Your remarks above are confusing. I see 2 wires into the 3 pin connector on smoke. Should be AC in. The 2 pin routes 5V made on the smoke unit PCB to the smoke motor. Should have diode, cap, and small 5V reg on underneath of PCB. If there is a 3rd black wire coming in to the smoke unit it may be to independently control smoke unit 5V components. Se my remarks above.
As far as wiring the AC reg, john gave you the pin/wire info. But Lionel wired these many different ways. So you might have to lift the MB to follow the wiring.
This is why I hate working on Lionel, especially now that diagrams seem to be leaving the old tech search function.
First you could unplug the 3 pin on smoke, plug one in with AC wires available to independently test smoke unit. Does it work, including fan. Go from there. Does switch work, swap r2lc, then swap ac reg.
Or, use meter and find out how it is wired checking pin to pin.
If this was conventional TMCC no AC reg, the smoke out of the R2LC would go to switch for conventional and tmcc on/off control. IE if switch off smoke does not work either mode. From switch to smoke unit power in. Now if the AC reg is inserted, it could go between switch and smoke unit, with serial data also coming from R2LC. G
