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Hue (Tint) drift can be due to one of the many cost cutting experiments in the CTC-5 Super chassis. They used burst injection to lock the local oscillator, rather than a phase-locked loop (PLL) with a phase detector and reactance tube. A PLL (as used in the Deluxe chassis and all subsequent chassis) can drive the static phase offset near to zero if it has sufficient loop gain, but the injection locked oscillator is more at the mercy of the oscillator drift with temperature, depending on the "Q" of the circuit and the injection level. So, increasing the burst injection level may improve things.
Years later, Norm Parker at Motorola analyzed the requirements for an injection lock circuit to perform as well as a PLL, and it was successfully used in some Motorola designs. |
AGC was not set properly. Turned that up to max and the picture looks BEAUTIFUL. No more tint/hue drift. Looks almost like my CTC-7! :banana:
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The 3.58 MHz circuit on the CTC-5 looks a lot like the one in the GE Portacolor and some of the full sized GE color sets.
Increasing the AGC would most likely increase the burst which would help stabilize the 3.58 MHz oscillator. |
I noticed that on red colored objects there is a slight magenta glow on the border of the object not too noticeable but still a bit irritating. How do I adjust the flesh tones and get rid of that magenta glow that borders red objects?
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Here is a video of the set. https://www.youtube.com/watch?v=9W3kZNQPxbY
It looks a lot better in person since my camera isnt the best for recording. Cant seem to get decent lighting in the room either. |
Nice work dude. Glad you changed your avatar. The old one was frankly a bit off-putting and could make a person less inclined to wanna participate in the thread.
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I just watched the video on YouTube, that looks great, good job!
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And a BIG thanks to all for the help they provided in helping me get this beautiful set running! :yes: Glad I was able to do more by myself with this restoration unlike my CTC-7 restoration. I'm starting to get the hang of this stuff.
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Hey now, that is looking good!
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Very impressive. All you need now is a TV lamp facing the back walls, then you can turn the room lights off and enjoy that great picture. But it looks pretty darn good even in that bright room lighting. :thmbsp:
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Your TV looks great! Excellent picture for a set that was made sixty years ago (the CTC5 Westcott was made the year I was born).
I don't see a converter box or a VCR/DVD anywhere near the TV. Is that Bonanza episode off the air or cable? :scratch2: Keep up the good work. These old TVs deserve much better than to be sent to a landfill, and this one obviously won't be. |
Thanks a bunch everyone! To reply to jeffhs question, the set is receiving a wired signal from a BT modulator. I can get all the stations provided by my cable company. The modulator is hooked up to my cable box. To be honest, my CTC-5 is producing a better picture than my CTC-7! :D
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I figured as much, that you might have been using an RF modulator fed by a cable box. Do you have an in-house type of system similar to the one Kamakiri (Tim) in Buffalo uses for his antique TVs? Since Orlando only has three VHF network TV stations (not counting PBS, Fox, et al.), you wouldn't need that many modulators to build a good local distribution system. I think Tim only uses one and changes the input signal at the modulator, depending on what channel he wants to watch. The modulator's output is on channel 9 in his installation, but since Orlando has a local channel 9 any modulator you use would have to output to some other VHF channel.
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Yes I do have a home broadcasting system. With plenty of power to reach the whole house. I had it wired temporarily but now I get everything off the rabbit ears! I use only one modulator to do the job.
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Found the original house where this TV came from. Interestingly enough, the house was finished in 1956, the same year this set was manufactured. The set belonged to Mr. Vahram Bagian. Mr. Bagian passed in 1995. He must have been a pretty wealthy man to own this set back in 1956! http://www.realtor.com/realestateand...0_M48576-54870
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I have noticed that when I am watching the set and a picture with a lot of white light comes on the whole screen has a shade of green to it, once the white light goes away the green tint goes away. I remember reading that the 21AXP22's phosphors gave everything a greenish tint. Is this the same with the A version? Or is this occurrence circuit related?
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Sounds like the green screen is up too high, or you need to turn down the brightness.
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This effect has to be electrical, not the phosphors.
