I've posted already a couple of times about my sparkless 740 (B230K with rare
EZ100K system). I'm checking it over a little more carefully as I'm
completely stumped, and find that the 5 volt parts of the ignition electronics
(i.e. the blue signal wire on the hall sensor, the trigger wire leading from
the ecu to the power stage, etc..) are in fact running at 3.7 volts (I should
have been more careful reading my analogue meter - it's pretty much 5v on the
AC scale not DC - doh!). I swapped the ecu for one off of a B230E
engine - EZ118K - and still saw 3.7v. I'm guessing then that the 5v parts of
the cicuitry are derived from a separate voltage regulator not onboard the
ecu. Is that right? I'm guessing that if I'm only generating 3.7v pulses from
the ecu that these may well be insufficient for triggering the power stage and
hence explain why I see no spark.

Any ideas as to why I only see 3.7v at the hall sensor, ecu, ... and how I
can fix this?