Videokarma.org

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

We appreciate your help

in keeping this site going.
 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #1  
Old 01-06-2017, 05:16 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
CTC-5 21AXP22 convergence

When my CTC-5 had a glass 21FJP22 subbed in, I was able to get excellent convergence. When I finally got a 21AX to put in it, I found the dynamic convergence to be much poorer. I recently went back to trying to improve it, and here's what I'm finding:

I have to move the yoke almost all the way forward to get full screen purity. Maybe this is normal, but with the yoke in this position, it appears there is not enough dynamic convergence action to converge red and green at the edges, either vertically or horizontally. Pulling the yoke backwards improves the convergence, but of course then purity occurs only in the center of the screen. I have experimented with the position of the convergence coils, since you cannot see the pole pieces beneath the dag in the neck, but at the point of strongest action there is still not enough.

The DC adjustments have enough range, and generally want to be near center range, which is as it should be.

I am beginning to wonder if the gun is in the right position, since this is a rebuilt tube.

I also need to recheck whether the resistance values of the DC convergence controls that I hacked in (because the original tapped controls were burned) could affect the dynamic current. Not sure yet if they are in series with the dynamic voltages or not. (Apparently burning was a common problem, because the pulled parts some kind people here sent me were burned too, so I had to give up on originals.)

Looking at the top and bottom convergence, I wondered if a weak vertical output could produce low convergence amplitude, but both V and H are bad, so I'm discounting that.

One thing I did learn: the purity magnets have short springs on the base, which apparently act as small pole pieces as well as mechanical mounts, and it helps to keep them properly oriented while the magnetic rings are rotated. One of the rings binds to the base, and if you're not careful, they rotate together, making it more difficult to get uniform purity.

Any thoughts of what I may be missing here would be appreciated!
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
 


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 03:25 PM.



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