blowing fuses

I own a 1994 pickup. I jump started a pickup the other day and blew my 80 amp fuse under the hood. My truck would not start. I didnt have another fuse so I soldered the old one. It worked for a day or so. Then I started blowing the 40 amp fuse. AM1 is the fuse. It is located in the fuse block under the hood. I keep blowing this fuse. I have replaced the alternator and the 80 amp fuse. The truck ran ok for a day then the 40amp fuse started blowing again. Does any have an idea on where to start.