I purchased a few of the JV Digital Electronic E-Units for some tinplate projects using can motors (profiled in the April/May 2019 issue of OGR). To my surprise, they wouldn’t change direction. Tested with an open frame motor (Lionel) and it worked fine. Contacted Jeff at JV Digital and he was puzzled by my problem. He tested his units and they exhibited the same problem. Turns out, when power is secured on a DC motor, it acts as a generator and back feeds the E-Unit, preventing it from changing state. This only occurs on the latest software version, 2.11, on the chip. Previous versions don’t have this problem.
Jeff has been very accommodating working though these issues and has sent earlier version PROMs to fix this problem. So, if you purchased any E-Units from JV Digital with the latest software version and plan to use them with can motors, contact Jeff for a replacement chip. He working on a revision that will have the latest features and accommodate both open frame and DC motors.
FWIW, I believe it's Williams reverse boards that do the same thing unless you let them totally stop so the motor isn't generating any voltage. A DC can motor is a generator if you drive it mechanically.
