'51 Zenith Porthole

[Charlie]

Recently, I've acquired my first Zenith Porthole... Model H2438R from 1951 with the 24H20 chassis.

The wood is in good condition, however the finish is lacking. Most of the finish has come off the top and the base... needs to be sanded down and refinished. No big deal... this cabinet will be pretty easy to make look nice again.

The chassis was very dusty, but a couple of make-up brushes and the vacuum cleaner got things pretty clean. Under the chassis looked pretty good. On top, there's been some tubes changed. Most of the tubes are the original Zenith tubes, and the replacements are all RCA and it appears they may have been all changed at the same time. The flyback looks good.

I suspect it's possible the yoke has been changed. The wires to the yoke were still quite bright with color and little if no dirt. Also noticed the the paint has been broken on screws used for evidence of tampering.

The CRT has been replaced with an RCA Silverama and tests EXCELLENT on my B/K 470! The meter nearly goes all the way to the top of the scale! I really like that! I kinda suspect the CRT may have been changed at the same time as the chassis tubes.

The guy I got it from told me he bought the set 15 years ago, and has turned it on from time to time. He said he quit turning it on five years ago when the power cord's insulation start cracking and falling off.

I'm considering pulling the HO tubes and bring the chassis up slowly to see if I can get any life out of it, and if all goes well, plugging the HO back in to see if there's any light on the screen. Of course, the chassis will get recapped, but being that everything looks good, I'll attempt getting a raster only for a few seconds and then shut it down.

I need some input from others that have dealt with metal/glass CRT sets. At the front of the CRT, there's a big grey rubber molding around the edge. I'm going to assume that this molding acts as an HV insulator between the CRT front lip and the metal bezel on the front of the cabinet. Being that the front of the CRT is only about an inch from the rear of the metal bezel, I'm guessing that rubber molding keeps you from getting zapped by the front of the set. Right?

I notice that my Raytheon Porthole set uses this same rubber molding in the same manner.

Here's my concern: The rubber molding around the CRT front has developed several cracks (see photo). With this in mind, I'm afraid there could be some HV leakage and cause an extremely unpleasant shock from the front of the set. After Dave's recent enlightenment, I'm reminded to pay close attention and be very careful.

Question: Am I putting way too much thought into this, or am I right in assuming I'll get a jolt? If I am indeed right, I'm seeking suggestions on how to remedy this molding issue.

[jeyurkon]

Congratulations on the nice acquisition! Sounds like you really lucked out getting a great CRT.

I haven't started working on my porthole yet, so I don't have actual experience; but your fears sound well grounded.

Actually, is the bezel grounded? If so, you should be safe from the front.

John

[ohohyodafarted]

You are correct in assuming that if the insulator bezel around the front of the crt is defective you could get a jolt if you are grounded if the front trim ring around the safety glass is touched. To check if you have a problem, simply take an insulated wire and ground one end to the chassis and then touch the other end to the metal trim around the front of the set. If the metal trim is "live" you will get arcing to the wire.

No arcing=you are probably OK

[Charlie]

The front bezel is not grounded (that I noticed), so I will try grounding a wire to the chassis and touching the other end to the front to see what I get.

I might see if I can fill in those cracks... perhaps with some silicon caulk. Too bad it's clear instead of grey. I think I can do a neat job with that, and perhaps prevent an episode! Another thought would be to use an expoxy (such as jb weld) to fill the cracks. That's grey, and would likely serve as a good insulator.

Another thought would be to remove the molding and wrap the front lip of the CRT with electric tape (at least a few layers) and then replace the molding.

I'd prefer not to leave it as is (even if it doesn't seem to cause a problem) being that the cracks could get worse over time... increasing the chances of a zap.

As an added precaution, I could also ground the bezel to the chassis from the inside. If leakage did eventually occur, it appears there's a fuse in the HV section, and that would blow if things got hairy.

[jr_tech]

The black rubber surround around my 16" is cracked/very wrinkled also (very ugly)... does anybody make a replacement part? I am surprised that Zenith did not ground the bezel, but mine does not appear/measure to be grounded either.

jr

[Eric H]

What size is that tube?
I have a good insulator but it's for a 12" set.

[Charlie]

Thanks, Eric, but this one has the 16" tube.

[jr_tech]

I have never tried it, but always thought that I might be able to cut a reasonable replacement from a small bicycle inner-tube

Any other ideas?

jr

[Charlie]

Jr, I could take your inner-tube and simply line the inside of the molding... that would also work just like the elect tape... but maybe provide as a better insulator!

[Sandy G]

I'm still jealous...I've Lusted Mightily for a Porthole Zenith for quite awhile now...There's just something SO "1950" about them...1950 was sort of in an earlier age, but by '59, things had REALLY changed....

[marty59]

That's a nice find Charlie!!

[Big Dave]

Another thought may be, once you are ready to install the chassis in the cabinet permanantly, seal the cracks with automotive grade silicone of the correct color. I would go around the entire front to maintain consistancy.

[bandersen]

Nice find I think that's my favorite model of porthole. So much easier to move around than the giant combo units.

[Reece]

I was trying to think of some other rubber gasket similar to that and it occurred to me that some washing machines have a grey rubber gasket that is seen when you open the lid. There could be a useful one from an old machine or even take the Zenith gasket to a big appliance parts store and see if they could come up with something similar. Even if the right profile gasket was too large a diameter, a piece could be cut out to reduce the size. It might mean reusing the old gasket and just using the new one for cosmetics out front.

[jr_tech]

Good one! perhaps far easier than cutting up bike inner-tubes. Perhaps another possibility is visible in Charlie's avatar... a REAL Porthole! Do those things have gaskets?

jr