And if we dismiss the oft apt claim of : “well its junk made in china”, I may have stumbled onto a problem last night with DC control, that just might factor in and apply here…
Have ANY of these failures occurred if you lost track AC power WHILE the train was moving, or a bad section ‘second-tarily’ interrupted the AC power?
the key is, the train was moving…
If so it might be that when the motor and its fully contained rectification and filtered stopped getting power, it started GIVING power, and each time it did, the polarity was reversed from what the gizmos were driving it at.
Can this hurt the gizmo? yup. I am seeing athearn BB gold motor units affect 5 and 10 amp, 160v darlingtons, ergo the grain of rice sized ‘whatsit’ on the decoder board? childs play.
Since I dont know how the unit handles reversing - gate driven to op amps? i have no solution for a flyback setup and I dont know if that function is built in, but if this happens a lot, you might wanna consider an RC circuit on the motor to trap the field induced voltage spike on power loss, which can and will be greater in net volts than what the decoder feeds the loco.
I also have a bunch of DCC-equipped locos (about 75) of various vintages and manufacturers, and have been using DCC exclusively for 25+ years (Bought a Digitrax Super Chief shortly after they were released).
I have had exactly ONE decoder failure - IIRC, it was an old Atlas OEM dual-mode. I do remember it was made by Lenz. Anyway, it failed when the loco was in storage. I took it out of the box, put it back on the layout, and it took off like a scared cat. I learned later those decoders were prone to failure.
So no, your proposed scenario wouldn’t have applied in my case at all.
Having fried several decoders myself, this is a subject that interests me. I would like to know if there is an accessory that can test to determine if a decoder is actually toast or if it might just be a wiring problem either in the loco or the layout itself.