MOTM

On Tue, 19 Oct 1999, Tkacs, Ken wrote:

> years. I opened it up expecting to find a Pratt-Read-style wire & rail
> keyswitch mechanism, something I could clean, but instead found this odd
> contraption where the keys have little gray 'suckers' on them that press
> against a PCB. I never saw this design before and was afraid to go wiping
> alcohol all over the place without knowing what I was doing.
> 
> Do any of you have suggestions of what I might do to clean up this type of
> keyboard? I don't quite understand its principle. I'd like to use the

  I *just* got done this past weekend repairing yet another Korg Polysix,
and photographed the whole process, including the cleaning of the key
contacts.  The web pages for the cleaning procedure are not done yet, but
here is a quick list of them in order: (each file is ~25K)

http://www.oldcrows.net/~oldcrow/synth/polysix/keyclean/kbddisassem_sm.jpg

  --Unscrew the 16 screws holding the long, narrow diode-matrix contact
board to the keyboard frame.

http://www.oldcrows.net/~oldcrow/synth/polysix/keyclean/kbdpcbliftout_sm.jpg

  --The PCB lifts up and out of the frame.

http://www.oldcrows.net/~oldcrow/synth/polysix/keyclean/keycapremove_sm.jpg

  --These rubber keycap assemblies appear delicate, but are more resilient
than might appear.  Even so, don't just yank them loose.  they will pull
up easily enough, provided you give a little push the rubber "pins" that
poke through the PCB.

http://www.oldcrows.net/~oldcrow/synth/polysix/keyclean/keycapclean_sm.jpg

  -- I use a pencil eraser to give a little rub to each black contact
face.  These things dry out over time, leaving a 'film' over the
conductive surface.  The idea is to rub the film off.  Don't tear them.

http://www.oldcrows.net/~oldcrow/synth/polysix/keyclean/contactclean_sm.jpg

  -- Using a *different* eraser, I clean the gold interleaved contact
areas on the PCB.  Be careful not to rub the gold away.  A quick 2 or
3-pass rub should do fine.

  Do this for all the contacts.  When done, make sure there are no eraser
crumbs hanging around, then put the rubber keycap strips back on the
board, and carefully fit the PCB back into the frame.  I usually pull up a
set of keycaps, clean them & PCB contacts, then put that strip back and
pull up the next one until done.

http://www.oldcrows.net/~oldcrow/synth/polysix/keyclean/keycapsfit_sm.jpg

  --when reinstalling the PCB, make sure the keycaps don't scrunch up
under the frame.  Pay attention to the ones on either end in particular.

** ** **

  I may as well say hello to the MOTM list while I'm at it.  I've been
building analog synthesizers, both modular and 'normalised', since 1977.
I just recently started on the MOTM modules series, primarily because of
the degree of effort put into the module designs.  I spend most of my free
time trying to keep old analog synthesizers alive.  I spend most of my
not-free time working at http://wv.ewa.com/ and http://www.temp-inc.com/

  --Scott

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