Mac – shift + p does not work on apple keyboard

hardware-failurekeyboardmac

I recently bought a used apple keyboard on ebay and today I had to realize that the following is not working:

  • Left Shift+P and Right Shift+P doesn't print a capitalized P
  • Right Shift+0 doesn't print a = (it's a german layout)

The keys Left Shift, Right Shift, P and 0 themself are all working fine. Only in the above combinations they do not work. So it doesn't seem to be a problem with the keys themself.

I tested this on a mac with macOS as well as on a PC with Windows 10 and it's the same problem with both of them. Therefore I don't believe that it is a software issue.

The keyboard is a wired one with an aluminium body and a numpad.

What could be the reason for this? Is it likely that it can be fixed, e.g. by cleaning the keyboard somehow?

EDIT:

After reading about this specific symptoms where a shift does not work with certain other keys I read that if another key on the same path isn't working for any reason it can lead to this behaviour. In this specific case Left Shift+O wasn't working because 2 on the keypad was wedged down by a food crumb and didn't come up again. I will test when I am back home and report if it solves my problem.

EDIT 2:

After inspecting the issue in the keyboard viewer it shows that the 6 on the numpad always shows as pressed. I removed the plastic cover of the key and cleaned it with a q-tip and alcohol but the problem still persists. Also when I plug the keyboard in while being e.g. in a text editor it types a 6 once although I did not press it.

Best Answer

This problem seems to occur for quite a few people. It happened to me (failed Shift+p key, but caps-lock works), faulty 6 on the number keypad, the Right-Shift+0, and the left-Command+/. There's a long discussion at https://forums.macrumors.com/threads/only-one-key-is-not-functioning-in-keyboard-of-my-macbook-pro.631264/, but not many effective solutions. If you have it under warranty, Apple seems to replace the keyboard if this issue occurs. For the rest of us, it's not clear what you can do. Mine happened after cleaning the keyboard, and this is also not uncommon (see https://discussions.apple.com/thread/3891120) -- people suggest using alcohol or distilled water to remove contaminants, but I'm not at the point of risking that yet.

Overall, my guess is that the weirdness of the issue (i.e., the weird key combinations) is because these Mac keyboards do not use n-key rollover (https://en.wikipedia.org/wiki/Rollover_(key)#n-key_rollover)

In short, there doesn't seem to be a reliable fix, other than replacing the keyboard.

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