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EEVblog #1334 – Mystery Dumpster Teardown

Mystery dumpster teardown time! With the most amazing mechanical mains power switch you’ll ever see! ...


  1. Nice review.

    I have one or two of that brand around. Not precision.

    What I took note of was your description that the to-3 transistor was dissipating the full series pass wattage.

    In my greybeard test equipment repair days, My unit was marketed as “this design dissipates the heat outside of the cabinet”.

    In my unit, there is a big resistor mounted in a cage behind the unit.

    The series pass transistor would be in parallel, and just ” trim” the voltage drop.

    Now you have made me want to keep them for display.

    Looks like I will never clean out my man cave in my lifetime.

  2. Fascinating. That looks like a Sziklai pair rather than Darlington series pass configuration.

  3. R83 Cal resistor, without value. Hmmm..
    Synthetase: thank you, another famous Hungarian, Sziklai György! 🙂

  4. I kinda started collecting these. Have five here on the desk right now (2 of newer design). I like to clean and calibrate them. They are not very precision until you clean the switch contacts really good. Then they are spot on.

    I bought a few for about $15 in not working condition. They came and worked perfectly. That was a disappointment 🙂

  5. You can take the oven apart pretty easily. Just undo the 3 screws on the bottom, Twist and pull up the red can. Then you can pull out all the circuitry inside. It is on a board with a connector. There is a lot of insulation in there (asbestos? or glass fiber) though.

  6. Mission Engineering

    Nice. That looks like a turret board. Some tube (valve) guitar amps are still wired this way today!

  7. Dave I would appreciate one of your Fundamentals Fridays about transistors, an insight on what the figures on their datasheets mean and some “traps for young players”. If you want to add some transistor configurations then better too! Thanks (:

  8. Michael Bo Madsen

    I was only 4 years old when the power supply was manufactured. I would
    love to see more, because it looks like the same as the first transistor
    electronics I designed as a teenager in the late 1970s, and improved
    later when I got to know the 741 ic. after that, my cheap analog
    multimeter no longer sufficient to measure the improvements. Try to zero
    trim using the R39

  9. I know those boards as “Peg boards” but I don’t have a beard at the moment so I could be wrong.

  10. Maybe be a bit more forgiving of more modern constructions that have components hanging upside down with stretched out wires all higgledy-piggledy if you think this looks lovely, Dave!! It is not often the looks inside the box that count, you fickle creature.

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