I have a MTH 20-2221-1 SD70MAC (proto 1) that when powered lights up and the smoke machine motor operates but I have no sound or movement. I temporarily installed a 9 volt batt to see if that was the issue ,no change. I have turned the volume control to both ends of its travel, still no change. I am suspecting a burnt board but this has 2 boards. Anyone tell me which is most suspect?.
Douglionel - Welcome to trains.com! [C):-)]
You may have to do re-set of the circuit board, best to use an MTH Z-1000 or Z-4000 transformer to do this. I use MTH transformers with my MTH items.
I had this same locomotive with the same problem. I contacted MTH and found out it is a software problem that happens in a few locomotives and if using a Z 1000 the locomotive wont move. MTH said to send it back and they will fix it at no cost as it is a software issue that was a manufacturing defect.