I picked up a fully loaded Zenith Chancellor roundy combo

[Electronic M]

So I've had a goal of getting a Zenith space command 600 roundy, and getting a loaded roundy combo with tube stereo and remote preferably in a Danish modern cabinet.

Several months ago I found one with everything except the Danish modern cabinet for a crazy price(1500), which I negotiated down to a dumb high price (500), set up a time to see the set and see if the CRT was good, the amp was tube and the condition good enough to merit top dollar, and the seller went MIA on the scheduled day... Only to inform me a few days later they were in the hospital with 'pneumonia'...given no covid vaccines were out yet back then. We assumed covid and let the whole thing fade into memory.



Back on Wednesday a friend found it relisted for $300 in a way that I thought it was a different set/seller. It was 30 minutes away so I went to see it. The new listing also showed the original manuals. If the CRT was good $300 wouldn't have been bad. When I got there its finish was shabbier than the pictures would suggest and I found the neck cover knocked loose from the back. Removing the back cover revealed it had been necked so hard the glass from the base to behind the convergence coils had disintegrated leaving the all neck hardware behind the yoke wrapped around the naked gun...

After seeing that I almost walked out in disgust, but curiousity demanded I have a look at the amp to see if it was tube or Solid State. I was impressed to find a 7 tube 7K31 amp chassis with push-pull 6BQ5s... Probably Zenith's best console amp of that year. And a 12 tube tuner. Still half way wanting to walk away I negotiated down to $150 if he could find the remote and manual he had elsewhere in the house.

The TV chassis is a 25MC43 with UHF and space command 600. The only option this thing didn't get ordered with is the reverb chassis for the stereo (part of me wants to find one). Whats interesting is the TV is a 65 model but the Sam's for the stereo indicates 1963...the cabinet, it's badging and the tuner definitely look 1963. It's interesting Zenith would mix parts from different model years like this.
This set is monsterously heavy to the point I pulled the chassis and yoke before moving it and it still was like carrying a heavy intact TV only console up the stairs of the basement it lurked in. I learned remote Zenith's have a lot more complicated tethering between chassis and cabinet than non-remote sets.

While I was there I picked up a Philco 84 cathedral, a Delco console chassis, knobs, dial bezel/glass and speaker (bottom of the cabinet was gone so I saved what could be saved), and a Kraco cassette to 8-track adapter.

When he pulled out the manual there were other manuals in the folder and I got a free manual for my portacolor out of the deal.


The set had one last surprise...when I pulled the necked CRT (to facilitate unloading the cabinet from my truck) I discovered that the CRT in it was a Setchel Carlson branded CRT!...Now I wish even more that they hadn't necked it. That's the closest to a Setchel Carlson roundy I have gotten.

I plan to salvage the safety glass and stickers and chuck the rest of the ruined CRT.
I have a CRT that was earmarked for a set that's almost used up it's current CRT that I'll probably use...I need to find another good 21FJ/FBP22.

I've got other stuff on my plate at the moment but I look forward to fixing this elephant in the coming month.

[DavGoodlin]

Nice deal even if it needs a universally-available CRT. A 7K31 amp is truly hard to find in anything, much less a combo! I have that TOTL record changer and same tuner in a 1963 MK-2635, a very common console HiFi.

Are you sure that chassis is 25MC43? If so this is a rare bird indeed. K-models were '63s so maybe the best SS amp for '65 was no match for that 7K31.
I have a 65 Zenith 25MC36 combo with a 25ABP22 and 140 "watt" stereo receiver that is all SS. No separate amp chassis either. If that SS receiver were in your combo instead, value would be half or even less with a busted CRT - LOL

Every Zenith with that earlier (TOTL for 1963) 12- tube tuner chassis I have found was paired with 3K31 amp, like one I have and others I did not buy for that reason. All seemed to have those better speakers though.

Zenith SE6BQ5 amps are not very powerful, yet do sound very sweet when all restored especially if you replace often cracked-looking ceramic disc caps with mylar film-dips. I bet that preamp and 7K31 amp chassis would rival a similar Fisher amp.

