Firstly, apologies that I'm not an electrical engineering enthusiast, I just have a piece of hardware that's stopped working, and I want to get it solved.

I have a midi keyboard, and some of the keys have stopped working. So I opened it up and cleaned the contacts with contact cleaner.

The same keys don't work. I tried pressing the pads directly, and they don't work.

Does this just mean that the contacts are burned out and there's nothing I can do about it? Or is it possible that the cause of this is some where else? (On the multi-pin plugs?).

  • \$\begingroup\$ I just looked at this video - I might need to get a mechanical pencil, and try that trick. \$\endgroup\$ Oct 30 '13 at 9:01
  • 1
    \$\begingroup\$ If your keyboard is similar to the one shown in the video and has been used for a while,then it's quite possible that the contacts themselves are dead. Basically they printed two carbon shapes onto the PCB. When you press the key, the pad on the bottom of the rubber dome connects the two shapes together. Over time, the carbon wears out by using a graphite pencil, you can add some more. There are special sprays that can be used to repair such contacts, but I've found them messy to use. \$\endgroup\$
    – AndrejaKo
    Oct 30 '13 at 9:47
  • \$\begingroup\$ The other problem is that you only seem to know that the key aren't working. We provide a good answer with just that. Most likely cause in my opinion is the key contact deterioration, but the actual problem could be more or less anywhere. \$\endgroup\$
    – AndrejaKo
    Oct 30 '13 at 9:50
  • \$\begingroup\$ I will get a mechanical pencil tomorrow, and see if that works, and report back. \$\endgroup\$ Oct 30 '13 at 9:52
  • \$\begingroup\$ @user1068446 Any pencil will work, not just a mechanical one. It's the graphite lead that's important. \$\endgroup\$
    – Passerby
    Oct 31 '13 at 5:13

Use a graphite pencil to clean up the pads of the PCB.

See this video for example instructions. https://www.youtube.com/watch?v=LepU7L2qFdw


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