Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Early Color Television

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 09-01-2010, 09:36 PM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
lack of horz sweep on color roundie

this ties into my old thread about a purple edge on my roundie, which was related to a lack of horz sweep (I think). I may have found something. while reviewing some other schematics I decided to put a 78pf cap across the horz windings (there is one internal to the yoke). This increased the sweep about 1/2 an inch, enough to get rid of the purple edge and make the horz centering less critical.

Now I dont know if the internal cap in the yoke has just opened up or what, but at least I am getting somewhere with more width.

My plan was to pull the yoke and just replace the existing cap and see if thaty does it.
Reply With Quote
  #2  
Old 09-01-2010, 10:09 PM
DaveWM DaveWM is offline
VideoKarma Member
 
Join Date: Feb 2009
Location: Orlando FL
Posts: 5,607
oh a little history, all the bias/hv/drive waveforms check out, sweep tube is good, just a bit short on sweep. I could increase it by adj the horz tube bias 9there is a pot for it on this one) but that would shoot the HV up too high. when HV was adj to 25kv (brightness all down for min beam current) I would get the correct HOT current but just not enough sweep. I even went so far as to buy a new yoke, but never got around to installing it. The cap thing was just an experement based on looking at other schematics that had a provision for increasing the sweep, which involved a cap from the red lead of the horz sweep to ground. There was no such cap in this set or provision for it but I did see the 68pf internal cap across the horz sweep leads.
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 08:20 AM.



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