#46
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Quote:
jr |
#47
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My CT-100 has just the knurled shafts, and this diagram seems to show them without knobs.
Regards, Phil Nelson Phil's Old Radios http://antiqueradio.org/index.html |
#48
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Well, Steve then must have been right ... it was all there.
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#49
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I'm watching the Bear's game on the CT100.
From 4 feet away. Other than the screen size, I don't see the complaints people made in 1954. There is simply nothing wrong with the picture, even brightness. Is it that Videokarmites are more picky about adjustments? |
#50
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The CT-100 can make an awfully nice picture. It's also complex and it requires careful setup. I wasn't watching color TV in 1954, but I wonder if many of those complaints were due to plain old misadjustment -- either because Grandpa started fiddling with controls or because the TV was never set up perfectly in the first place.
It looks like your CT-100 is dialed in very nicely, in any case. Impressive. Regards, Phil Nelson Phil's Old Radios http://antiqueradio.org/index.html |
Audiokarma |
#51
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As bad as it sounds, I wonder if early complaints about color TV were just a variation of "flashing 12:00 syndrome"-people having one too many adjustments to handle and then losing everything as a result?
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#52
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There's a story of when Zenith engineers were shown the chassis, one of them commenting "Twenty-seven controls, each one making it worse!"
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#53
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The set was working great on program material and most
test signals from the Digital Video Essentials DVD, and my own test patterns, but not the horizontal and vertical color bars and the red and magenta full 100% screens from the DVE DVD. The bars showed incorrect luma for different bars and color changes vertically across the horizontal bars. This was traced after a VERY long session with a scope (and the chassis in the set) looking at test points at the grids of the first video amp, I and Q demodulators (removed from sockets), and the three CRT grids. The luma problem was a very slight misalignment of the RF which I had simply not done (fixed), and the other is (not fixed) a great sensitivity to the horizontal hold when there is a saturated color right at the start of a lot of horiziontal lines. Its got to be just right so the burst sync timing is just right. This does not usually matter. The waveform when I was aligning the burst stripper looked OK but not great. I will have to study the circuit a lot before removing the chassis, which I will have to do anyway to insert a UHF strip. I was worried about signal overload, but tests show the set works OK over a 66dB range from extreme noise and barely syncing up to the normal power of my Blonder-Tongue modulator (which is set well below max). At high powers one sees a few percent of nonlinearities, not visible on pictures. |
#54
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"27 adjustments and every one makes it worse". That's
a quote I read in an earlier thread, attributed to a Zenith guy. Was it a complaint or a compliment? Did he mean 27 was too many or that somebody had all of them perfect so that any change made it worse? I see what he means though ... 27 is a lot. But I count exactly 69, counting only one channel in the tuner. I adjusted the last one today, the I-Q phase difference for the two synchronous detectors. This make the red and green waveforms perfect and the blue within a 10% resistor tolerance. Yellow is now yellow. I'm theoretically done! The only thing left is to get Ch. 39 working and replace a temporary resistor mess in the power supply. |
#55
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Oh! 69 is only the chassis. If you count all the tilts and pushes and
magnets on the CRT neck its 80. Add CRT rotation itself and its 81. |
Audiokarma |
#56
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81 adjustments! You are making me think I should charge more, if I ever make a business out of restoring early color TV sets.
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#57
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Charge by the hour!
Of course, the vast majority, once done, will last a long time. If the remaining white peaking coils go, I don't think new ones will change alignment. Not to mention that this was a great learning experience for me ... I'd never done a color TV setup since the late 60s, and those were Heathkits. Doing it again would be faster, but not easier. For a restoration you don't know whether a problem is a bad part or adjustment until it is completely fixed, and there are wrong leads ... like the modulator adjustment below. But the symptoms it caused were also in part caused by wrong IF and RF alignment. Two different problems, each of which required the same two different fixes. I found another adjustment that needed fixing for "blown whites", wrong gamma of luma as color came near saturation, and what looked like poor DC restoration, but it was not on the TV, it was the video level on my Blonder-Tongue BAVM modulators. If set for auto level, which seems to work perfectly on my Sony LCD monster, and is extremely subtle but there on my 40's B&W sets, it was causing these problems. I now have two channels to watch on NTSC: Ch. 6 for OTA digital, and Ch. 10 for DVD. Hopefully tomorrow I will have OTA Ch. 39 (HSN) for a few more months. |
#58
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Thanks to Dave A for the UHF tuner strip.
I was particularly impressed by the free shipping and the return address on the box. The strip had the worst case of sulfide attack I have ever seen. Everything copper, silver, or brass was covered with a thick black fuzz. This responded to no chemical attack alone so I used a half a box of Q tips and Brasso, followed by lots of alcohol, more Q tips, and then De-oxit. The strip comes as Ch. 34 but changing to 39 is very easy: tune the oscillator with a spectrum analyzer, tune in the station, and tweek the RF adjustments for a good picture. I'm now now looking at some woman with horrible splotches of something white on her face ... this is a shopping channel. But its real, analog NTSC, OTA TV. I think she is in need of a sunburn remedy. That's probably what it is ... I have the sound off. |
#59
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Doug, thanks for a tip of the rabbit ears for my contribution. The sulfide is not surprising given 60 years in a sealed box. Awaiting pix of the OTA. More parts are available from my donor chassis if needed. But not the fly...saving for my CT100. PM me.
__________________
“Once you eliminate the impossible...whatever remains, no matter how improbable, must be the truth." Sherlock Holmes. |
#60
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Here are the true OTA pictures of Channel 39. This is a 12.5 kW station
2.75 miles from me .. through my walls, with a double bowtie antenna. The good picture is with a 16 dB amplifier with a 0.5 dB nf and the noisy one is direct. |
Audiokarma |
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