[clug] Ubuntu 8.1 on Toshiba Tecra black screen problem

[Andrew Loughhead]

doris ann wrote:
> 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
>
> Details:
> 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
> again.
> 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
> monitor).
>
> 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?
>
I *think* a couple of years ago I saw backlights stop working on desktop 
LCD screens at work when particular high resolution video modes were 
selected. Maybe when you were changing settings you also upped the 
resolution, or refresh rate? 

Andrew.