Zenith 40bc50 mystery set

[drh4683]

I've been doing some more research on this subject as it's been an interest of mine for years. Nobody really knows if the 40BC50 made it to production, or if it was just a short lived "test run".

I found an interesting bit of information that somehow I never saw before on one of my service manuals. CM-118, published in June, 1970, was the first and only service manual to include information about the 40BC50. Interestingly, in March, 1971, a revision to CM-118 was issued. In this revision, all information for the 40BC50 was intentionally "deleted" and information for the 19CC19 4 tube hybrid chassis took it's place. What's interesting to note is that the CM-118 revision states to "discard the previous CM-118". Never before did a Zenith service manual mention to discard a previous volume. Most revisions to Zenith service manuals were supplements or addendums to original volumes.
This leads me to believe that the 40BC50 was indeed an idea that was intended for full production (hence the service information) and then suddenly scrapped. Zenith wouldn't make a statement to discard the 40BC50 service data unless they knew for certain that no such chassis was in use. With that being said, it's probably safe to assume no such TV will ever be found today.

Perhaps the 40BC50 had a reliability problem that was caught late in the lab and production was delayed, something similar to what should have been caught by Zenith over the 4 lead safety capacitor incident in the vertical chassis CCII's. Perhaps if any of the three different TV models that used this chassis were sold, there may have even been a recall? We may never know the real story behind the 40BC50.

This also reinforces Zeno's quote from the TP-6 training manual in which the 25CC55 can be considered Zenith's first all solid state color TV chassis.


Here's the original CM-118 from June, 1970:



Here is CM-118R, note the statement to discard the original CM-118



Here is an note from CM-118R: