[ltp] external monitor is blurred!

Ben Pearre linux-thinkpad@linux-thinkpad.org
Wed, 22 Dec 2004 14:26:54 -0700

I finally searched the archives and set up my R40 to talk to an
external monitor (Dell 2000FP flat panel).  The monitor takes digital
input, so I'm very sad that the Thinkpad doesn't have a DVI out, and
this is indeed a problem.

I've set the monitor to not scale incoming images when they are less
than the monitor's native 1600x1200, so there are no antialiasing
problems.  I guess I could scale 800x600...

In anything over 1024x768 the monitor only gets a fuzzy, shimmering
image.  Not unusable, but very far from crisp: looks like a really
cheap analog monitor.  And the default X background ("stipple")
shimmers unbearably in horrible vertical stripes.

I don't have much spare computer equipment here, so I can't isolate
the component that's causing the problem.  But I assume it's at least
one of:

* Dell uses cheap a crappy ADC in the monitor

* The analog monitor cable is poor (it's thinner than many I've seen
  and may be unshielded or poorly shielded but it does have the
  ferrous lumps at both ends).

* The Thinkpad has a crappy DAC that doesn't like high resolutions
  (how do I find out what the refresh rate is?  Does anyone have a
  ModeLine that lowers it?)  /var/log/XFree86.x.log suggests that I'm
  running at 60 Hz, but I do get "(WW) (1600x1200,Dell) mode clock
  162MHz exceeds DDC maximum 160MHz" --- is this bad?

* The X software is doing something funny

The problem persists when I unload the Atheros drivers, so at least
it's probably not interference from those...

Can anyone here answer at least for the third and fourth bullets?  Is
there a non-DDC modeline that works better?

Thanks much!  And happy solstice :)

Ben Pearre          http://hebb.mit.edu/~ben       PGP: CFDA6CDA
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