Got my 4-8-2 Spectrum HVY MNT today and DCC ready. I have a Bachmann 8 pin decoder. The decoder can be plugged in two ways. Does it matter which direction the plug goes in. Should the wires on the side of plug be on the same side the wires are soldered in to the circuit board. Or should the plug be plugged in with the plug wires facing the oposite side of the circuit board where there is no wiring soldered to it?
There should be a dot or a number 1 near one of the corners of the socket. This is where the pin connected to the orange decoder wire goes.
If you can not see the features that Jim mentions, plug it in, try it, if all the lights work correctly, you have it plugged in correctly, if not, un plug rotate the decoder 180° and plug it in. The NMRA standard was designed so that there would be no damage.
See the NMRA website for more information on DCC standards.