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.

11 thoughts on “Oscilloscope VFD Repair Like Doing Brain Surgery On Yourself

  1. >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)

    1. 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.

      1. 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.

    2. 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. 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.

    1. ive tried using my volt meter to measure its own battery, bad idea!

      due to how things where wired internaly, i wound up shorting the battery out thru the test-leads for a moment

      didnt really cause any harm, but didnt work either

    1. 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

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.