#61
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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 |
#62
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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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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#63
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How can the wrong yoke cause no color. An incorrect yoke would definitely affect convergence.
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Just look at those channels whiz on by. - Fred Sanford |
#64
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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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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 |
#65
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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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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
Audiokarma |
#66
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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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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 |
#67
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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
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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 |
#69
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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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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#70
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Have you tried resistance measurements? The Photofact has them.
I can email you the Sams if needed. |
Audiokarma |
#71
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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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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 |
#72
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Quote:
N2LCJ@yahoo.com
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"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#73
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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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"When resistors increase in value, they're worthless" -Dave G |
#74
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Photofact
On the way.
6 meg file. Good luck. |
#75
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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.....
__________________
"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
Audiokarma |
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