Zenith 40bc50 mystery set

[zeno]

No I dont have one !
But some old threads mention this rarity.
A quote from Zeniths TP-6 training manual.

"The 25cc55 chassis is an all solid-state chassis similar to the
40bc50 chassis ( preliminary data was listed in CM118 ).
Since the 40bc50 chassis was never produced in quantities
for the commercial market, the 25cc55 can be considered
a new, all solid state chassis, introduced for the first time. "

Other references are that the power supply, vert, & hoz
are almost the same. The 9-75 replaces the 9-48 vert
module in the 40bc50. Anyone got an old price book ??

Also noted was Zeniths first varactor tuner ( C line) with "3 band lights &
a tuning meter". Never seen one myself. Shows pictures,
looks very Zenth.

Anyone ever find more on this set or check Zeniths archives
( if they still exist ) ?

73 Zeno

[AUdubon5425]

DRH4683 has been looking for one of those for as long as I've been reading this board. From what I remember of his research there's a good possibility they never made it into production.

[drh4683]

I've been trying to solve the 40BC50 mystery for quite some time, and with no success. The factory Zenith service manuals only provide a schematic, yet they do not provide a top view of the chassis or any of the additional chassis details or drawings as they do for every other chassis. I have a 1971 Zenith brochure and there are two models shown that supposedly use the 40BC50. These sets were higher end cabinets with bi-folding doors, which of course means all the emphasis is on the appearance of the cabinet, so they only show you what the set looks like with the doors closed. Go figure. So who knows what the escutcheon and control panels really looks like. The 40BC50 chassis also used an electronic tuner. It was a motor driven varactor type, but its mechanical design resembled that of a Zenith's Super Gold Video Guard (turret) tuner. This electro-mechanical varactor tuner incorporated a rotating drum channel indicator. It was a totally different set up compared to the vertical channel strip motor drive varactor tuners used on the more familiar D and E series flat chassis SS sets for '73 and '74 (respectively). I'm pretty sure that the 1972 25CC55 chassis only used conventional VHF turret and continuous UHF tuners. The only reason I know about the layout of this early electronic tuner for the 40BC50 is because Zenith took a picture of it for the brochure to show off the "latest and greatest" in tuner technology... The tuner appears to also have a very small tuning meter which was most likely used as a channel indicator for adjusting the channel presets. Very neat looking set up. Will anyone ever be lucky enough to find one? Who knows...

[zeno]

A few notes on this. They must have built some,
but maybe they went to a select few & probably got called
back in after testing ala Chrysler turbine cars. Being in the line
folder they probably intended to release them but didnt for
an unknown reason. Bose sets were limited distribution at
first & probably the digital process chassis also, I cant remember.
Another thing that I noticed back then the parts for both the
digi set & projo were listed in the book way before we knew
about them. Wonder if 40bc50 only parts were listed ??

Varactor tuner: C-line intro
In the TM it dont look like a SGVG tuner. A small box with pots
that look a lot like the newer ones in a turret. Bandswitch cams
that work one bandswitch. Plasic part on front probably mounts
from front not back as the norm. On rear some gears & the
usual SC twist for stop or off setup. Motor hangs underneath.
Tuning meter & bandlamps shown off board in schematic.
Tuners were modern with FET RF amps on both U & V.
I worked at a Big Zenith dealer from 1970 on and never saw one
& we covered several very high end towns. C line SS set were
not common, most we sold & serviced were E line, lots of them
& they were plain fun to work on. (not so much the vert chassis)

73 Zeno

[AdamAnt316]

Not sure about the 40BC50, but the 25CC55-based Space Command console my grandparents had (sold to technicolor) sported the aforementioned bi-fold doors, and the motor-driven tuner (with a horizontal drum) involved a small meter with lights behind it, so maybe some details did survive. You might want to ask Joe about it.
-Adam

[zeno]

Originally Posted by AdamAnt316

Not sure about the 40BC50, but the 25CC55-based Space Command console my grandparents had (sold to technicolor) sported the aforementioned bi-fold doors, and the motor-driven tuner (with a horizontal drum) involved a small meter with lights behind it, so maybe some details did survive. You might want to ask Joe about it.
-Adam

I have the training manual for 25cc55, I described the tuner above.
Never seen one in person & not even a pix of the front, just
the guts. The set has to be super rare. You pay a premium for a
Zenith, doors, solid state, varactor tuners & remote. Had to be
$900-$1100 back then, a LOT of money. Never sold many door sets,
not popular & only on high end sets. At the end of the model year
we would buy some on close out cheap & usually removed the doors.

73 Zeno

[jstout66]

Hey Zeno,
I have an old Zenith CRSP book. (printed June 1984)
It says the 9-75 ( vert osc) was 14.75 and first used in 1973
It says the 9-48 (AGC Amp) was 18.88 and first used in 1972

[zeno]

Originally Posted by jstout66

Hey Zeno,
I have an old Zenith CRSP book. (printed June 1984)
It says the 9-75 ( vert osc) was 14.75 and first used in 1973
It says the 9-48 (AGC Amp) was 18.88 and first used in 1972

Interesting that shows different boards, TM must be wrong.
Was that in the pocket sized book or the full blown price book ?

73 Zeno

[jstout66]

it was the pocket sized one, so perhaps it was a boo-boo.....
I can't believe how cheap those boards seem to me now. I remember sometimes the customer would be po'd on how "expensive" they were.....
You wanna talk expensive tho... I remember the boards for the Quasar " works in the drawer" sets, WERE expensive.. and they were hard to get by 1984, and this was for rebuilt!

[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:

[Electronic M]

Now I gotta see if I have the CM118, and which version I have.

[zeno]

Interesting change in the manual. I only remember supliments,
not replacements. It would also be interesting to see if there
was more than one line folder that year & if the "big book"
ever had pages on the sets published. Or if the sets were in the
specs & features charts.
Probably never know unless we can find an engineer that was in
the color TV dept & still alive. If there is one out there it must be
in the Chicago area..........

73 Zeno

[drh4683]

Originally Posted by zeno

If there is one out there it must be
in the Chicago area..........

73 Zeno

I can only hope!

[rca2000]

I MAY have some news on this subject....

A guy I know though the Dayton Hamfest, named Bill wade--who helped to write the "Zenith story " book, may know someone who is/was a top Zenith engineer==who just MAY hold some definitive answers to this mystery we all have. He will speak this this man soon, and may give him my phone #, so I can ask him about the 40BC50 set. ANY pertinent info I get--will be passed on here.

[rca2000]

I have some news....

I have been told that the 40BC50 set was only released as a test mule---released only to employees and such. evidently--It had way too many bugs in it, for them to do a full release. After some changes--it became the 25CC55, and was given a full release. Zenith was too concerned with high quality--to release a set that was not extremely reliable-and evidently the 40BC50 set was not.

This is from a former zenith engineer.....