There are never any shorts on the power pack when it stalls, it even stalls on straight track. I'm really wondering if its the decoder messing up on DC. My curves are 18" minimum, so i know that's not an issue and its the only locomotive I have that has problems with the code 80 switches. The previous issue Big Boys and Challengers never had one problem. And it doesn't matter which direction through the turnout. VERY frustrating.
Seemingly random cut-out issue with mine was due to the tender pickup wipers not making contact with the wheels. Opened the tender truck, tweaked and cleaned the wipers and wheels, and that seemed to do the trick.
a-HA! Indeed, a likely culprit. These "smart" decoders ain't as smart as the manufacturers would have you believe. What happens with many of them is that even a momentary loss of contact on DC causes them to re-set. The locomotive stops while they re-set. Not all alleged "smart" decoders do this when the locomotive loses contact, but some do. I have a BLI centipede that does this. It has sound, so you can tell when it does it. The locomotive will be running, the sound will be in "running" mode. The sound suddenly dies, the locomotive coasts to a stop, then the sound re-starts. You will hear the "firing off", then the engine will catch, the speed of the sound slowly increases, then the locomotive starts to move slowly, then gains speed and starts to run, again. Sometimes, though, if the locomotive can not re-establish contact, it will simply sit. If you mentioned its stalling on straight and level before, I must have missed it. If your track is dirty, that can cause a momentary loss of contact that will cause some decoders to re-set. The BLI Centipede will stall on straight and level, but, if I clean the track where it stalled, I can run it fifty times through that section without its stalling. You may have identified the culprit, here. It may be necessary to wire around the decoder. At some point, I do plan to do that to my centipede. I do wonder if there is a way to wire around the motor control part of the decoder while preserving the sound.
I just seen a utube video on the Bigboy and he said all the tender wheels and trailing truck on the loco was out of gauge, to narrow. The drivers he said were fine and front truck. This maybe the problem ?? The tender wheels not making contact since the wheels are to narrow and messing with the DCC chip. Rick
