Installing a DCC decoder in a Bachmann Class 205 "Thumper"

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Last updated 29 March, 2020
Bachmann 205

Before installing chip into any loco it is advisable to check the current being drawn by the loco. You should test the current drawn when the loco is stalled to find the peak current and select a decoder that will cope with that maximum current requirement.

This installation is quite straightforward and uses a TCS EU621 direct plug 21-pin decoder, though any 21-pin decoder would do the job.

Bachmann 205

Removing the body is reasonably easy, but you will need both a small philips screwdriver and a some pieces of thick card to carry out this installation.

First undo the two small screws located at the front end of the underside of the loco.

Bachmann 205

The body fits very tightly to the chassis. In addition, the glazing on the model locks the body in place against lugs located on the sides of the seating unit.

Once the screws have been removed the front end of the body will move slightly with some pressure. Pull it upwards as far as you can. Then gently slide a finger nail between body and chassis on one side and put a thick piece of card between the two parts, sliding the card as far from the front as possible. Repeat this on the other side. Then move further towards the back and repeat the process on each side, trying to locate the card close to the rear lug (shown left). Once the lugs have been cleared the body should come away quite easily.

Bachmann 205

Once the chassis is clear the location of the decoder socket becomes obvious. You will need the small flat headed screwdriver to gently lever out the blanking plug. Be careful not to bend any of the pins.

Bachmann 205 Bachmann 205

Insert the 21-pin decoder into the socket. Make sure it is up the right way!

Test and program the loco before fitting the body. Refit the body and fit the special coupling which completes the electronic control of lighting in the trailer car. Lighting, both indicator panels and internal lighting of both carriages, are operated from F0 on your DCC throttle.

Beware when refitting the body! I found it easier to fit the front end first, making sure the indicator lighting bar doesn't get bent on reassembly, then snapping the rest of the body back into place.



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