I am modifying a G scale Toby to run with a BlueRail board. Inside Toby, a set of orange and brown wires lead to a small round circuit board on the end of the motor. It seems to have some resistors and a few capacitors. What does this circuit board do? Can I leave this circuit board in place? (BlueRail uses the same pulse-width-modulation to run motors that a decoder does to run motors).
The circuit board at the end of the motor is for RF suppression. It contains a set of capacitors and inductors. This part is a Bachmann common part and used on a lot of locomotives.
As a manufacturer, to be able to sell the locomotive you need it for FCC compliance. If you put a DCC decoder or I suspect a BlueRail unit some or all of this suppression is done in the actual decoder.
As an end user it is common to remove this board as to the user it serves no useful purpose. It can safely be removed but it may increase RF motor noise.
Thanks