[ltp] external monitor is blurred!

[André Wyrwa]

--=-hFlOlWEWQRJml9vgNqol
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: quoted-printable

Hi,

On Mi, 2004-12-22 at 14:26 -0700, Ben Pearre wrote:
> 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.

Yepp, seems that DVI is supported starting from the 50s of R series
only.

> 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.

Especially the latter one is a typical sign of bad AD conversion and the
higher the resolution, the more likely the effect is to show up.
Usually the effect (moving/shimmering stripes, blurry image) should not
be homogenic throughout the whole display, but should rather be more
intense in some parts and in other parts the picture should look quite
ok.

Did you try playing with the Dells phase settings? The autoadjust
function of such monitors often doesn't deliver the best results.

> 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:
>=20
> * Dell uses cheap a crappy ADC in the monitor

Probably not as good as a NEC one, but the Dell ADC should get better
results than you describe - if you didn't get a faulty model.

> * 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).

That sounds more likely. It is really important to use a good, shielded,
short-as-can-be monitor cable with a 1600x1200 TFT on VGA since the
display will have enough problems with the AD conversion even of a
perfect signal at this resolution. Maybe you can borrow a better one
from a friend and try with that.

> * The Thinkpad has a crappy DAC that doesn't like high resolutions

Also unlikely.

>   (how do I find out what the refresh rate is?

cat /var/log/Xorg.0.log | grep "*Mode"

Or run xvidtune and look at what it shows you.

>   Does anyone have a ModeLine that lowers it?)

According to the specs the Dell should be fine with 60Hz.

>   /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?

That might be bad indeed. According to this page...
http://support.jp.dell.com/docs/monitors/2000fp/English/specs.htm
...the 162MHz pixelclock mode is the only 1600x1200 preset mode of the
monitor. You might try adding "NoDDC" "true" to your device section, but
then you might need to provide a modeline.

> * The X software is doing something funny

X is always doing something funny. Its part of it's nature.

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

You can try figuring one out by disabling DDC in general and fiddling
with xvidtune. But don't blow your display.

Andr=E9.


--=-hFlOlWEWQRJml9vgNqol
Content-Type: application/pgp-signature; name=signature.asc
Content-Description: This is a digitally signed message part

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.5 (GNU/Linux)

iD8DBQBByiPLEOp8fsnyxsQRAkj7AJ9nweLZLDs/geyVcOySh1rtSpyhHACeOBOP
G4GMv0Zv/4g2RrvBV2e1MYg=
=afjs
-----END PGP SIGNATURE-----

--=-hFlOlWEWQRJml9vgNqol--