Tony Duell wrote:
I guess :-( I
took one of the buckling spring mechanisms and "manually"
struck keys with it, and also ran it lightly across the board. Most of
the keys worked except the ones I am having trouble with.
Have you removed the PCB from the baseplate to look for possible damage
to the PSB or to the mylar insulator under it?. Is it possible there are
broken traces on the PCB?
I have not removed it yet, although with broken keys I guess there's no
reason to hold back now. So I'll take the PCB off of the baseplate and
have a look.
Unfortunately, the scheamtic in the IBM Techref
doesn''t include a
diagram of the key matrix. Which means it's not possible to see if the
keys you ar ehaving trouble with are in the same row or column (is it
just 2 keys?)
Most of the keys having trouble were on the same horizontal line except
the enter key, but those may have been somewhat mechanical because
repeated use got them 90% functional. I'll try to visually inspect the
back of the PCB tonight, and put it together one last time. If nothing
is obviously wrong and it still fails, I will throw it in the spare
parts bin (and then tentatively start working on the other broken XT
keyboard).
Even if I find a trace issue, my skill with a soldering iron is worse
than that of a moose wearing boxing gloves, so I might ask my brother to
come over and help with the soldering (I was always the software guy,
and he was always the hardware guy :-)
--
Jim Leonard (trixter at
oldskool.org)
http://www.oldskool.org/
Help our electronic games project:
http://www.mobygames.com/
Or check out some trippy MindCandy at
http://www.mindcandydvd.com/
A child borne of the home computer wars:
http://trixter.wordpress.com/