If you have, or can borrow, a scope, it might be useful to watch the
various S&H voltages during the auto-tune process, to find out at what
point the autotune fails. The order of operations is:

pitch 1 (5 different control voltages, width = mid, cutoff = max)
pitch 2 (5 different control voltages, width = mid, cutoff = max)
width 1 (2 different control voltages, pitch = 35Hz, cutoff = max)
width 2 (2 different control voltages, pitch = 35Hz, cutoff = max)
cutoff (2 different control voltages, pitch = 0, width = 0)

If you don't see the cutoff doing anything (other than momentarily going
to max), then it's never getting as far as tuning the filter. If you never
see the width doing anything (other than momentarily going to mid), then
it's never getting as far as measuring the pulse width. Etc.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...