From: Brent Hilpert
I don't have a full enough picture of the circuit
and circumstances to
provide a definitive suggestion but, some principles:
It's not clear C-coupling is what's going on here (the wave shape looks
pretty sharp for what I understand of the circuit/layout).
Thanks for taking the time for that detailed message.
I suspect, however, that Jon Elson has nailed it (thanks Jon :-); if that's
what's happening, it explains why we couldn't understand what the devil was
(You've mentioned both 470K and 270K for the R,
could make a difference
to the analysis).
Yeah, that was just a typo; going from memory.