On 2011-02-16, kwamena banson wrote:

To be very sure you disconect the motor and test it on the mains at a
reduced voltage.

The BTB15-600C is hard to find but RS carry the BTB16-600C.
Swapping in a new triac made no difference, though.

So I tried exactly what you're suggesting : motor on a big 24 V
transformer. If the rotor is a certain angle (or 180° from it),
the motor doesn't start when power is applied.

When you reverse the phase on the stator (for reverse), you
still have a pair of diametrically opposed "dead spots" but
they're at an angle from the original ones.

--
André Majorel http://www.teaser.fr/~amajorel/
"The object of this year's expedition is to see if we can find
trace of last year's expedition."