Re: [iPAQ] Re: Touchscreen very erratic

> Mikael Bouillot said:
> > Mine does something like that, but with vertical jumps (when holding
> > the PDA in portrait mode). When the "bug" kicks in, a horizontal line I
> > try to draw looks like avery jagged seismic graph, and I have a very
> > hard time pushing any button in the interface. It works fine most of the
> > time, but the malfunction happens usually when I plug the CF sleeve. The
> > only way to get it to work again is to gently slap the iPaq flat on the
> > thigh until whatever has gotten loose in it falls back in place :-)

I had a very similar problem with a 3700. My problem was so bad I
ended up replacing the 3700. (I still have it, as a backup.)

In my case, I found that it was a little bit worse with the sleeve
plugged in, especially with a wireless card active, but the overwhelming
determinant was the frontlight. If the frontlight was off, I usually
had little or no problem (although I might notice some jaggies if
I had a sleeve plugged in). If the backlight had been on for a while,
the problem was really bad, even with the most aggressive smoothing
configured in /proc/hal/ts/whateveritwas - I had a very hard time
getting a single tap (or other xstroke strokes) to register, and a
double-tap was impossible.

The backlight issue, and the fact that it seemed to get worse over
time, suggests to me that it has something to do with heat. In fact,
this winter I had to use the 3700 again for a bit due to some problems
upgrading my 3800, and while I noticed the problem, it was nowhere
near as bad as it had been the previous summer when it was bad enough
to drive me to shell out for a replacement.

(Aside: Does anybody have any idea whether replacing the touchscreen
on the 3700 would be likely to fix this? It seems like it *might*
be the touchscreen, but it might also be a controller chip of some
sort, or a connector, or something.)

Oh, and here's the weird part - most of the time the jaggies were
vertical (and at their worst, they were a quarter-screen long; i.e.
about 75 pixels). There was no shaking in the horizontal direction.
However, at one point, following an upgrade, they switched orientation
and became horizontal instead of vertical! That almost convinced
me it was a software problem. (After a while, they switched back
to vertical on their own, and then got a lot worse.)

-- 
Jay Sekora             http://www.aq.org/~js/            js.a.t.aq.org
Today I can say ``we don't take your sons away by force to fight at the
front line.''  But that's about all I can say.' - Ahmed Wali Karzai,
brother of Afghan president Hamid Karzai, on the pace of change in
postwar Afghanistan, quoted by Newsday.com