I’m attempting to install a Digitrax SDH164D decoder on a DC Rivarossi HO 2-8-8-2 Y6B N&W locomotive. The left side wheels on the tender send current to the right wheels of the loco which also has continuity to the frame so I’m assuming this is the neg side. My problem is finding the loco’s pos pickup. I’ve tested continuity between the left side wheels and every conceivable part of the loco to no avail. Help!
Are you testing continuity with the motor still connected? That would be why there is continuity from left tender to right loco. Rivarossi used a split power pick up scheme. The loco picks up from one rail and the tender the other. The wheels on the other side are dead. I think you will find the right wheels of the loco is one power pick-up (hook to red wire) and the left side wheels of the tender are the other power pick up (hook to black wire).
Make certain you disconnect the motor from the frame, the orange wire replaces the place on the motor that was connected to the frame. The grey wire goes where the wire from the tender connected to the motor.
It appears you have continuity but not a short. The resistance of the motor and the headlight. Probably under 100 ohms resistance I would think.
Connect a decoder with the motor still connected to the track and you will burn up the decoder. Lights and motor need to be disconnected and only connected to the decoder.
Rich
Thanks! I was afraid to install the decoder for fear of frying it. Turns out the tender is the left side pickup and the weight in the loco is the right side. And it works!