Even if you have no vacuuum to the booster, you should still have brakes. All the booster does is make it easier to pull the pedal down. If you have brake fail failure it could come from several sources, including not having the shoe adjusted up properly. Check the fliud level first, if its fine then you have either a bad master, a bad slave in the booster, or the shoes arent contacting the drums. If you dont have any fluid in the master then its going out some place, and should be easy to find.
