Picture Tube Removal

[VA561]

I have a 1950 Zenith porthole tv with a 16" picture tube. I need information on the proper procedure in removing the picture tube. The first tv I worked on , a 1952 Philco had a split chassis and I didn't have to remove the picture tube. I now have a work bench and would like to put the zenith chassis/picture tube on the work bench to begin evaluating and repairing this set. Any advice is appreciated.

[cwmoser]

Looks like my Zenith porthole - mine is a 16" CRT - 16EP4.

You will find that the CRT is supported with the front mask - a rubber flange like thing that surrounds the front of the CRT. There are also springs that hold it in position too.

There is an ION trap around the neck of the CRT and you unscrew it to remove it. Mark how its position and the orientation, also mark an arrow on it so you know which way the ION trap goes on.

The first think I would do is remove the chassis from the cabinet. There is a slide switch on the front that needs to be unscrewed first. Make sure you discharge the CRT using a clip lead from the chassis to the wire that attaches to the metal cone.

Take a lot of pictures with your digital camera so you know how to reassemble it.

Remove the connector on the back of the CRT.
Then loosen the ION trap and slide it off.
Then remove the springs and wire hangers but make sure you have pictures to refer to when you want to put it all back together.

Now the tricky part is this ... after doing the above, the CRT is held by the neck in the yoke and by the front mask. You have to loosen the 2 screws holding the mask and also hold the CRT so you don't break the tube at the neck. With the mask removed, carefully slide the CRT out of the yoke. If it won't easily slide out, it might be hung on a paper spacer in the yoke. If that happens, take a piece of paper like a post card and wrap it around the neck and slide it in the neck. What we are trying to do is use the post card as guide. If the post card won't go one way, remove it and push it in the other way. I had to use the post card trick to put the CRT back in too.

With the CRT removed, you can use a small test CRT till you get the TV working.

How about posting some more pictures of your Zenith porthole TV?
Your Zenith porthole chassis looks exactly like mine. Bet it has two chassis's.


Carl

[VA561]

Thanks for the information. Its really appreciated. i will post more pictures as I proceed with the crt removal. Excellent info.

[jr_tech]

Consider having another set of hands around. If the CRT neck gets caught in the yoke part-way out, things can get pretty exciting ... you can't let go of the tube without the neck snapping, but you would really like to get to the yoke to do the card trick or use some other means to un-stick the neck...NOT a one person job.
jr

[cwmoser]

I'll second that -- its really a 2-person job.
After you do it one time with a helper, you can remove it by yourself but you have to carefully plan it with all the tools within reach and have a lot of patience. Still, make it a 2-person job for safety.

You will need a helper even more when you want to reattach the CRT. I attached mine by myself and it was really frustrating. One time I had to holler for my wife to come and help me as I was in a compromised position holding the CRT and couldn't attach the mask.

That 16" CRT is too valuable for it to be a one-person job.

[John Marinello]

I wrap the neck and the socket with a sheet of paper, and tape it in place.
The CRT will then slide right out of the yoke.