Thanks Dave.
We have several Versions of the Berkshire and my son converted the sound board in one of them to a TCS WOW Sound for some of the additional features. He picked up an unlettered unit with just the DCC and was in the process of installing the Sound board when he noticed the SMK terminal. Of course he never noticed it when he removed it from the original engine.
And as you mentioned, it already had the leads attached so he though he was missing a connection somewhere. Then he wondered where the power pickup connections from the engine landed. Only made sense to parallel them with the tender connections. He did and all is well. Just surprised , I couldn't find any info on line about it. 
Appreciate your response.
Chris

Looking for a wiring schematic for the soundboard found in the Berkshire model 52401. Can't seem to locate anything on the Bachmann site or the Soundtraxx site.
It seems straight forward but I'm lost when it comes to the V+ and SMK pads.
Thanks in advance.

Bach-Man,
Is there a part number for the red cable that runs between the E-Z Command Controller and the E-Z Track rerailer?
This is the cable with the flat connector on one end that goes to the track, and the 2.3 or 2.5mm round connector that plugs into the controller.
Thank you.