You don't have a voltmeter/multimeter? If not, then I would suggest getting one and then verifying what the current alternator is doing. It may have failed, but it could also be something simple like a bad connection or broken wire somewhere, or even a blown fuse.
Also, electrical output is normally marked on an alternator somewhere. Look and see if it has any decals with the output info. But I agree with @dave_r check connectors and get a multimeter (doesn't need to be an expensive one) and see if it is really not working. In my experience they will freeze a bearing and not spin and that can be fixed on some of them.