My dad's Zenith - been in the family since new
 

My great aunt and uncle bought this brand new in 1940. Then, in the early 50's they traded with my grandmother and grandfather, and in 1968, my dad got it. By then, it didn't work anymore, and it hasn't played since. I grew up with this in the house, and I'm determined to revive it. At the very least, it needs a new cord, new electrolytics, and the dual 6X5's need to be dealt with.

I have a similar set.
http://i1095.photobucket.com/albums/...ps5cd1aba7.jpg

I got it for $20 at the MARK Extravaganza meet some years back.....Mine is a model designed for 25Hz power, and surprisingly it worked GREAT on it's original parts....I still recapped it though.

So do I. A 1940 Zenith 8S563. Mine works, but it needs a new dial belt. It has a 6X5, so I don't use it much. I need to get some 1N4007's in there, but I'm still not sure how. I want to keep the filament voltage so I can keep a tube in there and it be lit, but not operational.

Just fuse the plate leads with #47 bulbs. If the 6X5 should heater-cathode short, the bulbs will expire immediately, much too quickly to put your transformer in danger. I have yet to experience a 6X5 failure myself and have not a tiny number of sets that use it, both radio and TV. One of the TVs uses it as a damper! So taking the bulb-fuse precaution is definitely worthwhile, but don't be scared of the things.

From what I've been told by some on here is that the 6X5GTs are safe to use but not the 6X5Gs or the 6X5s (the ones with the metal jacket), so if you have a 6X5GT in your radio you should be safe and shouldn't have to worry about any sort of shortouts.

Okay thanks. The 11S474 has 1 6X5G and 1 6X5GT. My 8S563 has a 6X5GT and it has not given me any trouble. I would like to know the secret with the diodes, though. I've heard that you connect the diodes to 1 and 3, 5 and 7. But I'm really not sure. I'd like to put the original Zenith 6X5G in my 8S563 for looks.

There are three distinctly different variations of 6X5GT construction and there's pretty much a consensus of how reliable they are from most to least. But the least reliable construction lived happily in your radio for almost 30 years. It's your radio, but if you care about its originality, my suggestion is the least invasive fix.

I prefer to remove the plate and cathode leads and use a terminal strip for the diodes. Google "6X5 tube data" and search "diode" on wikipedia. There should be more than enough data there for you to figure it out....I was able to do mine based on that info.

One more thing: The #47 trick was Zenith's own recommendation, straight from the horse's mouth so to speak. ISTR that no radio so modified has ever been known to burn up a(nother) power transformer. Keeping the 6X5 in the radio as intended also keeps the voltages correct, as a voltage drop through the tube would have been factored into the design. A diode has no voltage drop.

I got the old girl cleaned up...
 

But not without one casualty. When I took the volume, tuning, and band select switch off, the cheap pot metal linkage that connects to the chassis got hung up on the lever and broke. Will J-B weld fix this? I can't find another on Revovated Radios or anywhere.

Here is the chassis after 3 hours of cleaning. I vacuumed the cabinet out, used contact cleaner on all the switches and tube sockets, cleaned the tubes, and cleaned the chassis. This radio has all the original tubes except for one RCA 6X5GT/G. Even the 6U5 eye tube is original!

JB weld might work. What I would do is epoxy the break back to gether and while doing that also epoxy some flat pieces of sheet metal over the broad flat areas on either side of the break to add extra strength (I think I repaired one like that, but it's been a long time).

I'm sure a good machinist could make you a new one. You might be able cast a new one out of aluminum or similar if you have experience or know someone who does that kind of thing (the inner shaft hole would still need to be machined).

These parts are VERY prone to breakage when removing the chassis if due care is not taken. IIRC there is supposed to be something like a C clip on the tuning shaft to keep those from yanking off with the band switch lever, but those are often missing......

I have the eight tube model and I can't get the band selector lever off. I don't want to break either.

Does your 11S474 have 10 or 11 tubes. They kept the same model number, even though some models had only 10 tubes. The 10 tube model used a 6Q7G and is chassis #1005. :scratch2:

It has eleven tubes. Thank you for the advice, Electronic M.

You are welcome.

Have you tried penetrating oil on it? PB Blaster has worked wonders on rusted bolts on my car....If it can do that it should be able to help with that radio....Assuming the pot-metal has not swollen over the years.

Yes. Definitely put plenty of penetrating oil on it. Don't break it off like I did. It's weird, because my when I took my 8S563 apart, I had no issuses with this piece. And it was in much worse condition.

The eight tube model I have, is the first one I had trouble with. I bought the radio at a thrift about 12 years ago. It has a shorted 'lytic and it smoked the transformer a bit. Someone plugged it in and it stunk up the place. The eight tube job has only one 6X5. If the transformer is bad, I have an extra. :thmbsp:

I got this Zenith fixed today. All I did was change 1 lytic, five bad tubes, and put on a new cord. After that easy work, it sounds absolutely incredible. Much better than my lowly 8S563. I will be buying a dial belt next week so it can tune properly. My dad got slightly emotional because he grew up with this playing all the time, and it hasn't played since 1968.

It's best to change the bypass and coupling caps, especially the coupling caps in the audio stages. A strong possibility, that the output tubes have positive voltage on the grids.
Maybe the caps were changed in the late 60's, the last time it was used.
I don't mean to criticize your repair job, as I did the same thing, ages ago.
I just repaired it enough, to get it going.

After I got this radio playing, the president of the radio club told me to make a list of all the tubes I had to get. I had to get 2 6X5GT's, 2 6V6GT's, and a 6K7. The total bill was $59. I was stunned that the 6V6's could cost $20 a pop. Is that a good deal?

Most audio output types are hunted by audiophools who have more money than sense.....They buy them up voraciously and the price climbs skyward.
You might find them cheaper somewhere, but don't count on it.

To expand on dieseljeep's point: When the audio coupling caps get leaky and bias the audio grids positive (it may still sound fine this way) the cathode current in those tubes skyrocket which rapidly uses up the cathode.....Prematurely killing your expensive audio tubes....So unless you want to spend that $40 in output tubes again soon after the new ones are installed, you REALLY SHOULD recap the audio section.

Congrats! Your dad sounds like a great guy....and a proud papa! :thmbsp:

Thanks. He really is an awesome dad. It's because of this radio that I'm interested in radios today. I've been around this radio my whole life.

I've got a '29 Philco 86 that was my father's first antique radio - lots of memories with it - mostly Dad showing it off to guests at our house when I was (much) younger. It didn't spark my interest in electronics - mine was more of a TV and test equipment thing, but a similar connection with dear old dad.

Antique electronic supply used to sell a repro band sector linkage for this era of zeniths. I bought one for my 10S464 a few years ago for around $10-15. Might check and see if they still do!