Minitrix Class 27 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.

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This guide covers the Minitrix Class 27 models, including:

• N205 Class 27 D5379 (British Rail Green)

Step 1 - Remove Body

Remove the two screws in the roof of the body and then gently lift upwards away from the chassis.

Step 2 - Prepare PCBs

Remove the upper PCB. Remove the screws holding the motor bracket in place, and take out the motor. Remove the lower PCB.

Take the upper PCB, and desolder the two wires coming from the lower PCB. Remove both resistors - these are not needed for DCC operation, so can be discarded.

Take the lower PCB, and remove the capacitor and choke. Add a piece of kapton tape as shown so that the two copper contacts can no longer make an electrical connection.

Step 3 - Connect Lower PCB

Solder the red decoder wire to the centre strip of the PCB. Solder the black, grey and orange decoder wires to the contact points as shown in the photo. Replace the lower PCB back into the chassis.

Step 4 - Refit Motor

Route the four wires up through the gap and re-seat the motor. At this point, it is a good idea to check that the track pickups are completely isolated from the motor wires using a multimeter. There should be no continuity between red/black and orange/grey.

Step 5 - Modify Lighting

Solder a blue wire (common lighting positive) to the tip contact of each bulb. Solder a white wire to the outer casing of one bulb, and a yellow wire to the other (note that in the photos both lighting wires are white). To avoid having to solder two blue wires to the decoder, you can join them together and just run a single wire instead.

Add shrink sleeve around the outside of each bulb so that it cannot come into contact with the chassis, then refit them both.

Step 6 - Connect Decoder

Fix the decoder to the top of the upper PCB using a sticky pad or black tack. Note the black insulating tape, which is used to temporarily hold the PCB to the chassis so it doesn't spring up while it is being worked on. Make sure the decoder and wires are well clear of the holes where the body screws go.

Solder the red, black, grey and orange wires to the decoder. Connect the front and rear (white/yellow) lights and finally the blue common positive(s). If your decoder does not provide a common positive, you can usually connect that side of each bulb to one of the track pickups instead.

Step 7 - Test

Put the loco on your programming track and check that you can read the loco ID. If all is well, refit the body and the conversion is complete. Depending on the decoder you have used, and your preferences, you may want to dim the lights a little as the default decoder setting can make them very bright. Sending too much power to the lights can also burn them out. Consult your decoder manual for which CVV values change the brightness.

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