Screen management gone crazy

[franzmaximilian]

Running Kubuntu 14.04 on an old (2011), cheap, laptop that hosted 12.04 before (and something else that I can't remember before that).
Since the beginning I set the video output configuration so that my desktop is output to an external HD monitor via VGA when at home (in this case I keep the lid closed. The laptop is used like a desktop pc, with USB keyboard and mouse as well). When I am not at my home desk, the internal default monitor (1366x768) is used. This way of working did not require any adjustment of settings after boot in any of the two configurations. I suppose this is a very common setting for lots of users.

Now, since yesterday it does not work anymore. I have no idea what happened, if I changed something, if some program or update changed something, or what. For sure nothing was intentional and nobody played with System Settings- Screen Configuration.

What happens now is that I can no longer see my desktop on the internal video alone.
When I boot the laptop without an external VGA monitor I can see the screen up to immediately after KDE login. Then the display turns black (not off, just black). With Ctrl-Alt-F1 (or F2...F6) I can still see and access login into different sessions. Nevertheless the KDE session (Ctrl-Alt-F7) is output to the VGA port, even if nothing is connected to it! Hot plugging the VGA monitor causes the KDE session to appear on both the internal and external monitor.

Ok, then it should be simply a problem of properly setting the video output from System Settings - Screen Configuration.... Wrong assumption! Whatever I set (and save), nothing changes. Even disabling the external monitor has no other effect than causing the display on the internal monitor to disappear.

In short I now have a laptop that I cannot use for a KDE session unless there is a VGA monitor connected. And that is impractical an frustrating as you can imagine...

Any help is welcome!

Franzmaximilian

[elijathegold]

Does your laptop have a Fn key for switching between internal / external monitors?
Could it have been pressed accidentally?
Is unify outputs turned on in the Display configuration?

[franzmaximilian]

Does your laptop have a Fn key for switching between internal / external monitors?
Could it have been pressed accidentally?
Is unify outputs turned on in the Display configuration?

Yes it has the Fn key. If pressed when both monitors are on, it only causes the laptop internal monitor to switch off. If pressed when the only internal monitor is on (but black), it switches off the internal monitor as well. If I reconnect the VGA while in the latter state, the desktop appears on the external monitor.

I do not get what you exactly mean with "unify outputs" in Display configuration. On that screen there is only two actions I can do: toggle on and off one or both the two monitors and graphically move the monitors to overlap (partially, because they are different sizes) or be separated in any direction.

I played with that page a lot in the last few hours, with no useful result at all. If anyone can post a screenshot showing how settings should look like to have the configuration set as described in my first post, I would be grateful.

Thank you anyway for your suggestions.
Franzmaximilian

[franzmaximilian]

My problem is still there!
It looks like if the system "needs" to have an external VGA connected. Otherwise it does not send the correct screen on the internal LCD.
I found that the VGA unit does not need to be on! With the external monitor in standby, the screen on the internal monitor is correct. If I disconnect the cable I see only an imageless screen on the internal monitor. Could it be a hardware issue?
My problem is that I cannot go around with a laptop AND an external monitor!
Any help is welcome!
Franz