I am new to DCC and will be trying to modify some older engines and would like to know if the Blue lead marked lighting common(positve) attaches to the chasis of the engine or do I have to isolate the lights from the chasis?
You have to isolate the light and motor leads for DCC.
Rich
Common means that wire will go to one leg of every light bulb/led in the loco.
The other light leads will be the function leads (fo f1 f2 ect) for each bulb/led you use.
one common connection to every light,one function connection....No frame connections to anything BUT the decoder power input.
Jim