Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #16  
Old 12-19-2014, 03:09 AM
fsjonsey's Avatar
fsjonsey fsjonsey is offline
Living The Draper Ethos
 
Join Date: Jul 2006
Location: Northeast Ohio
Posts: 539
Well, I replaced all the caps and the bottom of the horiz has started to collapse again. I can't get the HV over 22KV. The Flyback still looks good and resistance is in spec. I looked at the VDR, and it's already been replaced at least once, some other tech tacked a pink and white Zenith replacement VDR onto the leads of the original. I ordered one of the replacement Speer MOV's that Doug recommended in another thread. It should be here today. I'll let you all know the results once I solder it in. It would be hilarious if the caps were either fine or marginal and the VDR was the real culprit. If that's the case, I guess that'll teach me not to trust a $30 Chinese ESR cap tester.

Last edited by fsjonsey; 12-19-2014 at 03:20 AM.
Reply With Quote
  #17  
Old 12-24-2014, 04:09 AM
fsjonsey's Avatar
fsjonsey fsjonsey is offline
Living The Draper Ethos
 
Join Date: Jul 2006
Location: Northeast Ohio
Posts: 539
I soldered in the new VDR. HV control is back, but the picture is still shrunken horizontally on the bottom third of the screen. It gets worse as the set warms up. I know for a fact that the Yoke is not the issue, as this is a NOS Thordarsen replacement. Once the set warms up, the bottom corners of the CRT shrink to black and the picture almost looks like a trapezoid. There are three white vertical lines centered in the bottom of the screen that fade out about a third of the screen up. Where the ticker on a cable news station would go, as an example, the text passes these lines, it shrinks and expands back to a normal size as it passes the vert. lines.

I really need help with this. I'm stumped.

Last edited by fsjonsey; 12-24-2014 at 04:25 AM. Reason: new info.
Reply With Quote
  #18  
Old 12-24-2014, 09:50 AM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
a pic would be helpful
Reply With Quote
  #19  
Old 12-24-2014, 09:56 AM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
fyi, part of the pincushion correction in a zenith uses a pulse from the vert to modulate the output from the horz out tube. If you look a the circuit you can see a connection to I think a 40 uf cap (C7) that ties the screen of the horz out to the vert out.

This presents as a subtle narrowing and slight keystone of the pic (much less keystone than a bad yoke).

Last edited by DaveWM; 12-24-2014 at 12:06 PM.
Reply With Quote
  #20  
Old 12-24-2014, 02:57 PM
Username1's Avatar
Username1 Username1 is offline
Not sure how I got here.
 
Join Date: Dec 2009
Location: Orange County NY
Posts: 3,584
Sounds like the yoke....... yah, I know it's a new one.... you still got the original....?

We need a picture, several... when it's first on, and after a while...

.
__________________
Yes you can call me "Squirrel boy"
Reply With Quote
Audiokarma
  #21  
Old 12-24-2014, 03:36 PM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
its the after a while bit that makes me think its the pin cushion correction cap, if its just a 1/2 inch narrowing from top to bottom or bottom to top, then I would put money on that cap being an issue. Its even mentioned in the zenith tab manual case history as something that is often thought to be a yoke issue. Its just a lot less.
Reply With Quote
  #22  
Old 12-24-2014, 03:51 PM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
found it, knew I had messed with this before

http://www.videokarma.org/showpost.p...2&postcount=39

the full description stars on post 33
Reply With Quote
  #23  
Old 12-25-2014, 03:50 AM
Username1's Avatar
Username1 Username1 is offline
Not sure how I got here.
 
Join Date: Dec 2009
Location: Orange County NY
Posts: 3,584
That entire thread was pretty good...... Boy you talk to yerself a lot....

.
__________________
Yes you can call me "Squirrel boy"
Reply With Quote
  #24  
Old 12-25-2014, 09:26 AM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
I do that a lot, where I live its the only way to have an intelligent discussion.
Reply With Quote
  #25  
Old 07-08-2015, 02:37 AM
fsjonsey's Avatar
fsjonsey fsjonsey is offline
Living The Draper Ethos
 
Join Date: Jul 2006
Location: Northeast Ohio
Posts: 539
Quote:
Originally Posted by DaveWM View Post
I do that a lot, where I live its the only way to have an intelligent discussion.
This is really late, but thanks, Dave. That fixed it.
Reply With Quote
Audiokarma
  #26  
Old 07-08-2015, 05:06 AM
Username1's Avatar
Username1 Username1 is offline
Not sure how I got here.
 
Join Date: Dec 2009
Location: Orange County NY
Posts: 3,584
Quote:
Originally Posted by DaveWM View Post
I do that a lot, where I live its the only way to have an intelligent discussion.
Works for where I live too.........

.
__________________
Yes you can call me "Squirrel boy"
Reply With Quote
  #27  
Old 07-08-2015, 10:44 AM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
Quote:
Originally Posted by fsjonsey View Post
This is really late, but thanks, Dave. That fixed it.
Great, glad that did it. Odd kind of failure, too subtle to be the yoke.
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 07:30 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.