily? I'm not equipped to remove this monster tube by myself and risk ruining it. help.

I honestly do not know how to remove it safely and my friend Bob who will help with the resto won't be over for weeks. Is there something I can put under the tube to support it temporarily? I'm not equipped to remove this monster tube by myself and risk ruining it. help.


Disconnect the rear connector.
The ION Trap is a clamp like device that you loosen and slide off the back of the CRT.

Then, you should be able to pull the CRT out from the front.

I had ready an paper index card that I had to insert between the neck and the Yoke as the rear connector wanted to snag on something. I carefully supported the CRT so as not to let the long neck break, noted that the neck snagged, then inserted the index card so it would slide out easy.

Carl

Okay, will follow your instructions this weekend and get it out. Temporarily I inserted a 1/8 in. thick piece of flexible rubber under the front edge of the tube. Once the tube is out just lay it on its front supported with some foam in a box? Seems like I read that somewhere recently. Thanks.

CW - Just to make sure we're on the same page, here are some photos just taken of the tube from the rear. Steve

Yes. With one hand hold the black plastic base and with your other hand carefully pull the part with the wires on it. You want to hold the black plastic base as sometimes these come loose and you don't want to pull off the black plastic base. If you find the black plastic base is loose, you can use Super Glue to make it tight - but wait and do this later when your friend tests the CRT.

Once the back connector is removed, looking forward is the ION TRAP. With a pencil write an arrow pointing to the front on it so you know how it goes back on. Then, loosen the long screw and slid it off the back.

Have an index card ready just in case - you may or may not need it.
From the front of the CRT, carefully pull the CRT out and away from the chassis Yoke. If you feel it snag, you can push is back into the Yoke.

If it snags, its because the black plastic base on the CRT. From the back, insert the index card under the CRT neck where it enters the YOKE hole. The idea is that the index card allows for a smooth surface for the black plastic base to ride on.

Don't put pressure such that it bends the CRT neck - you don't want to break it.
If the CRT stil will not come out, just push it back in the Yoke assembly all the way and support the CRT front slightly with the piece of rubber such that you are taking pressure off the neck. But, you really want to remove the CRT so you can get to cleaning the chassis before your friend comes over. Also, when you fully remove the CRT, turn the chassis upside down and take some pictures and post back here.

Once you extract the CRT, store it in a safe place face down. What I did was to store it in the corner of the room face down on carpet. But, I did not have pets or kids that would mess with it.

Let us know how this worked for you.

Carl

Okay, thanks for the play-by-play. I'm a little bit more comfortable now. Will try to do this later today or tonight. Steve

The picture tube is out, no damage inflicted. Resting comfortably in custom cut box with lotsa foam at the bottom. Here are some pics just taken. Relying on you guys to tell me what you see is obviously wrong. I cut the resolution in half on these so if you want me to email any they will be abt 1mb each in original format. The only thing obvious I see is the covering on the winding inside the HV cage has flaked off, a piece lying at the bottom. Steve

Your chassis looks pretty clean and rust free.

As far as your Flyback in the HV cage, this person had the same problem and solved it - see this thread:
http://antiqueradios.com/forums/viewtopic.php?f=3&t=191551&start=80

This link takes you to page 5 of his Zenith restoration thread. You should find it interesting reading all of his thread - especially about recoating the Flyback.

Carl

CW, is it necessary to remove the flyback winding and recoat it to ensure it works? If continuity checks out okay won't it work in its present state? What are the pitfalls if continuity is okay and I leave it as is? Will it overheat and destroy itself or components nearby?

I would not remove the winding.
Those wires are fine and fragile.
I would think it needs a coating if the wires are showing - but you cannot use just anything. Perhaps some other folks can advise.

Before going to the trouble to recoat the Flyback, do check for continuity. If a winding is open, that needs to be inspected to see if it can be repaired. There are some folks who have repaired windings but usually its when the open is near the surface.

First step is like you mentioned -- check for continuity on all windings. See if the Flyback as numbers or letters for each wired connection and compare that with the Schematic.

Carl