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
  #46  
Old 02-25-2015, 10:57 PM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
Quote:
Originally Posted by dieseljeep View Post
The only time, I used a SS replacement, was when the filiment loop was punctured through and arcing. I cut it short or tried to remove it completely.
Never had any problems. Usually on an RCA or one of the clones.
Well, I sort of opt for originality when possible, so I called that supplier that Zenith6S321 posted a link for and have a couple of those and one or two other radio tubes I needed on the way. I inquired about what brands were available and was blown away as the guy named almost anything one would desire or not (International Serivicemaster). They actually had Zenith and put me down as preferring that. As a second option I told them Sylvania. I don't think I can go wrong with either of those.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
Reply With Quote
  #47  
Old 02-26-2015, 09:32 AM
dieseljeep dieseljeep is offline
VideoKarma Member
 
Join Date: Jul 2010
Posts: 7,562
Quote:
Originally Posted by Tubejunke View Post
Well, I sort of opt for originality when possible, so I called that supplier that Zenith6S321 posted a link for and have a couple of those and one or two other radio tubes I needed on the way. I inquired about what brands were available and was blown away as the guy named almost anything one would desire or not (International Serivicemaster). They actually had Zenith and put me down as preferring that. As a second option I told them Sylvania. I don't think I can go wrong with either of those.
IIRC, the original 3AT2's were made by GE. The Zenith replacements were made by Sylvania.
You should've mentioned the 3AT2. I could've included a good used one or two.
Reply With Quote
  #48  
Old 02-26-2015, 09:35 PM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
Quote:
Originally Posted by dieseljeep View Post
IIRC, the original 3AT2's were made by GE. The Zenith replacements were made by Sylvania.
You should've mentioned the 3AT2. I could've included a good used one or two.
All is well that ends well with that. They did send me 2 Zeniths, so I will have a couple of good NOS tubes. I haven't had time to try one in my set yet. A third and different tube for a 40s radio was a Ken-Rad. I've had some, but I can't remember how they held out. Shouldn't be a problem. I sent you a PM.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
Reply With Quote
  #49  
Old 02-27-2015, 09:40 AM
dieseljeep dieseljeep is offline
VideoKarma Member
 
Join Date: Jul 2010
Posts: 7,562
Quote:
Originally Posted by Tubejunke View Post
All is well that ends well with that. They did send me 2 Zeniths, so I will have a couple of good NOS tubes. I haven't had time to try one in my set yet. A third and different tube for a 40s radio was a Ken-Rad. I've had some, but I can't remember how they held out. Shouldn't be a problem. I sent you a PM.
Ken-Rad was one of the oldest tube suppliers out there. Their tube stood up as well or better, than a lot of the other brands.
Reply With Quote
  #50  
Old 03-03-2015, 01:44 AM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
Quote:
Originally Posted by Tubejunke View Post
OK, I just figured out that I have been using Sams Set 722, Folder 4 which is for the 25LC30/U! Geez! It only specifies pins 1 &12 as heater connections. I need to get a .pdf on my 25MC30 somewhere. H
For the sake of this thread's information being accurate I must correct what is quoted above. My set's chassis is indeed a 25LC30 and the model is 5111. I don't even know where I came up with 25MC30 being what mine is. I am guessing that the L & M identifiers must have to do with production year. Mine should be the 1964 and the MCs should be 1965 and the last of that style plain metal cabinet round crt TV production.

Thinking I had the wrong schematic, I ended up finding a .pdf Sam's folder on the 25MC30 and was happy. Looking over the horizontal output and HV sections of the schematic I noticed that the 6JS6 horizontal output tube was used. I knew that my set employed the 6HF5 sweep tube. That led me to look at all the models covered for that year 1965 on the first page. I saw that the models were all different and mine 5111 was not there. I think instead there is a 5211 which is probably that year's equivalent. From there I opened my original file for the 25LC30 and saw my model and the right 6HF5 sweep circuit

In a way I wish that my mistake was correct as I have heard that the 6JS6 H Output tube was a better tube by design (plus I have a few in my useless compactron box). I don't think that they are subs for one another, so I won't even worry about that. The 6HF5 seems to do as well as any. I'm not sure how many other changes that there were in that one year. Most everything I glanced at looked the same. I notice Zenith regularly made small changes such as one or two tubes from year to year. That's the world of engineering for better or worse. I wonder how much better the 6JS6 really is just out of curiosity.