[mr_rye89]

That’s a pretty awesome set! Too bad about that jug/yoke but that shouldn’t be too hard to find. And with the PP stereo amp that thing could probably really rock. Is the stereo reverb option just a reverb tank like you would find in a guitar amp?

[John Adams]

Just curious as to the EIA code on the crt label.

[Electronic M]

So I put the stereo on the variac today and it came to life... Because Zenith! Right channel is a bit weak and MPX isn't working but with all the bumble bees and ceramic body tubular papers in it I'm impressed it works this well. I posted a video of it up on Facebook. https://m.facebook.com/groups/233107...9611167070738/

Originally Posted by mr_rye89

That’s a pretty awesome set! Too bad about that jug/yoke but that shouldn’t be too hard to find. And with the PP stereo amp that thing could probably really rock. Is the stereo reverb option just a reverb tank like you would find in a guitar amp?

I need to look into it. There's about 6 different Sam's for the tuner and amp and the only one I could pull without moving a TV away from my filing cabinets didn't show the reverb...Just it's socket and reverb delete jumper plug. Based on what goes to the plug there should be tubes on the reverb chassis...The delete plug connects a 20W resistor to ground to load the B+ to compensate for the reduced load with the delete. It would be cool to find and add the reverb to it... gotta find the reverb chassis number first.

Originally Posted by John Adams

Just curious as to the EIA code on the crt label.

If you click the pic you can zoom in and read EIA 274....RCA. Which jibes with the legend that RCA sent engineers to SC to find out how the made a better picture than RCA TVs despite using an RCA made CRT. Looking closer at the safety glass there are a couple deep 2" scratches in the center of the viewing area so I can't even save the safety glass.

Originally Posted by DavGoodlin

Nice deal even if it needs a universally-available CRT. A 7K31 amp is truly hard to find in anything, much less a combo! I have that TOTL record changer and same tuner in a 1963 MK-2635, a very common console HiFi.

Are you sure that chassis is 25MC43? If so this is a rare bird indeed. K-models were '63s so maybe the best SS amp for '65 was no match for that 7K31.
I have a 65 Zenith 25MC36 combo with a 25ABP22 and 140 "watt" stereo receiver that is all SS. No separate amp chassis either. If that SS receiver were in your combo instead, value would be half or even less with a busted CRT - LOL

Every Zenith with that earlier (TOTL for 1963) 12- tube tuner chassis I have found was paired with 3K31 amp, like one I have and others I did not buy for that reason. All seemed to have those better speakers though.

Zenith SE6BQ5 amps are not very powerful, yet do sound very sweet when all restored especially if you replace often cracked-looking ceramic disc caps with mylar film-dips. I bet that preamp and 7K31 amp chassis would rival a similar Fisher amp.

Yes the TV chassis has its ID sticker clearly legible.


It's facinating that they put chassis 2 model years apart into the same cabinet, but not totally shocking to me either I have a Y line rectangular console (20Ysomething) and a 20CC50 table top that both use the same face and single knob VHF/UHF tuner.

Thanks for confirming my gut feeling about that amp. I had a hunch it was rare/special but I haven't owned or opened many Zenith stereo consoles so I have a limited frame of reference.

It's already pretty darn good so I'd imagine with a full service it will be one of my best tube stereos. Once I get time to look at the TV chassis I kinda want to variac it and see if it would have worked if the CRT hadn't gotten crunched.

[WISCOJIM]

Originally Posted by Electronic M

I posted a video of it up on Facebook.

Tom, the FB link doesn't work here.

.

[Electronic M]

Originally Posted by WISCOJIM

Tom, the FB link doesn't work here.

.

I replaced the link with something more likely to work... Not sure how to directly link the video so click on the "+3" picture and scroll down to the video.

[DavGoodlin]

Zenith service manual HF-9 confirms your HiFi equipment matches a model 7500 and undoubtedly a top of the line model, using a color chassis 27KC20QS and that's space command of course! Just add the KV-24 reverb tank
1963 model page.jpg
7K31 amp.jpg
I will see if a 1965 HF-13 has any info on a later combo.

I DID find the reverb in HF-9, so PM me your email so I can attach a pdf.

