> I heard/read/dreamed/made up somewhere that, in the absence of a
> replacement motor starting capacitor, a TEMPORARY motor starting
> capacitor substitution (for testing purposes only) can be made by
> putting two electrolytic capacitors of about 250Ufd/100VDC back to
> back (plus-neg-neg-plus? neg-plus-plus-neg?) to see if it is indeed
> the motor starting capacitor that is the problem.
That works perfectly well for short tests, and will last a long time
if you put a reverse polarity protection diode across each capacitor.
The power rectifier type diode would go cathode (banded end) to + and
anode (unbanded end) to - of each electrolytic.
The effective value *remains the same* as with one capacitor, it
neither doubles or halves. If you connect two in series without the
diode, the effective value is something between the same and half of
the original value. You can NOT parallel the capacitors and use
steering diodes, they have to be in series with shunt clamping diodes
across each individual cap.
73, Tom W8JI