This video discusses the DCC/DCS switch on MTH Proto 3 O-Gauge 3-Rail Locomotives.
As I understand it:
*1 Proto 1 locomotives were "sound-only"
*2 Proto 2 locomotives added DCS capability, but did not run on DCC.
*3 Proto 3 locomotives were introduced around 2011, and added the capability to run on DCC.
*4 All Proto 3 Premier locomotives have the DCC/DCS switch.
*5 The Proto 3 Railking locomotives from about 2011 to 2014 had the DCC/DCS switch.
*6 The Proto 3 Railking locomotives after 2014 no longer have the DCC/DCS switch.
*7 The Railking locomotives made after 2014 still have the DCC/DCS decoders, but in order to run the loco on DCC, you have to either add the switch yourself, or cut a jumper wire inside the loco.
*8 If you cut that jumper wire, the loco will then run on DCC, but not on DCS.
*9 Adding the switch allows you to essentially "disconnect" the jumper wire to run on DCC, or to "re-connect" that jumper wire to run on DCS.
*10 MTH publishes a 2-page bulletin describing how to add the switch; you can view a copy on AutoControls.wordpress.com ; look for "Video #820".
* This iMovie10 video was uploaded by JamesIngram.net .
TEMPORARY DCC VIDEO: The TEMPORARY video vimeo.com/367613757 shows DCC Operation of a Proto 3 Alco S2 loco, and also automatic DCC operation. The Temporary video is in the process of being SPLIT-UP into 2 separate videos.