How to convert Tomix Thomas The Tank Engine 1 (93706) to DCC

This guide covers the following models:

• Tomix N Scale (N Gauge) Thomas The Tank Engine 1 (93706)
• Tomix N Scale (N Gauge) Thomas The Tank Engine 1 (93810)

The process for converting other locos in the Thomas & Friends range is broadly similar. This particular Thomas model has room in the cab for a small decoder, others such as the Tomix Percy require some of the chassis milling away for it to fit.

Step 1 - Remove body

Unclip the body and gently pull upwards to remove it. Do the same for the running board frame.

Remove the three screws underneath, the keeper plate and the entire wheelset.

Step 2 - Disassemble Chassis

Remove the two screws from the side of the chassis, then split the two halves. Note the two contact springs that electrtically bridge each side of the chassis to the motor contacts - they need to be removed too, and won't be needed.

File down the two nubs where the contact springs were sat. This makes absolutely sure that they cannot touch the motor contacts once wires have been soldered on. It isn't necessary if your soldering skills are good enough to solder the wires to the inside of the contacts, leaving a gap.

Step 3 - Modify Motor

Remove the motor from the chassis, and remove the plastic holder. This makes it much easier to solder to without melting anything. Solder an orange and grey wire to the motor contacts.

Refit the motor and replace the gears if removed previously.

Put the two chassis halves back together.

Step 4 - Connect Track Pickups

There are two different ways to connect power to the decoder from the track pickups. The easiest way is to scrape a little of the black paint off under where the screw/nut touches the chassis and then trap the red/black wires underneath while gently tightening the screw.

An alternative is to scrape away some of the black paint and use conductive copper tape, which is easy to solder to. Both methods are reliable, however the latter is neater and avoids the possibility of shorting the two chassis halves accidentally.

Either way, you should end up with four wires: grey/orange, red/black. Test that the grey and orange wires have no continuity with the red/black wires, or the chassis itself. Solder the wires to your decoder.

Step 5 - Refit body

The decoder will fit above the motor inside the cab. There isn't much room, so try to avoid using excess wire if you can. Make sure the decoder is protected in either kapton tape, or heat shrink sleeving.

Refit the running board frame from the top, then clip the body back on. Place Thomas on your test track, and the conversion is complete.