Zenith Chassis Research

[TUD1]

I'm trying to learn more about what chassis Zenith used in their console color TV's from 1961 to 1975. I know the later ones, such as the 20BC50, 25CC50, 25DC56, and 25EC58, but I don't know the exact years of these, or anything about the pre 1971 chassis designations. If some Zenith experts could weigh in on this and make a chart or something, I'd greatly appreciate it.

[zeno]

There are 2 systems for numbering Zenith chassii. The old
system started with the tube count just like the radio days.
The first color was a 29JC20. 29 tubes, J=model year C=color ?
20 would change if there were different chassii. If one
were not changed the next year it would just have the letter
changed example 29KC20. Some times there is a letter at
the end. This is for minor changes & factory UHF I believe.

In the B line things started changing example 19EC45.
19", E model year, chassis. Same thing next year but 19FC45.

Model years are involved so here is a list best I remember it.

A, B, C, D, E, F, G, H, J, K, L, M, N, Y, Z then back to A........
Some letters were used only on big store sets, as I remember
S & SS, T&ST, V& SV.
Examples K1960W K line, 19", mid to high level, walnut finish
K1960P Same but pecan finish.
SK1961W same as above with remote, walnut.
Older sets used a "wrong" screen size ex. D4025W 40
means 19". This changed starting in H line to real sizes.
The second pair of numbers is the feature level. An
F4001L was a stripped carry over hybrid. An SM1971P a
high level TOTL set.

BTW there are exceptions & this is from a foggy memory !!
Need more ? Just ask.......

73 Zeno
LFOD !

[dieseljeep]

Originally Posted by zeno

There are 2 systems for numbering Zenith chassii. The old
system started with the tube count just like the radio days.
The first color was a 29JC20. 29 tubes, J=model year C=color ?
20 would change if there were different chassii. If one
were not changed the next year it would just have the letter
changed example 29KC20. Some times there is a letter at
the end. This is for minor changes & factory UHF I believe.

In the B line things started changing example 19EC45.
19", E model year, chassis. Same thing next year but 19FC45.

Model years are involved so here is a list best I remember it.

A, B, C, D, E, F, G, H, J, K, L, M, N, Y, Z then back to A........
Some letters were used only on big store sets, as I remember
S & SS, T&ST, V& SV.
Examples K1960W K line, 19", mid to high level, walnut finish
K1960P Same but pecan finish.
SK1961W same as above with remote, walnut.
Older sets used a "wrong" screen size ex. D4025W 40
means 19". This changed starting in H line to real sizes.
The second pair of numbers is the feature level. An
F4001L was a stripped carry over hybrid. An SM1971P a
high level TOTL set.

BTW there are exceptions & this is from a foggy memory !!
Need more ? Just ask.......

73 Zeno
LFOD !

The thought the "K" chassis was a 27KC20, where the two 3DG3's were eliminated and they went to a voltage doubler, unless the first runs, remain unchanged.

[zeno]

Originally Posted by dieseljeep

The thought the "K" chassis was a 27KC20, where the two 3DG3's were eliminated and they went to a voltage doubler, unless the first runs, remain unchanged.

Just using a non existent example on that. & I believe you are
right on the doubler on the rest of the roundies.

There are many exceptions like aircraft carriers would often
carry over the model number, some others too. Then there were model#'s
with numbers at the end & the run numbers ! Screen sizes were a mix
(like 40 vs 19 etc) with both some years. And System 3 triple X
chassis was out in late J line TOL consoles but not known as S3's.
Flat chassis was switched mid year E-line to to the upright but
F-line lit shows the Avanti combo still using it !!

It do get cornfusin at times.......

73 Zeno
LFOD !

[DavGoodlin]

Zeno really has the mid-end of 70s figured out. I never knew what some of those letters meant beyond the year.
Many chassis numbers in the 60's ended with a Z, which must mean something special.

TUD - if you know the post 1971 years, then I offer the rest of the story.
feel free to jump in on this all you Zenith fans out there, I am only but one of many here


I'm probably leaving a few smaller color chassis out... but here are the chassis numbers from the early glory years

29JC20 was the first in 1962, few here are lucky enough to have one in their collections
27KC20 second chassis - 1963 - consumer reports notices Zenith has so few repairs and no need for "factory service"
25LC20 and 25LC30 Third chassis - 1964 (my personal favorite as I have a Space Command and we are the same age)
25MC30 thru 33 fourth chassis - early 1965
24MC30 thru 32 fifth chassis - mid 1965 - narrow HV cage on top of chassis, uses 6Z10 instead of 6BN6 and 6BQ5 for audio det/out tubes
25MC36 first 25" rectangular (25AP22 CRT) chassis - late 1965
***** Zenith is pounding the competition at this point, RCA suffers but not like some others ****
24NC31 last roundie chassis - late 1965 lower cost alternative to a 25" rectangular with legendary durability
25NC38 second 25" rectangular
20XC36 thru 38 (aka 20X1C38) 19"?, 22" and 25" - 1967 many models (I have the full-line 1967 brochure )
15Y6C15 first 15" color chassis 1968 a bulletproof heavy bastard
20Y1C36 thru 48 - 19"?, 22" and 25" 1968
14Z8C50 19" and 16Z8C50 22" thru 25" 1969
14A9C50 19" and 12A12C50/52 22" thru 25" 1970 - SS IF strip and color demods, tube count drops
4B25C19 1st 4-tube hybrid 19" 1971 - not sure of other 19" and under
12B14C50/52 - 25" and 25V" 1971 - still using tubes in VHF tuner
*****1971 was last year for tube count as first number*****
14CC14/15 14" sets 20CC50 19", 25CC50 22" and larger 1972
19DC11/12 19" 4-tube hybrids 19" 1973
25DC56/57 the first all-transistor and IC modular chassis for 25V" models 1973
23EC15 the last four-tube hybrid (except 25V") budget 25" models 1974
25EC58 2nd all-transistor and IC modular chassis for 25V" models 1974
17EC45, 19EC45, 23EC45, 25EC45 the first "vertical chassis" series used from 1974 thru 1978(?)

[Electronic M]

Originally Posted by DavGoodlin

29JC20 was the first in 1962, few here are lucky enough to have one in their collections
15Y6C15 first 19" set chassis 1968 a bulletproof heavy bastard

The 15Y6C15 was the first 13" Zenith color set....I have shabby examples of both trim versions of that set. You missed some larger chassis too (such as the 23"/25" 12B13C52 and it's variants)...If I had time to comb through my Zenith service lit I could REALLY add to this, but time is at a premium lately.

BTW: I am one of the 'lucky few' 29JC20 owners.

[zeno]

Foggy memory but IIRC 15Y6C15 was the first 14" Zenith. A tin can set with a console chassis stuffed in. Probably the first to use
the IF module & drive the tube count by 3. Ball buster to carry but
it did have a handle. Someones sick sense of humor.......

First SS set was C-line 25CC55 IIRC. Big difference was it
used a pass regulator instead of the self regulating transformer.
Also there is a schematic for a B line SS set in one of Zeniths CM's.
Probably never sold, maybe a test / show set.

73 Zeno
LFOD !

[Electronic M]

IIRC the first SS color Zenith was a test set that got recalled and none survive....IIRC Doug H. (DRH4683) had a thread about those here.

[DavGoodlin]

Doug would do this list justice for sure. I'm just going from memory - (I love Zenith enough so I made time to do it) and obviously did not see all the variations, just the survivors.

Zeno- One number makes a helluva difference. Sure enough that Zenith had an all SS by '72, I had a 25CC50 that had more than 4 tubes...IIRC