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
  #16  
Old 05-09-2018, 03:23 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
So the brightness control that's supposed to be 100k ohms is now about 800k, any idea where to find a replacement as it is also connected to the vert. hold and vert. linearity pots?
Reply With Quote
  #17  
Old 05-12-2018, 03:47 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
Well, I tested the CRT, which produced good emissions after a long warm up from it's 50 year nap. The HV section is producing the needed 10kv for the annode, but still no raster nor indication of life. Any ideas?

Thanks,
Zach
Reply With Quote
  #18  
Old 05-12-2018, 06:22 PM
Eric H's Avatar
Eric H Eric H is offline
Administrator
 
Join Date: Jun 2002
Location: So. Calif
Posts: 11,565
Does it have an Ion trap on the neck of the tube? It might need adjusted.
Reply With Quote
  #19  
Old 05-12-2018, 07:11 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
Quote:
Originally Posted by Eric H View Post
Does it have an Ion trap on the neck of the tube? It might need adjusted.
Would this Ion trap work? It didn't have one but I had a spare from a salvaged crossly TV (10BP4)

20180512_195134.jpg
20180512_195138.jpg
Reply With Quote
  #20  
Old 05-12-2018, 07:21 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
What is the crt number?

jr
Reply With Quote
Audiokarma
  #21  
Old 05-12-2018, 07:25 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
Quote:
Originally Posted by jr_tech View Post
What is the crt number?

jr
It's a 14NP4A
Reply With Quote
  #22  
Old 05-12-2018, 08:25 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
The tube does require an ion trap:

https://frank.pocnet.net/sheets/201/1/14NP4.pdf

I have never seen one that looks like the one you pictured... guess it can't hurt to try it.

jr
Reply With Quote
  #23  
Old 05-12-2018, 09:01 PM
Eric H's Avatar
Eric H Eric H is offline
Administrator
 
Join Date: Jun 2002
Location: So. Calif
Posts: 11,565
It requires a single field trap and that's a double. Still might work enough to give you something, you could also try removing one of the magnets from that trap.

It's theoretically possible to damage a tube by running it with a misadjusted trap, keep the brightness control turned down about halfway while experimenting with the trap.

If you get a raster adjust the trap for the maximum brightness and focus.
Reply With Quote
  #24  
Old 05-12-2018, 09:03 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
Great News! After finding an ion trap suitable for the TV, I hesitantly powered the set on and hooked up my DAC hoping for the best. After adjusting the raster for maximum brightness, I then proceeded to mess with all the controls and received this picture.
20180512_215104.jpg
Thanks for everyone's help with this, this has been a fun first TV repair.
Now to just fix the sound problems, Vertical Compression, and reverse the yoke

Thanks all,
Zach
Reply With Quote
  #25  
Old 05-14-2018, 03:32 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
Quick question, the image appears to be shifted downwards, making it difficult to see the bottom text, and a black bar at the top. I've checked all the resistors in the vertical Linearity circuit, replaced two but still no solution. The raster fills the screen, but TV programs do not. Any ideas where this could be stemming from?

20180514_162032.jpg
(The rest of the screen is fine, my camera picks it up weird. Picture is also upside down)
Reply With Quote
Audiokarma
  #26  
Old 05-14-2018, 03:47 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
Does the yoke have positioning tabs at the rear like those shown in the Marconi TV thread? ( shiny tabs @ 11 o clock and 9 o clock position on the rear of the yoke).

http://www.videokarma.org/attachment...7&d=1526186137

Rotate the two tabs together to change position... change the distance between the two tabs to adjust the strength of the position magnet.

jr
Reply With Quote
  #27  
Old 05-14-2018, 04:49 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Have you heard of Letterbox movies/TV shows? All newer HD shows are 16x9 aspect ratio and most sources convert them to 4x3 aspect ratio by letterboxing the content...It is a fact of life when trying to fit a rectangular show into a square hole these days.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #28  
Old 05-14-2018, 05:21 PM
Zsuttle's Avatar
Zsuttle Zsuttle is offline
VideoKarma Member
 
Join Date: Apr 2018
Location: Virginia Beach, VA
Posts: 159
Quote:
Originally Posted by jr_tech View Post
Does the yoke have positioning tabs at the rear like those shown in the Marconi TV thread? ( shiny tabs @ 11 o clock and 9 o clock position on the rear of the yoke).

http://www.videokarma.org/attachment...7&d=1526186137

Rotate the two tabs together to change position... change the distance between the two tabs to adjust the strength of the position magnet.

jr
Yes, thanks, I was able to properly center the image, although the part that covered the yoke is almost disintegrated.


Quote:
Originally Posted by Electronic M View Post
Have you heard of Letterbox movies/TV shows? All newer HD shows are 16x9 aspect ratio and most sources convert them to 4x3 aspect ratio by letterboxing the content...It is a fact of life when trying to fit a rectangular show into a square hole these days.
Yes, although I adjusted this tv so that there isn't any space surrounding the newer pictures, I figured that a few cut off areas aren't gonna hurt my viewing experience.

Thanks all,
Zach
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 12:39 PM.



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