1937 Zenith 5-S-126 Tune-Up

From the Rain City Audio Repair Blog:

This very nice Zenith 5-S-126 came through the shop a little while ago. It was originally purchased by a local collector from eBay already restored and playing, and served well for a couple of years, until it started having some trouble.

The 5-S-126 is a 1937 Zenith radio, with 5 tubes and a 6″ speaker firing up through the top of the cabinet. It receives the AM broadcast band and two shortwave bands. The owner reported that it used to have great reception, but it had slowly picked up a bit of hum, as the reception faded to nothing.

The previous technician did a workable, if not especially pretty, repair job. I cleaned up some of the wiring, moving the two filter capacitors to more secure tie points and replacing them with brand new units for long life and reliability; the installed ones were starting to wear out. The radio then received an IF alignment which was pretty significantly off, but there was still no over-the-air reception.

That would be why! The 6A8 converter tube was dead, showing no emissions at all. Replacing it with a new old stock 6A8G tube brought the radio to life right away with great sensitivity and tone. Then it was back in the case and back home!

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6 Responses to 1937 Zenith 5-S-126 Tune-Up

  1. cgjung9 says:

    I get the feeling that you were a little bored with such a simple, uninteresting repair, J.W. . I enjoyed seeing your fotos of this one, though. Thanks. Real wood and old electronics are a hard combination to beat! Take care.

  2. Walter Czyz says:

    Is there any way to test a tube without a tube tester such as the one you have? If so, are there any good videos showing step by step how to?
    That’s a great looking radio by the way!

    • jwk says:

      About the only test you can do without specialized equipment is checking the filament or heater for continuity. Otherwise….not really. If you don’t have a tube tester, the next-best thing is in-circuit substitution of other tubes – which relies on you having known-good tubes to swap out, for instance. Kind of a Catch-22.

  3. David DeRosier says:

    Nice Job. I had a Philco 37-620 that was very picky about what 6A8G you would use. It would not go into oscillation with a 6A8GT but would with a taller 6A8G. All the caps and out of tolerance resistors were replaced but it was still picky.

  4. radiosurgeon says:

    Nice job

    Sent from my iPad Robert J Richard


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