[Olpc-open] jumpy cursor problem and sugar issue

Bryan Berry bryan.berry at gmail.com
Fri May 2 01:20:28 EDT 2008

On Sun, 2008-04-27 at 09:36 -0400, Steve Holton wrote:
> Do you have a way to accurately measure relative humidity?

currenlty, no. something I should investigate.

> On the other hand, I have seen (and fixed) a very similar behavior on
> a NintendoDS touchpad which was caused by dust or sand becoming
> trapped under the frame along one edge.

Trapped sand can't be the issue because we have brought some to the most
troublesome XO's back to the office and they work fine here.

> Just a theory (I have no data to indicate this works) but when you see
> the touchpad problem on an XO could you try this and report back with
> success/failure/experiences:
> On an XO showing jumpy trackpad problems:
>      1. Raise the screen to full vertical / perpendicular.
>      2. Rotate the screen 1/8 turn clockwise (reverse this for
>         left-handers)
>      3. With the right hand palm facing up, reach under the screen and
>         put a finger on the metal mounting bracket or screw of the
>         swivel hinge.
>      4. With the finger still in contact with that (essentially a
>         chassis ground), lightly brush the trackpad with a finger of
>         the other hand to drain stray static charges into the chassis.
>      5. Re-calibrate afterwards, if necessary.
> If you have an available earth ground, discharging to that as well
> might make an interesting variation on the test.

will try this but first need to replicate the problem. Unfortunately, it
rained last night so it's not nearly as dry as usual.

Something else bothersome. I have found that if you lick your finger and
then touch the touchpad, it gets jumpy right away. This isn't the
problem in question though because the kids are keeping their hands dry.

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