[clug] Ubuntu 8.1 on Toshiba Tecra black screen problem

doris ann doris at pcug.org.au
Fri May 15 03:16:30 GMT 2009

Hi. I'm new to this list.
Can anyone offer some suggestions on this problem with my laptop, please?

Problem summary:
no backlight on laptop, black screen, no response to live cd, no change 
to new inverter, it is running an external monitor ok

I'm new to Ubuntu, installed 8.1, and it was running for a couple of
months before this black screen problem occurred.

laptop Toshiba Tecra A8-S8414,
display 15.4" TruBrite TFT LCD 128x800 wxga,
Intel Graphic Media Accelerator 950, 8MB graphics memory.

Externally shining a bright light into the black laptop screen, reveals
that the text is there, but no backlight.
Just before it failed, the screen was flashing intermittantly.
Also on power-up, the screen WAS illuminating for about three seconds.

Is it something I did? A few days before the problem, I made some
changes via System/Preferences/Power Management.
Under tab "On AC Power": I moved the slider switches to different times,
and checked the box "Dim Display when idle."
Under tab "On Battery Power: Also moved the slider switches,
and checked both boxes to:"Reduce backlight brightness" and
"Dim Display when idle".

For a couple of days, it seemed to be working with those changes, but
then, flashing, and then black.

As a result of the black laptop screen, I connected an external monitor
to the system, and the external monitor works ok.

I have also removed the checks on System/Preferences/PowerManagement
boxes: "Dim Display when idle" and "Reduce backlight brightness" boxes.

Boxes unchecked, however, the problem persists on the laptop monitor.

The function key to increase brightness [Fn]+[F7] does not change the
black screen.

I saw a post (http://linuxhappy.wordpress.com/2007/12/17/bright...) that
said to try Ctrl+Alt+F1 and then Ctrl+Alt+f7.
That sequence of keys gave me three seconds viewable on my laptop
screen, although the color was red and washed out. Then it went black
Now, the black screen stays black - no response to that technique.

In terminal mode,
sudo gconf-editor /apps/gnome-power-manager/backlight
and unchecked idle_dim_battery.
That didn't make any difference to the dark screen problem.

Yet another post (http://ubuntuforums.org/archive/index.php/t-75678.html),
said to try adding a second line to /etc/acpi/resume.sh,
adding /usr/bin/toshset -bl on
Again on powerup, that made no difference either.
So, not knowing what I'm doing, I removed the line I added.

And from info on another post
(http://ubuntuforums.org/archive/index.php/t-976384.html), I ran lspci
to obtain video info:
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS,
943/940GML Express Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME,
943/940GML Express Integrated Graphics Controller (rev 03)

 From this http://ubuntuforums.org/showthread.php?t=1115429
I followed the directions,
esc on bootup into -11 generic (recovery)
Then selected xfix Try to fix X server
then, resume Resume normal boot
However, I still have a black laptop screen.

I tried a live cd of PuppyLinux and had the same black screen result, so
I bought an inverter and hoped it would fix the problem.

It didn't. I returned the original inverter back into the laptop.

As before, if I put a bright light against the laptop screen, I can see
the contents of the screen dimly (same contents as on my auxilliary

An external monitor connected to the laptop works ok.
Does that mean the video card is ok.

Could the problem still be the video card?
Or the LCD?
Or is it software related - because of the changes I made?

I have noted that there is a lot of discussion regarding backlights on
laptops in the Ubuntu forums.

I don't know whether to think the problem is purely hardware or
software induced.

I'm planning to do a clean install of Ubuntu 9.04 just in case the 
changes I made had a temporary effect on the hardware.

Any thoughts about what the problem might be and how to fix it?

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