[ltp] T30: Video frequency to external projector?

[Michael Hagemann]

Hi Atul,

Atul Chitnis wrote:
> I have a problem that's been bugging me for a while:
> 
> I now know how to get my T30 talking to an external projector without too 
> many issues (I dont connect the projector until I am all booted up, and 
> switched X to 1024x768 using xrandr), but I seem to have an issue with the 
> frequency of the output to the projector.
> 
> I use FC3, with xorg-x11-6.8.1-12.FC3.21. Though the output is correct at 
> 1024x768, it seems to be the wrong frequency, be cause I invariably end up 
> with a stretched or distorted image on the projector, usually wider than 
> it should be. Any true 1024x768 notebooks display normally, but when I 
> switch to 1024x768 from 1400x1050, the display is ok in height, but too 
> wide, resulting in the sides of teh image to be cut off.
> 
> Any tweaking that I can do to fix this issue? My xorg.conf is at 
> http://atulchitnis.net/tmp/xorg.conf

I (and other people as well, see thread in 2nd week of january), have 
similar problems.  I have a T42 with 1400x1050.  The problem I had, was 
that the left edge of the screen was "cut-off" in the projected image, 
i.e. the image was "shifted" ca. 100 pixels to the left.

As you suggest, playing with the refresh rates might help.  The 
corresponding entries in the xorg.conf file are "CRT2HSync" and 
"CRT2VRefresh".  I tried to change these to low settings for LCDs for a 
little talk I gave last week, and it worked... (don't have the exact 
frequencies here, but vertical was 50Hz)  This might of course be 
attributed to the projector, who was definitely newer than the one I had 
problems with.  On a CRT both settings seem to work fine (except for the 
flicker, of course ;)


hth,
michael