#61
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Two questions:
Do you invite people to see your Rembrandt? What is the lighted object on the wall to the left of the clock? |
#62
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Quote:
Wow, you spotted the Rembrandt! Object next to clock can be identified here |
#63
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It's not really beer unless it ends with a "Z".
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#64
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Quote:
I'll probably be able to improve it more in the future. For now, I plan to focus on the video circuits...The lumina channel will pass very weak video with the chroma off, but not nearly as much as it should, with chroma up it will get VERY bright but it seems like the color demod is not working correctly...Looking at the clock I should probably sleep and worry about it tomorrow.
__________________
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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Experienced techs would have been skeptical of the description of this auction item as "two good guns + one no emission" doesn't add up as typical failure/aging. So definitely worth gambling on this item.
As far as vacuum goes, this is another miracle survivor of RCA's ridiculous glass-tin-glass picture tube. Note to RCA: If Lawrence & CBS can make all-glass color tubes, so should you with your unlimited budgets. |
Audiokarma |
#66
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Hi Tom,
Great to see all three guns working on your CT-100. Ed |
#67
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Wow, next time I want to shake your hand to see if any of this luck rubs off! Congrats on making past the big "if" of a good tube!
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#68
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Quote:
That's my old CT-100, well, kind of. The CRT in it is a different one but the chassis and cabinet are the same. The chassis was sold to me as having been restored and my reaction to the work on the chassis was the same as yours. It was making inadequate HV when I bought it, and was frankly, a complete trainwreck. If I had known how poor the previous "restoration" was, I'd have run screaming in the opposite direction. In addition, every single IF transformer and adjustable coil in that set had been screwed with. I focused on alignment and let the caps go for the time being. I got it to the point where I could get some semblance of a signal through the IF strip and finally got frustrated, shoved the chassis back in the cabinet, and eventually sold it to John. I never did any of the recapping. Given my experience with recapping from this individual in my 630TCS, every single capacitor will need to be checked to ensure it was installed correctly. IIRC, there were also some originals tucked up in there somewhere... I'm not sure if John did any work with it or not. I'm inclined to believe the chassis is exactly as it was left when I had it. I was able to get good strong audio and decent looking luma through it around the time I gave up on it; I watched an entire episode of the Honeymooners on it and it OK looking. Marginal, but watchable. It will need another check of the alignment. I can guarantee it is still fairly far from usable. As far as I know, the chroma sections on that set never worked post-"restoration". Best of luck, as you'll need it. -Ben |
#69
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Thanks, everyone. Ben thank you for giving me some backstory on it. It seems the HV is around 19KV according to my backup HV meter (I still have not gotten to replacing my main meter since it broke). I built a good video injection amp for the CTC-2 family a few months ago so I plan to ignore the IF system completely until the video and chroma are working properly...Even then I probably will need to learn alignment on something else first. The look I had under the chassis was a 2min low light search for peaking coils and rough sizing up of the work on it. I'm sure the pending full exam is going to be interesting.
__________________
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 |
#70
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This is the second time in 12 months that I know of that a 15GP22 has been falsely accused of being a dud. This is why anything I'm interested in gets tested with my modified Beltron. Always test a tube with a tester you're comfortable with and trust, to do otherwise could be an extremely expensive mistake.
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Audiokarma |
#71
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Quote:
__________________
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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Success and failure: the tale of two coils
The luminance deficiency was the most obvious culprit. The original white peaking coil on the contrast control above chassis had opened...I took the longest, but the most educational approach to finding it: comparing video at various points between my CT-100 and 21CT55 on a scope...I could have saved myself a half hour by following my hunch and putting a DMM on it, but the scope was more fun.
That got me a monochrome picture with all the contrast and brightness I could ask for...Turning up the color got me horizontal chroma stripes. Best yet color was actually synching periodically. This is the only pic I got. I had it making a great picture on a different source when it would occasionally sync. Then I tried to adjust L43 (RCA part 78891) the reactance coil to make the sync permanent. It was sticky but came loose...Unfortunately, it was not the slug that came loose but the coil form and with it the wires that connected it to the terminals. leaving me with the osc. way off sync but still working. Once I realized what happened I removed the coil and tried to free the slug. Sadly the cardboard form was too brittle, and also ~1/8" of the very long slug chipped off...I managed to grab a similar form and rewind the wire, but it will not oscillate with my repair...I'm kind of up a creek presently. Only thing I can think of is a CT-100 parts chassis....Or there is a very slim chance that coil may have been used in a 15" Dumont color monitor carcass I acquired recently. The Dumont is missing CRT/deflection hardware, flyback, and other things, but it seems to be CT-100 based. The Dumont's HV cage (what is left of it) appears to be exactly the same as that in a CT-100 as do the purity and field neutralizer coil connectors...If I'm lucky it uses the same reactance coil too...But then again I would like to make the Dumont work again someday and hacking it up for parts does not sit well with me. After brief success, I'm back to monochrome again.
__________________
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 |
#73
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Well, I'm now crying! That price for a good 15GP22!
You'll eventually get the oscillator to oscillate again. Coils at 3.58 MHz can be rewound, you;ll eventually succeed. There are parts chassis around. That color bar picture looks exactly like the one I first got on my set. Good luck getting the red and magenta balancing well with the other colors. Beware of AGC setting and color level on the modulator. |
#74
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Hi Tom,
I was thinking of any easy way for you to fix or replace your broken L43 coil. You could use an old 4.5mc sound coil. You would have to add some more capacitance in the tank circuit. Increase the 5pf to get a center frequency of 3.58Mhz. If you have an inductance meter, maybe you can measure your broken coil if it is still intact. Ed |
#75
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Using a coil that resonates with a different size cap may work, but it's not the best idea because it will change the strength of the effect of the AFC circuit and therefore affect the stability of the pull-in as temperature changes, etc.
Better to get the right inductance and capacitance. |
Audiokarma |
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