Earlier in the year I made a start renumbering and rebranding a Hornby King to King Richard I, the conversion hit a bit of a blocker when fitting the DCC decoder (which wouldn't work). This evening I finally made a start on trying to get it operational, and have decided to share the fault finding process here in case it is of use to anyone.

Step 1: Check for known issues. So far I have had three major faults with Hornby tenders, potential for a short circuit between the tender pickup connectors, short circuits due to poor QC on the loco to tender socket, and poor wiring of the 8 pin socket. In this case a minor fix was applied to prevent the first two potential issues (cutting between the pads on the socket and checking with a multimeter / insulating the pickup solder pads. Checking the 8 pin socket with the multimeter showed it was wired correctly. - All OK

Step 2: Check the loco and tender sockets are correctly wired. Again with the multi meter I checked to ensure that the loco and tender sockets had been wired correctly. I have heard of instances where different tenders had the pins wired in different orders and wanted to be 100% certain this was correct. checking the resistance between wheels and socket did the job - Issue: one pin is not connected to the motor.

Step 3: Dismantle the loco body to get access to the wires, again checking the pins of the loco to tender connector I identified which wire was at fault. Further checks showed that the soldering to the motor was ok, as presumably was the connection to the plug.

Step 4: remove motor to release all the wiring, this immediately showed up part of the problem, with a wire having been crushed between the chassis and motor mount. This was cut out, resoldered and then replaced. This still hasn't cleared up the problem (and I stupidly sealed on the heat shrink before testing.

Step 5: ​which will have to wait until Friday​ remove heat shrink and test connection between repair and motor. Identify if the issue is between the repair and motor (in which case re wire) or if it is between the repair and the plug (in which case its the poor quality plug at fault). In the latter case my gut feel is to just hard wire the motor to the tender.

This loco has been out of action for far too long, and needs to be fixed!