Minitrix A4 Pacific 'Mallard' DCC Conversion

Mistakes may damage your locomotive, controller or other accessories. Use a multimeter to make absolutely sure you have completely isolated the motor from the track before testing. Always use the Programming Track for testing. Our guides are provided for reference only, and you proceed entirely at your own risk. Unsure about something - try our DCC Conversion Service instead.

This conversion follows the Minitrix Steam Loco method.

Step 1 - Remove body

Remove the loco body by unscrewing the screw in the top, then gently pulling upwards. Remove the tender body by removing the screw underneath. The valve gear can be a bit tight, but it should unclip with a bit of pressure.

Step 2 - Remove motor

Remove the two screws holding the motor in the bracket and pop it out.

Step 3 - Modify tender PCB

Desolder the black and green wires from the motor and run them back through the holes in the motor bracket. Then desolder them from the PCB. Also remove the copper choke and the blue wire that runs to the pickup pillar in the loco chassis.

This model has lights, so you will need a blue lighting common positive wire. The decoder used here is a Doehler & Haass PD10MU, which has a solder point on the back for this.

Fix your decoder temporarily for now using some black tack, and solder the red and black (track pickup) wires from the decoder to the tracks on the PCB as shown. Add a link wire on the bottom of the PCB as shown. Refit the PCB.

Step 4 - Modify loco chassis

Remove all wires from the chassis, and the brass contact that sits underneath the motor. Add some Kapton tape around the motor bay.

Step 5 - Connect the motor

Refit the motor, and secure with the two screws. Pass the motor wires from the decoder (orange and grey) through the left-hand hole in the back of the motor bracket. Pass the light wires (blue and white) through the right-hand side. Solder the orange and grey wires to the motor. At this point, it is a good idea to test that you have correctly isolated the track pickups from the motor using a multimeter.

Step 6 - Connect the light

Solder the white and blue wires to the bulb. You can test it works at this point if you wish. Add some insulating heat shrink to isolate it from the chassis, and refit into the light holder.

Step 7 - Reassemble

Refit the loco body and tender body if you haven't already, put it on your DCC programming track to test. Note that the tender weight is not refitted as the decoder is now in the way. Generally, you should find that the tender is heavy enough to provide strong running. If you wish, you can either cut the weight down and refit (taking care to ensure it does not make electrical contact with the decoder) or add your own weight. Ideally, the weight will be evenly distributed, so adding it to the inside top of the tender body is a good method.

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