Are you coming from Mine Tunnel area? If so, it is just on the ground of one of the rooms. If you see T-rangs that won't let you pass, you already past the room where you can pick up Pulse pick. (It is on one of the 3 rooms next to the room where you need the pulse lock to unlock it).On the T-rangs that won't let you pass, some of them(there are more than one place where they won't let you go near), you can walk past them by start the combat first(when you are really close, but not close enough to make them attack you) and walk by really fast and end up on the other side. You can use this trick to access t-rangs' teleporter faster.