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Unread 25-01-2016, 09:46
philso philso is offline
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Re: 3-way PWM Splitter

Quote:
Originally Posted by Al Skierkiewicz View Post
philso,
None of the controllers that I have looked at have a raw opto-coupler input connected to the PWM port. There should be a series current limiting resistor so the V forward difference should not show up as a problem. That being said, single point of failure is likely to raise it's ugly head if one is not careful. A bad controller will take down all three, a pinched wire will take down all three. Your mileage will vary.
We confirmed with the manufacturer that we should not have been paralleling the inputs of the two types of motor controllers we had and that the LED VF's were the problem. Once we had only controllers of one type connected together, they all worked properly. We had no defective motor controllers.

Perhaps some of the motor controllers have a current limiting resistor in series with the LED. If the one with the lowest VF does not have a current limiting resistor, it will still prevent the other ones from turning on.