I completed my first conversion of an MTH PS-2 Scale Engine to PS-32 to capitalize on the DCC capability and removing the polarity issues involved with running PS-2 on Two Rail.
The modification was pretty easy and nothing required to be done on the Steam engine. I modified the 3R-2R switch to keep the capability to run either way but with less wires on the switch because the polarity switch is not required. I then wired the polarity switch to be the DCS/DCC switch.
Worked great. Engine can run on 3 rail or 2 rail, AC or DC power, via conventional, DCS, or DCC. No worries about DC polarity or which rail has the DCS/DCC signal. G