LM-2S vs. LM-3S

[Tom]

Can anyone tell me what the significant differences are between the LM-2S and the LM-3S - it has been an while?

My recollection is that I had to use a rectified for something with an LM-2S which is not required with an LM-3S.

And the LM-2S seemingly usable by a DCC controller actually does not work - maybe.

Are any of these recollections correct, and is there anything else?

Thank you to anyone who knows.

[G8B4Life]

Your recollections are close.

Functionally, the LM-2S and 3S are pretty much the same.

• The LM-2S had 2 input wires but the 3S only has one (it got a negative wire instead). Since there was never a way to use both input wires on the 2S as a locomotive module this is a moot difference.
• You only had to use a bridge rectifier with the LM-2S if you wanted to use a keep alive. The 3S made the connections available on the LM itself so an external bridge rectifier isn't needed.
• DCC capability is determined by the firmware loaded into the LM. It's been a long, long time since I played with LM's on DCC but I suspect the LM-2S's capability is the same as the LM-3S. There used to be an issue about not being able to do consists with NCE but that was an NCE issue. I would imagine it is not fixed.

The 3S may also have a bit more onboard storage space; I can't remember for sure though.

- Tim

[KPack]

LM-3S has double the storage memory of the LM-2S.  As Tim said, it is much easier to install a keep-alive with an LM-3S because you don't need to use a bridge rectifier.  On that note, if you are installing a keep-alive I would highly recommend using Ring's PBM-2.  Yes it big but in my own experience it performs far better than normal DCC keep alives.  Far more stable.