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  #16  
Old 04-28-2013, 12:21 PM
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Quote:
Originally Posted by benman94 View Post
Would the 19VP22 be NTSC correct also? It was my understanding that they were, but I could be mistaken. ...
-Benny
Unknown to me. However, a working one could be measured.

--

Here's a laugh: the original patent on the sulfide phosphors touts not only their brightness, but claims that the restricted color gamut is an advantage because the tube cannot make extremely wrong colors! In other words, if you don't correct the reduced saturation (which everyone WOULD do by turning up the color), you can't see variations in transmission so clearly.

Also, there is a story behind the NTSC blue vs. the modern blue. RCA experiments with the triniscope used very pure primary colors, including a blue nearer to present sulfide blue. But sulfide blue is very sensitive to copper impurities, which turn it green. Therefore, RCA chose a different blue phosphor that was slightly toward cyan, but doesn't change due to presence of copper during the processing of the CRT. There is a futher confusion, in that it is not clear that RCA intended the cyanish blue to go into the NTSC specs - the color coordinates that ended up in the FCC rules look suspiciously like a typo.
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  #17  
Old 04-28-2013, 03:26 PM
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21CT55 Screen-Shot Test

Thanks for your responses. In reviewing this thread I noticed the third screen shot of my Beth, Andy and Baby Jack was not interlaced. So I replaced it with a shot having proper interlace. This correction emphasizes my contention all posted Roundy screen shots should be taken in total darkness, sized full edge to edge and presented on the viewing monitor full size edge to edge. Conveying cabinet detail is a separate issue and should be taken full room lighting. Since I have no cabinet I have no problem with this. I also added two more good shots plus a saturated color bar shot. Check it out. The bar colors appear quite accurate on my 19 inch Acer LCD monitor. The red bar’s hue is virtually indistinguishable from my clock’s red led numerical dial color hue. The CRT is a 21FBP22A rare-earth with a white-paper gray face plate. I always considered this CRT’s red to be more “pure” compared to my Sony Pro monitor which specs SMPTE-C color phosphor. The Sony’s red bar is more “orangish” like all my other CRT TVs.

Last edited by Tomcomm; 09-25-2017 at 04:12 PM.
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  #18  
Old 04-29-2013, 02:55 PM
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While my Samsung isn't a roundie, I have found it's reds to be seriously awesome. It's greens seem a little "wrong" in my opinion though. Blue looks ok but doesn't look at all like your blues.

This is the color test my TV performed with a colorimeter.

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  #19  
Old 04-29-2013, 03:00 PM
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  #20  
Old 04-29-2013, 03:11 PM
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I have no idea what language that is.
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  #21  
Old 04-29-2013, 07:34 PM
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Quote:
Originally Posted by Mal Fuller View Post
What's wrong with this picture?
I remember that the CTC2B chassis sat flat in its cabinet and that the CTC4 chassis was the first to be mounted vertically as shown.
Tom explained at one time, that he modified his CTC-2B by repositioning the chassis vertically (and discarding the cabinet if he ever had it) in the 1960s when he first got that set.
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  #22  
Old 04-30-2013, 02:24 PM
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If I remember right doesn't this set have video inputs installed?
I remember a thread about it a while ago. If so, can I get a link to the thread?
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  #23  
Old 04-30-2013, 03:30 PM
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It must be modified for standard composite video input, I see no RF distortion AT ALL.

If it is RF, I am highly surprised.
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  #24  
Old 04-30-2013, 03:48 PM
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21CT55 # 2897 Modifications

I bought this TV in 1964 for $50 not working. Once I got it operational I decided to keep it in the garage TV shop area. I modified the consul cabinet into a table model by rotating the chassis from horizontal to vertical to take up less room in the cramped garage, also make chassis modification and repair much easier. Yes, in 2007 it became direct composite video input only. Reactivating the RF/IF portions seemed unnecessary since I had good DVD players and the 21CT55 was never intended as a restoration item.
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  #25  
Old 09-29-2013, 06:14 PM
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More BIG Screen Shots

Got back to the 21CT55 after 16 weeks “sanitizing” my “bought new” 1980 BMW 320i sports coupe. The CRT set came right up with nominal voltages, same as last operating. At 115vac in, B+ is 420v, Boost is 750v, FBI is 190ma, Ultor is 28kv and Focus is 5.1kv.

