If you are working with this board without a physical diagram in hand, check these common failure points first:
This usually consists of two high-power MOSFETs or IGBTs mounted to a large heatsink. These are the most common points of failure if the lathe is overloaded. jymc220bi schematic full
Always check the glass fuse on the board. If it’s black, a MOSFET likely shorted. If you are working with this board without
If you hear the relay click but the motor doesn't spin, check the brushes on the DC motor itself. Finding Documentation jymc220bi schematic full