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  #61  
Old 05-11-2018, 10:53 AM
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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?
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  #62  
Old 05-11-2018, 10:50 PM
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Quote:
Originally Posted by old_tv_nut View Post
Two questions:

Do you invite people to see your Rembrandt?


What is the lighted object on the wall to the left of the clock?

Wow, you spotted the Rembrandt!

Object next to clock can be identified here
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  #63  
Old 05-11-2018, 11:13 PM
Chip Chester Chip Chester is offline
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It's not really beer unless it ends with a "Z".
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  #64  
Old 05-12-2018, 12:55 AM
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Quote:
Originally Posted by dtvmcdonald View Post
What we all want to see, or at least I want to see, before I start crying
in my coffee for not bidding, is a raster only, two guns cut off, that has
good purity. I have a theory that might make it possible.
Ask and ye shall eventually sort of receive...Video is still wacky which makes getting a bright plain raster tricky, and getting a pattern to attempt static convergence a downright pain in the but. It would seem the initial recap left several of those lousy chalk peaking coils, and sloppily j-hooked in many of the new caps...I'm glad it is pre-recapped, but some of the workmanship, to put it kindly, is not how I would have done it. Soon I hope to bench it and go over the video circuits. Purity and convergence pics shown below represent my first attempt on a 15GP22 based set. It is a completely different process from every CRT type that followed. Most of the time I felt like I had been dropped in Brittan and asked to drive one of their backward cars on one of their backward roads. Static convergence was off by a mile when I did the purity so if it is anything like a later set then that will affect the purity, and I'm probably going to have to go back and forth between static convergence and purity a few times before it is right (only did purity once followed by one round of convergence). Static convergence is REALLY weird on this set there is the side knob (which gave me a choice of how wrong I wanted it at first) then the static magnets are similar but different from later CRTs...Specifically, there is only blue lateral action from the magnet and the DC convergence knob on the HV cage needs to be used in conjunction (and it affects all three guns)...In summary purity and convergence are sort of decent, but not perfect.



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.
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  #65  
Old 05-12-2018, 09:06 AM
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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.
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  #66  
Old 05-12-2018, 09:25 AM
EdKozk2 EdKozk2 is offline
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Hi Tom,
Great to see all three guns working on your CT-100.
Ed
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  #67  
Old 05-12-2018, 09:47 AM
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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  
Old 05-12-2018, 11:55 AM
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Quote:
Originally Posted by Electronic M View Post
Ask and ye shall eventually sort of receive...Video is still wacky which makes getting a bright plain raster tricky, and getting a pattern to attempt static convergence a downright pain in the but. It would seem the initial recap left several of those lousy chalk peaking coils, and sloppily j-hooked in many of the new caps...I'm glad it is pre-recapped, but some of the workmanship, to put it kindly, is not how I would have done it. Soon I hope to bench it and go over the video circuits. Purity and convergence pics shown below represent my first attempt on a 15GP22 based set. It is a completely different process from every CRT type that followed. Most of the time I felt like I had been dropped in Brittan and asked to drive one of their backward cars on one of their backward roads. Static convergence was off by a mile when I did the purity so if it is anything like a later set then that will affect the purity, and I'm probably going to have to go back and forth between static convergence and purity a few times before it is right (only did purity once followed by one round of convergence). Static convergence is REALLY weird on this set there is the side knob (which gave me a choice of how wrong I wanted it at first) then the static magnets are similar but different from later CRTs...Specifically, there is only blue lateral action from the magnet and the DC convergence knob on the HV cage needs to be used in conjunction (and it affects all three guns)...In summary purity and convergence are sort of decent, but not perfect.



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,

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
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  #69  
Old 05-12-2018, 01:13 PM
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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.
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  #70  
Old 05-12-2018, 02:58 PM
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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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  #71  
Old 05-12-2018, 03:23 PM
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Quote:
Originally Posted by benman94 View Post
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.
That, in a nutshell, is why I did not bid either of the 21" sets to my limit. I brought all the equipment I needed to vet all CRTs in the sets there, and the ~1-2 hours I had before the auction got eaten by swapmeet so I never had the chance to see for myself if the claims of good and bad CRTs were accurate. I've seen enough bad tubes called good and enough good tubes pronounced dead that I don't like to take others' word on things unless I'm letting go of a small enough sum, or getting enough out of the rest of the set to not care if the CRT is good. I've had several people get but hurt over my not taking their word on CRT condition, but if I'm shelling out a C-note or more and the rest of the set is not worth far enough over the purchase price to make up for a dead CRT then I feel it is only fair to allow the buyer to check the CRT for themselves first...And I'd encourage any buyers of my sets to do so if they feel the need.
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  #72  
Old 05-13-2018, 01:14 AM
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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.
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  #73  
Old 05-13-2018, 08:37 AM
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dtvmcdonald dtvmcdonald is offline
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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.
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  #74  
Old 05-13-2018, 05:26 PM
EdKozk2 EdKozk2 is offline
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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
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  #75  
Old 05-13-2018, 05:56 PM
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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.
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