A Couple of Logitech K400 Wireless Keyboard Issues

arthurbach88 on 29/03/2023 - 13:18

I have a couple of Logitech K400 wireless keyboards at home (and a couple at work) and generally they work really well.

Just recently one of them developed one issue and another one developed a second, different issue.

  1. The 'O' and bottom-left 'Ctrl' key have stopped working on one of the keyboards.

I purchased a high-powered handheld air compressor thingy and pried the two offending keys off to give them a good blast. Even though one of the keys had a good deal of fluff in it neither key worked post the air-blasting.

  1. The other keyboard requires me to stand really close when I first turn the keyboard on to connect with the bluetooth dongle. Even then it might not turn on until I have turned the keyboard on and off a few times. If I happen to the leave the keyboard on (rather then turning it off in between usage) the issue does NOT occur.

Any ideas?

Thanks

Electrical & Electronics Computer Peripheral Keyboard Logitech

Comments

  • rumblytangara on 29/03/2023 - 13:52
    +2

    I purchased a high-powered handheld air compressor thingy and pried the two offending keys off to give them a good blast. Even though one of the keys had a good deal of fluff in it neither key worked post the air-blasting.

    There is a rubber membrane under the keys, under the membrane there is an electrical contact that registered whether the key is pressed. So an air duster is unlikely to do anything to fix an electrical contact problem. Try getting under the dome and cleaning with a q-tip and rubbing alcohol.

    https://www.ifixit.com/Guide/Logitech+K400r+Wireless+Keyboar…

    The other keyboard requires me to stand really close when I first turn the keyboard on to connect with the bluetooth dongle. Even then it might not turn on until I have turned the keyboard on and off a few times. If I happen to the leave the keyboard on (rather then turning it off in between usage) the issue does NOT occur.

    Then just keep the keyboard on. I don't turn mine off.

    • BewareOfThe Dog on 29/03/2023 - 14:49

      @rumblytangara Yes, I agree.
      The membrane I think was also known as a Mylar.
      Generally there are 2 sheets, which have different patterns, which run to an encoder. Chances are one of the paths is blocked, possibly a breadcrumb, or something else etc. The problem keys despite being nowhere near each other, are most likely on the same path/circuit. You could possibly take it apart from the bottom, and clean the sheets, but take a pick of the key layout, and be prepared to deal with up to 104 pads falling out if you are not careful.
      I was playing with keyboard about 20 years ago, when I was rewiring an arcade cabinet to use with Mame , and you had to make sure that all the keys mapper wouldn't clash, being on the same circuit.

      • rumblytangara on 29/03/2023 - 19:45

        I think that these days the traces are on a standard PCB and the domed membrane only has perhaps a contact on it. It's generally pretty well shielded from contaminants entering from above, which is one reason they're so popular- they're durable as well as cheap to make. It's also just the one big sheet.

        I could be wrong, people don't usually bother to take these things apart anymore, most enthusiasts save their efforts for mechanical keyboards instead.

  • arthurbach88 on 29/03/2023 - 17:08

    The reason I turn it off is because we have the world's most curious toddler running wild in the living room.

    Also, popping off two keys and squirting it with pressurised air is as electronically handy as I get. I'll just suck it up and wait for the next sale I think.

    Thanks for everyone's help.

    • jv on 29/03/2023 - 17:43
      +1

      The reason I turn it off is because we have the world's most curious toddler running wild in the living room.

      When our kids were that age, I just setup an electric fence around the PC.

      Hope that helps…

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