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
  #61  
Old 10-13-2014, 02:41 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
Haven't had much time to work on it. The anode lead is about 6 inches to short to make it to the other side of the CRT.

As near as I can tell, there's no resistor in series with the anode lead or in parallel with the 1B3 rectifier tube filament.

When I find time, I'll try to run a new anode lead. The only way to get at that area is to take the HV box off which is not so easy since the flyback is mounted to it.

__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #62  
Old 10-14-2014, 02:41 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
Here it is stripped down.


I get about 0.1 ohms from the anode cap the the rectifier base, but I'll try replacing the lead anyway.

Flyback close up. The shiny goo around the HV lead is some RTV133 I applied to reduce the odds of it snapping off.


HV rectifier area looks clean. I'll try using a solid state rectifier as suggested.
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery

Last edited by bandersen; 10-14-2014 at 02:51 PM.
Reply With Quote
  #63  
Old 11-14-2014, 04:54 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
I recently won a little assortment of vintage TV parts on ebay and it including this air core flyback. The part # is different but it sure looks like the one in the Capehart and it ohms out very close as well. Might as well give it a try.

__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #64  
Old 11-15-2014, 08:56 AM
kvflyer kvflyer is offline
VideoKarma Member
 
Join Date: Nov 2006
Location: Fernandina Beach, FL
Posts: 1,057
[QUOTE=bandersen;3119451]I recently won a little assortment of vintage TV parts on ebay and it including this air core flyback. The part # is different but it sure looks like the one in the Capehart and it ohms out very close as well. Might as well give it a try.

Bob, you certainly have nothing to loose and a lot to gain! Good on 'ya, Mate!
Reply With Quote
  #65  
Old 11-15-2014, 02:25 PM
Kevin Kuehn's Avatar
Kevin Kuehn Kevin Kuehn is offline
Workin' Late Again
 
Join Date: Jan 2011
Location: WI
Posts: 3,824
I think I'd have me a peek under that electrical tape before applying power.
Reply With Quote
Audiokarma
  #66  
Old 11-15-2014, 10:45 PM
StellarTV's Avatar
StellarTV StellarTV is offline
VideoKarma Member
 
Join Date: Jan 2007
Location: Sacramento, CA
Posts: 503
Nothing wrong with using a temporary alligator clip jumper lead to lengthen that second anode wire. I've never had the HV arc through the insulation to the dag, chassis, or wherever else it may be contacting or draped, even with cheapies.
Reply With Quote
  #67  
Old 11-16-2014, 01:47 AM
NoPegs's Avatar
NoPegs NoPegs is offline
The glass is -3dB.
 
Join Date: Mar 2014
Location: Amish Country PA.
Posts: 376
Quote:
Originally Posted by Kevin Kuehn View Post
I think I'd have me a peek under that electrical tape before applying power.
I'd be more scared to risk removing it absent any other justifiable reasons for investigating underneath. Obviously I'd spend a good few minutes going over the whole thing with all the bright bench lights on and with my mag-visor for signs of trouble.
Reply With Quote
  #68  
Old 11-16-2014, 09:45 AM
Reece's Avatar
Reece Reece is offline
VideoKarma Member
 
Join Date: Jul 2004
Location: Cleona, PA
Posts: 2,178
I don't like those wafer-type sockets, especially on high voltage. They can have secret interwafer problems. It would be a valuable adventure to change them to good new molded ones, even ceramic ones if you're paranoid like me.
__________________
Reece

Perfection is hard to reach with a screwdriver.
Reply With Quote
  #69  
Old 02-15-2015, 05:11 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
I finally got back to working on this chassis

The ceramic HV cap on the damper tube has been replaced and a new HV anode lead installed.





I also installed a genuine Farnsworth 160AR CRT I stumbled across on craigslist.

It had no trace of any external coating but I did fine a ground spring on the chassis so it probably should have one. I went with a temporary one made from aluminum foil and tape
If I get it working, I'll coat it with some Slip Plate.






The old hardened tape was replaced wit some cloth tape.


While I had the brackets off, I finally found the chassis revision number - C-281.


TIme to fire it up again.
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #70  
Old 02-15-2015, 05:16 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
HV is around 10kV. I'd rather see 11 or 12, but should be plenty to produce an image.

Sure enough after a lot of fiddling with the trap magnet, I got a raster.

I get occasional arcing. I think it's my temporary aluminum dag isn't making good ground contact.


I'm gonna let it run a while and see if any problems crop up. If not, I'll give that CRT a proper coating
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
Audiokarma
  #71  
Old 02-15-2015, 06:14 PM
NoPegs's Avatar
NoPegs NoPegs is offline
The glass is -3dB.
 
Join Date: Mar 2014
Location: Amish Country PA.
Posts: 376
Quote:
Originally Posted by bandersen View Post
HV is around 10kV. I'd rather see 11 or 12, but should be plenty to produce an image.
Sooooooo, are we listing the HV lead as the culprit? Glad to see that you climbed right back up on this horse and got rewarded with some success.
Reply With Quote
  #72  
Old 02-15-2015, 07:57 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 bandersen View Post
TIme to fire it up again.
Did you connect that HV lead before the power up, or was there a brief lightning show before you noticed?
__________________
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
  #73  
Old 02-15-2015, 10:00 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
Quote:
Originally Posted by NoPegs View Post
Sooooooo, are we listing the HV lead as the culprit? Glad to see that you climbed right back up on this horse and got rewarded with some success.
No, unfortunately replacing the HV lead had no effect. The HV is still about 20% low and for a while it dropped down to only 5 kV. Still not sure what the problem is. Also, I just discovered the sporadic arcing is actually inside the electron gun. Maybe there's a loose bit of metal ?

Quote:
Originally Posted by Electronic M View Post
Did you connect that HV lead before the power up, or was there a brief lightning show before you noticed?
Yes, I did remember to connect it up
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #74  
Old 02-18-2015, 03:40 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
My Sencore CR70 has the meter right at the edge of bad in the HK short position. It typically arcs once or twice on power up the settles down.

I went through the centering and linearity adjustments and it's looking pretty good.
I'll install an isolation type CRT booster if I can find one


Meanwhile, I decided to go ahead and coat it with Slip Plate. I'm quite happy with the results
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #75  
Old 02-23-2015, 12:51 PM
bandersen's Avatar
bandersen bandersen is offline
RCA 741PCS
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 8,085
Installed the recoated CRT and did all the ion trap, focus coil linearity etc adjustments again. It's playing well but still get the occasional arc in the CRT on power up. Will try an isolation type booster when it arrives in a couple days.

Meanwhile, the picture isn't quite as sharp as I think it could be so I'll try a video IF alignment. It used a staggered tuner IF and it's a an easy procedure. Feed an RF signal into the mixer tube shield an peak each coil to the specified frequency frequency.


__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery

Last edited by bandersen; 02-23-2015 at 12:59 PM.
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 01:33 PM.



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