I have long held a dislike of Hornby's own DCC decoders (their Sapphire excepted), so when I purchased the Peckett W4 saddle tank loco, I declared at the outset that I would use something different, even if it meant hard-wiring it. Unfortunately, Hornby are the only manufacturer offering a 4-pin decoder. I never took photos of that conversion, so when I received Hornby's Sentinel diesel shunter, I resolved to treat it the same way.

The decoders I favoured for these conversions were TCS M1 (2-function) or M4 (4-function); they cost me the same at the time I bought them and the shop had run out of M1s. I doubt that I'll use the functions in the short-term, but if I ever get brave later I might fit lights, firebox glows ... that sort of thing! These decoders are smaller than the Hornby one, so they actually fit in the places provided with room to spare.

I did have a brainwave, though, and decided to retain the 4-pin socket and use the 'blanking plug' to connect the decoder by the relatively simple expedient of replacing the two looped wires and soldering in the correct decoder wires. Hornby have wired the plugs so that the track feed wires are on the outer pins and the brush feeds on the inner ones, so even if the plug is accidentally (or deliberately) reversed, no harm will come to the decoder.

The metal sockets can be slid out of the plastic shell by lifting the little plastic tags. This allows the Hornby wires to be removed - I just cut mine off flush but you can choose any method you like to get rid of them.

After this, the decoder wires were soldered on, using the end tags on the metal bits to clamp the wires in place as well.

Then the assemblies can be slid back into their respective sockets, ensuring that they are correctly positioned - black - grey - orange - red.

Spare wires on the decoders were cropped short and secured with a bit of heat-shrink tubing.

The idea worked well with the Peckett, making it easy to restore to DC or swap decoders later if desired. However, the Sentinel wasn't as cooperative, and I ended up stripping it completely and rewiring it, including hard-wiring the decoder. The photos show how it all worked for the Peckett, and how it could have been for the Sentinel.