[diviney]

Al:

The Victors and the Jags do not switch the same way... Yes, this is a single +12V system, but when you observe the motor voltage (line to line), it is bipolar because the H-bridge reverses the polarity as you state. What I was referring to is the observation that the Victors are switching between zero and +12 when any forward command is given, and zero and -12 when any reverse command is given. Another way to put it --- When the motor is commanded to stop, a Victor will park it's output at zero volts (does not connect to either forward or reverse). The Jag (as I observed it) was operating with a 50% duty, toggling at 15 KHz between +12 (fwd), and -12 (rev). This was a little surprising to me, but it does yield a net zero volt average. Perhaps there is a setting that can be programmed to make it work differently, but we have never changed anything from the factory defaults.

Regarding the shorted winding theory, the likelyhood of two motors having a shorted winding is not great. Also, you would have to experience what it feels like when "nudging" the motor, but I don't believe we can turn the armature at all. The ratio of the worm gear makes it so this thing just cannot be back-driven from it's output shaft (after all, you don't want your window falling down and having Junior fall out while driving down the road!).

-Tom