Character Encoding - Find broken character?

Simple problem.. I need to detect this 开发者_StackOverflowcharacter �. If it exists I need to utf8_encode the string. strpos doesn't find it.. Server doesn't have mb_detect_encoding. Any ideas?

Some strings are valid so I can't utf8 encode a valid utf8 string or bad things happen..

Are you sure all of the below are set to UTF-8:

1. Your database table/fields are set to store UTF-8.
2. Your MySQL (or other database) connection is transmitting in UTF-8.
3. Your definitive output is set to be UTF-8.