#196
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We played with the background controls a lot. I don’t have professional test equipment, so I used the blue filter with the Video Esentials disk to calibrate. I know this is not the best way, at a disadvantage without proper tools.
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#197
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Your last comment duly noted.
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#198
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This technique should be fine if the DC restoration is good or bad, because the usual test patterns (gray scale or color bars) have constant average current in the three guns. But, on regular video, when a scene has a lot of one color in the highlights, the DC restorers have to work to counter the change in average currents between the guns; so when you have a face and yellow hat filling much of the screen, the tracking gets pushed towards blue if the DC restorers are weak. I think replacing that tube would be worth a try.
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#199
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Great suggestion. In case you don’t know, Mike Doyle restored this set. He lives about 50 miles NW of me. When he comes in to town, he will call to see if the sets need adjustment. What is the tube number. I can check that.
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#200
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Confession...I started this comparison to see the colors on this great movie on the set. My curiosity was to see the dark brown/black costumes to see if they are reproduced in phosphors. The pastel Technicolor is spectacular as usual. I do see the blue and added a similar still from the original and a brown/black scene for reference.
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“Once you eliminate the impossible...whatever remains, no matter how improbable, must be the truth." Sherlock Holmes. |
Audiokarma |
#201
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SAMS calls it V36 (a,b,c), a 6BC7 triple diode.
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#202
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Quote:
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#203
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Dave, I can take a shot of the second scene. Posted that first shot.
Your shots look like they are from a flat panel?
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#204
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#205
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My stills are from a download of the original movie and captured by VLC Media Player. Pure movie.
I have to find the K Greyson closeup to compare the blueish in your screenshot.
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“Once you eliminate the impossible...whatever remains, no matter how improbable, must be the truth." Sherlock Holmes. |
Audiokarma |
#206
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I will change the tube with a new one, if I can find one. Mike may have one. Will see what happens.
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#207
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By the way, the CTC-5 super chassis has DC coupled demods instead of DC restorers, and they bypass part of the resistor network, giving less than 100% DC restoration; so the background definitely drifts opposte the dominant color. I'm guessing they did this to reduce the effects of demodulator bias drift or differences with tube replacements, but it bothers me enough that I have considered snipping out the caps. The DC restoration of the chroma signals in the RCA X/Z demod scheme is much superior, although in those sets the luminance DC coupling is less than 100%.
The individual DC restorers on R,G,B should be best if they are stiff enough, but maybe they would have to be pulse gated to get there and what's seen is due to them not being 100% effective, something I hadn't considered until looking at these pics. Solid state diode clamps are usually quite stiff enough, but maybe tube diode impedances are too high to work 100% without pulsed gating. Looking at the TM21 monitor manual, I see they used a pulse-driven feedback clamp circuit. |
#208
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Three screen grabs from a video I made of the 2018 Rose Parade. The first two show differences in green between the two sets. It varies from scene to scene. The third shows a problem I’d like to eliminate. Is this ringing?
Video: https://vimeo.com/250371760
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Last edited by etype2; 05-18-2018 at 11:03 PM. |
#209
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Don't see the third shot?
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#210
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Just posted.
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