Scaletrains definitely does not integrate well with 3rd party 21 pins.  It's a known issue between ST and other DCC boards...

There was a lengthy discussion about this over at Model Railroad Hobbyist awhile back (Link, look for Yarons posts on page 76-100 and 126-150). What it really boiled down to was all the other decoder brands aren't fully NMRA compliant and lack the required function outputs from the standard to work with Scaletrains; there wasn't anything non standard about Loksound or Scaletrains motherboards at all.

Now, the LM-3S-21 does have the required function outputs so why doesn't it apparently work in place? Mystery!

- Tim

Scaletrains definitely does not integrate well with 3rd party 21 pins.  It's a known issue between ST and other DCC boards.

I can report that Rapido is a direct drop in for the LM-3S-21.  Plugs right in and has access to all functions, as well as the built-in Rapido keep alive.  Couldn't be any easier.

I just installed an LM-3S-21 in an Athearn Genesis MP15AC — no issues at all, and I’m able to access all the functions without a hitch (headlights, ditch lights, ground lights).

As far as I know Scaletrains is the only manufacturer that doesn't 100% work with 3rd party 21 pin modules/decoders. Here is a link to more info on the Scaletrains issue with the LM-3S-21: https://rpug.pdc.ca/index.php/topic,1666.msg11645.html#msg11645


I’m planning to install more LM-3S-21 modules in Rapido and Walthers locomotives soon, and based on my understanding, I don’t anticipate any major issues there either.

Not denigrating the product, but the overcurrent detection circuit/algorithm needs improvement.

It needs to be "programmed" like a slow blow fuse, not an immediate trip, needs to take consideration of overcurrent into account.

Many many decoders have no issue with these Pittman motors.

Wow, well that is a good datapoint. I suspect the RP decoder is tripping much earlier than (in my opinion) is needed.

So, probably tripping at rated current, not double as often is done.

I can understand the conservative "restriction", as the model 3 decoder was not up to the G scale locos in general..

which decoder is this, the 4 or the 5?  Can't be the 5 or its not living up to it's rating.