Oscilloscope VFD repair like doing brain surgery on yourself

[Jerry Pommer] has an old Tektronix 2236 that is having some issues. Just to the right of the top corner of the screen is a VFD display that is used to show various numerical measurements. Unfortunately this has stopped working, so he made the oscilloscope probe itself in order to trouble-shoot the situation.

The entire repair process was filmed and you can see the 42-minute job embedded after the break. There’s a lot of stuff crammed inside that oscilloscope, and we see a tour of it all at the beginning of the video. Once [Jerry] gets down to business he traces the problem to a JK Flip-Flop used to feed the display. The output appears correct at first, but the clock signal is not functioning as expected. His solution is to use an MSP430 chip to replace the Flip-Flop functions.

The confidence to try this repair was sparked by [Todd Harrington's] car-stereo VFD repair video.

Comments

  1. rasz says:

    >CD4027 J-K flip flop as the culprit, and not
    >having one on hand to replace it I had the idea of
    >programming a TI MSP430

    I died inside a little (even more than during the last FVD repair video)

    • Sven says:

      But two of them with shipping will cost over a DOLLAR on ebay!

      I could understand if he stuck the 430 there just for testing, but leaving it there instead of ordering the correct part and making a proper repair in the end? Dumb.

    • Al says:

      LOL. Its like replacing the car’s battery with a nuclear reactor. A little over kill.

      Nice to see what to look for in a dying VFD.

      • messmaker says:

        But he didn’t leave it in there… he said he might actually replace the chip in the future. He only used the TI MSP430 to emulate the 4027 for testing purposes. In the end he only added an 8.6v+ line to the vfd.

    • Leif says:

      I don’t think this was that bad. It’s not like he threw a $50 microcontroller development board in there just because that was the only tool he knew how to use so to him that was the solution to every problem.

      He just used what he had on hand, a cheaper than dirt MSP430 and made his nice tool work again. I can’t watch the video from here but assuming he has it mounted in a reasonably secure way I wouldn’t bother changing anything. It works! He’s only out an MSP430. Why order a new chip, pay shipping, wait, wait some more, wait even longer, finally get the chip and have to open the scope up again. Instead he can be just using it!

      It would be fun to be a fly on the wall if he ever sold it and if the new owner had to do repairs on it, opened it up and had a nice WTF moment. What are the odds of that though?

  2. thatcherc says:

    Brain surgery? Well that’s not exactly rocket surgery, now is it?
    Sorry, had to do that.

    Very neat, however. I wouldn’t have thought you could use a tool to repair itself.

  3. Slanderer says:

    It’s far more ballsy to use your soldering iron to make some repairs to itself.

    • NewCommentor1283 says:

      lol! ive actually SEEN THAT!!!! its hilarious when it ends in a bunch of swear words and ONE MORE broken iron… hahahahaha

      he was a professional working in a real repair shop. i had to leave until i stopped laughing

      i guess that was his “bad day” XD

  4. pcf11 says:

    Poor old scope. I have a 2336 myself and the Y option display is going on it.

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