Loco to Tender wiring by 4 pin connector on Duchess of Sheffield.

[ColinB]

I am repairing an old City Of Sheffield Duchess. This has a 21 pin DCC socket in the tender with I assume a LokSound decoder. Looking at the web it was supplied with this. Needless to say there were lots of issues with the loco, but I noticed that the Loco/Tender connector is wired different. The two inner wires pins 2 and 3 go to pickups, whereas pins 1 and 4 go to motor. This is the opposite to my current Hornby locos and the ones where I have added the loco/tender connection. Did Hornby originally wire it this way, because it means if you connect the tender to a more modern loco for testing you would blow up the decoder.

[Chrissaf]

Colin, I have a Hornby RnnnnXS A4 loco with a 21 pin factory fitted Loksound in the tender using the X6113 / X9958 4 pin wiring between Tender and Loco. I have just separated the tender from the loco and checked the continuity of the loco plug with a meter. My loco is wired with the motor on the inner 2 & 3 pins and the pick-ups on the outer 1 & 4 pins as per what is considered normal.

For some reason your Duchess seems to be reversed from all the normally accepted Hornby wiring configs.

Therefore my wiring check does not support the theory that all earlier XS locos are wired reversed from the later TTS locos.

[ColinB]

Yes all mine are wired like that, but this one is different. I had a look at the 4 pin socket and it looks like it left the factory like that. I suppose I was lucky I didn't connect it to any of my other Duchess tenders. I think seeing as I am replacing the broken loco lead I will rewire to conform to the later Hornby wiring of 2 and 3 as the motor connections. This loco is eleven years old so I suspect it is one of the first with the 4 pin lead. Loksound don't support that decoder anymore, as I found out when trying to fix one before, so I have to be super careful with any of the wiring.

Anyway thank you for the information, I was getting a bit worried because all the locos where I have added the 4 pin lead, I have followed that same convention of 2 and 3 as the motor.