Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: Keyboard problem

  1. #1
    Join Date
    Jan 2008
    Location
    queensland, australia
    Beans
    165
    Distro
    Ubuntu

    Keyboard problem

    I can’t decide whether this is a hardware or software problem:

    I am typing an email (Thunderbird) or a document (Libreoffice) and randomly, after a few minutes or a few hours, the Shift key sticks on and I find myself typing in upper case. If I hit the Shift key, it will revert to lower case either immediately or after several attempts. A simple case of a stuck key? No, I have tried three keyboards with no change. I have tried different USB ports and have checked the motherboard voltages in BIOS.

    All other keys seem to work normally.

    Restarting the computer always fixes the problem, for a few minutes or a few hours. As an electronics engineer I am used to dealing with hardware issues but this doesn’t feel like one.

    Anybody got any bright ideas?

    Ubuntu 21.04
    Gigabyte B360M-HD3

  2. #2
    Join Date
    Sep 2009
    Location
    Pennsylvania
    Beans
    3,596
    Distro
    Xubuntu

    Re: Keyboard problem

    Well I agree with you that it doesn't feel like a hardware problem, it feels even less likely a software one. Are you by chance using any USB hub on the machine at all? Do you have the capability to actually measure the voltage of the 5 volt line? A meter that will give (and store) your minimum voltage would be helpful. Try running the PC without ANYTHING else connected to any port. Does that help?

  3. #3
    Join Date
    Jan 2008
    Location
    queensland, australia
    Beans
    165
    Distro
    Ubuntu

    Re: Keyboard problem

    Thanks for your advice. No USB hub. It is a pity that lm-sensors doesn't support the sensing chip on my motherboard but I now have a DMM sitting on the adjacent USB port, 5.06V at present. When the problem occurs I can check the voltage again.

    I have no other USB devices connected apart from the mouse, which I have changed. I do have an RJ45 LAN connector, an HDMI monitor connector and an analogue audio connector. I can't see what effect they may have on my problem?

  4. #4
    Join Date
    Mar 2007
    Location
    Promiseland
    Beans
    1,204
    Distro
    Xubuntu 20.04 Focal Fossa

    Re: Keyboard problem

    That used to happen to me occasionally, but I figured out I was inadvertently pressing the Caps Lock key instead of one of the adjacent keys, Tab or Shift. This is what I did...
    # Keyboard tips
    Swap keys, Caps Lock with Escape
    Edit /etc/default/keyboard
    change the line
    XKBOPTIONS=""
    to read
    XKBOPTIONS="caps:swapescape"
    save the file
    reboot
    test the newly reassigned keys
    Then I made a little note and stuck it to a flat space on the upper part of my keyboard, 'CAPS Lock switched with ESC.' I think Google had the right idea with eliminating CAPS Lock from Chromebooks.
    Cheers,


    The Linux Command Line at http://linuxcommand.org/

  5. #5
    Join Date
    Sep 2009
    Location
    Pennsylvania
    Beans
    3,596
    Distro
    Xubuntu

    Re: Keyboard problem

    I have no other USB devices connected apart from the mouse, which I have changed. I do have an RJ45 LAN connector, an HDMI monitor connector and an analogue audio connector. I can't see what effect they may have on my problem?

    I don't think that any of them would cause the problem. I really think that something is pulling that 5V line down too low. I have seen it happen too many times for too many different reasons including a hard drive that would pull almost 3 times the amperage that it was supposed to pull. That one took a little while to figure out. I know that you don't have this, but I have a powered USB port sitting right here which is now just a rather expensive fast charger for my cell phone. At times, when booting, it would cause my monitor to change resolution, my keyboard and/or mouse to quit working. And they were NOT hooked up to it! Only way to fix it was to power it down and back up again. That would last several weeks at first, Then several days, then minutes.

    If you don't find any problem with the 5V line, check the 12V next just to be sure. If your power supply is OE, that could very well be the problem since they usually just have enough power to run the machine the way it was built when purchased. I always keep 2 or 3 extra, new PSUs around. Can go a year w/o seeing a bad one and then run into a couple in a week's time.

  6. #6
    Join Date
    Jan 2008
    Location
    queensland, australia
    Beans
    165
    Distro
    Ubuntu

    Re: Keyboard problem

    @him610
    Definitely not Caps Lock as other shift functions (!@#$ etc) occur when the fault appears. Thanks for the suggestion anyway.

    @ Autodave
    I set my Fluke DMM to MIN after booting my PC. I induced the fault in Writer by pressing the Shift key and a letter a few times. Minimum voltage 5.04V so that can't be it. How would the 12v line affect the keyboard? I built this PC myself using a Gigabyte PW400 PSU which is more than adequate for the other hardware (SSD and DVD). If it was a PSU problem wouldn't it affect other keys? It just acts like a faulty key but I have eliminated that by changing keyboards. Weird.

  7. #7
    Join Date
    Sep 2009
    Location
    Pennsylvania
    Beans
    3,596
    Distro
    Xubuntu

    Re: Keyboard problem

    The 12V line will not directly affect the keyboard, but it could be affecting something else which could be causing a problem. If you have the ability to get a maximum over/under reading on your Fluke, just do it and then you'll know.

    Another idea just to see if it is a software glitch: make a bootable medium and boot to it and run from that. If you still have the issue, you can be pretty sure that it is hardware at that point.

  8. #8
    Join Date
    Jan 2008
    Location
    queensland, australia
    Beans
    165
    Distro
    Ubuntu

    Re: Keyboard problem

    Thanks Autodave. I do have a live USB stick so I'll give that a go and report back - it might be a while.

  9. #9
    Join Date
    Jan 2008
    Location
    queensland, australia
    Beans
    165
    Distro
    Ubuntu

    Re: Keyboard problem

    I ran 20.04 with a live USB stick for an hour or so with no problem. Not conclusive but it's pointing to a software problem. Back in 21.04 I have disabled Sticky Keys so I'll see how that goes

  10. #10
    Join Date
    Sep 2009
    Location
    Pennsylvania
    Beans
    3,596
    Distro
    Xubuntu

    Re: Keyboard problem

    If you upgraded your 20.04 to 21.04, that could be the problem. I have seen too many weird things happen when one release is updated to another. I learned a looooong time ago to stick with the LTS releases only and to do a clean install after backing up my data.

Page 1 of 2 12 LastLast

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •