[NTLK] Newton touchscreen not responding

Simone Picchioni simonepsp at gmail.com
Thu Dec 25 15:56:19 EST 2014


Hi,
thanks for your analysis Frank :)

I took my multimeter and I made some measures using my multimeter (hope I
didn't made mistakes) :

WITHOUT TOUCHING TOUCHSCREEN:
- Contact 1 - 3 : 528 Ohm
- Contact 2 - 4 : 404 Ohm
- Contact 1 - 2: /
- Contact 3 - 4: /

TAPPING THE SCREEN:

- Contact 1 - 2 :
A)  890 Ohm
B) 710 Ohm
C) 1200 Ohm
D) 860-900 Ohm

- Contact 3 - 4 :
A) 794 Ohm
B) 1158 Ohm
C) 541 Ohm
D) 873 Ohm

Results are very different from yours. Tell me what you think about :(

Here's the photos of interconnect port connector you asked me:
http://img673.imageshack.us/img673/5945/cHa0oV.jpg
http://img661.imageshack.us/img661/1355/nmN0t2.jpg
http://img661.imageshack.us/img661/6242/Fa7Xnr.jpg


Thanks for your help.
Simone

2014-12-25 0:31 GMT+01:00 Frank Gruendel <newtontalk at pda-soft.de>:

> Simone,
>
> 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:
>
>
> <
> http://www.pda-soft.de/common/img/hardware/2x00/DigitizerResistanceValues.j
> pg>
>
> 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
>
> Frank
>
> -- Newton software and hardware at http://www.pda-soft.de
>
>


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