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
  #16  
Old 01-25-2017, 08:11 AM
miniman82's Avatar
miniman82 miniman82 is offline
First Light: 1952-2011
 
Join Date: Jun 2009
Location: Great Mills, MD
Posts: 4,087
Quote:
Originally Posted by Penthode View Post
The biggest drawback of the CTC5 in my opinion is the low high voltage coupled with the relatively dim (compared to tubes a few years later) 21AXP22A.

Low anode voltage is a big problem with the 5 chassis, which exacerbates brightness issues with a CRT that isn't as efficient as later ones.

Quote:
If I get the time, I would like to explore further the Horizontal Output/ Flyback to see if I can get a bit more HV.
Already have: I added drive and HV controls to my Wingate, nothing I did got any more than 22kv out of it and it was still saggy. Lack of current at the anode is just as big a problem as lack of voltage.


There are two things I have yet to try: installing a solid state 3A3 replacement, and feeding the horizontal section more B+ by using silicon rectifiers in the power supply. I would still run the rest of the chassis on the 5U4 rectifiers, only horizontal would get a boost. I've come to the conclusion that the flyback in the 5 has higher primary D.C. resistance, which means you can only sink so much current into it at a given B+ value. Can't change the flyback windings, so the only thing you can try is feeding it higher amplitude pulses. This may in fact lead to higher anode voltages, but I'm not sure what effect it would have on sweep width and so on.

Another possibility is subbing another flyback, but that's not an easy chore.
__________________
Evolution...
Reply With Quote
  #17  
Old 01-25-2017, 09:46 AM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 798
Break down. Do it! Hold your nose. control your emotions. DO IT!

SpellmanHV.com SMS series. (not cheap, of course.)

Last edited by dtvmcdonald; 01-25-2017 at 09:49 AM. Reason: removed a joke
Reply With Quote
  #18  
Old 02-19-2017, 10:58 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: 4,319
I went back to fiddle with the purity today, because I noticed the lower center reds have some green impurity, enough to mess up skin tones. Went back to ground zero with edge magnets retracted, degaussed the tube, but I cannot get rid of it. Just above center is reasonably pure, but just below center is greenish.

I also noticed when adjusting the purity rings that when the purity towards the top edge goes out, it shows up in finger-width "waves" of impurity. This higher order effect is surprising and must be due to detailed yoke winding structure, I guess.

I'm also considering whether fiddling with some small added magnets (strictly ad hoc, have never seen it recommended) might help.

Question for those who have done more 21AX setups: When you degauss the tube, do you do it entirely from the front, or do you also run the coil into the back of the set and around the CRT bell?
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #19  
Old 02-20-2017, 12:29 AM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 9,000
Not had a good AXP to set up, but on the later glass types degausing the back of the CRT can be useful on some tough cases.
__________________
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
  #20  
Old 02-20-2017, 01:03 AM
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: 4,319
Quote:
Originally Posted by Electronic M View Post
Not had a good AXP to set up, but on the later glass types degausing the back of the CRT can be useful on some tough cases.
I'll try it - can't hurt, anyway.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Audiokarma
  #21  
Old 02-21-2017, 01:09 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: 4,319
OK - latest on trying for better purity.

I tried degaussing the cone of the tube from the rear, as well as the front, and along the way discovered I had not fully retracted a couple of the edge magnets. In thinking about the procedure, I had always had a vague feeling that the reason for retracting the magnets as the first step was to protect them from the degausser, but on further thought, I realize that using the degausser with the magnets not retracted would actually magnetize the CRT in the opposite direction of the edge magnet fields (just the same as degaussing actually magnetizes the CRT opposite the Earth's field, to make the net field close to zero).

So, this morning, I was careful to retract all the edge magnets and then did the full front and rear degaussing again. This greatly improved the center purity. The edge magnet strength required is now rather large on the right side and lower right, much less on the left side, and very little on top.

