[sdiy] Repairing Key Contacts (OB-8)

[Gene Stopp]

My OB-8 had this problem terribly. Now it's completely better. I removed the
Toshiba keyboard and put in a new shiny 5-octave Pratt/Read with J-wires.
Well OK, not new, but kept in plastic for years. :) It "clonks" a little
more mechanically, but that's OK becuase:

a) I'm used to Pratt/Read keyboards
b) if it's turned up loud enough it don't matter

This is probably not a good solution for everybody, however. You have to
have a brand new 61-key Pratt/Read laying around...

I was considering changing the resistor values to a higher value in the
keyboard diode matrix circuitry, so that the relative resistance of the
rubber contacts would be less, but this would have required experimentation
and I was in a hurry. I honestly don't remember which resistor, or
resistors, or what values, but somebody may want to investigate this as it
may be the cure-all for everbody's OB-8 problems. The original pull-up
(pull-down, whatever, I forget the circuit) values may have been too low.

Uh-oh I'd better not spread this around as it may increase the e-bay bid
prices...

Best Regards,

- Gene


-----Original Message-----
From: Anderson, Robert O [mailto:RobertOAnderson at eaton.com]
Sent: Friday, July 20, 2001 11:27 AM
To: 'Synth-DIY'
Subject: RE: [sdiy] Repairing Key Contacts (OB-8)


> I am amazed that the repair kit was not able to fix this problem.

I fixed a Korg Polysix once by glueing pieces of silver foil over the carbon
contacts on the rubber posts.  I had tried other methods without success but
finally found that the silver foil worked.
Regards, Bob A.