Zenith Console Restore & Troubleshooting

[Brow2070]

Just picked up a Zenith Tube console I want to restore. It powers on and I have sound coming out of the small tweeters but nothing out of the 12" woofers. I'm going to start with cleaning the pots first before I move on unless there are any other suggestions. Everything inside looks to be original without any modifications. I will post pictures soon.

 

[Brow2070]

Pictures

 

[century tek]

Take some pics with the back being off and try to show the wires to the speakers. If the external speaker plugs are messed up, it is pretty easy to just wire the speakers straight to the amp.

 

[Brow2070]

Pictures of the inside. I haven't removed anything besides looking at a couple of the tubes.

 

[gadget73]

looks to me that the amplifier output goes to those plugs on the back, and the internal speakers also go to it. Seems there has to be jumpers or something in there to connect the amp output to the speakers. Can't quite tell which pins are for what though. Red, white, black come from the amp. The brown wires go to the speakers. Guessing one brown goes to the tweeters, the other goes to the woofer. I'm guessing you need to jumper the red or the white to each of the brown wires on the plug.

 

[century tek]

Looks like a broken wire in pic #3. The tweeters are connected to the woofers so if they are working then your woofers might be bad but then again I can't see how they would get blown unless previous owner was attempting an external speaker connection and didn't know what he was doing.

 

[Tom Bavis]

Two different Sams folders (1962) for amp 7F30 and tuner 7F20 - I should have them both. I checked Radiomuseum - they don't have those scans... yet.

 

[orthophonic]

Those jacks are for the extended stereo option and someone has boogered up at least one of the plugs. When the optional Zenith extended stereo speakers
were plugged into those jacks, the mid/high's were cut off from the main console speakers and sent to the external speakers and the console was only used for
the lower frequencies.
If the wiring of the plugs is changed, it could cut off the woofers instead of the other way around. The plug on the left appears to be wired correctly from
what I remember.

My guess is someone wanted one full range external speaker in another room and wired it so both the console and the external speaker were full range
and now that the external speaker has been cut off (as evidenced from the picture of the plug on the right), the circuit is incomplete and no full range
from the console.

 

[cademan]

What a pain!

 

[electronjohn]

Looks like it has a reverb tank, too. Groovy!

 

[Tom Bavis]

The connector with wires should be connected like the other one - 3 pins connect together to connect internal speakers.

I have the service data - 5 pages of schematics including the tuner. email tbavis(at)rochester(dot)rr(dot)com

 

[jdsalinger]

Those 49CZ speakers are the cat’s pajamas. Actually, all Zenith speakers from that era are gems.

Try connecting speaker wires from another amp to them directly with alligator clips.

I have a lot of respect for Zenith gear of that era.

 

[Brow2070]

After cleaning all the pots, the speakers are working correctly. Now moving on the next issue, no am/fm (just static). Also fixed the broken tuning string and cleaned up the face plate a little bit.

 

[gadget73]

wiggle each of the tubes in the tuner, or just pull and re-install them. I've had a lot of tuners come back from the dead by doing that.

 

[Brow2070]

Wiggled the tubes, no change. Also, balance works through the auxiliary but not on phono.

 

[gadget73]

well, it was cheap enough to try. Probably time for tube testing and voltage measurements.

 

[Brow2070]

I don't have a tube tester...yet.

 

[gadget73]

whereabouts are you? might be someone local to you with one. There is a post up at the top of this forum with who has what tester and where.

 

[Brow2070]

whereabouts are you? might be someone local to you with one. There is a post up at the top of this forum with who has what tester and where.

Minnesota

 

[mibag6]

If you are in the Twin Cities area, there are a number of members who can probably assist with testing. I thought I saw that console on CL, should be a pretty nice machine with a little work.
I'm in Duluth and have a tester if you happen to be nearby but my testers are strictly emissions testers, good enough for basic testing but nothing fancy.