Zenith ch 24NC31...Z

[DavGoodlin]

The Z prefix after the chassis number is an extended run of this last Zenith round 21" CRT color set. I am restoring this for a friend who is trying to match furniture and decor. Since he is also an appliance collector and has little room to add TVs, I have been saving this fully-appropriate match among my treasures. I was trying for a 20Y1C48 in a legged EA cabinet, which didn't materialize.

On a constant hunt for this same TV in a plain compact walnut with Scandinavian-style legs, Some late relatives had one like this, lasting some 12 years of brutal daily use.

This loss leader had the best color design to date, with a retro CRT! Zenith was using the 25" rectangular for two years already in 25MC36 and 25NC38 versions. I wonder if they did not always figure on the reverse-use of a newer and narrower chassis for a budget 21" model, not rectangular either.

Just like Philco's last 21" round chassis (17MT80 and 19MT79) which offered a hybrid design using all-transistor tuner, IF and video driver, THIS Zenith was what the budget-minded bought for their upgrade to color, after doing all the homework. See also RCA CTC-20 and GE CB-21, having their very own similar entry-into-color affordable sets.

While we may see the Z suffix and not think much would be different, this chassis had an obvious change in the audio tube to 6J10,

Not obvious is the dozen more changes listed in Sams 803, folder 4 update in the Set 945 "production change bulletin". A must-have document if you encounter issues in one of these fine examples of the "service saver chassis".

The issue pictured below is obviously loss of sync. My broadcast mod's channel 3 in the house is coming from the garage. Having the only conformed schematic for this set, a supplemental in Zenith CM-109 covering the aforementioned 25NC37/38. The resistor feeding the 6BA11's sync-side plate is suspect, stay tuned election results still unclear here.
Zenith 21X4122M-1967.jpg
Zenith 24NC31Z-1967.jpg