Thank you guys for your fast answer, so now the loco just run very lowwww at max speed  and the motor smell, I open it and no trace of black marck on the engine,
How come the loco can broke so fast because of wrong wire (A.C. current acsessory terminals)

thanks

I bought for XMAS Harry potter  train but I plugged  the wire to the accessories slot, and I think I damage the loco engine, it goes very slowly and smell like burning .  Do I need to buy a new engine???