Installing an Engine Decoder Power Pack with Martin Tärnrot

Specifically in this video, Martin will demonstrate how to install a power pack on a 21-pole decoder connector on the NEM 660 or 21 MTC. The power pack he will install has three main components. A capacitor stores electric energy, and the charging goes on through the resistor and discharges through the diode. Sometimes it is necessary to use multiple small capacitors in order to make it fit inside the locomotive or engine. He shows the resistor in the charging network, which is connected to the diode below it. Martin solders them together.

Next it is time to remove the decoder from the engine. To do so, he uses a wrist strap that is grounded to avoid electrostatic discharges that might damage the electronics. There are paths already available on the motherboard for a power pack. Unfortunately, this is not true in many cases, so he recommends soldering the cables directly to the connector.

These wires are then connected to the power pack, starting with the negative side of the capacitor. When both are connected, he isolates with some plastic tape. The last step is to fix the capacitor somewhere. Model train power packs are great for any disruptions in sound over dirt spots.

For more on locomotive decoder installation or to learn how to use decoders on model railroad DCC systems, visit the Model Railroad Academy archives.