check the drive tension if to slack this will cause the burning smell,tighten the belt when happy with belt tension use a DMM (digital multi meter) set on DC scale at 20v start engine and run at 1500rpm the reading should be around the 14.5 v mark start turning on accessories alternator should still maintain approx the same voltage output
if your output is only 12v -12.5v replacement unit needed
wirecutterman, November 2011