This application note is courtesy of Michael K. Perrin, and addresses the installation of an N-Scale decoder in the Bachmann F40PH (now discontinued). This note calls for using either DN93 or DN140, both of which have been discontinued. Current decoders such as the DZ125 or DZ143 and other similar N scale decoders can be used.
1) Cut a place for the decoder in the back recess in the frame. Because this is a "sandwich" frame there is no room for the decoder without using a saw or Dremel tool to make a cavity for the decoder. (This is the hardest part of the installation as far as I am concerned).
2) Solder a pair of jumper wires from the rear wipers to the front wipers and then solder the red and black wires from the decoder to the front wipers.
3) Isolate the motor by cutting the two contact strips, noting the arrow pointing down designating bottom on the motor.
4) Solder the orange wire to the bottom contact on the motor and the gray wire to the top contact. Cover with electrical tape.
5) To use the circuit board in the engine for the lighting effect with the forward light and strobes on whenever F0 in on follows: With the shell upside down, looking at it from the rear, solder the blue wire to the left contact strip. Solder the white and yellow wires to the right contact strip. Cut the contact strips short and cover with electrical tape.