OBSERVED PROBLEM: The engine has poor motor speed control in contrast to the primary benefit of using a "BEMF" motor drive based decoder.
PROBLEM: Bachmann Engines have electronic parts that can interfere with the proper operation of the motor when one uses a modern DCC decoder with a feature called BEMF. Modern BEMF DCC decoders offer the benefit of extral slow and smooth speed operation without stalling regardless of the size of the train being pulled by the engine. To learn more about BEMF, go here: Back-EMF (BEMF)
PROBLEM DETAILS: Every Bachmann Engine has two electronic devices call Capacitors that are electrically placed in parallel with the motor terminals. The capacitors may physically be mounted directly on the motor itself or on some green PCB board found inside the engine that feeds power to the motor.
WHY CAPACITORS: They are control the Radio Frequency Interference (RFI) noise generated inside the motor during rotation as an electrical side effect of the motor's commutation action. Uncontrolled RFI noise can interfere with ANY radio wave reception devices such as TV's, AM/FM Radios, Walkie-Talkies and FRS-radios depending on what frequencies the noise contains. The capacitors, as part of the RFI filters, are installed to meet all international radio frequency regulations regarding radio frequency interference (RFI) which is electrical/radio noise problems.
To learn more about the capacitor problem go here: Motor Caps VS Noise
SOLUTIONS:
1) Remove the capacitors if mounted on the motor.
2) Remove the capacitors if mounted on the PCB. To learn more go here: Bachmann Engines
3) Remove the PCB containing the capacitors.
WILL REMOVING THE CAPACITORS VIOLATE THE ENGINE WARRANTY?
No. Bachmann in fact has stated this on the companies website. To learn more go here: Bachmann Engines