The Repair And Refurbishment Of Silicone Keyboards

There are a lot of retrocomputers out there sitting in garages and attics, and most of them need work. After thirty or forty years, you’re looking at a lot of corrosion, leaking caps, and general wear and tear. When it comes to extreme refurbishment, we haven’t seen anyone better than [Drygol], and this time he’s back with an exceptional example of how far repair and refurbishment can go. He’s repairing the silicone keyboard of a Commodore 116 using some very interesting techniques, and something that opens up the door to anyone building their own silicone keypad.

This project comes from from a member of a demoscene group that found an old C116 that needed a lot of work. The C116 shipped with a silicone membrane keyboard instead of the mechanical keyswitches of the C64 and other, higher-end computers. Unfortunately, this silicone keypad had a few keys ripped out of it. No one, as far as we can tell, has ever figured out how to make these silicone keypads from scratch, but [Drygol] did come up with a way to replace the ripped and missing keys. The process starts with making a silicone mold of the existing keyboard, then casting silicone into the negative of that mold. After a few attempts , [Drygol] had a custom silicone button that matched the shape and color of the original C116 keyboard. The only thing left to do was to attach tiny conductive carbon pads to the bottom of the newly cast buttons and fit them into the existing keyboard.

This is an interesting refurbishment, because there are a lot of vintage computers that used silicone keyboards in the place of mechanical keyswitches. The Speccy, The Commodore TED machines, and a lot of vintage calculators all used silicone keyboards. Until now, no one has figured out how to make DIY silicone keypads, and repairing silicone was out of the question. [Drygol]’s attempt isn’t perfect — it needs key labels, but screen or pad printing will take care of that — but it’s the best we’ve seen yet and opens the doors to a lot of interesting projects in the world of vintage computer repair.

19 thoughts on “The Repair And Refurbishment Of Silicone Keyboards

    1. Screen printing is pretty easy. I bought a kit from Amazon (£40 from “Hunt the Moon”) and printed a set of STMBL servo drive cases. It went right first time, using sunlight exposure. I was astonished. To my further surprise the water-based ink takes well on painted metal and cures fairly resiliently.

    2. Wasn’t a perfect repair but still impressive that all the keys now work on it.
      Fun fact the C116 machines were originally intended to sell for $79 new to compete with the Speccy which is why there’s a lot of cost engineering in them.
      Commodore’s new management after Tramiel left had decided to try and market it as another C64 which it wasn’t and was instead originally intended to be a new Vic-20.

  1. How well do the little carbon rubber contacts stick to the original silicone. I would think nothing will. This problem is in almost all keyboards both piano and organ and is a major service problem.

    1. I’ve always assumed that the most durable were the ones where the pad is actually conductive silicone itself and just molded at the same time as the rest so it all becomes one.

  2. Oh good a non-hyperbolic Benchoff write up. This has been done for well over 6 years in certain communities. There are even full replacement kits available for a reasonable amount of money (<$30) so spare us the disbelief.
    Kudos to drygol for getting in there and learning something.

    1. “Oh good a non-hyperbolic Benchoff write up. This has been done for well over 6 years in certain communities.”

      Please tell us of the “certain communities” that have had “non-hyperbolic Benchoff write up[s]” in the past 6 years!

    2. Hmm… I wasn’t aware of that and believed mr. B on his word, still I’m not surprised by someone saying that it has already been done. But, to save us all the trouble of finding out ourselves, could you please give some examples?

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