[sdiy] MS20 woes

[John Henson]

Hi all
I am in the middle of repairing a Korg MS20,
The problem it came in with was an endless drone once a key was played.
I obviously zoned in on the envelope generator section, and did find
anomylous behaviour in that area.
I replaced the 4069UBC chip (after changing everything else), and it sort of
works, but if the sustain control is turned up, there is a long delay until
the output VCA is shut down.
Any thoughts or wisdom on this one?
Regards
John