Ubuntu – Laptop screen goes blank after 33 seconds of inactivity


I have a Lenovo Thinkpad T60 running 12.04.4 LTS, Precise Pangolin; the desktop is KDE. Starting today, the display goes blank after 33 seconds of inactivity. Clicking or even moving the mouse, or pressing a key, resets the 33-second timer.

I have checked the following settings:

  • System Settings / Screen Saver Settings (screenshot): These are turned off. Turning them on and setting an explicit timeout of 9 minutes did not change the behavior.
  • System Settings / Energy Saving Settings (screenshot): These are turned off. Turning on "Dim Display and setting to 10 minutes did not change the behavior.
  • X server settings (xset) : The xset q command reported:

    Screen Saver:
      prefer blanking:  yes    allow exposures:  yes
      timeout:  0    cycle:  600

    The timeout: 0 indicates that the X screen saver feature is disabled. Explicitly disabling it with xset s off did not change the behavior.

How do I stop this annoying screen blanking?

Best Answer

The problem was in the DPMS settings. These are settable in two places:

  • Under System Settings / Configure Energy Saving Settings / Screen Energy Saving. (Screenshot). Enabling this and then disabling it again fixed the problem.

  • Under the X server DPMS settings, accessible through xset. The output of xset q included:

    DPMS (Energy Star):
      Standby: 33    Suspend: 49    Off: 66
      DPMS is Enabled
      Monitor is On

which explains the 33 seconds. Enabling and disabling “Screen Energy Saving” as described above reset this to:

DPMS (Energy Star):
  Standby: 21600    Suspend: 32400    Off: 43200
  DPMS is Disabled

presumably the command xset -dpms or xset dpms off would have fixed the problem in the same way.