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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?).

user1068446
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  • I just looked at this video - I might need to get a mechanical pencil, and try that trick. – user1068446 Oct 30 '13 at 09:01
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    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. – AndrejaKo Oct 30 '13 at 09:47
  • 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. – AndrejaKo Oct 30 '13 at 09:50
  • I will get a mechanical pencil tomorrow, and see if that works, and report back. – user1068446 Oct 30 '13 at 09:52
  • @user1068446 Any pencil will work, not just a mechanical one. It's the graphite lead that's important. – Passerby Oct 31 '13 at 05:13
  • @Passerby The idea is to just draw where the black contact area is, right? – user1068446 Oct 31 '13 at 05:16
  • @user1068446 yes, just like in that video. – Passerby Oct 31 '13 at 05:22
  • So I did the pencil trick, and that didn't solve it. I've taken a photo of the board here. http://tinypic.com/r/11cdz6s/5 The contact that isn't working is the third from the right.

    You can see that the each part of the contacts share a path with all the other contacts, and then there's the two paths that go up to two metal links. These are resistors on the other side of the board. Is it possible that a resistor has burned out?

     – user1068446 Oct 31 '13 at 20:02
  • Otherwise it would seem that the issue is where the contact board plugs into the rest of the keyboard (where the USB port is). ie. a problem with the plug. Would the pattern of which contacts aren't working help determine this? – user1068446 Oct 31 '13 at 20:21

1 Answers1

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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

smashtastic
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