How do I find/replace strange characters in notepad++?

How do I find/replace strange characters in notepad++?

When I open a sql dump file in notepad++ and view it with utf8 encoding, (as that was it was encoded as) I see these strange block characters such as A0 or 93 that I can't find/replace. My friend using emacs can see these characters as /204 or /205, and so on, and was able to find/replace on his editor.