What happens if you power a Lionel or MTH Engine with DC Power?

Interesting question.  First thing that comes to mind, is that most of the Lionel and MTH offerings are (3)rail AC. Most DC offerings are for (2) rail.   Most (3) rail offerings placed on a (2) rail DC track would short the track.  Get past that concern, MTH does have a 3/2rail offering, which isolates the wheel sets. I'm not sure what happens applying DC to an AC electronic system.

From the MTH website....

There are 4 options for operating your MTH Proto-Sound 3.0-equipped engine;

-Conventional AC

-Conventional DC

-DCS - MTH Digital Command System

-DCC

I really don't know about Lionel.

Gilly

A late Proto-2 or Proto-3 MTH engine will operate normally on DC -- forward with positive applied to the center rail (or right hand rail in 2-rail) and reverse with negative on the center rail (or right hand rail in 2-rail). Engine sounds will operate, but no horn/bell.

DCS will operate with a DC voltage source. There's some speculation that DCS will actually work better with a DC source.

A modern Lionel with can motors may or may not run on DC, but the old Universal-motored (postwar) units will, but the horn will sound. The E-units will function normally requiring power interruption to reverse direction.

TMCC requires an AC voltage source as far as I know. I've heard/read no reports of anyone operating TMCC under DC.

I thought I had read in various manuals for my trains that it says do not power with DC as it will damage the electronics.  But then I have TMCC/Legacy and Protosound (PS-1) trains.

The PS/2 3V boards and all PS/3 boards will run fine with DCS and DC on the rails.  I've done a number of 2-rail upgrades with PS/2, and I test them with DC power.

TMCC and Legacy REQUIRE AC.

Thank You One and All for your inputs.  It's on to smoke testing.