|Re: buttons on HP-25|
Message #2 Posted by Vieira, Luiz C. (Brazil) on 3 Mar 2003, 10:39 p.m.,
in response to message #1 by Stan MFarland
please, check if there is a small, golden-coated hole in the printed circuit board under the very middle of each key. There is a type of keyboard assy that does not have these holes; if yours have, you may clean the contact.
As you do it, I'll try to find the thread where the cleanning procedure is detailed. Anyway, if you want to try, use a brush with long, thick bristles. You can even separate a couple of them as a bundle, soak them with the contact cleanner, and gently insert them in the mentioned holes. Move the blisters in and out, rotate them, remove them and try again.
If the keyboard's PCB does not have holes, it seems your keyboard is the one with plastic bubbles under each key. This assy has copper trails in the inner side of the bubbles, and these copper trails tend to crack. I am trying to find a better solution for this kind of problem. It seems that self-adherent cooper foil is a possible solution, but fixing it in a permanent, steady state is another issue.
I know it does not help that much, but maybe you can use this info as a guidance for your own skills.
Luiz C. Vieira - Brazil