Here is an interview with his guitar tech. Apparently, he uses no effects at all. See page 2.
http://www.musiciansfriend.com/document?doc_id=92644
It's amazing that this interview takes 3 pages. This is how it should have been written:
musician.com: "So, what gear does Angus use?"
tech: "What do you think?"
musician.com: "Uh, SGs and Marshalls?"
tech: "Yep."