3

Ubuntu 18.04.4 Toshiba Satellite A305 PSAG8U-04001W

I want to setup an external monitor to play videos on my TV. It has a VGA port that I can plug into the side of my old Toshiba laptop. The problem is whenever I plug the VGA cable into the VGA port on my laptop my laptop screen goes black but shows my mouse pointer.

I was able to detect the external monitor one time and I changed the display setting to mirror image before the screen went black. Now I can't detect the external monitor (and my screen goes black so I can't see anything anyway)

I tried shutting down my laptop and plugging the VGA cable in before restarting and I can't even see my boot screen

I tried changing the display settings to 800x600 to see if that changed anything - same problem

How do I fix this?

peetah
  • 51
  • 1
  • 5

3 Answers3

3

This is a very frustrating problem that I too am struggling with after upgrading to Ubuntu 18.04.

A temporary solution that I have found is:

  1. Open the terminal
  2. Copy your equivalent of the following into the terminal (but don't run it yet!)

xrandr --output VGA-1 --off && xrandr --output LVDS-1 --auto --output VGA-1 --auto --same-as LVDS-1

  1. Plug in the external monitor. After being plugged in, both screens will go black, but the cursor will still be seen on the primary monitor.
  2. Press 'Enter' to run the line above.
  3. Wait a while. Both screens should start working after a short time. Sometimes I've had to blindly push 'Up' and 'Enter' to run the command a second time before it works.

Unfortunately, the above is only useful in a single session. I haven't yet worked out what options need to be changed where to make it persistent. However, hopefully it gets both your screens running in the short term at least.

When looking at /var/log/syslog at the times when my monitor gets plugged in, there are some entries which I suspect are indicative of the root problem:

gnome-shell: Failed to use linear monitor configuration: No available CRTC for monitor 'VSC VA2226w' not found

gsd-xsettings: Failed to get current display configuration state: Timeout was reached

and then when the monitors are properly displaying:

/usr/lib/gdm3/gdm-x-session[1498]: (II) modeset(0): Modeline "1280x800"x0.0 68.94 1280 1296 1344 1408 800 801 804 816 -hsync -vsync (49.0 kHz eP)

I haven't yet learned how to interpret these, but hopefully they'll help lead us both to a more permanent solution!

lipothyrea
  • 51
  • Wow, that's an amazing workaround. Your grasp of Linux seems far better than my own. I wouldn't even know where to look for the system log on my Linux machine. I more of a Windows person until this point. I'll try it and let you know how it goes! Please keep me updated on what you find. – peetah Apr 12 '20 at 13:57
  • OK, so I ran the xrandr --output VGA-1 --off && xrandr --output LVDS-1 --auto --output VGA-1 --auto --same-as LVDS-1 script and nothing changed. I tried to go to the /var/sys/syslog but I couldn't find it. Where would I go to find that in Ubuntu 18.04.4? On my TV it says there is no signal detected before it shuts off. – peetah Apr 12 '20 at 14:14
  • Thanks! This workaround isn't the most reliable. I had to try it three times this evening before it ended up working. – lipothyrea Apr 13 '20 at 09:26
  • /var/sys/syslog is the file syslog in the folder sys in the root folder var. An easy way to view it is by opening up a terminal and running gedit /var/sys/syslog. It keeps a record of the inner workings of your computer. – lipothyrea Apr 13 '20 at 09:29
  • There's another strange thing that I'm finding with this issue. When I turn on my computer with the external monitor plugged in, both monitors work fine on the login screen. Only after I log in do both monitors go black. Fixing it from here requires unplugging the external monitor and following the steps outlined above. – lipothyrea Apr 13 '20 at 10:16
  • Thanks! it worked – Yusuf Şengün Aug 18 '21 at 09:05
2

Here's my permanent solution to the problem, which required I install:

sudo apt install gnome-session-wayland

Once installed, reboot. When at the login screen, a cog should be visible beside the 'Sign In' button. Click on the cog and choose from a selection of desktop environments. I had four:

  • Gnome
  • Gnome on Xorg
  • Ubuntu
  • Ubuntu on Wayland

The two environments in bold supported the external monitor without any problems.

It seems that Wayland is necessary for my external monitor to be recognised.

This became apparent when preventing gdm3 from using Wayland caused my login screen to fail, when it had previously displayed properly.

From there I was able to find what package was necessary to use Wayland on the Desktop, which resulted in the fix described above.

More information on Wayland and Xorg is available here.

lipothyrea
  • 51
  • I ran sudo apt install gnome-session-wayland and now my symptoms have changed. Now my monitor will flash black with a cursor on it for a few minutes before seemingly dropping the external monitor connection and then showing a regular desktop. I'm still using a VGA cable. I'm wondering if maybe it's my resolution? I tried looking for the VGA connection on my computer but I didn't really know how to see anything - I looked under /dev. – peetah Apr 17 '20 at 19:07
  • Did you try the different desktop environments? That was the critical step for me. – lipothyrea Apr 18 '20 at 09:41
0

I just made lipothyrea's one-session solution permanent by adding the command to Startup Applications, as described here. For some reason, the Alt+F2 method didn't work for me, so I opened Startup Applications via Activities. So far it works if I leave the external monitor connected and restart my laptop.

Jorge G. Merizalde Dobles
  • 1