Dapol Class 73 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.

Buy Dapol Class 73 DCC Conversion for £50.00

This conversion covers a number of the older, non-DCC ready Dapol Class 73 models including:

• Dapol Class 73 73129 'City of Winchester' in Network Southeast livery (ND012A)
• Dapol Class 73 73195 in Network Southeast livery (ND012B)
• Dapol Class 73 73114 'Stewarts Lane' in Mainline blue livery (ND021A)
• Dapol Class 73 73133 in Mainline blue livery (ND021B)
• Dapol Class 73 73119 'Kentish Mercury' in Civil Engineers Dutch livery (ND022A)
• Dapol Class 73 73110 in Civil Engineers Dutch livery (ND022B)
• Dapol Class 73 73142 'Broadlands' in BR blue livery (ND036A)
• Dapol Class 73 73108 in BR blue livery (ND036B)
• Dapol Class 73 73111 in BR blue livery (ND036C)

Similar to other Dapol models released around the same time (e.g. Class 66), these models have a two-part split chassis. To convert this model to DCC, it is necessary to remove some of the chassis block to make room for the decoder. There is a single white LED at each end. If you also want to convert these to DCC control, the existing contact strip arrangement in the roof of the body needs to be removed, and the LEDs must be completely re-wired directly to the decoder.

Power is transmitted from the wheels to the motor via copper contact strips. On one side, the contact strip is attached to the plastic motor surround and directly touches the chassis. There is a capacitor between this strip and the motor contact. Another copper contact is trapped between the plastic spacer and touches the other half of the chassis. An arrangement of capacitors and resistors connects this side to the other motor contact.

Step 1 - Remove body

Remove the body by gently pulling upwards.

Step 2 - Disassemble Chassis

Remove the four screws from each side of the chassis. Now, gently split the two halves so it can come away from the underfloor/buffer detail plastic.

Step 3 - Disassemble Motor

Remove the motor from the chassis.

Remove the copper contact strip attached to the plastic motor housing. Desolder the capacitors, resistors and the other smaller contact strip.

Step 4 - Modify Motor

Solder a grey and orange wire to the motor contacts. Route the orange wire to the top of the motor via the inside of the plastic casing. A small dot of glue or blacktack will help keep the wire in place.

Step 5 - Modify Chassis

Remove the plastic spacer from the end where there is already a slight recess in the chassis, i.e. where the collection of three components was previously. Modify the spacer by removing part of the plastic as shown.

Mill out part of each chassis half as shown to create room for the decoder.

Step 6 - Reassemble Chassis

Refit the motor, then place the two chassis halves back together.

Place the two chassis halves back inside the underfloor frame.

Step 7 - Refit Bogies

Refititng the bogies is a little fiddly. First, move one end slightly out of the underfloor frame, then prise the two halves slightly apart by a few millimetres. This makes it easier to refit the bogie towers.

Refit the motor shaft using some tweezers, then refit the bogie tower. The bogie tower should clip into the plastic peg facing down from the chassis spacer. Make sure the two copper pickups can smoothly wipe across the inside surface of the chassis throughout the full turning arc of the bogie.

Repeat for the other side.

At this stage, check the bogies are fitted correctly by applying a small voltage to the grey and orange wires. All wheels should turn. If you find that the wheels on one bogie do not turn, it is likely the shaft is not in properly.

Refit all eight chassis screws.

Step 8 - Connect Track Pickups

Tin the end of a red wire, and trap it behind one of the chassis screws on one side. Do the same with a black wire on the other side.

Step 9 - Test Motor Conversion

At this point, check there is no continuity between the red, black, grey or orange wires. Also check that your red/black wires do have continuity with the wheels on their respective sides.

Step 10 - Remove Light Wiring

Remove as much of the wiring in the roof as you can, including the two copper strips and the resistor. The glue is very strong, so most likely some remnants will remain. It is safer to leave the odd piece of old wire rather than risk damaging the body. Note from the factory wiring diagram above that the +/- are switched at each end so that the correct LED illuminates depending on the loco's direction of travel on DC.

Step 11 - Rewire Lighting

Extend the red/black wires from each lighting unit, using blue for positive and white (front light) / yellow (rear light) for negative.

Join the blue wires to another shorter blue wire and tape or glue them to the centre section where the resistor was originally.

Step 12 - Fit Decoder

Solder the red, black, grey and orange wires to the decoder.

Solder the white and yellow wires to the decoder, followed by another short blue one.

Solder a 1kOhm resistor between the two blue wires. Cover with resistor and the decoder with shrink sleeving.

Using glue or black tack, fix the decoder and the resistor into the milled-out recess.

Step 13 - Refit Body

Neatly arrange the wires so they sit as flat as possible, then cover the entire top surface with kapton tape.

Clip the body back onto the underfloor frame, and the conversion is complete.

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