Altenator Belt noise and breaking
 

Just bought somebody elses headaches ... 1990 passat. Thought i had squeeky belt ... due to looseness ... was going to tighten and checked belts and notice alot of wear on all belts so changed all 3 belts. On start up squeak still there ... then poof belt broke. replaced belt ... and poof again after noticing it was intermitten. seems to be in and out with heater fan ... turn switch off and no noise ... someone suggested voltage regulater ... changed it still same said problem. most noticable between 1500 and 2000 rpm. Belt is tight as should be ( about a finger width play in). Would bearings be intermitten? Any suggestions?