This weekend I opened up my Athearn SD50 to put in a decoder. I had previously test run the loco on my switching layout DCC at address 0. After installing the decoder I set my throttle at address 3 and it ran ok except I noticed something (probably one of the wires to the headlights) was interferring with one of the drive shafts. I took the shell off again and moved the wires and with the shell on but loose I put it on the track which promptly tripped the circuit breaker on the throttle. I then removed the decoder and installed it in anothe loco and it ran fine. I put the original plug on the SD50 and it still tripped the circuit breaker. I cannot find the “short” anywhere. Does anyone have any suggestions as to where to start to look?
I believe that if it’s an athrean locomotive you’re going to have to insulate the motor from the frame…pull out the motor, put in a piece of electrical tape on the frame between the frame and motor, replace the motor, and install and run a wire from the frame to the decoder…chuck
It already has all that from the factory. It comes with a DCC plug already attached. I’m not a DCC newbie, I have modified several old Athearn BB locos with DCC. This problem baffles me though since it originally ran OK on DCC.
mb,
are you sure it’s a decoder problem or something wrong with the locomotive, the reason being is that i have a life like gp- 18 loco (an athearn clone)…that did the same thing…it would run, stop, and when i started it again, it would trip the breaker…I found that one of the gears in the drive truck was not meshing with another gear, would lock up the motor, over amp, and trip the breaker…it may be a problem along these lines…don’t you just hate it when there’s an “unknown” in the equation…chuck
I think it’s an electrical problem but I will check to see if the mechanism is bound up when I get home tonight. I consulted with a friend at work who suggested that I check the wires to the grain of rice bulbs to see if they shorted out right near the bulb where the bare wires are exposed.
I finally found the problem with this SD50. At some point I must have noticed that the sideframe on the front truck was a little loose so I pressed on it to get it all the way home. In doing so I must have pressed a wheel in too tight and the ends of the metal axles met and shorted out. I just pulled the wheel out a bit checked it for gauge and the short went away. I would have thought there was a plastic separator in the gear to prevent the axles from making contact.