Mike:
Check out this ERA Alternator Wiring Diagram from the ERA website:
www.erareplicas.com/427man/wiring/alt.htm
also try this link as well...
http://www.erareplicas.com/427man/wi...or/trouble.htm
Hopefully this can help. ALso, check the Manual Supplement, (Wiring Your ERA 427SC).
I am not personnally familiar with the PowerMaster alternator.
However, the alternator should be grounded thru the Black Wire as well as thru the case thru the bracket to the engine block.
So make sure to try a continuity test of the alternator case and the block. Sometimes a heavily painted alternator bracket can insulate this needed ground.
Hope these pointer help amigo!