Quoted from Mahoyvan:I push the coin mech to start a game > A motor runs in the backbox, lights flash at the same time, then the same 10A breaker pops.
I assume what you're calling a motor is really a stepper.
Blowing fuses aren't as straighforward to diagnose as some problems but there are some techniques that work. Does the fuse/breaker blow when the stepper is at the same position every time?
For more than that, see the reply I sent you in a private message.