mrhoef wrote:
I have got a power scooter (CTM HS686) for repair and experience a strange
phenomenum. Powering the scooter up works with an ordinary on/off keyswitch,
but the scooter only powers up when the the switch is turned on and then off
immediately. The scooter works fine then. To switch the scooter off one has
to do the same; switch on and then off.
When leaving the switch in the "on" position part of the functions won't
work.
Apparently the board now only needs a power pulse to activate, however the
original keyswitch is of the ordinary on/off type.
I have checked the board as good as I can, but cannot find anything wrong
with it.
Anybody any ideas how to approach this problem.

Thanks
Gerard

Is it possible that the keyswitch input to the circuit board (or at
least a portion of it) was designed to be an AC coupled connection?
Such connection type may have been designed to allow the controller to
work with either a ON-OFF keyswitch or a momentary ON push buton). This
way they could offer the keyswitch as an optional item at a higher
price for the scooter.

If the design is AC coupled in this manner and the coupling circuitry
became shorted it could account for the behavior you are seeing.

- mkaras