Aristo-Craft "DCC" socket This is for large scale trains, and variations of this socket have turned up in Bachmann products. I'll try to give some history at the end but basically this was first produced by Aristo Craft and only recently Bachmann has taken the basic pinout and modified it. In addition over the years, Aristo has informally added some functionality, but not on a published or consistent basis. Aristo-Craft documentation below is the link from the Aristo site: http://www.aristocraftforum.com/techinfo/dcc%20rcc%20pin%20connectors/index.html From this page are the PIN designations Basic layout: There are 2 rows of sockets, with 0.1" spacing. One row has 12 "holes" and this is about the only "standard" part. The second row was for expansion and also mechanical support. The 12 pin socket is called J1 and the 10 pin one is called J2. Pin # J1 12 Pin Plug Functions DCC Wire Color Code (Theoretical)** 1 Power Pick-up Right Side Red 2 Power Pick-up Right Side 3 Motor(s) Right Side Orange 4 Front Lamp Control White 5 Smoke On/Off* Accessory Color 6 + Out 7 Ground Common Blue 8 Smoke On/Off* Accessory Color 9 Rear Lamp Control Yellow 10 Motor(s) Left Side Gray 11 Power Pick-up Left Side Black 12 Power Pick-up Left Side J2 AUX plugs not used for power/control purposes (but sometimes the speaker is wired to it) * Pin 5 & 8 must be bridged for DCC **See DCC decoder manual for more color code information DC "dummy" / jumper plug When running DC you need this plug installed (came installed from the factory) Pins 1-4 jumpered (motor and front lamp connected to right rail) Pins 9-12 jumpered (other motor lead and rear lamp connected to left rail) Pins 5 & 8 jumpered (enables power to smoke unit) Pin # Pin Function 1 Power Pick-up Right Side 2 Power Pick-up Right Side 3 Motor(s) Right Side 4 Front Lamp Control 9 Rear Lamp Control 10 Motor(s) Left Side 11 Power Pick-up Left Side 12 Power Pick-up Left Side The dummy plug provided with the plug and play PC board can be used with a DCC decoder or RCC receiver that do not have the 12 pin plug. Sever the jumper between pins 2&3 and pins 10&11 Solder one motor lead to pin 3 and the second to pin 10 Solder one power pick-up lead to pin 1 and the second to pin 12 Notes/ exceptions: Bachmann socket On the Bachmann implementation, Bachmann locos EXPECT to see positive unregulated rectified track power (or battery) on J1-6. (as with all DCC decoder connections, this is also the common for function "outputs"). Negative unregulated rectified track power (or battery) is on is J1-7 If this power is not supplied to these pins, the lighting does not work. On most Bachmann boards, if you have a decoder that violates the Aristo specification (Like an Aristo Revolution sound decoder HAH!) rather than try to feed the socket directly, you can feed power to the B+ and B- terminals on the Bachmann main board. Digitrax decoders Digitrax decoder, DG583AR has a pin missing #7 and #8 is marked not connected. This can cause 2 problems, lighting not to work, and smoke not to work. This seems a silly way to address the problem, but my opinion is that early on, Digitrax interpreted the "Aristo standard" in their own way, which led to electrical issues that destroyed the Digitrax decoder. Rather than use the socket as documented, they told people to just bend the "offending" pins up so they would not enter the socket... well this led to the current situation since not everyone followed the instructions. A simple design change would allow things to work properly.