Today I did a reboot of my M2 Mac Studio. Upon reboot, the keyboard did not generate characters and I was unable to log in.
This is an Apple A1243 wired USB-A keyboard, Mac M2 Studio, Sequoia 15.3.2.
Normally it is plugged into the rear USB-A port. To check the port I plugged in other USB peripherals (including an even older Apple keyboard) and they worked fine. So probably not the port.
Next, I used an Apple USB-A to USB-C adaptor and plugged it into the front USB ports. It works. I also tried plugging it into the USB-C ports on the back of the Apple 27" Studio Display. It works.
So the ports are good and the keyboard is good but the keyboard does not work in the rear USB-A port.
I tried doing an NVRAM reset (via terminal; sudo nvram -c) and also a Safe Boot but the problem remains.
So I went to to lunch and when I returned it was working. It’s not a “Magic Keyboard” but that sure is some kind of magic.
In the absence of any other information, I’m inclined to believe that the keyboard itself has an intermittent problem. Perhaps the cable has gotten damaged over the years and it just isn’t always making good contact. This happens with lots of electronics.
Is your mouse plugged into the Apple keyboard? Does it work when they keyboard isn’t working? If so, then that would clearly rule out a cable issue. If not, then maybe…
The next time the keyboard drops out, see if you can use your mouse (maybe plugged in to something else) and check the system information (option-click the Apple menu) to see if the keyboard is seen on any of the USB buses.
Unfortunately, the A1243 has a hard-wired cable, so you can’t just swap it (unlike the Magic Keyboard, where the charge-cable works as a data cable and is replaceable).
I should have mentioned that this happened once before about a week ago – and it happened after a reboot.
The mouse is plugged into the right side of the keyboard. When the keyboard fails (after a reboot) the mouse also fails and the mouse cursor is always located in the upper left corner of the display.
I used my very old Apple Pro keyboard (A1048) plugged in to the front USB-C ports (using an A-to-C adaptor). The System Information did not show the A1243 keyboard.
Now that it’s working again, here is what System Information has to say.
I had a similar problem whilst travelling in 2023. I was trying to use an M2 MacBook Air (running macOS 12.5) with a A1243 wired keyboard (same model as the OP).
I plugged the keyboard in to the Mac, using a USB-A to USB-C adaptor. The keyboard didn’t function, didn’t show up in System Information.app, and the caps lock light on the keyboard didn’t come on when I pressed caps lock.
This problem persisted when I tried a different USB-A to USB-C adaptor (an entirely different design), when I flipped the USB-C connector 180° into the other orientation, and when I tried the other USB-C port on the Mac.
The keyboard worked when I plugged it in to an older Mac (mid 2012 MacBook Pro).
One of the suggestions at this Stack Exchange question worked for me: I added a 2 metre long USB-A extension cable, and it worked, much to my surprise.
The most plausible explanation I’ve seen for this was in another answer at that same Stack Exchange page, which suggests that “the keyboard draws so little current that it won´t wake the port”. That author suggests plugging a USB memory stick into the keyboard, to increase the current draw. (And I suppose adding an extension cable will add some resistance, also increasing current draw.)
Note the Stack Exchange answers I’m referring to here date from 2015, so this issue seems to pre-date Apple Silicon. Magic indeed!
It sounds to me like there’s a break somewhere in the USB cable. When it is flexed just-right, it makes contact and the keyboard works. When it’s not, there’s no connection.
If you’re handy with a soldering iron, you could probably replace the cord with a new one. Otherwise, I think the failure will happen with increasing frequency until it finally dies altogether.
Looking at iFixit, there are no repair guides for this keyboard and there are no user-serviceable parts inside. But looking at its teardown, it appears that the USB cable’s four wires are soldered to the surface of the logic board:
So, if you can open and close it without damaging anything (and this may be difficult to do), the cord should be replaceable.
Alternatively, you might be able to just cut the cable 1-2" from where it enters the keyboard, cut the end off of a USB-A cable, and solder the two together. Use some heat-shrink tubing to insulate the result and make it look pretty. Of course, if the damage in the cable is close to the keyboard or if it is inside the keyboard assembly, then this won’t do a thing.
I haven’t measured, but I’m using the same keyboard with a mid 2011 iMac at the moment, and there, System Information.app reports “Current Required (mA): 20”.
I had the opposite result. I was already using the Apple-supplied USB extension cable. When I removed it the keyboard worked again. Suspecting the extension cable to be at fault, I tested it separately and it works as designed.
The graphic I posted earlier shows the keyboard draws 20 mA. The mouse–plugged into the keyboard hub–draws 100 mA.
The combination of keyboard and mouse–as shown in the graphic above–is 120 mA which should be enough if that was the reason.
