[NTLK] Newton touchscreen not responding

Frank Gruendel newtontalk at pda-soft.de
Wed Dec 24 18:31:38 EST 2014


I will send further communciation only to NewtonTalk since it might benefit
others. Moreover, it'll be easier for both of us.

I assume that you have noticed that one of the ribbon cable traces is
somewhat bent out of the way. Since in the first set of pictures you
published this was not so, this is most likely not the reason for your
problem, but make sure to realign it before you try your luck again.

I have just uploaded some technical details of the 2x00 digitizer here:


Provided you have a multimeter that can measure resistance, this will help
you figuring out what is wrong with your digitizer.

Some words of explanation:

The rectangular thingie on the left-hand side is the digitizer. The drawing
on the right-hand side is the end of the ribbon cable.

Contacts 1 and 2 sense the horizontal position, contacts 3 and 4 the
vertical position.

If the touchscreen isn't touched by anything, you should measure
approximately 575 Ohm across contacts 1 and 2 and approximately 435 Ohm
across contacts 3 and 4. 1/2 and 3/4 must not be connected by anything. If
you measure any resistance between the two pairs, there's a short somewhere
that shouldn't be there.

If you tap in the middle of the top, left-hand, bottom and right-hand edges,
you should measure approximately what I wrote next to the little dots. If
you tap in the corners (A, B, C, D), you should measure the values I wrote
at the top.

Please let us know your findings.

I would also like a close-up image of the interconnect port connector. This
will most likely not be the cause of your digitizer problem, but as I said
in one of my previous mails, I am under the impression that before long it
will tear off since some soldering joints are already broken.

Good luck


-- Newton software and hardware at http://www.pda-soft.de

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