d2240r Zenith B&W TV - Videokarma.org TV - Video

willy3486 · #1 09-10-2023, 07:12 PM

I have a Zenith d2240r B&W TV from the late 50s. This is in a wooden case and its in sams 449. I have had it in storage in my workshop and pulled it out to look at it. I did take the back off and it looks clean inside for that era, its been stored in a dry place since it was no longer used.

I am a little worried and have a question on it. My TV repair skills are rusty, I was a novice at that years ago. I am more familiar with radios and amps. The one thing I did notice is the Yolk on the back of the tube. I noticed it had got hot and was charred. So it looks like it overheated and burned the varnish off the windings.

With that said are these yolks from the late 50s Zenith hard to find and is this a symptom of something that would make it not worth fixing? I would really like to get this set going and such but I don't want to put a lot of time and money in it to find out its not fixable. I have some dealership signs I picked up and I think they are from the same era so that is one reason I would like to fix it. Another reason is I had one of the old Zenith B&W tvs when I was a kid and I have been looking for one for years.

Electronic M · #2 09-10-2023, 07:49 PM

This era of Zenith the yoke back covers are made of an unstable plastic that crystalizes and turns to dust, also the varnish on the windings often was clear instead of the vivid red used later. It's possible that the yoke is still ok.
You can check the yoke by ringing it with an oscilloscope, B&K Analyst, or a dedicated yoke ringing meter.

Sam's probably lists some generic replacements for the yoke in the parts list. Merit, Thordarson/Haldorson, ram, etc... Sometimes those generic subs can still be located if you search the brand and number.

willy3486 · #3 09-13-2023, 05:57 PM

Quote:

Originally Posted by Electronic M

This era of Zenith the yoke back covers are made of an unstable plastic that crystalizes and turns to dust, also the varnish on the windings often was clear instead of the vivid red used later. It's possible that the yoke is still ok.

I went out there to get the chassis number so I took the back off completely. While I was there I looked at the yoke again and you were right about the plastic. The odd thing is the way it crystalized the plastic looked like burned wires, the plastic was in lines about the size of the yoke wires.

Anyway on the yoke how is the best way to stabilize it? Could a person find a plastic jug or something and make it fit in the place of the old plastic? This gives me hope I can fix it. Buy the way the chassis is 16c21.

Electronic M · #4 09-14-2023, 10:05 PM

Quote:

Originally Posted by willy3486

I went out there to get the chassis number so I took the back off completely. While I was there I looked at the yoke again and you were right about the plastic. The odd thing is the way it crystalized the plastic looked like burned wires, the plastic was in lines about the size of the yoke wires.

Anyway on the yoke how is the best way to stabilize it? Could a person find a plastic jug or something and make it fit in the place of the old plastic? This gives me hope I can fix it. Buy the way the chassis is 16c21.

You may be able to find something like a 2L soda bottle for the side material. People have made yoke back covers too. I haven't found the side housing necessary on Zenith's as the bracketry prevents touching anything you shouldn't touch. The easiest rear housing I've found is stealing one from the yoke of a newer junk set...I've encountered enough bad yokes I've put a couple such covers aside for the future.

willy3486 · #5 09-10-2023, 08:02 PM

Thanks! I will look that up sometime this week, I have the sams folder for it I believe. The winding was black and brittle so I will check it out. I think I have a ringing adapter for my old sencore scope but the scope is dead as well. I will see if the ringing tester will work on my scope now.

dieseljeep · #6 09-13-2023, 08:11 AM

Quote:

Originally Posted by willy3486

Thanks! I will look that up sometime this week, I have the sams folder for it I believe. The winding was black and brittle so I will check it out. I think I have a ringing adapter for my old sencore scope but the scope is dead as well. I will see if the ringing tester will work on my scope now.

State the chassis number! Model numbers don't mean much.
That way, members that have a lot of junk chassis laying around, can check if they have a yoke that will work!

willy3486 · #7 09-13-2023, 08:16 AM

Quote:

Originally Posted by dieseljeep

State the chassis number! Model numbers don't mean much.
That way, members that have a lot of junk chassis laying around, can check if they have a yoke that will work!

Thanks! I will get it in the next few days. I am working on moving stuff to my new workshop and the old one is a mess right now, I can't get to my sams photofacts as stuff is piled in the way. I am having to dig a path to get this TV out to the new place. I hope to get it moved this weekend and check the number at least by then.

Yamamaya42 · #8 09-13-2023, 08:24 AM

Quote:

Originally Posted by dieseljeep

State the chassis number! Model numbers don't mean much.
That way, members that have a lot of junk chassis laying around, can check if they have a yoke that will work!

Correct, there are so many very similar types out there, often hard to get an exact match, chassis number does help, that way you won't end up with egg on your face!

Could not resist!

Electronic M · #9 09-11-2023, 05:22 PM

If your current working scope has a square wave calibration oscillator you can use that as ringing stimulus for the coil.

willy3486 · #10 09-11-2023, 06:05 PM

I looked at it again this afternoon when I got home from work. Bad news on the coil, its burnt to a crisp. The wires disintegrated all over when touched. I didn't get the photofact yet as I am moving stuff out of my old shop to a new one. I have boxes in front of the isle where the photofacts are. But I will get it soon. As far as the TV I still plan to move it to the new shop and use it as a display until I can work on the TV later in the winter. I do have some older coils that I bought a few years back so maybe I will get lucky with them and find one. I had about 30 or so out there.

Alex KL-1 · #11 09-13-2023, 06:44 AM

Oh no, bad luck...
To find a substitute, is a matter to first try to find the suggested substitutes, but, in the end, is a matter of finding a yoke compatible with the CRT neck, deflection angle (a lot of CRT from this era have surprisingly close properties), and the electrical properties (inductance/self capacitance), to match with the TV flyback. This *can* add some hope BUT... too bad most parts don't refer to electrical properties, so is difficult to follow this path (for trying to use yoke from another maker). And these values varies radically from some models... for example, some European yokes have rather low inductances.

willy3486 · #12 09-15-2023, 07:55 AM

Thanks, I will look at a 2 liter soda bottle when I get it moved and start working on it. I plan to take it out of the cabinet this winter and replace all the caps and test the tubes. This type of set but from the late 60s/early 70s Zenith was the first TVs I worked on. When I was a teenager in the late 70s I had about 3 of them I fixed. Thats one reason I wanted to fix it as I loved the metal hand wired chassis.