C128D keyboard failure mechanism

From: Steve Judd (sjudd_at_ffd2.com)
Date: 2004-04-11 15:28:32

Hola all,

This is barely worthy of cbm-hackers, but for what it's worth, I had my
C128D keyboard open to fix up my barely-functional cursor left-right and
right-shift keys.  The plastic frame holding the keys is attached to the
PCB and metal backplate via 21 tiny screws, which screw into small plastic
posts on the upper piece.  A close look showed that most of these posts
have cracks in them, and hence are no longer holding the screws securely
(there are also some stress cracks/creases beginning on the upper plastic
key holder).

I believe that what's been happening is that when I press shift or
cursor-lr, it actually pushes the upper part away from the PCB instead of
making good contact -- the only way to make these keys work has been to
push down extremely hard.

My solution here was to drill a hole through the metal/pcb/keyboard holder
near the space bar and put a small 4-40 bolt+nut through, to hold the
assembly together (there are several raised plastic surfaces near the
space bar, giving a more secure/even point of contact).  Time will tell if
this is effective; so far so good.

I also took a look at the plastic enclosure for the keyboard and sure
enough, cracks were forming in the much thicker plastic posts that receive
the screws.

For what it's worth...

-S


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