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1937 Zenith 5S127 Radio Restoration

1938 Zenith 5S127

1938 Zenith 5S127

I found this little project via a local estate auction. Got it for next to nothing – like $7.50. I bid based only on a couple of photos I had seen of it. It looks like someone started the project and was never able to finish it. The cabinet finish was stripped, the speaker was torn badly, but it looked like most of the parts were all there.

March 23, 2017 Initial findings: It is a 1937 Zenith 5-S-127 “tombstone” tabletop radio on a 5-tube 5516 chassis. The cabinet is stripped and possibly sanded, and some minor veneer chips need repaired. The speaker cone is badly torn. The metal dial clips are missing. The power cord insulation is brittle and falling apart. The dial cord is missing, with monofilament in its place. Tube 6K7’s filament is open. Old repairs are evident – the large electrolytic capacitors were bypassed below chassis with Sprague Atoms, paralleled across the metal-can originals. Power transformer primary checks good. Speaker field coil and voice coil check good.

1938 Zenith 5S127March 29, 2017 Update: I have replaced the electrolytic capacitors, choosing to install them below chassis and bypass the original above-chassis cans – leaving them in place for appearance sake. Also replaced all the cardboard capacitors. Tube 6K7 was replaced due to the bad filament in the original. I also found that the antenna-resonator variable-capacitor’s adjustment screw is missing. With all the capacitors replaced, I powered it up through a variac to bring it back to life. The main power switch is bad – so I’ve bypassed it for now. The dial lights came on, and the temporarily repaired speaker cone came alive with a loud hum. The hum was caused by a rechargeable LED light I was using nearby – once I turned it off and moved it away, the hum went completely away. But that was it. No stations could be tuned. No static could be heard. So…time to dig deeper.

March 30, 2017 Update: It dawned on me last night, being new to antique radios, that I may have needed to connect an antenna in order to receive anything. So, to test my theory I first wanted to reinstall the tube shields, but in doing so the 6A8 1st Detector/Oscillator tube broke while pulling the grid cap. Ugh, shut down, and replacement 6A8 tubes are expensive!!!! There went any hopes of working on this project over the weekend – or so I thought. It hit me this morning that I might have a 6A8 in a 1939 Zenith 6-S-249 Chairside I found at a local pawn shop a couple of days ago – same manufacturer, only one model year newer. And sure enough, it has one! It’s not the glass version, but it should work nonetheless. I finished installing the tube shields, replaced the broken 6A8, and added an antenna wire. It works! And more so than it did yesterday. In retrospect I think my 6A8 might have been bad to begin with. The tube should not have broken with as little force as I was using to pull the grid cap, and when it did break, it wasn’t dramatic, no pop – instead it was like the glass just pulled off the top, as if the tube may already have been compromised. Now, with or without the antenna wire, I can pull in faint stations. The reception is not great, and the selectivity is poor, but we haven’t tuned this yet. Just made my day, and I’ve now heard my first audio from an antique radio that I brought back to life!