TCS T4X Decoder Installation for HO-Scale Hornby Class 47 diesel. It was performed by Robert Lewis of Tilehust, Reading, United Kingdom

Important Soldering Tip:
Please do not use any flux either liquid or paste on the mother board. It will damage it. Use only Rosin core solder approved for electronics use.
We recommend to use only Kester "44" rosin core, SN63PB37, .015" diameter, part number 24-6337-0007.
This can be ordered from Techni-Tool under Techni-Tool part number 488SO157


This locomotive is a Hornby class 47, in the original British Railways two tone green livery. This is an early model in the "silver seal" series. I have used a TCS-T4X decoder for this installation.


The motor chassis is "live", connection to the rail is via the metal wheel/axle assembly, The outer non-traction tired wheels need to be replaced with insulated geared wheels. These are available from

Unfortunately I found the un insulated wheel problem after I had smoked a decoder, with the model on its side there was no continuity between the wheels and the motor terminals, only when the locomotive was on the rails with the weight pressing down on the axle did the short circuit occur. Lesson learned !!

.   To remove the body you will need to pry away the body in 4 positions underneath each cab door, it should then lift up easily.

Remove all the existing wiring, diodes and motor capacitor. Lift off the cab interiors and pull out the 2 (each end) bulb retaining plugs, retain the 2 headcode bulbs.  Then remove the 2 slotted screws which hold the bogie sideframes to the motor chassis, the motor block can then be removed from the bottom of the sideframe moulding.


The all metal wheels can be removed by tapping the axle through with a fine punch. Then refit the new wheels on the axle, the insulated centre and gear teeth will ensure that the metal rim cannot touch the motor frame.  Then refit the motor frame to the plastic bogie frame  with the 2 screws.


Solder the orange and grey wires to the brush terminals, and the blue and yellow to the head code bulb, sleeve the bulb joints. The sleeving/wires can run through slots of the cab interior moulding.


Connect the red and black decoder wire to the un powered bogie pickups. The blue wire will have to have another piece of wire spliced into it to feed the other bulb, along the the white wire, connect these in the same way as the bulb at the motor end.


All the un used wires have been sleeved and coiled up into the fuel tank recess, there is also space here for the decoder, which has been held in place by double sided tape.
The cab interiors can also be held down with a piece of double sided tape, this helps when re-fitting the body. Test the installation. Refit the body.


Other solder tips: When stripping wire, only strip a tiny little bit of the insulation. Strip no more then a 1/64 of an inch. When the wire gets tinned with solder the insulation will shrink back more. Try to not expose any more wire then half the length of the solder pad at most. In no case should solder or exposed wire wire ever be outside the boundary of the the solder pad you are attaching a wire to.
Click here for important information on properly Stripping and Tinning wire

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