MacBook inserting numbers while typing.
January 11, 2014 4:42 PM   Subscribe

My roommate's MacBook has suddenly started inserting certain numbers behind certain letters while she's typing (and vice versa).

She's not accidentally hitting number keys, and the letter/number pairings are consistently the same; whenever she types b, it's followed by 5, and likewise for c/3, m/7, n/6, v/4, x/2, z/1, comma(,)/9 and period(.)/0. The reverse happens when typing numbers (5 is automatically followed by a b, etc.). This is a 2013 MacBook running OS X 10.8.5. Is there some sort of numeric keypad emulator mode that accidentally got switched on? If so, how to turn it off? Or is this a hardware issue? Or something else entirely?
posted by cathodeheart to Technology (7 answers total) 1 user marked this as a favorite
What happens if she plugs in a USB keyboard?

To be honest my first thought is that she spilled something in the keyboard and it shorted.
posted by empath at 4:48 PM on January 11, 2014 [1 favorite]

Response by poster: Unfortunately, we don't have a USB keyboard handy. And as far as we know, it has never been spilled on.
posted by cathodeheart at 5:00 PM on January 11, 2014

Reset the SMC. Follow all the instrucions in order.
posted by blob at 5:01 PM on January 11, 2014

It sounds to me like something conductive is lodged in the keyboard, along a part of the matrix of wires which handle the top row and the bottom row. Look at where the two pairs fall, and you'll see the pattern.

You can look at the keyboard viewer, which is turned on in the Keyboard System Preference Pane, and then opened with an icon in the menu bar.

If you turn the keyboard viewer on, and type the offending letters, do the numbers also light up? If so, probably something sitting on a couple of traces in the keyboard sandwich.

You can sometimes get the offending particle to move by turning the computer over and shaking it, or by using canned air, but replacing the keyboard is sometimes the only way.
posted by tomierna at 5:28 PM on January 11, 2014

This exact thing happened to my Mac down to which numbers were being inserted. I believe the tech said keyboard short as suggested by empath. Some sort of hardware problem, anyway. I do know that the Genius Bar at the Apple Store couldn't fix it onsite and I had to have them send it off to have something replaced. (Free as I was still under warranty--does your roommate have AppleCare?) The tech was suspicious of a spill/checked for one, which also indicates the problem was a short. Can you get to an Apple Store? Either way, I'd back up because something is probably going to need to be fiddled with. (Technical terminology, I know.)
posted by HonoriaGlossop at 5:29 PM on January 11, 2014

Response by poster: Using the keyboard viewer shows that the letter and numbers are both lighting up when the letters are pressed. SMC reset doesn't seem to fix the issue, and shaking it hasn't dislodged anything as far as we can tell. Looks like she'll have to bring it in to an Apple store. Thanks for the answers so far, it's been helpful narrowing down what's going on.
posted by cathodeheart at 5:52 PM on January 11, 2014

Try fn-F6, which should unlock the num-lock.
posted by acorncup at 12:09 PM on January 13, 2014

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