MOTM

The TM's HF clock does NOT like negative voltages on the Delay In or Ext
Mod Int.....unless you use the Delay control to bias the voltage hitting
the HF clock into the + side. The HF clock shuts down and cycling the
power restores normal operation. If you want to avoid this, add a 1K
resistor and 1N4148 diode reversed biased to common on the Delay Input
(and Ext Mod In). This will dump *most* of any negative voltage to
ground.

A characteristic of the HF clock is that if you ask it to go too fast,
it just stops. Since the "Delay" control is reversed (shorter delays
equal faster clocking), a minimum Delay pot setting and some negative
control voltage at the IN equals shut down.

I'm sure the designer will find a better approach next time!
___________________
John Blacet
Blacet Research
http://www.blacet.com