I have never heard of the phosphors giving everything a greenish tint. However, the usual white balance for sets for decades was on the cyan side ("9300K + 27 MPCD") due to the dimness of the red phosphor and a desire not to overdrive the red gun too much. (This was not true of the very earliest sets such as the CT-100, as they were supposed to be set to illuminant C [daylight white] even though this meant pushing the red gun extremely hard compared to the green and blue.) By the way, I suspect that CT-100 as used in the home varied greatly, as servicemen had no instruments to tell them when they had achieved the correct white balance. Grayscale tracking (whites and grays being the same color) is much easier to judge by eye than the actual color of those whites and grays. |
Your greenish tint is definitely electrical in nature. That said, the earliest 21AXP22s, when not in use, do have an ever so slight green tint, just like a 15GP22, 15HP22, or 19VP22. Perhaps it was discussion of the appearance of the tubes when not in use that SwizzyMan was reading?
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I am currently solving a horizontal issue with this set. I have since fixed this but it seems the tuner and IF circuits have gone out of whack. Ive tried all adjustments and tubes. What I would like to do since this TV will soon be in a cabin in Minnesota where over the air and cable is hard to find is to see if it is simple to inject a composite signal into the video and sound amp to bypass the tuner and IF. Is this possible by just connecting a direct video source or will I have to build a preamp for this set too?
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I have the same problem with my CTC5. The emission on the 21AXP22A is okay. Advancing the brightness affects grey scale. At lower brightness the greyscale is not bad.
The root problem may be the design of the final luma stage. Compared with the CTC7 upward, the anode current at the quiescent point of the CTC5 appears too high at cart cutoff. I earlier was investigating means reducing anode current quiescent point by shifting the CRT cutoff point. I looked at this a couple of years ago and put it aside. Now that I know the problem isn't unique to my CTC5, I am going to revisit this. I would be curious if any of you have thoughts on this. I haven't substituted the 21AXP22A and am wondering despite the emission being okay that perhaps the guns aren't tracking properly? |
I recommend modifying the CTC-5 video output stage to the CTC-7 configuration.
http://www.videokarma.org/showthread...ication&page=2 |
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I ended up modifying the cathode circuit on the 12BY7 because of the blooming problem. But the green cast at high brightness remained. I think there is more to do because to drive the CRT to conduct, the 12BY7 current remains too high. If I recall correctly, the 12BY7 control grid bias needs to increase (greater minus). Comparing the CTC5 to the CTC7 or CTC9 should reveal the difference. |
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After about 1 hour I lose horizontal sync... which I thought I fixed. After checking back on the horizontal board, I found I did not replace one cap (C606?). Tracing everything in front of it makes it seem like it is a very critical cap. Perhaps the cap drifts as it gets warmer considering its proximity to the 6CG7? Does this seem like a critical cap to you guys? By the way it is the only original component left on the board besides the waveform coil.
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Yes, critical - determines horizontal frequency in combination with the coil (cut off at the top of your image). Replace with the same type / temperature coefficient.
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Here are some obligatory Oz shots from the 5 before I lost sync. Not pleased with how the camera made these out, but it gives you an idea. Picture is not as bright, but a lot more crisp and clear than displayed on camera. This is taken with a composite video signal injected into the video amp. Not too shabby. :yes:
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It looks like your camera didn't focus exactly on the screen. Other than that, the pictures are great. You've got better vertical linearity on yours than I have on mine.
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Great, could be focused better.
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Color level looks a bit high. When skin tones start to glow, look neon, look tan when their not I know to back down the color level a bit. Great picture aside from that.
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I remember a few customers back in the day who deliberately ran the color wide open. Their attitude was "I'm paying for a color set, so I want all the color it'll make." :headscrat
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I used to roll the vertical hold till the customer told me which picture looked the best. LOL
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Ok NOW the horizontal is fixed. I fooled with the camera setting a bit and was able to get a darker picture and cant get the camera to focus correctly, but still...the picture is so much better in person. Thanks to Phil Nelson for the A/V input box idea! This TV is ready to move up north.
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There have been these faint vertical lines all across the screen and I have been trying to just ignore it but it is driving me nuts. It goes away when the chroma is turned off so it has to be chroma related interference. Anyone know what these are and how I get rid of them?
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