So besides retracting the edge magnets before degaussing, the procedure should also say don't try to do any "touch up" degaussing after the edge magnets are adjusted, unless you are willing to go back to ground zero again.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #22  
Old 02-21-2017, 07:48 PM
Kamakiri's Avatar
Kamakiri Kamakiri is offline
Administrator
 
Join Date: Jun 2002
Location: Buffalo, New York
Posts: 4,968
It's pure hell. Try to get it "just a little better" and end up undoing all your previous work.....
__________________
"Restoring a tube TV is like going to war. A color one is like a land war in Asia."
Reply With Quote
  #23  
Old 02-21-2017, 09:04 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: 4,319
People said the shadow-mask CRT would never work, and they were right!
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #24  
Old 02-21-2017, 10:25 PM
etype2's Avatar
etype2 etype2 is offline
VideoKarma Member
 
Join Date: Mar 2010
Location: Valley of the Sun, formerly Silicon Valley, formerly Packer Land.
Posts: 675
People also said .... it was a standing joke. "When you buy a color TV, you need to hire an on call television engineer to maintain it."
__________________
Personal website dedicated to Vintage Television https://visions4netjournal.com
Reply With Quote
  #25  
Old 07-31-2017, 08:01 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: 4,319
Latest news on owning this white elephant:

The last time I turned it on, the blue dynamic convergence was out again (that's what I thought at a quick glance - it was really ALL dynamic convergence gone). So, I went in the back and wiggled the blue H wire that seemed to be the problem before, but it had no effect. My first thought was "Now it's permanently broken, I will have to sub the cloverleaf." But when I reached for the convergence plug, I had a better thought and wiggled it - Voila! Dirty connections.

A little exercise of the contacts, and it's back to where I struggled to get it months ago.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Audiokarma
  #26  
Old 08-01-2017, 09:26 PM
Kamakiri's Avatar
Kamakiri Kamakiri is offline
Administrator
 
Join Date: Jun 2002
Location: Buffalo, New York
Posts: 4,968
Nice!! Ever end up needing any of those coils?
__________________
"Restoring a tube TV is like going to war. A color one is like a land war in Asia."
Reply With Quote
  #27  
Old 08-02-2017, 04:04 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: 4,319
Quote:
Originally Posted by Kamakiri View Post
Nice!! Ever end up needing any of those coils?
Well, I don't need them now, but good to have a backup, and the pots may still be useful.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #28  
Old 08-03-2017, 12:32 AM
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: 4,319
Quote:
Originally Posted by old_tv_nut View Post
Well, I don't need them now, but good to have a backup, and the pots may still be useful.
A little expansion - I've been too busy/lazy to extract and open the pots, but still hoping they aren't burned like every other example I've seen. That 100 ohms tapped at 25/75 was just a bad idea for carbon pots.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #29  
Old 08-04-2017, 12:49 AM
Penthode's Avatar
Penthode Penthode is offline
VideoKarma Member
 
Join Date: Jun 2009
Location: Syracuse, NY
Posts: 659
The static convergence pot elements appeared to have shrunk with age on my CTC5. This led to an open carbon element which resulted in intermittent static convergence problems. The shrinkage caused a crack in the carbon element at the rivet where the element was tapped. I ended up using a conductive paint normally used for repairing car window heating elements to bridge the gap on the carbon element.

The paint was applied four years ago and the pot is still fine.
Reply With Quote
  #30  
Old 08-04-2017, 01:02 AM
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: 4,319
Quote:
Originally Posted by Penthode View Post
The static convergence pot elements appeared to have shrunk with age on my CTC5. This led to an open carbon element which resulted in intermittent static convergence problems. The shrinkage caused a crack in the carbon element at the rivet where the element was tapped. I ended up using a conductive paint normally used for repairing car window heating elements to bridge the gap on the carbon element.

The paint was applied four years ago and the pot is still fine.
Wow, I never would have expected that's the problem. Thanks!

The proper setting on mine is very close to the tap, and that is the place that's broken. I thought it was due to burning the element.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Audiokarma
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 10:30 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
ęCopyright 2012 VideoKarma.org, All rights reserved.