"p.cousens" writes:
>Try giving them 120v for a few minutes (in series with a 100n cap to
>limit the current if they decide to go short).
>They may be a type of thermo-pneumatic actuator

al smith writes:
>replaced it and was assured the part was defective I opened it up.  It was
>based on heating up a waxy substance that once liquid would release the
>lever....then when it cooled down, it would allow the plunger to return.
>Kinda interesting.....

        Thank you both.  I am at work as I write this, but I am pretty
sure it is something like what you describe.  The parts are fairly
light feeling in the hand to have the iron one would expect in a
solenoid of that size so it almost has to be something else.  I'll
hook a light bulb in series just in case and cook it for a while.  I
do know that initially, they draw next to no current at all so the
only thing to watch out for is a sudden drop in resistance like a
surgistor.

        It is also remotely possible that they need DC.  There could
have been a rectifier buried in the harness somewhere to the timer.
If AC doesn't do anything, I'll stick a suitable diode in series with
it and the bulb and see what blows up.:-)

        By the way, my variac is on the output of an isolation
transformer which is the setup I use when messing with circuits of
this kind.  This makes life a wee bit safer, anyway.  You never know
where a surprise path from the mains through you to Earth might show
up.  For all I know, those plungers on the ends of the actuators in
question might be hot or become hot.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Information Technology Division Network Operations Group

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