If you use Modchip, it is easier to install.
http://www.tototek.com/store/index.php?main_page=product_info&cPath=1_35&products_id=143
You need to mod both Power Board and Drive Board.
If not, you can check here :
http://famicomworld.com/workshop/tech/famicom-disk-system-fd3206-write-mod/
http://famicomworld.com/workshop/tech/fds-power-board-modifications/
Drive PCB mod :
1) Modchip pins don’t touch anything from PCB.
2) Drive PCB need to cut two wires and solder 8 wires to the Modchip.
Power Board v05 Mod :
Cut two wires and solder two wires.