I am interested to find out if anyone here has what I believe to be the very first zenith solid state chassis color TV which also had varactor tuning. Perhaps some of you are familiar with the 40BC50 chassis, for 1971. There were apparently only three models available that year with this chassis. I have the service manual for the 40BC50 but for some reason it does not show a top view of the chassis, and a side view of the rear apron. All you get is a schmatic diagram. Normally, the other side of the fold out schematic is the actual top view of the chassis with component locations. For some reason, zenith manual CM-118 fails to show that information. I am lead to believe that the 40BC50 is very similar to the 1972 chassis, 25CC55 which is a little more common.

What I find interesting is that the 40BC50 as well as a select number of models using the 25CC55 used this unique looking varactor tuning system which I have a photo of out of a 1972 zenith brochure. The system was not mentioned in my 1971 consumer brochure, but it was listed in the 1971 showroom book which I have.

If you look closely at the photos of the tuner, it uses the motor drivin star wheel tuning stop system like the rest of the space command sets of the 60's-early 70's. The bottom of the control appears to be a meter which points to the various stations. The meter appears to be an electronic type? I dont see it being a mechanical channel indicator is it? I know many varactor tuners used a worm gear drivin mechanical indiator. Not sure, again, never seen one before.

The reason Im showing these pictures is to get an idea what a TV with this particular tuning set up looked like. This tuner apparenly was only available on the "highest" of the high end models, thus you only get to see the cabinet with the doors closed. Due to zeniths marketing technique by not showing another view of the TV with the doors open, I have no idea what the control panel and escutcheon looks like.

Whats also interesting, zenith didnt really make a big deal about this "new" varactor tuner in the brochures, it was just part of the lineup of optional tuners like the common "gold video gaurd" tuners and they just make a mention of it being a "new exciting concept in TV tuning".

The models shown are from the 1971 Zenith showroom catalog and using the 40BC50 chassis: B6786P, the "Newland" and the B6788DE, the "Ravenna". 1972 models look exactly like these ones but are models C6790P and C6792P respectively. Those ones must use the the 25CC55 chassis. For some reason I do not have any of those 1972 models in any of my service manuals.
Just as a note, the 25CC55 was available in a good number of models and available with conventional tuning methods.
Does anyone have any of these early varactor zenith TVs and can post pictures? Id really like to see one. I have the more common 25DC56 and 25DC58 varactor tuner horizontal solid state sets from '73. hopefully I can find one of these first generation models someday. We've all periodically discussed the RCA Transvista color, but I dont recall one of these sets ever being discussed with the 40BC50 (1971) which was introduced only a few years after the transvista (1968) and was 100% solid state right off the bat.

Anyone work on a 40BC50, was it a good reliable chassis?

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1) Never seen or heard of 40BC50. I just check the Sams index, my Zenith manuals binders, and an aftermarket Zenith handbook by Goodman... I wonder if it's a foreign-market set?

2) VERY interested to know more

3) I WANT ONE!!!!!


Charles


I am interested to find out if anyone here has what I believe to be the very first zenith solid state chassis color TV which also had varactor tuning. Perhaps some of you are familiar with the 40BC50 chassis, for 1971. There were apparently only three models available that year with this chassis. I have the service manual for the 40BC50 but for some reason it does not show a top view of the chassis, and a side view of the rear apron. All you get is a schmatic diagram. Normally, the other side of the fold out schematic is the actual top view of the chassis with component locations. For some reason, zenith manual CM-118 fails to show that information. I am lead to believe that the 40BC50 is very similar to the 1972 chassis, 25CC55 which is a little more common.

What I find interesting is that the 40BC50 as well as a select number of models using the 25CC55 used this unique looking varactor tuning system which I have a photo of out of a 1972 zenith brochure. The system was not mentioned in my 1971 consumer brochure, but it was listed in the 1971 showroom book which I have.

If you look closely at the photos of the tuner, it uses the motor drivin star wheel tuning stop system like the rest of the space command sets of the 60's-early 70's. The bottom of the control appears to be a meter which points to the various stations. The meter appears to be an electronic type? I dont see it being a mechanical channel indicator is it? I know many varactor tuners used a worm gear drivin mechanical indiator. Not sure, again, never seen one before.

The reason Im showing these pictures is to get an idea what a TV with this particular tuning set up looked like. This tuner apparenly was only available on the "highest" of the high end models, thus you only get to see the cabinet with the doors closed. Due to zeniths marketing technique by not showing another view of the TV with the doors open, I have no idea what the control panel and escutcheon looks like.

Whats also interesting, zenith didnt really make a big deal about this "new" varactor tuner in the brochures, it was just part of the lineup of optional tuners like the common "gold video gaurd" tuners and they just make a mention of it being a "new exciting concept in TV tuning".

The models shown are from the 1971 Zenith showroom catalog and using the 40BC50 chassis: B6786P, the "Newland" and the B6788DE, the "Ravenna". 1972 models look exactly like these ones but are models C6790P and C6792P respectively. Those ones must use the the 25CC55 chassis. For some reason I do not have any of those 1972 models in any of my service manuals.
Just as a note, the 25CC55 was available in a good number of models and available with conventional tuning methods.
Does anyone have any of these early varactor zenith TVs and can post pictures? Id really like to see one. I have the more common 25DC56 and 25DC58 varactor tuner horizontal solid state sets from '73. hopefully I can find one of these first generation models someday. We've all periodically discussed the RCA Transvista color, but I dont recall one of these sets ever being discussed with the 40BC50 (1971) which was introduced only a few years after the transvista (1968) and was 100% solid state right off the bat.

