Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Early B&W and Projection TV

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 10-10-2018, 02:15 PM
gweedo767 gweedo767 is offline
VideoKarma Member
 
Join Date: Oct 2018
Posts: 1
Mid 50's Zenith Set

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
Attached Images
File Type: jpg IMG_20181007_175222.jpg (58.2 KB, 52 views)
File Type: jpg IMG_20181009_122423.jpg (52.8 KB, 66 views)
File Type: jpg IMG_20181008_113724.jpg (102.3 KB, 62 views)
File Type: jpg IMG_20181008_113748.jpg (102.8 KB, 45 views)
File Type: jpg MVIMG_20181008_113752.jpg (84.4 KB, 44 views)
Reply With Quote
  #2  
Old 10-10-2018, 02:59 PM
old_coot88 old_coot88 is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 1,919
Smile

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.
Reply With Quote
  #3  
Old 10-10-2018, 03:00 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 10,006
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.
__________________
Tom C.

What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4

Reading between the scan lines since the mid 2000's.
Reply With Quote
  #4  
Old 10-10-2018, 05:47 PM
Phil Nelson's Avatar
Phil Nelson Phil Nelson is offline
VideoKarma Member
 
Join Date: Jan 2006
Posts: 3,949
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

Last edited by Phil Nelson; 10-10-2018 at 06:48 PM.
Reply With Quote
  #5  
Old 10-12-2018, 10:28 AM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 166
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.
Reply With Quote
Audiokarma
  #6  
Old 10-12-2018, 10:46 AM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 166
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.
Reply With Quote
  #7  
Old 10-12-2018, 12:31 PM
init4fun's Avatar
init4fun init4fun is offline
VideoKarma Member
 
Join Date: Mar 2011
Location: Eastern Massachusetts
Posts: 634
Quote:
Originally Posted by Notimetolooz View Post
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
Reply With Quote
  #8  
Old 10-12-2018, 06:48 PM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 166
Quote:
Originally Posted by init4fun View Post
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
I wasn't saying he should do anything risky, rather use a "work around".
That work around would be to use probe clips on the test equipment so that he doesn't have to touch the set while it is powered up. Of course he would only be able to use un-grounded test equipment like a battery powered meter.
Reply With Quote
  #9  
Old 10-12-2018, 07:58 PM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 166
I just noticed that the set in Phil's article uses chassis 16T20, where as your's is a 16Y20 chassis. Probably very similar, but you should try to get the correct schematic.
Reply With Quote
  #10  
Old 10-13-2018, 01:52 PM
Jeffhs's Avatar
Jeffhs Jeffhs is offline
<----Zenith C845
 
Join Date: Feb 2003
Location: Fairport Harbor, Ohio (near Lake Erie)
Posts: 3,562
Quote:
Originally Posted by Notimetolooz View Post
I wasn't saying he should do anything risky, rather use a "work around".
That work around would be to use probe clips on the test equipment so that he doesn't have to touch the set while it is powered up. Of course he would only be able to use un-grounded test equipment like a battery powered meter.
I wouldn't try to repair a hot-chassis TV, radio or any other device while it was plugged in and turned on, due to the shock hazard; I'd use an isolation transformer, as one other poster suggested. Using insulated probes isn't enough. The set's chassis will still be "hot" with the line voltage, and will still be a shock hazard and possibly a fire hazard as well, particularly if any metal object (probe tip, etc.) shorts to the chassis. This will effectively short the AC line directly to ground since, in transformerless televisions and radios, one side of the line is connected directly to the chassis. The house fuse or the equipment's own line fuse may blow, but I wouldn't count on it. The safest way to work on so-called AC-DC radios and transformerless televisions is to unplug the AC power cord (and discharge any filter capacitors) before doing anything in, on or under the chassis.
__________________
Jeff, WB8NHV

Collecting, restoring and enjoying vintage Zenith radios since 2002

Zenith. Gone, but not forgotten.
Reply With Quote
Audiokarma
  #11  
Old 10-14-2018, 09:55 AM
Notimetolooz's Avatar
Notimetolooz Notimetolooz is offline
VideoKarma Member
 
Join Date: Mar 2014
Location: Dallas, TX
Posts: 166
I think that an important word in my earlier post was missed. I was talking about using CLIPS, insulated alligator clips or the like, to attach the test equipment to the set so that the set doesn't have to be touched during a measurement.
https://www.digikey.com/product-deta...1173-ND/573996
Set unplugged.
Attach clips. Hands off set.
Plug in set.
Note measurement.
Unplug set.
Repeat as necessary.
It is not fast or convenient but it will work.
Anyway the original poster may be satisfied with just replacing the capacitors. Although I would also replace the selenium rectifiers with silicon ones. I'm not sure, but it seems like this is his first venture into working on vintage equipment. It is bad enough to tell someone, that thinks he got a great deal on a TV set, that he will have to buy new parts and test equipment, costing several times what he paid, to get it to work right. I don't want to discourage someone by insisting on another $ 50 or more piece of equipment unless he will be working on more TVs.
Reply With Quote
  #12  
Old 10-14-2018, 03:15 PM
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 3,148
Quote:
Originally Posted by Phil Nelson View Post
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 !
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:23 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
ęCopyright 2012 VideoKarma.org, All rights reserved.