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  #46  
Old 04-05-2017, 04:19 AM
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Tubejunke Tubejunke is offline
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The metal control panel door definitely isn't as tough as they made the chassis and such. I wish I knew where to get a better one. Those screen shots look good. Did you have to do dynamic convergence work? Hope I didn't miss the answer to that in this thread. Just curious as mine needs it. I can live without it, but the Zenith's make such a nice picture, it a shame to go without.
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  #47  
Old 04-05-2017, 08:40 AM
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Quote:
Originally Posted by Tubejunke View Post
The metal control panel door definitely isn't as tough as they made the chassis and such. I wish I knew where to get a better one. Those screen shots look good. Did you have to do dynamic convergence work? Hope I didn't miss the answer to that in this thread. Just curious as mine needs it. I can live without it, but the Zenith's make such a nice picture, it a shame to go without.
Got a test pattern gen, hex diddle stick, and a chassis #? You'll need a gen with cross hatch to do it, and a diddle stick. I've got some Zenith issued color service manuals....It would be a trivial matter for me to post pics of the convergence procedure documentation for your chassis (or the closest one I have lit for).

Most deltagun sets have the same convergence procedure and some makes/models were kind enough to essentially number controls to walk you through the procedure.
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  #48  
Old 04-05-2017, 09:13 AM
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Quote:
Originally Posted by Tubejunke View Post
The metal control panel door definitely isn't as tough as they made the chassis and such. I wish I knew where to get a better one. Those screen shots look good. Did you have to do dynamic convergence work? Hope I didn't miss the answer to that in this thread. Just curious as mine needs it. I can live without it, but the Zenith's make such a nice picture, it a shame to go without.
I haven't done anything yet except replace three tubes. Guess I got lucky New caps should arrive today.
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  #49  
Old 04-06-2017, 10:48 AM
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New caps from Digi-Key have arrived and they were very well packed.
I went with them because they have a decent selection of 500v caps. I wanted them to replace the six original 475v rated caps.

All the caps are rated for 105C and long life. The two caps in the B+ voltage doubler are also rated for high ripple current.






The main B+ runs at 330 with a voltage divider tapped for 235 and 120 - all well below 475.
Then it occurred to me it uses a solid state rectifier so B+ will be available instantly while the tubes are still warming up.
I expect B+ runs fairly high until the tubes start conducting.


Two of the caps are 4uF and the only 500V+ ones at Digi-key below 10uF are surface mount.
10uF would probably work just fine but I decided to give these 3.9uF SMDs a shot. I think it'll be easy to solder on extension wires.

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Last edited by bandersen; 04-06-2017 at 10:53 AM.
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  #50  
Old 04-06-2017, 10:57 AM
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I'm a little wary of pulling the chassis, but it needs to be done. The width slowly grows about 20% over 15 minutes from a cold power up, controls are dirty and some HV arcing persists. A recap, cleaning and new tubes should improve things.
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  #51  
Old 04-08-2017, 06:30 AM
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If cleaning does not cure the arcing problem, You may have to replace all of the hi voltage wires in the cage. Inc the wire to the crt anode. Had to do this to two of my Zenith color set's. The color circuits are working good so, DO NOT touch the coils in the color circuit. They get brittle from heat and will break if the core is turned to adjust. Another problem is you may see some slight bars in the picture on a black screen. I was not able to track down that problem. Not that noticeable, And most people would not even see them.
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  #52  
Old 04-08-2017, 09:13 AM
jstout66 jstout66 is offline
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the set used mylar caps, so why are you doing a full re-cap? Slow width is a weak horizontal output tube.
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  #53  
Old 04-08-2017, 09:43 AM
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the set used mylar caps, so why are you doing a full re-cap? Slow width is a weak horizontal output tube.
He's right you know... the HO tube is just getting tired.
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  #54  
Old 04-08-2017, 11:25 AM
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I was thinking it was electrolytic slowly forming up. I can check that by monitoring the B+. Wasn't planning on replacing all the caps - just the stripped bumblebees looking ones. Are you sure all the caps are mylar?
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  #55  
Old 04-08-2017, 12:37 PM
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I tend to change the bees and the tubular white ceramic cased ones...I've found bad or dying ones in sets of this vintage so if I'm in there for something I tend to change those.
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  #56  
Old 04-09-2017, 09:58 AM
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Be watchful of those surface mount caps. Mitsubishi sets used them everywhere and the capacitor plaque was terrible. Just watch for goo coming out after a while.
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  #57  
Old 04-09-2017, 05:27 PM
jstout66 jstout66 is offline
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For the most part, what Tom said.
Most are Mylar tho. It's not like the older sets you're used to where you have to change ALL of those horrid wax caps. Sets from about 1963 on up are pretty stable. You won't have to worry about capacitor plague. That was mainly a "Jap" set thing.....
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  #58  
Old 04-11-2017, 05:04 AM
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Quote:
Originally Posted by Electronic M View Post
Got a test pattern gen, hex diddle stick, and a chassis #? You'll need a gen with cross hatch to do it, and a diddle stick. I've got some Zenith issued color service manuals....It would be a trivial matter for me to post pics of the convergence procedure documentation for your chassis (or the closest one I have lit for).

Most deltagun sets have the same convergence procedure and some makes/models were kind enough to essentially number controls to walk you through the procedure.
I do in fact have an old RCA dot bar generator and a diddle stick. I would need to check the stability of the generator as I seem to remember it being a bit persnickety last I used it. Someone rigged the end of the input with a bunch of resistors in a haphazard way for some reason. Anyway, yes I would like to do that. I think I have the Sam's folder in .pdf for the set. Sorry, it's just been sitting for a few years waiting for the "significant" to vacate.
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  #59  
Old 04-24-2017, 11:32 AM
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"Another problem is you may see some slight bars in the picture on a black screen. I was not able to track down that problem. Not that noticeable, And most people would not even see them."

I've always noticed them too, quite common on roundie Zeniths. About three light/transparent vertical bars, no foldover, just there!
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  #60  
Old 04-25-2017, 11:13 AM
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Quote:
Originally Posted by marty59 View Post
"Another problem is you may see some slight bars in the picture on a black screen. I was not able to track down that problem. Not that noticeable, And most people would not even see them."

I've always noticed them too, quite common on roundie Zeniths. About three light/transparent vertical bars, no foldover, just there!
Interesting you mention that. Mine has them too. They are not a problem, but just there.
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