Console rotates through all tty's after sitting for a bit

Valeri Galtsev galtsev at
Thu Jan 21 15:35:36 UTC 2016

On Thu, January 21, 2016 2:23 am, Malcolm Matalka wrote:
> Polytropon <freebsd at> writes:
>> On Wed, 20 Jan 2016 10:11:24 -0700 (MST), Warren Block wrote:
>>> On Wed, 20 Jan 2016, Malcolm Matalka wrote:
>>> > I installed FreeBSD on a machine (Dell OptiPlex 7010).  I'm in the
>>> > regular text console and if I just leave it, it starts rotating
>>> through
>>> > all the tty's rather than going into a screen saver or anything (I
>>> have
>>> > explicitly set the screen saver to a Blank screen).  It did this
>>> during
>>> > the install process as well.
>>> >
>>> > Has anyone experienced this and know why?  It doesn't seem to
>>> > negatively affect anything so far, it's just annoying.
>>> Something is hitting the PrintScrn key.
>> My first thought exactly. :-)
>> Check the physical keyboard, and if it is a wireless keyboard,
>> check possible "offending" other keyboards of that kind, too.
> Interesting.  It's a wired, but USB, keyboard.  The keyboard itself is
> in Swedish but I am using an English (US) keymap.
> I'm curious though, why would this happen after sitting for awhile
> instead of all the time?  Just random keyboard driver freaking out after
> idling for a bit?

I only can just speculate. Keyboard keys are attached to high impedance
inputs (think CMOS), and as they are arranged as electric matrix, they are
connected through analog switches. Now imagine some key(s) have tiny leaks
between contacts (due to dirt) which may lead to gradual charging of some
capacitance thus running one or more of the input over threshold when
keyboard keys are not hit randomly... Then you may have what you observe.
Of course, this is just a speculation. But as soon as clever person
mentioned it can be some key on keyboard pressed, I would try to rule out
keyboard by replacing it with another one (even it if is the same model).

Sorry about idle speculations. Try to replace keyboard though.


Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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