How to convert Graham Farish Class 40 to DCC Sound

This guide covers the following models:

• Graham Farish Class 40 'Atlantic Conveyor' D306 in BR Green (371-175)
• Graham Farish Class 40 40052 in BR Blue (371-176)
• Graham Farish Class 40 D351 in BR Green (371-177)
• Graham Farish Class 40 D382 in BR Green (371-177A)
• Graham Farish Class 40 40192 in BR Blue (371-178)
• Graham Farish Class 40 40150 in BR Blue (371-178A)

Step 1 - Disassemble

The DCC part of this conversion follows the standard Chinese Split Chassis conversion process, where part of the chassis next to the motor contacts is removed. The sound conversion requires more of the chassis removing so there is room for a speaker and the larger sound decoder.

Follow the Chinese Split Chassis guide for detailed steps to disassemble the loco. The two parts of the chassis need to be separated, and everything removed so you are left with just the two bare metal chassis halves.

Step 2 - Mill Chassis Parts

Mill out the three areas highlighted in red. Get as close to the body roof supports as you can at the outer edges, and as close to the chassis screw holes on the inner edge.

When the decoder and speakers are fitted, everything must stay within the profile of the roof supports, otherwise the body will not sit flush.

Reassemble the chassis. Again, the Chinese Split Chassis guide has detailed steps for how to do this.

Step 3 - Fit Speaker

Glue the speaker into the left hand recess. Depending on the space available, you will be able to fit either of the standard ESU speakers, or a small YouChoos speaker.

Step 4 - Add Track Pickup Contacts

Ordinarily, this chassis has a suppressor fitted across the two chassis halves. Each leg of the capacitor is soldered to a copper tab, which is held onto the chassis by a small screw. These have been lost during the chassis milling.

There are a few ways to reliably get power from the track pickups to the decoder. In this example, one side of the chassis has a new solder tab fitted between the chassis screw and the chassis.

On the other side, a tap has been used to create a new threaded screw hole that the original copper tab can be fixed screwed to.

Other methods include simply trapping wires behind the chassis screws, or using copper adhesive tape.

Step 5 - Fit Decoder

Fit the sound decoder into the right-hand recess. Here we have used an ESU LokSound 5 Nano Next18 decoder, with an ESU Next18 wiring harness. Wrap the decoder in some kapton tape to protect it from shorting against the chassis.

Solder the orange and grey wires to the motor contacts.

Solder the red and black wires to the track pickup tabs.

Solder the brown wires to the speaker.

Step 6 - Test

Place the model on your programming track and test.