I have a 1993 Volvo 240 Wagon. I tried to save some money by replacing
the alternator myself when the old one started acting up (battery
wouldn't charge any more, battery light glowing faintly).  But now that
I've installed the new one it seems that I can't figure out how to get
the wires on properly.

I made note of the connections on the old unit, and put the wires on
the new one in the same positions (Thick red - B+, Thin red - D+, Thick
Green - third terminal), but everytime I connect the battery cables the
alternator sparks and acrid smoke comes out of it.

I attached the placed the lug loops over the terminals and secured them
with nuts. Is there something else I need to know about connecting the
wires?

Any help would be appreciated.

Thanks