Anyway, I think the confusion on my part started with all the talk about the HV rectifier pin #s shown on my LC schematic. They appear to be wrong as pins 1 and 12 are shown to apparently be the heater terminals. Well, they are and they aren't, but you have to have the tube data to see what is going on internally with the 3AT2. Many pins are duplicate or NC. The MC schematic shows the same thing and it thew me off because I expected my set to be wired like the schematic as I would think a factory would adhere to; evidently not so.

If anyone here needs a good copy of the 25MC30, I now have it and would be glad to share it with anyone. Just let me know....
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
Reply With Quote
Audiokarma
  #51  
Old 03-03-2015, 11:41 PM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
OK, it's official! My HV is back. The surgery was a success thank goodness. I was a bit nervous of what new surprises may arise, but the only changes were definitely positive. Good, stable HV with no corona hissing and/or related screen anomalies.

I did use Electronic M's advice and paralleled a .47mfd cap across my meter leads measuring cathode current at the horizontal output tube. The readings were the same and unfortunately still a bit higher than I want, or Zenith wanted for that matter. The spec is 200mA and at line potential upward of 120VAC I get about 220mA. So I still run the set on my Select a Volt at about 110VAC and can maintain 200mA. Once an older tech said that they used to dip all the Zeniths at 210mA as a rule, but I feel that I should be able to achieve the spec. Now I do believe that the fly is now running much cooler for whatever reason. VERY happy there!

I probably just need to change out the HO coupling cap to get the 200mA. That should be next because for whatever reason I have to throw a bit more line voltage at the set before the color will come in. Once it comes in I can back it down. The color problem has been with the set since I brought it home. Actually, there was no color for a long time and I changed out the 6GH8 one day and had a DVD player hooked up and wa la. Great color!

For now though I'm just glad to have a playable set again. Many, many thanks to all for the help on this!
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"

Last edited by Tubejunke; 03-03-2015 at 11:41 PM. Reason: mA
Reply With Quote
  #52  
Old 03-04-2015, 11:02 AM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,762
Quote:
Originally Posted by Tubejunke View Post
OK, it's official! My HV is back. The surgery was a success thank goodness. I was a bit nervous of what new surprises may arise, but the only changes were definitely positive. Good, stable HV with no corona hissing and/or related screen anomalies.

I did use Electronic M's advice and paralleled a .47mfd cap across my meter leads measuring cathode current at the horizontal output tube. The readings were the same and unfortunately still a bit higher than I want, or Zenith wanted for that matter. The spec is 200mA and at line potential upward of 120VAC I get about 220mA. So I still run the set on my Select a Volt at about 110VAC and can maintain 200mA. Once an older tech said that they used to dip all the Zeniths at 210mA as a rule, but I feel that I should be able to achieve the spec. Now I do believe that the fly is now running much cooler for whatever reason. VERY happy there!

I probably just need to change out the HO coupling cap to get the 200mA. That should be next because for whatever reason I have to throw a bit more line voltage at the set before the color will come in. Once it comes in I can back it down. The color problem has been with the set since I brought it home. Actually, there was no color for a long time and I changed out the 6GH8 one day and had a DVD player hooked up and wa la. Great color!

For now though I'm just glad to have a playable set again. Many, many thanks to all for the help on this!
Have you tested all the tubes in the color section? If not I recommend doing so. My set had no color, then I tested the tubes in the color section, and found most were testing bad to very weak. After replacing all the color tubes that did not test decently the color section came back STRONG.
__________________
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
  #53  
Old 03-04-2015, 01:44 PM
old_coot88 old_coot88 is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 2,541
Quote:
...for whatever reason I have to throw a bit more line voltage at the set before the color will come in.
Are you familiar with the color killer adjustment?
To set it, you first turn the color control on full, and go to a snowy screen. There should be color speckling in the snow. If not, turn the color killer to the threshold point where color first appears in the snow, then back just a hair. That's the correct setting.

Of course this is assuming the tubes are all good.
Reply With Quote
  #54  
Old 03-04-2015, 06:18 PM
Zenith6S321's Avatar
Zenith6S321 Zenith6S321 is offline
VideoKarma Member
 
Join Date: Aug 2010
Location: Charleston, West Virginia
Posts: 303
Great hear you got the HV problem solved and the set operating again. Good tubes and caps can make for big improvements.