Anyone work on a 40BC50, was it a good reliable chassis?

The channel indicator drum setup looks identical to the later Zenith single-knob varactor tuners (although the rest looks different).
I know I had a Toshiba varactor set with touch pads that used a voltmeter as a channel indicator when you were tuning in UHF channels...maybe that is what the meter is for here as I don't see the 6 individual tuning bar indicators for UHF that the later varactor sets had.

How does the control panel look on the early varactor Zenith sets you have Doug? Does it have the line of channel numbers with channel up-down switch or is it the single knob? Have never seen one of the horizontal chassis sets with a varactor tuner.

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This must be one rare set to have. The 40BC50 is definitly a chassis for the US market. Zenith service manual CM-118 includes the 4B25C19 chassis which is the first generation 4 tube hybrid chassis. There appears to be no supplements or addendums to CM-118 that include anything about the 40BC50.

This must have been a very short lived chassis. I have many zenith tech topics issues, which is basically a mailed out list to TV shops by zenith to aid the techs in quickly repairing sets as it was a trouble and cause list for various TV chassis, and those TV shops that discovered and repaired the symptoms got the credit with their name and the TV shop they worked for. Very helpful information to have for those techs that perhaps found a similiar symptom, they could identfy the problem then go ahead and replace C243 for example. Problem solved.

Well, I have issue 85 which is a list of ALL US marketed zenith color TV chassis from 1968 (when zenith introduced "tech topics") up to the "F" line of 1975. It was simply an index, you find the chassis and then it indicates what issues had that chassis listed with symptoms. Just about all the chassis had "X" mark for january-december of all of the years as various techs across the country would find something wrong and report it.

What is interesting to note is that the 40BC50 was empty boxes for all the months indicating that nothing was discussed in any of the issues. this issue 85 is from 1975, which is more than enough time for a trouble to show up considering how many of these sets would have been in service at the time. For the sake of the argument, the 25CC55 had numerous reports. I only say this because the chassis is apparently very similar. Either the chassis was extremely reliable, or hardly any were sold and or produced. Im going to assume it was a very short lived version that was replaced quickly by the 25CC55.

Chad, these are the oldest varactor tuning sets I have, both are from 1973. Like I say, 71 and 72 models would have used this more mechanically involved varactor tuning system. You can see the one of the '73 sets at this thread which I show a close up of the tuner controls:

http://audiokarma.org/forums/showthread.php?t=90178&highlight=25DC56

And you can see the other one at the "estate sale finds in 2006" thread tward the end as I found another one in December.

vintagecollect, these sets would have used the 25VAMP22 crt.

The other photos are from CM-118. The other photo is a 1971 model B4774W, which you can also see listed in CM-118 as having the 40BC50 chassis. The other models Ive listed before are also on this list and as you can see are the only three models produced with this chassis. The B4774W set is extremely similar to the one I just found with the tube type 12B14C50 chassis. what makes it different is the that the top of the TV overhangs the cabinet and the legs are slightly different configuration, but uses the exact same front eschuteon and control panels.

The channel indicator drum setup looks identical to the later Zenith single-knob varactor tuners (although the rest looks different).
I know I had a Toshiba varactor set with touch pads that used a voltmeter as a channel indicator when you were tuning in UHF channels...maybe that is what the meter is for here as I don't see the 6 individual tuning bar indicators for UHF that the later varactor sets had.

How does the control panel look on the early varactor Zenith sets you have Doug? Does it have the line of channel numbers with channel up-down switch or is it the single knob? Have never seen one of the horizontal chassis sets with a varactor tuner.

I've always wondered if there was a 4-tube hybrid Zenith with either the one knob or the motorized varactor tuner with the channel tuning thumbwheels?

Chad, I think the Horizontal chassis SS Zenith's with varactor tuning are pretty scarce (at least around here). All the ones I used to see had the seperate VHF/UHF tuner...except until a few weeks ago. There is a 25" Zenith space command console set with motorized varactor tuning with thumbwheel knobs for tuning each channel. There's one with a similar control panel on Doug's web site. I don't know what chassis is in it; but, I do know it's a flat SS chassis. The remote is the more modern looking 4-button "clicker." I saw the shop owner Saturday and he says the set is still there & I plan on taking possession of it early next week. When I was messing with it at his shop; the horizontal hold was slightly off and the tuner sometimes wouldn't stop changing channels. I'll start a thread (with pictures, I hope) when I get the set. Needless to say, I'm very excited since this is the first "vintage" set I've found around here in a long time!

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I'm really glad your getting that set, vintage. It is NOT junk! I think that is the ultramatic tuner but more research should be done. I keep my eyes open for any set up through the early 70s. I really don't want solid state consoles but I know others do. I did a lot of flea-marketing over the weekend and there sure aren't many of these monsters left.

vintagecollect,

The TV you posted a picture of from bgadow is indeed an ultramatic tuner. If you havnt had one before, you will appriciate it very much.

finally got the set, hopefully drh wil find that 40 # chassis SS TV, for now this must be one of the oldest color zenith SS tvs surviving, has 1971 date codes, considered a 71-72 tv

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I'm very happy about that save! The guy I got it from was trying hard to find a dumpster to put it in. Good to see it is now being appreciated.

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