Prodigy mod: Adding hold switch...??

[Brad Taylor]

hello all:

i'm trying to add a "hold" switch to a moog prodigy with some success.
using a multimeter i figured out where to wire the switch in to gate
the  VCF/VCA (the connector that connects the keyboard with the
mainboard). This seems to work with only one problem: when i switch "on"
the gate and let go of a key, the vco sweeps towards a very high pitch.
I assume this is because I didn't put a resistor on the "away from
keyboard" side of the switch. yes? no?

if it is the case that i need to add a resistor, how do i know what
type? Will the following method determine the proper resistor to use?

1. measure the resistance of with switch "on" and hold the furthest
right key (highest pitch).
2. then measure the resistance of just the switch "on"
3. subtract measurement 1 from measurement 2 to get required
resistance??


any help is greatly apprieciate. 


thanks,
brad



ps - if someone has some schematics or service manual for this synth,
please email!