This installation of TCS M1 Digital Decoder is for HO Scale Bachmann Spectrum K4 Pacific 4-6-2 and was performed by a TCS Customer.
First the shell was removed from the frame. The screw holding the rear drawbar was removed to accomplish shell removal. This locomotive has a split frame design. Bachmann uses the frame as a conductor of electricity to the motor. Decoder installation will not require the use of the frame for conducting electricity.
Remove the weight inserted in a rectangular cavity in the top front of the frame.
Dismantling the split frame to access the motor is necessary. Remove two screws on the bottom of the unit between the drive wheels. Using great care remove the cover over the drive wheels. The leading and trailing trucks are attached to the cover. The cover cannot be completely separated from the locomotive because the pick up wires are attached to the frame from the leading and trailing trucks. Separate the cover from the frame as far as possible.
Next the drive wheel assembly will need to be removed. The piston housing and support for the running gear are attached to the frame. Remove the piston housing and running gear support with care. The drive wheel assembly will now be free from the locomotive. Now the split frame can be separated by removing two screws on the side of the frame. Remove the motor. There are two metal contacts that extend from the positive and negative poles of the motor. The negative pole is identified by the letter "N". Remove the contact extensions by bending the contacts back and forth many times. Solder a gray wire to the "N" negative pole and an orange wire to the other pole. Isolate the motor contacts by covering with tape. Be sure to remove the tape from two ventilation holes on each side of the motor. The ventilation holes on the black plastic between contact poles.
Remove the brass contact plates soldered to the pick up wires attached to the leading and trailing trucks. Make sure to mark the right rail from the left rail pick up wires. Reassemble the frame inserting the motor and make sure to reinstall the plastic spacers. Reattach the drive wheel assembly and bottom cover.Following the decoder instructions wire the decoder to the appropriate wires. Remove the green circuit board from the inside top of the shell. Disconnect the headlight wires from the green circuit board. In this installation a 910 Ohms resistor was added in-line for the headlight. Place the M1 decoder in the vacant well in the front of the frame. Tape down loose wires and reattach the shell.