Truck Repair: 1986 pick upcharging system, inline fuse, fuse box

Question
its not charging the alt is new. the only way it starts to charge is when i put a direct 12v to the battery side of the alt. also it does not have any power to the fuse box.  

Answer
the only thing on this i can think of is to pull the fuse box out and check the main wire going to the box..also there should be a inline fuse on that main wire in the engine comp. it should be black and inline covered with rubber you can run a multimeter test on that link .let me know how that works out thanks