Mid 50's Zenith Set

[gweedo767]

I bought this 1955 (or 56) Zenith at an estate auction. It turns on and gets to static. I hooked my NES up to it with "some" success. You can see the results in the pictures and I uploaded a few videos to YouTube. Any ideas on how I can get it to "fully" working?

Thanks!

Videos:

First power on:
https://www.youtube.com/watch?v=OvMUXrubhzo

First run with NES hooked up:
https://www.youtube.com/watch?v=WGW1LfbEWD8

Mario "running" on it:
https://www.youtube.com/watch?v=zm_3xDY8bMo

[old_coot88]

The 'hourglass' effect and heavy hum bar indicate the main filter cap is shot. CRT looks good and strong (no brightener on it). Excellent fixer-upper candidate.

[Electronic M]

First off how much do you know about tube based electronics? Before working on a TV it is best to replace capacitors and practice soldering, component identification and schematic tracing on a 5 tube am radio or two.

Assuming you do have tube radio knowledge: it looks like the main problem is vertical roll. That should clear up if you adjust the vertical hold control...if it doesn't and you can get it to roll slowly in either direction with the control then sync is not being coupled to the vertical osc, and the vertical integrator is probably bad. If it only rolls one way the frequency of the vertical osc is off likely from bad capacitors.
Also while many radios of that vintage still work fine on their original capacitors TVs stress those parts much more and when those capacitors inevitably fail they can take out other much harder to find parts. If you haven't replace the electrolytic and paper dielectric capacitors I strongly recommend you do so before using that set.

[Phil Nelson]

This article answers common questions about getting an old TV to work:

https://antiqueradio.org/howfixtv.htm

As Electronic M noted, recapping (replacing old paper & electrolytic capacitors) is pretty standard, for safety and reliability reasons.

I restored a very similar Zenith TV twenty years ago. It, too, made a picture without any restoration:



After restoration, it looked better and I'm more confident about playing it:



An advantage of restoring a set that already "mostly works" is that you can turn on the set and play it briefly, after replacing every couple of capacitors, to make sure you haven't made any wiring mistakes. If all goes well, you'll see things gradually improve, as you replace more and more bad old caps.

Regards,

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

[Notimetolooz]

Looks to me that someone added a metal can electrolytic cap just above the high voltage cage ( the box with the "Warning" label). Sometimes people add new caps across bad caps, but that is incorrect.
Since the vertical frequency is nearly the same as the 60 Hz power line frequency and faulty electrolytic caps (filter caps) do not suppress the power line frequency, bad filter caps commonly mess up the vertical sweep.
Working on TVs is a bit more dangerous than working on radios, because of the large CRT and the high voltages involved. Make sure you learn about the added danger.
Phil's site is very good.

[Notimetolooz]

I think this set doesn't use a power transformer, that means that the chassis may be "live" (connected to one side of the power line). This is an added danger if you touch the chassis while it is plugged in. The best way to protect yourself (and sometimes test equipment) is to use an isolation transformer, but for one set it probably isn't worth the expense. A good many radios were hot chassis also.
Zenith had a larger chassis (21", I think) version that did use a power transformer.
If you haven't worked on vintage equipment before be aware that things like cardboard, rubber and plastic get brittle and stiff with age. Replacements can get very difficult to find.

[init4fun]

Originally Posted by Notimetolooz

I think this set doesn't use a power transformer, that means that the chassis may be "live" (connected to one side of the power line). This is an added danger if you touch the chassis while it is plugged in. The best way to protect yourself (and sometimes test equipment) is to use an isolation transformer, but for one set it probably isn't worth the expense....

With all due respect , OF COURSE it's worth the expense !

To Hell with the TV or any test equipment , trinkets can be replaced , people can't , and there have been lots of folks done in by good ol 110 !

An Isolation transformer is a must for any hot chassis set , it's the electronics hobby's Jockstrap

[zeno]

Originally Posted by Phil Nelson

EDITED


An advantage of restoring a set that already "mostly works" is that you can turn on the set and play it briefly, after replacing every couple of capacitors, to make sure you haven't made any wiring mistakes. If all goes well, you'll see things gradually improve, as you replace more and more bad old caps.

Regards,

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

Same point I try to drive home. Take it slow & test as you go !
I spent almost 40 yrs fixing TV's & I made stupid mistakes almost to the last
day. There is NOTHING worse than finding a self induced problem.
For now I would pick up an isolation transformer & change out the electrolytic caps. Then go stage by stage changing certain caps ( but not all !!). The CRT is quite strong so this set will come out very nice & be
worth the small investment.

Good Luck
Zeno
LFOD !