EDIT: Here is CM-106 for the TV
https://www.ebay.com/itm/33391339164...YAAOSwUylgRVJk

[Electronic M]

PM sent.

It's cool to see the listing in the HF9 manual. That 40W (20W per channel I assume) audio rating is nice to see. I was stealing time from other stuff when I read the Sam's and forgot to check audio power. That honest 20WPC was probably better than the SS amp in any console that year.

[old_coot88]

Have you verified that the H efficiency coil is intact? That's the very first thing I'd check on any Zenith of that vintage. Even before the CRT.

[DavGoodlin]

Originally Posted by Electronic M

PM sent.

It's cool to see the listing in the HF9 manual. That 40W (20W per channel I assume) audio rating is nice to see. I was stealing time from other stuff when I read the Sam's and forgot to check audio power. That honest 20WPC was probably better than the SS amp in any console that year.

If my experience with early 60s Zenith HiFi tells me the ratings given in these manuals is honest, the later solid state ratings give much pause!

If this console was a special item in the 1965 line-up, maybe if you already could get 25" rectangular why settle for a 21" round I bet this amp sealed the deal when someone heard the stereo part, TV being a 25MCXX was the last wider-chassis 21" set, which this cabinet could certainly accommodate.

New for 65 (?) was the solid state TOTL Zenith chassis 8MT25 where two (121-270) in push-pull and a 55 volt single-ended power supply = 120 watts ??? I have restored damn near the same chassis in an RCA and Maggie TOTL model already

[Rythm]

Trying to figure out how to use this site yet
But are you sure about the power Ratings of a P-P 6BQ5 of this set ?
I think more like 12-13 Watts per channel would be correct I would think
nice set BTW

[Electronic M]

Originally Posted by old_coot88

Have you verified that the H efficiency coil is intact? That's the very first thing I'd check on any Zenith of that vintage. Even before the CRT.

I have a parts chassis and a couple spare forms (one of which is spoken for for a convergence coil in another set) so I should be able to deal with it if bad... I'll check on it eventually.

Originally Posted by Rythm

Trying to figure out how to use this site yet
But are you sure about the power Ratings of a P-P 6BQ5 of this set ?
I think more like 12-13 Watts per channel would be correct I would think
nice set BTW

The spec I quoted was from a Zenith service manual image Davgoodlin posted. Its not impossible Zenith overstated it, but it's also not impossible to achieve it in class AB. The max plate dissapation power in the 6BQ5 datasheet is 12W. Theoretically if you ran the tubes at the max plate dissapation and class AB biased to the ragged edge of going into class B you could get almost 24W out of a Push Pull 6BQ5 amp. At an amplifier calibration presentation at one of the last ARCI radiofest meets at the old Holliday Inn venue the presenter stated 20WPC as being about the max a HiFi PP 6BQ5 amp could do.

[maxhifi]

That amp is so cool. How many console amps let you null the DC imbalance in the output transformer for lower distortion? Looks like you need to have it plugged into the preamp for the negative feedback to work, I bet there is a tone control of some sort in the loop. And an actual split load phase inverter - how deluxe! This thing might actuslly not embarrass itself with better speakers and stuff.

That said, the speakers have big magnets too, and does it have the 2 gram phono cartridge? Condition is kind of nasty but this console is really really cool, what a nice find. Look forward to seeing it make a picture! Can't comment on the tv, don't know the first thing about non RCA color TVs of that era. I wonder if the zenith roundie has the buzzing discriminator and the slightly weird greens like the later zenith tube sets can.

[Electronic M]

The output balance is a cool circuit. I was nerding out over it in the sams last week.
The feedback goes to the presence control, which according to the audio section instructions effects the mid-range of the audio making it possible to have the soloist stand out from the band.

Zenith used the 6BN6 in every TV from the mid 50s till they replaced it with SS audio....in some sets they hid it in a multi-section compaction, but it was there if the detector was tube.

Some of the SS chroma detector sets had somewhat odd green/color in general. The gated beam color detector tube color demodulators this has tend to produce beautiful color. My 29JC20 gated beam looked better than my RCAs before the lousy Sylvania CRT started dying. Same with my old gated beam 25MC33 that I regret selling to a flake that used to visit this site.