Zenith 29JC20 21"--cataract and convergence

[reeferman]

I have a NOS cloverleaf. Might reproduction be a possibility with 3D printers? It would definitely have to be flexible to work.

As mentioned earlier, installing the hard plastic convergence assembly is the way to go.

Phil

[Electronic M]

Originally Posted by reeferman

I have a NOS cloverleaf. Might reproduction be a possibility with 3D printers? It would definitely have to be flexible to work.

Phil

Sure it should be possible. There are 3D scanners and printers around, and a variety of types of plastic filaments available...Once it has been scanned and any needed adjustments have been made to the CAD file then it should only be a matter of selecting the best-suited filament and figuring out how many copies to make.

[iong]

Anyone know if Zenith 29JC20 (First Zenith Color) Has as nice picture as a later roundy like 26KC20?
Perry

[Zenith6S321]

Originally Posted by iong

Anyone know if Zenith 29JC20 (First Zenith Color) Has as nice picture as a later roundy like 26KC20?
Perry

Post 91 of this forum thread compares my Zenith 29JC20 picture (first 3 pictures) to my RCA 21CT55 (last 2 pictures):

http://videokarma.org/showthread.php...th6S321&page=7


Dave

[old_tv_nut]

Originally Posted by iong

Anyone know if Zenith 29JC20 (First Zenith Color) Has as nice picture as a later roundy like 26KC20?
Perry

Regarding color, The first one most likely has a sulfide tube (unless it was replaced). I don't know if the later one came from the factory with a rare earth tube, but if so, that would make a difference, with both brighter and truer reds.

Also, at some time (I don't know when, maybe not until rectangular tubes), Zenith went from the original RCA "9300+27MPCD" white point (really meaning, the red is not strong enough to make 6500K daylight white), to a unique 8000 Kelvin white point that no one else used. Moving toward a daylight white meant that variations in transmission were not so strongly reflected in skin tone variations.

Also, tube sets varied from one set to another more than solid state, so comparing any two roundie tube sets, you may get very different results from the average engineering aim point. Variations could be not only in the gray scale set up, but also in tolerances for the gains and phase angles of the color demodulators.

In terms of picture sharpness comparisons, I have no idea. Because of the lack of real high definition detail in analog TV, receivers always used luminance peaking to enhance the contrast of edges and small details. The amount of peaking and the peak video frequency designed into a chassis was strictly a matter of taste, and you could see differences in different manufacturers. Peaking was affected by both video circuits and tuner/IF response shape. These parameters were always a matter of discussion in product engineering and marketing, with side-by-side viewing of different proposals. So, besides differences between manufacturers, you could see the choice of parameters drift from year to year within a single manufacturer as internal opinions changed. Of course, there were also set-to set differences due to alignment. Much later, alignment variations were reduced drastically by the introduction of surface wave IF's.

I'm afraid I haven't said much that's definitive about the two sets you asked about; maybe someone who saw a lot of both chassis could comment on the average trend.