Dave
Reply With Quote
  #55  
Old 03-04-2015, 07:29 PM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
Quote:
Originally Posted by Electronic M View Post
Have you tested all the tubes in the color section? If not I recommend doing so. My set had no color, then I tested the tubes in the color section, and found most were testing bad to very weak. After replacing all the color tubes that did not test decently the color section came back STRONG.
I did test the tubes a long time ago on my Hickok 6000A. I think I will do it again on my new B & K Precision 747. Oddly, I get color when the set wants to and when I do it is beautiful. It always seems to happen when I use a DVD/VCR combo and run the line E up a bit. Coincidence perhaps.

Old_coot88 mentioned the color killer adjustment. I am guite familiar with that adjustment. Worked with it last night and got the snow and color fringing. I backed off till that went away, and then a little more as some fringing was still there. The idea which follows common procedure is to shoot for the perfect black and white picture which I can achieve pretty much. Once I get the color actually working regularly I will go through the whole purity and convergence procedures using my vintage RCA dot bar generator.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
Reply With Quote
Audiokarma
  #56  
Old 03-04-2015, 09:15 PM
old_coot88 old_coot88 is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 2,541
While chasing the intermittent-color problem, leave the color killer adjustment full 'on', all the way to the stop, while troubleshooting.

In fact, you could leave it full 'on' these days, since everything is broadcast in color. Whereas in the old days when some broadcasting was still in B&W, the color killer circuit served to turn off the chroma to prevent color artifacts in the BW image.
It works by sensing the presence or absence of the burst signal.
Today, that function is moot unless something is being transmitted in actual (burstless) BW.
Reply With Quote
  #57  
Old 03-05-2015, 12:40 AM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
So if I leave it (killer) on and when everything is as it should be, the snow will more or less go away. I had assumed that not to be the case and setting it too high would be about like setting AGC too high. I fully admit more or less being fairly new to troubleshooting vintage color television beyond that of normal static convergence and other setup procedures.

This is the only vintage color set in my ever smaller TV collection (due to space and sanity). My primary interests have always been in earlier black and white sets and radios. I have owned a number of round tube color sets back when they were available very cheap and made great daily use sets. So bringing one back from decades of dormancy is new to me.

Thank God for the incredible pool of great people and knowledge here at VK to pass along what I as an electronics professional consider a lost art in the field that will vanish if not somehow kept alive. These days there are 'techs' who can barely read a meter; and I mean DIGITAL! They could care less about Ohm's Law, Kirchoff's Law,etc. To avoid a rant I will end this now as I must or that is what it will become.
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"

Last edited by Tubejunke; 03-05-2015 at 08:49 PM.
Reply With Quote
  #58  
Old 03-05-2015, 11:47 AM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,762
Quote:
Originally Posted by Tubejunke View Post
So leave it on and when everything is as it should be the snow and fringing will more or less go away. I had assumed that not to be the case and setting it too high would be about like setting AGC too high. I fully admit more or less being fairly new to troubleshooting vintage color television beyond that of normal static convergence and other setup procedures.
The color killer has nothing to do with convergence. If the set has color fringing from imperfect convergence, the color killer will not make that go away even if cranked to the B/W only end. Use a test pattern to get the static (center) convergence perfect, then adjust the killer so that the perfectly converged portion of the screen (center) has no confetti (ie color snow), and ignore any fringing from mis-convergence elsewhere on the screen.
__________________
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
  #59  
Old 03-05-2015, 08:47 PM
Tubejunke's Avatar
Tubejunke Tubejunke is offline
VideoKarma Member
 
Join Date: Apr 2003
Location: Martinsville, VA
Posts: 1,823
Quote:
Originally Posted by Electronic M View Post
The color killer has nothing to do with convergence. If the set has color fringing from imperfect convergence, the color killer will not make that go away even if cranked to the B/W only end. Use a test pattern to get the static (center) convergence perfect, then adjust the killer so that the perfectly converged portion of the screen (center) has no confetti (ie color snow), and ignore any fringing from mis-convergence elsewhere on the screen.
Sorry, I need to watch my terminology a bit better and give more precise descriptions. I will edit my post a bit. I did realize that the fringing would be there either way as far as the color killer went. When I mentioned everything (at times) being as it "should be" I meant when the color actually has worked and worked well. The fringing I mention is due to myself or someone turning the convergence clover several degrees.

Shouldn't I do a purity setup before any convergence?
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free"
Reply With Quote
  #60  
Old 03-06-2015, 12:56 AM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,762
If the purity is good one can often adjust the convergence without having to mess with it.
__________________
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
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 01:28 AM.



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