Took a few screen shots with my Olympus SP550UZ on full auto from 64in distance at 120 iso, 1/6 sec, 3.9 F.













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  #26  
Old 09-29-2013, 07:17 PM
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That is a really good picture, and very good convergence..... Nice job....
And really good pictures....
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  #27  
Old 09-29-2013, 07:30 PM
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Inx64;

Your color "gamut ICE " graph is wrong, in the green by a lot..... Someone here did those measurements and posted them on one of those 15gp's and another tube, and while people maintain the 15g's had better "full"gamut, the graph they posted showed a smaller triangle, than the other tube. I would sure be interested in seeing the response of your tube again, once you figure out what is going on with the green.... Also, try it and be sure that when the screens are turned down, the tube goes into cutoff. I have no idea how the test is run, but I find this testing interesting...
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  #28  
Old 09-29-2013, 07:39 PM
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Quote:
Originally Posted by lnx64 View Post
I have no idea what language that is.
Neither did Google translate.

Only thing I can say for sure that it's not English. As I'm a single language white trash American.

This gamut shows colors better:
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  #29  
Old 09-29-2013, 07:52 PM
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Quote:
Originally Posted by Tomcomm View Post
Got back to the 21CT55 after 16 weeks “sanitizing” my “bought new” 1980 BMW 320i sports coupe. The CRT set came right up with nominal voltages, same as last operating. At 115vac in, B+ is 420v, Boost is 750v, FBI is 190ma, Ultor is 28kv and Focus is 5.1kv.

Took a few screen shots with my Olympus SP550UZ on full auto from 64in distance at 120 iso, 1/6 sec, 3.9 F.



Is that line pairing on the test pattern, or just a fast shutter catching one field?
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  #30  
Old 09-29-2013, 08:11 PM
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Quote:
Originally Posted by Username1 View Post
Inx64;

Your color "gamut ICE " graph is wrong, in the green by a lot..... Someone here did those measurements and posted them on one of those 15gp's and another tube, and while people maintain the 15g's had better "full"gamut, the graph they posted showed a smaller triangle, than the other tube. I would sure be interested in seeing the response of your tube again, once you figure out what is going on with the green.... Also, try it and be sure that when the screens are turned down, the tube goes into cutoff. I have no idea how the test is run, but I find this testing interesting...
??
Not sure I follow what you said.

Inx64 did not explain his colorimeter software, but I believe what the CIE gamut display is showing is:
The light colored triangle and square boxes are the aim points for REC709 (HDTV) or sRGB monitors. The circles are the measured points for his set.


edit: bottom line, his green is not wrong, but is fairly typical for all tubes with sulfide green, which is all tubes after the 15GP22 and 21AXP22 (don't recall what green was in the 21CYP22 at the moment).


You can see that the triangle made by the RGB points for his set is slightly smaller than the REC709 spec because the green is slightly yellower.

The magenta is far off from the aim point towards red, and this has to be because of the demodulator gains and angles in his set, since moving the green primary towards yellow causes the magenta to move towards blue in order to keep the white point within spec (which it is). This error in magenta is not necessarily a bad thing, since it helps to prevent purple faces when there is an error in burst phase, and there are few recognizable magenta/purple objects (except maybe Barney the dinosaur). 2nd edit: it also compensates for the movement towards blue of magenta caused by the yellowish sulfide green, making the magenta a closer approximation to NTSC magenta.

A 15GP22 or 21AXP22 CRT has a green that is much less yellow, so the triangle is larger on the cyan side; but the blue in those CRTs is less violet and more cyan, so the triangle is smaller in the blue/purple area.

Last edited by old_tv_nut; 09-29-2013 at 08:22 PM.
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