MTH has always used relays to switch polarity and FET to control motor current, but continue to speculate. It is fun to do analysis without facts
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What is interesting and is a change on PS-3 O boards is there is a Brake motor FET. I was told it is to reduce heat on the board. Whether this FET shorts the motor current and prevents coast on loss of power is not full know. I have removed these on diesel boards when they short and still have had the board function. It is not designed as a brake, but does function similar to the smoke fan set up. In that it can short PV to PCB ground at the motor terminals when commanded too. I think I test the engine conventional with this FET removed and it still stopped abruptly, but I would have to go back and retest.
Could be software is flipping the PV via the relay and that is causing the braking. So may be a combination of how it is built also. G
