Add a DCC decoder to an Arnold Calf

Converting N-scale DC engines to DCC allows you to run them on your DCC layout. In this post, I’ll show how I added a TCS Z2 DCC decoder to my N-scale Arnold SW-1500 Calf. Similar methods can be applied to all sorts of model engines.

What we need

A TCS Z2 2-function DCC decoder in a small form factor
Kapton insulating tape
Multi-strand thin wires, red and black, each 50mm/2” long
Small 10W soldering iron and flux solder

Access the interior

Remove the shell from the frame by pressing the fuel tank together (watch out as tabs break easily)
Remove the hood from the frame (walkway) by pressing the front end inwards (again, wiggle gently before pulling as the tab might break)
Drop the trucks, the power pickup PCB and the DC engine with wire worms

Make room for the decoder

Mark the top of the frame towards the high end of the motor, as illustrated.
After the motor has been removed from the frame, use a saw and file to remove the marked part of the cast metal frame.

Convert the power pickup

Isolate the inside of the copper bracket on PCB with a piece of thin Kapton tape.
Instead of the PCB top directly feeding the DC engine, we solder a 50mm piece of thin red and black wire to the BCB tabs.
Tape the decoder in its new position on top of the frame.
Clip, strip and solder the gray and orange wires directly to the engine copper pads.

Decoder taped in place, guide wires up through frame

Finishing up

Reassemble the trucks, motor and pickup PCB, while guiding the red and black wires up alongside the motor
Clip the red and black wires to the decoder’s, folding them forward alongside the decoder.
As front headlight place an LED in series with a 500 Ohm 1/4 W resistor in the recess, and solder to the blue (+) and white (-) decoder wires.
Check all wiring, looking for shorts and polarity.
Test drive the loco on a DCC controlled piece of track. Check speed, motor noise, turn on the headlight.

Decoder in place, solder headlight and red/black wires

Find the full TCS instructions here
TCS provides a “GOOF-PROOF” Warranty, so go ahead and start converting your locos too.