Zenith tube console, need some help.

[Slinds9]

So I was looking for a couch and found an old Zenith stereophonic hifi console with a de-tatched powered speaker instead. I can see a couple burnt tubes and not sure where I should start in restoring these amps. I'm going to be doing a lot of reading this week and hopefully tearing it apart next weekend.

 

[RWood]

That is an interesting setup. Push-pull amps on separate chassis. The tubes might be fine, they burn for a living and are supposed to look like that :thmbsp: Great pictures; that helps a lot. Continue to do that with everything you unplug or re-do.

Those three chassis numbers are the keys. The first digit represents the tube count on the chassis. 5B24 has the power amp for the main unit, 9B22 has the tuner and 3B31 has the extension speaker's amp.

I would start with getting the schematics for each. They might be available from either Sams or Beitman's. There were a lot of variations in this era (looks like a 1958) so make sure you get the right ones. If you have the model number for the console itself it might help in finding a set that has all three.

EDIT: appears to be an SF188E. Schematics in Sams 448-16 (9B22 and 3B31) and Sams 444-22 (5B24).

Essentially you will need to recap power supply and coupling capacitors, check resistors and tube pin voltages, and then rebuild/relube the Cobra-matic (Voice of Music) changer.

Here's a similar one of mine that has what your's has, but all in one cabinet. My main beef with this one is that I don't get much channel separation. Yours would not have that problem:

 

[maxhifi]

Those woofers are beautiful, I wouldn't hesitate to sink some effort into this console.

 

[gadget73]

Unless the tubes are white and chalky looking, you can't really tell much by visual inspection. They are normally silver inside like yours. White indicates they have gone to air.

 

[Vintage Bert]

I like how the output stages are split with the power transformer together with one output on a "main unit" and the other output on a separate platform. Don't know if I have seen that before, but then I have not seen so many (see Gadget above ).

 

[cademan]

I know a few companies that built stereo systems using the companion speaker set-up along with their own built in amps.

I grew up with a Packard-Bell system in our living room where mom had both speakers on both ends of the couch. The main unit had the stereo turntable and mono am/fm tuner/preamp. The companion speaker had its own built in amp and controls and needed to be plugged into a near by wall socket. The companion only worked with the turntable.

 

[JohnMac]

I have a pair of 5B24s and after some modifications they sound quite nice. The main change was to remove the tone and presence controls and took the 6AT6 out of the circuit.

 

[gadget73]

The two cabinet thing wasn't uncommon in the early stereo days. I know Magnavox made some, and I have a Hoffman console that is a similar two amplifier rig. Magnavox made them in both 2 amplifier and single amp with remote speaker setups.

 

[JohnMac]

Here is a schematic for the 5B24

gadget73, I recall that you helped me out with these amps.

 

[Slinds9]

Thanks for the info everyone! I've been reading in between work all day, I can't wait to start the rebuilding process.
I'm going to order the schematic for the main chassis amps and start recapping. Thanks for the schematic for the 5B24!
I am a little iffy on the warm up procedure and I may have to drop everything off at a shop for that, but that's something I'll worry about down the road.
I've had my HK hooked up to the speakers and they sound pretty good for what they are and seem to be in great shape.

 

[Slinds9]

Rwood thanks for the info and that console looks awesome after the restoration!

 

[gadget73]

Hm, adjustable feedback with a dedicated cathode feedback winding. Interesting.

 

[ggizzy]

I have nothing of worth to add. I just want to say that, that is a cool console. I like the offset design a lot.