[sane-devel] Medion MD9850: scan range & noise probs?

edg1@tiscali.be edg1@tiscali.be
Thu, 30 Oct 2003 19:54:27 +0100

Wolfgang Fabics wrote:
> Ah, I wasn't precise on this one, forgive me. The scanner ran just fine
> on Win98 and Win2k... trouble started with WinXP (don't laugh ;-).

So you probably had to install a new driver? 
Did you get it from Mustek?

> 1. The noise is *really* loud and *really* precise (hope you know what
> mean, it's hard to describe a sound in ASCII). It's not like the sled
> jamming on the slider bars and breaking loose now & then... more like
> hitting the case with a No. 8 drum stick. Hard. Precise. Loud.

This sounds like the noice I got when the scan head hit the bottom
and the belt started jumping over the dents. Yes, it's only rubber,
but the sound is quite loud, just like you describe. But I don't
understand how this could happen somewhere in the middle of the
page, unless there is something wrong with the glider mechanism.

> 2. When the head slows down (after 2 or 3 consecutive *clank*), it
> apparently doesn't do that due to friction but bcs of the stepper motor
> slowing it down (same frequency but smaller spacing). The actual *clank*
> noise is not at all correlated with the head's movement. I will try and
> show you an example in ASCII (s=step, *=noise):
> head moves this way ---->
>     *      *  *  *            * *             *      * * * 
> s s s s s s s s s s ssssss s s s s sss s s s s s s s s s s sssss....
> (sorry it's not actual scale, there are of course many more s between
> the *... typical distance between consecutive * is about 1 sec.)

At low resolutions, the movement sometimes isn't very smooth because
the head must skip positions, but it should still be periodical, like:
  ss s ss s ss s ss s ss s ss

> Would you encourage me to open that scanner up and have a look? I'm
> quite comfortable with electronics... but mechanics?... ummm... still
> remember the last time I dismantled a VCR chassis :-/ Any special tips
> should obey?

If you still have access to a Windows 98 or 2000 machine, you could
first try to connect it to that one to see whether the problems
persist. If it disappears, it must be a driver problem.

Opening the scanner is not that risky. It's far less complicated
than a VCR, but if you're not comfortable with it, maybe you
shouldn't do it.



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