iM 4,1-14,4 Weird keyboard problem on my iMac (late 2013, 27, OCLP)

[pkw]

Recently my keyboard has been acting strange (Apple extended wired keyboard) - producing that system sound as if some invalid keys were being pressed. A couple of times it was a constand one like a stuck key, I unplugged the keyboard and plugged back and it stopped.

But today I noticed with the Accessibility Keyboard open that left and right arrow keys seem to press F5 and F6 at the same time, respectively, and it produces that sound, the cursor moves but it inserts characeters in text editor when I press arrow.

I reset NVRAM/SMC and started in safe mode, no help. Also the keyboard doesn't have any dust on it, I removed the affected key caps and cleaned with isopropyl alcohol. Also didn't solve it.

I didn't do anything to the system recenty except updating OCLP (I'm running Sonoma). I opened this iMac to upgrade SSD and clean it a while ago, and there was no problem with anything until a cuple of days ago when this keyboard problem appeared.

 

[DeltaMac]

Turn on your keyboard viewer (do a search for that in your system settings), and you can test the keys on your keyboard. I suspect you will find that you have a key, or two, that are not responding properly to your keypresses.

 

[pkw]

Thank you. I did check with keyboard viewer (as mentioned) but now I tested all the keys and

vol up key activates both vol up and Esc
§ activates ` but types § ok and vice versa (? my layout is GB)
\ does not activate on screen but types \ ok
left arrow activates both left arrow and f5
right arrow activates both right arrow nd f6

The first and last one produce the sound.

 

[Nguyen Duc Hieu]

Faulty circuit of the keyboard, I guess.
Nothing you can do on the software to fix a hardware issue.

 

[Raging Dufus]

Apple keyboards, like any piece of hardware, will flake out and downright fail sometimes. Here is a story about how I got a whole iMac for free because the previous owner thought the computer was broke, when instead it was just a faulty Apple wired keyboard.

I'm still using that iMac as my daily driver running Monterey - absolutely nothing wrong with it.