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

[Steven Webb]

5 minutes later it stopped working again. Any advice on how to debug
this would be greatly appreciated.

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.
>>
>