How to convert Bachmann OO Split Chassis DCC Conversion to DCC

This guide covers Bachmann OO gauge split chassis diesel and steam models, such as the Class 03 and Class 04 shunters, 6P Royal Scott, A4, Mallard and other similar locos.

• Bachmann Class 03 03197 in BR Blue livery (31-353)
• Bachmann Class 04 11217 in BR Black livery (31-339)
• Bachmann Class 6P Royal Scot 46100 in BR Green livery (31-020)
• Bachmann Class 6P Rebuilt Royal Scot 46102 'Black Watch' in BR Green livery (31-225)
• Bachmann Class 6P Rebuilt Royal Scot 6133 'Green Howards' in BR Green livery (31-226)
• Bachmann Class 6P Rebuilt Royal Scot 46162 'Queens Westminster Rifleman' in BR Green livery (31-227)
• Bachmann Class 6P Rebuilt Royal Scot 46141 'The North Staffordshire Regiment' in BR Green livery (31-228)
• Bachmann Class 6P Rebuilt Royal Scot 46159 'The Royal Airforce' in BR Green livery (31-230)
• Bachmann Class A4 60009 'Union of South Africa' in BR Green livery (31-951)

It may also be suitable for other models with a similar chassis and motor arrangement.

Step 1 - Disassemble Chassis

The motor sits inside two chassis halves, and gets power from the track via sprung contacts that touch at each side. To convert to DCC, it is necessary to stop the motor contacts touching the chassis.

The first step is to disassemble the loco and split the two halves.

Step 2 - Isolate Motor

Remove the motor. Put some kapton tape along the chassis surfaces where the motor contacts were previously touching it. While the motor is out, cut off the copper spring contacts as far back as you can. Solder a grey and orange wire to each side of the motor.

Put the motor back in, and route the grey and orange wires out. When the chassis is put back together, they will emerge from the gap between the two halves.

Step 3 - Connect Track Power

Strip about 8mm of insulation off the red and black wires. Scrape off any black paint from the inside of the circular holes where the chassis screws go. When the chassis is reassembled, the black and red wires will be trapped between the screw head and the chassis on one side, and the black retainer and the the chassis on the other.

Step 4 - Reassemble Chassis

Put the two chassis halves back together and tighten the three screws, trapping the red and black wires against the chassis at either side as previously described.

Step 5 - Connect Decoder

Solder the four wires onto the decoder as below. There is room inside the body for a 6-pin socket, so you can optionally install one of those for convenience if you wish.