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
  #1  
Old 03-24-2017, 09:19 PM
wb2mep's Avatar
wb2mep wb2mep is offline
VideoKarma Member
 
Join Date: Sep 2006
Location: near Orlando, FL
Posts: 48
1970's Color CRT substitution

I haven't been having any luck finding spec sheets or data books on the later rectangular color CRT's. I have a couple of questions on substituting CRT's in early 70's Zenith TVs.

Is the only difference between the 25VAMP22 and 25VDMP22 the dark tinted front safety glass?

The reason I ask is that I have a 25GC45 Chromacolor II with a 25VDWP22 that's showing its age, and I'd like to swap out the CRT if it becomes my daily watcher. My Sams tube sub book lists the 25VDM as a sub, but not the 25VAM. The original 25VDW doesn't have the dark tinted glass, so there must be another reason only the 25VDM is listed.

Could the difference be in maximum anode voltage rating? The 25VAMP22 is used in a mostly tube set 25CC50 with 25 kV high voltage, while the Chromacolor II runs 29.5 kV.

Has anybody successfully put a 25VDMP22 into a Chromacolor II?
Reply With Quote
  #2  
Old 03-24-2017, 09:35 PM
sampson159's Avatar
sampson159 sampson159 is offline
sampson159
 
Join Date: Sep 2007
Location: columbus,ohio
Posts: 2,170
i ve done that swap.this makes a stunning picture.25vdmp22 looks even better in a flat chassis zenith.
Reply With Quote
  #3  
Old 03-25-2017, 09:19 AM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,672
First all CC tubes probably used the same envelope so physically
should work. CC tubes differed in dot size, screen tint & HV rating.
The KV rating is probably just the amount of lead in the glass.
Besides the HV actual gun voltages should be the same.

I would NEVER use a lower KV rating in a customers set.
If it were mine I might. Like I have said I spent 40 yrs surrounded
by sets & I dont have 3 legs & 2 feet !

73 Zeno
LFOD !
Reply With Quote
  #4  
Old 03-25-2017, 11:29 AM
Findm-Keepm's Avatar
Findm-Keepm Findm-Keepm is offline
Followin' the Rules...
 
Join Date: Jun 2007
Posts: 2,832
For what it's worth:


Basing is the same, but there may be mechanical differences ("E" notation on sub...), and most likely slight. Longer neck on the VDW - we're talking 22.065" from faceplate to tip, vs 21.805" for the VDM...

All other dimensions are the same, same basing, same max KV, same safety specs, per RCA's Picture Tube Product Guide (PIX-300J), November 1975
__________________
Brian
USN RET (Avionics / Cal)
CET- Consumer Repair and Avionics ('88)
"Capacitor Cosmetologist since '79"

When fuses go to work, they quit!

Last edited by Findm-Keepm; 09-29-2017 at 06:39 PM.
Reply With Quote
  #5  
Old 03-25-2017, 02:04 PM
init4fun's Avatar
init4fun init4fun is offline
VideoKarma Member
 
Join Date: Mar 2011
Posts: 1,169
Quote:
Originally Posted by zeno View Post
...... I don't have 3 legs & 2 feet !

You lost your third leg ??? oh you poor poor guy ......

Reply With Quote
Audiokarma
  #6  
Old 03-25-2017, 03:08 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
Quote:
Originally Posted by init4fun View Post
You lost your third leg ??? oh you poor poor guy ......

If you take enough of those men's pills they advertise on TV, they claim it may grow back...Might even grow a 4th leg as a side effect.
__________________
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
  #7  
Old 03-28-2017, 10:07 PM
wb2mep's Avatar
wb2mep wb2mep is offline
VideoKarma Member
 
Join Date: Sep 2006
Location: near Orlando, FL
Posts: 48
Quote:
Originally Posted by Findm-Keepm View Post
For what it's worth:


Basing is the same, but there may be mechanical differences ("E" notation on sub...), and most likely slight. Longer neck on the VDW - we're talking 22.065" from faceplate to tip, vs 21.805" for the VDM...

All other dimensions are the same, same basing, same max KV, same safety specs, per RCA's Picture Tube Product Guide (PIX-300J), November 1975
Thanks, Brian,

I think I finally tracked down the last of the intermittent problems with my Zenith 25CC50 hybrid set, so the VDM gets to stay in there a while longer. It's good to know that it's a viable replacement for the CRT in the 25GC45 CCII, which it might need if it becomes my daily watcher.
Reply With Quote
  #8  
Old 04-04-2017, 06:55 PM
TUD1's Avatar
TUD1 TUD1 is offline
TheUniversalDave1
 
Join Date: Jan 2014
Location: Birmingham, AL
Posts: 1,611
I've often wondered if it was possible to replace an inline gun tube with a delta gun tube.
__________________
"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan
Reply With Quote
  #9  
Old 04-04-2017, 10:12 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
Quote:
Originally Posted by TUD1 View Post
I've often wondered if it was possible to replace an inline gun tube with a delta gun tube.
Nearly all inline gun sets lack the provisions (transformer windings) for driving dynamic convergence....You'd have to redesign the set around the CRT or live with lots of RGB splay at the edges of the screen.
HV and gun wise it is not impossible... I have a delta gun CRT test jig that was kept in use into the inline era and had adapter designs and settings for inline sets.
__________________
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
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 04:31 PM.



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