One Fried Zenith Porthole

[VA561]

I carefully removed the 16" picture tube in my 1950 zenith porthole tv. I took the chassis out becuse I was going to do a complete recap. When I turned the chassis over, I couldn't believe my eyes. As you can see in the pictures, what I believe is the high voltage transformer section melted. It looks as though that section has been burned for quite along time.

Is it possible to replace that part of the chassis only and salvage what looks otherwise to be a perfectly good chassis? How hard will it be to find this part?
Any advice would be greatly appreciated, especially in regards to where I can locate a replacement for the fried section.

[Phil Nelson]

Ow, that's as burned as they get.

I guess you could place a "wanted" ad in the Classified section. It may be easier to find an entire chassis or a whole TV with a wrecked cabinet.

Phil Nelson

[cwmoser]

The components in play are:
1- burned up Flyback Transformer
2- Door Knob capacitor
3- Width Coil and 15K resistor
4- 1B3 Socket
5- Arc Ring on the 1B3 Socket
6- Resistors: 470K, 2.2 ohms on the 1B3 socket.
7- Fuse socket topside
8- Phenolic board that the 1B3 socket sits on.

Most likely even if the Flyback did not burn up, you would still have to rebuild that high voltage area. These sets have arcing issues I've been told and mine did too.

You may have carbon on the Phenolic board and you might as well go ahead and replace it. The 1B3 Socket is Bakelite - I had lots of arcing issues with mine and I replaced it with a Ceramic socket and cut out the carbon arc area. Been better if I had just replaced the Phenolic board with a new one.

Looks like your Door Knob capacitor is OK.
Your Width coil might be OK. Mine was fried and I replaced it with a MWC-4 -- or Miller 6199-a. Replaced the 15K resistor too.

The Arc Ring on the 1B3 should be OK.
The Resistors needed to be replaced anyway.

I think the Flyback is a Merit HVO-11 or HVO-6. Check your schematic.

If you can find the Flyback, the rebuild should be relatively easy and it will look nice and neat when done.

Might as well replace the 1B3 tube too. Mine had carbon arc traces on it between two pins. 1B3's are cheap enough.

I learned the hard way that you cannot have any sharp points on solder connection and paint it with lots of Corona Dope.

BTW, mine in its day had the Flyback replaced and it was mounted on the top of the Chassis. You might want to relocate yours there too. Topside will give you more options in choosing a suitable Flyback as there is more space there.

Reflecting back on all my arcing issues I had with the HV area, I would recommend a total rebuild of everything in the HV - replace the Phenolic board, use a Ceramic socket for the 1B3, replace all the resistors, and put in new HV wiring. Mine was a bugger with arcing and I think I could have saved a lot of aggravation by replacing the Phenolic board from the get go.

BTW, if you decide to scrap the TV and that picture tube is a good 16EP4, I may like to purchase it.

Carl

[cwmoser]

BTW, how much rust did you find topside on the 2 chassis's in your TV?
Mine were heavily rusted.
So bad that I repainted them.

Carl

[tvdude1]

If it takes a HVO-11 I can help, I have 2 extra new ones.

[kx250rider]

Imagine the stench in the house when that thing went up....

I would think that if you're patient, you'll have no problem getting a new FBT for that chassis. Post here, and also look up the Stancor, Merrit, and other 3rd party replacement numbers for that flyback, and put a standing search on eBay.

Charles

[VA561]

Thanks to everyone for the information. Here are some additional pictures of the HV transformer and one of the chassis. CW, if I can find the needed parts, I want to keep this set because the cabinet and chassis (other than the HV transformer) is in very good shape. It would be really nice to have the set going to play some old Christmas shows on near the end of next month but that's questionable at this time

[cwmoser]

Originally Posted by VA561

Thanks to everyone for the information. Here are some additional pictures of the HV transformer and one of the chassis. CW, if I can find the needed parts, I want to keep this set because the cabinet and chassis (other than the HV transformer) is in very good shape. It would be really nice to have the set going to play some old Christmas shows on near the end of next month but that's questionable at this time

Personally, I strongly agree with your decision. That Chassis of yours looks in very good condition - very little rust. Mine had much more rust than yours. Your chassis looks like the same model as mine. Mine is the 24G26Z1 chassis.

Like you, my plans are to play some Christmas classics on it this season.

If you are interested, here is the saga of my restoration:
http://www.cerant.com/ZenithPorthole...ortholeTV.html

Looks like you will be going though much of what I went through. I thoroughly enjoyed the journey.

Carl

[John Marinello]

Did you get a good 16EP4?

I would suggest removing that white plastic channel drum while you work on the chassis. That thing has 3 plastic spokes and are easily broken. You also need to be very careful when sliding the chassis back into the cabinet, as that drum needs to clear a hole in the cabinet.

[VA561]

As usual, very helpful advice from everyone. The picture tube passed all tests on the Sencor crt analyzer. Filament set, H-K shorts, G1 shorts, cutoff and emissions tests were all good. If anyone can help locate a replacement for the high voltage section, I would greatly appreciated it. It it would be nice to locate the complete section if possible.

[VA561]

Carl I just looked at the restoration link of your zenith porthole. Well done would be an understatement! Thanks for taking the time to document your restoration. It will be a tremendous help to every zenith porthole owner.

[Eric H]

I replaced the bad Flyback in my 10" Zenith Porthole with a common Fly1 from an RCA.
Details here.

It's a completely different chassis than yours and it was a Fly designed to run a 10-12 inch tube so I don't know if it would work here or not but possibly another fly for a 16 inch tube would work in this application.

What tubes does your set use in the Horiz output, this was a set that had a 6BG6 output, 5V4 Damper and a 1B3 Rectifier, the only electronic mod I had to make was the capacitor inside the Yoke.

I have an HVO-5 for a 16" RCA, it looks about the same as the 10" Flyback but the windings are fatter, it's for a 16AP4 or similar tube.