Alternator question

[mattrains]

I picked up my hummer today and put a used alternator in it because the alternator that was in it was torn up.

When I installed the new one it worked fine and was charging the batteries and also had a good output from the back of the alternator. Now, 7 hours later its.not charging. Any ideas or does anyone have a wiring diagram for the alternator or know what each wire goes to?

Thanks in advance, I'm new to the 24 volt stuff.

 

[Mike82ndABN]

Were the batteries dead too, I've heard running it with dead batteries can damage the alternator

 

[86humv]

Dead or low batteries can kill the regulator.

 

[mattrains]

Turns out it was the adjustment screw on the top of the alternator was turned down to 20 volts. We pulled into a truck stop, adjusted the screw up to exactly 28 volts and everything has been running just fine. Thanks!