Troubleshooting Vacuum Based Electronics

Duck, duck, goose

Ions; we has them

Once the backbone of yesterday’s “modern” electronics and still widely used in guitar amplifiers today, vacuum tubes are one of the longest lived electronic device families in history.

Troubleshooting these ancient artifacts however has become something of a lost black art.

Several decades ago as a newly minted graduate of a comprehensive military electronics program, I had the opportunity to troubleshoot an old amplifier alongside my grandfather, himself an old WWII radio (Radar) technician.

He stood by silently and watched with great pride as I gathered my materials, Multimeter, Signal source and O-scope, carefully took measurements and poured over the schematics, attempting to locate the culprit.

Claiming it was hard to read the schematics he mostly just observed and listened to me ramble on, bragging about my new-found knowledge.

Then after a while when I appeared to be stuck, the old Pearl Harbor survivor held up his index finger as if to say “just a moment”, licked his finger and quickly touched the top of each tube.

Finding one that was cold within a few seconds, he pointed at it and said “That one is bad.”

And then went into the house to have a sandwich.

  • tonyola

    When I was a small child, you could find these self-service tube-testing machines in hardware and electronic stores. I'd go along with my dad and watched him as he tested tubes from the TV or console phonograph.
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    • Believe it or not… I have one of these coming to my house tomorrow. As well as about 2,000 NOS tubes and other brick-a-brack.

      Please shoot me.

  • Charles_Barrett

    Well, that works if the heaters are connected in parallel. If, however, the device has the heaters wired in series, one open heater 'breaks the chain' and all the tubes are cold. Then the hunt for Red October can begin in ernest…
    As a freshman with EE aspirations at Caltech in 1981, I was taught vacuum tube theory before we got to semiconductors. The medium may change, but electrons will always be electrons — until you get to quantum mechanics…!

  • jjd241

    I remember those testers too. Recently we just lost our “old school” TV repair shop. This place was just like Emmet’s Fix It shop in Mayberry. He was able to stretch out repairing TVs, radios and VCRs from a converted house on the main drag up through the early part of the 21st century. Of course, now most electronics are “disposable” or need a factory authorized facility to be touched. I was lucky enough to have a hand-me-down set in my room during high school. Those tubes gave off enough heat to keep you warm in the winter, that’s for sure!
    Here is a tube I found at an antique store. I bought as a piece of “art”, but it may come in handy when it comes time to build our communal robot space ship to escape our alien overlords…

    • jjd241

      Sorry about large image..still learning. width command did not seem to help…?

      • Deartháir

        Fixed the width for ya; you typed "with" instead of "width". 🙂

        • jjd241

          tanx mi know speel sew gud!

    • Charles_Barrett

      What is that…? A suppository for Gigantor the Space Age Robot…?

      • interroceiter flux coil. When they go out nothing works right.

        • Mr_Biggles

          I'm sort of with you on that, but of course once the cathermin tube with inindium complex of +4 fails, even the interocitor is incapacitated.

          • Ugh, god I hat those. Had one go out and it took forever to sort out.

          • texlenin

            Uhhh. maybe the "Amazing Rando" can fix that forya??

  • Smells_Homeless

    I truly dread the day my organ doesn't light up completely. It has more tubes than the average sewer.

    /It's a 43 Hammond Model D, ya weirdos.


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