12 votes

Fixing a broken popcorn machine

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So we have had this popcorn machine for ages and just recently it completely stopped working. Being a fan of bigclive on youtube I though why not try fix it and maybe get a sense of how it works.

The guts

The insides honestly are pretty underwhelming - both the impeller and heating elements are quite small considering it only takes a few minutes to make a bowl of popcorn.

Circuit board and Another shot

Considering how few components there it was not too time-consuming to draw up a diagram. Please excuse the crude drawing.

From what I can tell it uses a bridge rectifier with a some caps to convert DC and even out the signal - and what looks like two resistors to further drop the voltage to the motor, maybe two offered better cooling? idk why they didn't use one. It's also kind of interesting how they used two separate coils for the heating with one of them in series with the motor, that will drop the voltage right?

They also have overheating protection here, with a an sefuse and a thermo switch, it actually has the piece of metal and a contact that will bend away when it's hot, I've only seen these in a textbook. Not sure why there are two types of thermo fuses?

The fault

Finding the fault ended up being quite easy, the main heating coil that comes off blue wire had melted. A piece of corn, oil, bits of salt or a mixture had found their way in and somehow melted the wire in multiple places. It cut the circuit so not even the motor was working which was my initial though when it stopped. I wound some solid core wire around the two ends, hopefully it will not unfurl or melt in the heat.

6 comments

  1. [4]
    cfabbro
    (edited )
    Link
    Being able to do these sorts of electronics fixes myself is exactly the reason I recently bought myself an Arduino starter kit and dug out my old soldering kit from storage... so I can start to...

    Being able to do these sorts of electronics fixes myself is exactly the reason I recently bought myself an Arduino starter kit and dug out my old soldering kit from storage... so I can start to learn the basics of circuitry. It's kind of sad that after years of working in IT and even doing cleanroom work dismantling HDDs for a computer forensics/data recovery firm, I still don't actually really know how a circuit works. :(

    However I aim to fix that... so speaking of which, does anyone know any good tutorials or resources for starting down this path with an Arduino (or Raspberry Pi, which I am also thinking of buying)? The arduino kit I bought has a bunch of basic tutorials for using the included parts but they mostly seem geared towards a younger/casual audience, so I don't know how useful they will be for actually learning about circuitry and electronics.

    2 votes
    1. [2]
      s4b3r6
      Link Parent
      A few books that might be helpful came up in this thread.

      A few books that might be helpful came up in this thread.

      1 vote
      1. cfabbro
        Link Parent
        Those book recommendations are all on the programming side, rather than the basic circuitry side, but will still be useful for later once I do learn the basics first, so thanks. :)

        Those book recommendations are all on the programming side, rather than the basic circuitry side, but will still be useful for later once I do learn the basics first, so thanks. :)

        1 vote
    2. nsz
      Link Parent
      Well as silly as some of the basic exercise are it is helpful to go over them mainly because in trying to debug what's wrong you learn the most. I find best to work on a larger project and then...

      Well as silly as some of the basic exercise are it is helpful to go over them mainly because in trying to debug what's wrong you learn the most. I find best to work on a larger project and then look up how to do the various individual parts as you go. Instrucaabels is a good place to look for inspiration along with material to learn from.

      1 vote
  2. [2]
    Lynx
    Link
    Imgur links are broken for me on Android Firefox, they just redirect to the main imgur page.

    Imgur links are broken for me on Android Firefox, they just redirect to the main imgur page.

    1. nsz
      Link Parent
      ah damn, I tried to get around the imgur site by using direct links to the images, I added this album link to the top of the post so hopefully that should work.

      ah damn, I tried to get around the imgur site by using direct links to the images, I added this album link to the top of the post so hopefully that should work.

      1 vote