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  #61  
Old 01-10-2015, 02:31 PM
zeno zeno is offline
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May sound dumb but is the conv board plugged in ?
It looks so far off that it may not be. Try the center
convergence first & ignore the sides. Then do the sides.
Conv board troubles are almost always broken coils, diode
packs or cooked pots. Only other thing I ever saw was a
few open coils on the clover & cold joints on PCB
built ones.

As far as the no color goes make the set as good a B&W
you can first ! Then deal with the color.

Testing tubes dont always work. No tester will take a 6KT8
and make it oscillate at 3.58 mhz ! It can test good for
emission & shorts but not oscillate..........

keep up the good work.

73 Zeno
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  #62  
Old 04-18-2015, 06:51 AM
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Kamakiri Kamakiri is offline
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Got frustrated with this set, and since I now have the CTC-5 and 12, I passed it on to a local friend of mine who is nothing short of a genius with these sets.

It was the wrong damn yoke. That's why it had no color. No wonder.
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  #63  
Old 04-18-2015, 08:49 AM
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Quote:
Originally Posted by Kamakiri View Post
Got frustrated with this set, and since I now have the CTC-5 and 12, I passed it on to a local friend of mine who is nothing short of a genius with these sets.

It was the wrong damn yoke. That's why it had no color. No wonder.
How can the wrong yoke cause no color. An incorrect yoke would definitely affect convergence.
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  #64  
Old 04-18-2015, 12:27 PM
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The color killer/burst gate gets a pulse off of the fly which tells it when to look for the color synch burst. If that pulse is mistimed or otherwise screwed up from a disturbance in the horizontal system those key color circuits will not work correctly.
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  #65  
Old 12-08-2017, 02:27 PM
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So guess what's back?

And have a few issues. Again

First off, the set was working great, and I decided to get it back. Got it home, plugged it in, full raster, but no picture. Saw a wisp of smoke from the tuner

Replaced the tuner. Everything worked, but the picture was HUGELY vertically stretched and no color.

Turns out that the last owner who I got it back from who shall remain nameless yanked out the oscillator (6KT8) to stick in another set, and since the tube was buried I didn't know it was missing.



So now, everything seems okay, but I have vertical foldover at the bottom and to be honest, I'm not sure where to even go with this. I no longer have a schematic for it.....hopefully someone's got the Sams that can point me in some direction.

All tubes are checked, and the set's practically brand new with all the stuff that I've done to it......
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  #66  
Old 12-08-2017, 02:53 PM
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Probably no sams, but I should have the Zenith issued schematic. I'll check tonight and post pics if I have it.
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  #67  
Old 12-08-2017, 03:21 PM
6GH8cowboy 6GH8cowboy is offline
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Don't have a schematic to look at but I offer this just as a FYI. I had a RCA with a issue like this. ( fold-over and poor range) The Vert height control was fed with B+ on one end and B boost sourced on the other end. The control was open at one end. It appeared to "work" but, the control was open end to end. A replacement did the trick. Good luck
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  #68  
Old 12-08-2017, 08:57 PM
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Found the schematic.




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  #69  
Old 12-09-2017, 07:41 PM
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Can you get one more shot with the circuitry surrounding V22 and showing where it leads on both ends? That's the tube that was missing.

I assume there's no test voltages listed.......
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  #70  
Old 12-09-2017, 11:04 PM
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reeferman reeferman is offline
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Have you tried resistance measurements? The Photofact has them.
I can email you the Sams if needed.
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  #71  
Old 12-10-2017, 11:52 AM
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If you look closely there are DC bias voltages on the important elements of most tubes right on the posted schematic.

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  #72  
Old 12-11-2017, 11:01 AM
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Quote:
Originally Posted by reeferman View Post
Have you tried resistance measurements? The Photofact has them.
I can email you the Sams if needed.
That would be great!! I'm more used to using the Sams publications

N2LCJ@yahoo.com
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  #73  
Old 12-11-2017, 11:17 AM
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On the vertical issue; Nov 1962 PF reporter special color TV issue noted that thermistor was added starting with the 27KC20 chassis, to compensate for size variation during warm up.

Color: Id check all those peaking coils, and maybe Robert L. Goodman noted this chassis issue in the TAB color manual for Zenith.
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  #74  
Old 12-11-2017, 02:13 PM
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reeferman reeferman is offline
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Photofact

On the way.
6 meg file.
Good luck.
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  #75  
Old 12-17-2017, 06:20 PM
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After whining and bitching and bitching and whining that I didn't want to get into trying to diagnose it any further (what after all this crap over the years), I got the Sams from reeferman and traced the entire vertical circuit. Tested every component. Nothing.

Then I tested the vertical lin pot, and bingo.....seems that there's something broken off inside that with a gentle movement of the wire, makes the reading go from 1K to about 50 ohms. So that's next.....
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