Odyssey Keyboard Problem

[Douglas R. Kraul]

The ARP Oddessy used a multibus ( 3 - CV, Trig & Gate) keyboard controller.
The effect that you are hearing is what happens when the trigger and gate
busses are still functioning correctly for a key but the CV is not.  The tap
off of the voltage divider that is connected to bad key is not making
connection to the keyboard bus.  This is probably due to a dirty, corroded
or bent key wire (called a J-wire I think).

That is not Portamento that you are hearing but rather the capacitor that is
placed directly on the key board CV bus charging up due to leakage current.

To fix the problem you will need to get at the underside of the keyboard
assembly.  First try spraying contact cleaner on the offending key (which
you will probably have to count to figure out).  If this doesn't work see if
you can visually detect if the j-wire for that key to the CV bus is bent and
if so gently reshape it using some long nose pliers.  A DVM is very helpful
if you have access to it.  Put it into OHM mode.  Attach one lead to the
upper end of the resistor chain on the keyboard and the other to the VC buss
play some working keys and you will see the resistance vary, getting smaller
as you play higher keys (if it gets larger then on end is on the lower part
of the resistor ladder/chain).  Repeatedly press the offending key.  You
will see high resistance (an open circuit) if the key is not making contact.
Doing this while using the cleaner can indicate when the problem is fixed,
or it can be used to verify that your reshaping of the contact has worked.

Douglas Kraul

The Oddessy
-----Original Message-----
From: Andrew Puls Q-Bot Eye <q_bot at yahoo.com>
To: synth-diy <synth-diy at mailhost.bpa.nl>
Date: Tuesday, November 24, 1998 4:26 PM
Subject: Odyssey Keyboard Problem


>I just got an ARP Odyssey (Black w/gold no ppc, has trig/gate/CV ins)
>that is completely functional with the exception that every time you
>play one key (the uppermost "D" key, I think), it doesn't play a
>"D"... rather it plays a gliding note that ends up (at the end of it's
>slow glide) as one note above the highest note on the keyboard
>(actually, I think this IS just a "D" an octave higher, hmmm...). I
>tried turning the portamento all the way down, but this didn't change
>anything, it still glided <--(is that a word?) at the same rate and it
>still ended up at the same note.
>==
>Q-Bot, a02p20: q_bot at yahoo.com  Visit the home of the  most high-tech
musical experiment around the globe: the Automations Orchestra at:
http://www.angelfire.com/wi/CYO
>["""]      ["""] ["""] """"""
>[   ] ~~~  [ _ / [   ]   []
>[  \]      [   \ [   ]   []
>[___\      [___] [___]   []
>
>
>_________________________________________________________
>DO YOU YAHOO!?
>Get your free @yahoo.com address at http://mail.yahoo.com
>