Trouble shooting: xrandr, external monitor remains blank (black)

[Alex Deucher]

On Thu, Jul 10, 2008 at 2:53 AM, Steven Webb
<steven.daniel.webb at gmail.com> wrote:
> 5 minutes later it stopped working again. Any advice on how to debug
> this would be greatly appreciated.
>

If you are not already, can you try ati 6.9.0?

Alex

> Steve.
>
> 2008/7/10 Steven Webb <steven.daniel.webb at gmail.com>:
>> Update:
>>
>> My computer froze and when I rebooted (sysrq + RUB) the memcheck
>> displayed on the external monitor (which it hadn't been doing) and
>> then everything resumed correctly. I'm not sure why the external
>> monitor was working correctly under microsoft windows and nowhere
>> else.
>>
>> Steve.
>>
>> 2008/7/9 Steven Webb <steven.daniel.webb at gmail.com>:
>>> Problem: The external ViewSonic VA1912w monitor attached to my laptop
>>> at work stays blank (black) and refuses to display anything. The light
>>> on the monitor stays orange (no signal?). My external NEC monitor at
>>> home works correctly. The ViewSonic works correctly when I boot into
>>> microsoft windows; therefore, I do not believe that the problem is
>>> hardware based.
>>>
>>> xrandr appears to work correctly; however, the monitor does not switch on:
>>>
>>> two:~/>xrandr
>>> Screen 0: minimum 320 x 200, current 1280 x 800, maximum 2720 x 900
>>> VGA-0 connected (normal left inverted right x axis y axis)
>>>  1440x900       59.9 +   59.9
>>>  1152x864       74.8
>>>  1024x768       84.9     75.1     70.1     60.0
>>>  832x624        74.6
>>>  800x600        84.9     72.2     75.0     60.3     56.2
>>>  640x480        84.6     75.0     72.8     66.7     60.0
>>>  720x400        70.1
>>> LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
>>>  1280x800       59.5 +   60.0*
>>>  1280x768       60.0
>>>  1024x768       60.0
>>>  800x600        60.3
>>>  640x480        59.9
>>> S-video disconnected (normal left inverted right x axis y axis)
>>> two:~/>xrandr --output LVDS --pos 0x100 --output VGA-0 --pos 1280x0 --auto
>>> two:~/>xrandr
>>> Screen 0: minimum 320 x 200, current 2720 x 900, maximum 2720 x 900
>>> VGA-0 connected 1440x900+1280+0 (normal left inverted right x axis y
>>> axis) 410mm x 256mm
>>>  1440x900       59.9*+   59.9
>>>  1152x864       74.8
>>>  1024x768       84.9     75.1     70.1     60.0
>>>  832x624        74.6
>>>  800x600        84.9     72.2     75.0     60.3     56.2
>>>  640x480        84.6     75.0     72.8     66.7     60.0
>>>  720x400        70.1
>>> LVDS connected 1280x800+0+100 (normal left inverted right x axis y
>>> axis) 0mm x 0mm
>>>  1280x800       59.5 +   60.0*
>>>  1280x768       60.0
>>>  1024x768       60.0
>>>  800x600        60.3
>>>  640x480        59.9
>>> S-video disconnected (normal left inverted right x axis y axis)
>>>
>>> OS: Ubuntu Hardy Herron 8.04
>>> Laptop: Toshiba A70/7001
>>> Video Card: ATI Radeon Mobility 9100IGP
>>> External Monitor: ViewSonic VA1912w
>>> Native res on external monitor 1400x900
>>>
>>> This laptop/monitor combination works correctly under microsoft
>>> windows, but only when I enable composite synchronization (I don't
>>> know how to do this under X).
>>>
>>> Any information/advice would be greatly appreciated. I hope I have
>>> provided all relevant info.
>>>
>>> Cheers.
>>>
>>> Steve.
>>>
>>
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