How to convert N Gauge Graham Farish Class 251 Midland Pullman to DCC Sound

Step 1 - Remove Body

Both power cars are motorized in this model, and have 6-pin decoder sockets on the main PCB. Either or both can be converted to sound, the procedure is the same. Regardless, it is usually necessary to adjust the decoders at each end so both cars are speed matched. This improves running, particularly at lower speeds, and reduced strain on the motors when one end is pushing or pulling to hard on the other.

First, remove the body by pulling gently upwards. It's easiest to start from the back and work forwards.

Step 2 - Fit Speaker

Remove the screws holding the PCB in place, and remove the PCB. Unclip the interior seating detail plastic.

Cut away the plastic on the inner end just in front of the partition.

Glue the speaker in place and solder two brown wires to it. Refit the interior plastic into the model.

Add some kapton tape to the underside of the PCB to prevent any possibility of it making electrical contact with the top of the speaker.

Step 3 - Refit PCB

Add some kapton tape to the underside of the PCB to prevent any possibility of it making electrical contact with the top of the speaker.

Refit the PCB, and fix in place using the three screws.

Step 4 - Fit Decoder

The decoder used here is an ESU LokSound 5 Next18 decoder, with a 6-pin wiring harness. Solder the two brown speaker wires to the socket.

Plug the connector into the socket on the PCB, and clip the decoder into the Next18 socket.

Flatten the main harness ribbon cable and use a piece of tape to route the brown speaker wires neatly.

Step 5 - Refit Body

Refit the body.

If you are converting both ends to sound, repeat the above steps for the other driving car.

Step 6 - Test

Place both cars on your programming track, and confirm that the directional lights are correct according the direction of travel.

Test the sound functions work as expected.

With the units not coupled together, check that they both move at the same speed in both directions, i.e. one never catches up to the other. If they are not well speed matched, use your preferred decoder programming method to adjust the CVs accordingly.