"Jeff Liebermann" wrote in message
...

On Sun, 1 May 2016 13:47:13 -0400, bitrex
wrote:

I think the problem may not be mechanical, as I've noticed that now the
keyboard is having issues triggering as well, which is not connected to
the same area.

Well, it wouldn't hurt to eliminate the keyboard as a possibility. Put
an ohmmeter across a row and column on the keyboard and measure the
contact resistance with an ohmmeter. Try all the button combinations.
If the resistance seems resonable, move on to looking for another
culprit.

I think I screwed something up swapping R66 on page 18 near the LCD, and
the processor is having trouble with read/writes or something.

5.6K goes to Vo on the LCD display, whatever that does. If it's
carbon comp, check the resistance with an ohmmeter. They change over
time and absorb moisture. However R66 doesn't seem to go anywhere
except the display making changes to keyboard and buttons rather
unlikely. Dunno.








R66 is most likely contrast or viewing angle adjustment.
It might be a good idea to check all the pullup resistors (RA3) are all
present and correct.

It is probably another good idea to just resolder everything around that
part of the circuitry, including the Gate Array, just to eliminate dry
joints as the problem.
That's a 5 minute job at most.

And, if you (the OP) have replaced R66, go look at it again with a loupe or
magnifying glass and check you haven't inadvertently shorted something out,
or there is maybe some solder debris sitting on the Gate Array pins.



Gareth.



Gareth.