As Hans said, if it says DH treat it like an ILS or CDFA , otherwise it's a MDA and add 50 feet. It's actually a bit more complicated but that may be airline specific. In my airline's authorizations from the FAA we are allowed to treat the MDA for an ILS approach with the GS inop as a DH. Or if there is a note on the approach plate that authorized operators can use the MDA as a DH. I spent 5 minutes looking at a lot of the larger airports in the USA. I was (1) surprised how few non RNAV non precision approaches are left in service and (2) could not find any with the ball note.
I remember from years past we were also authorized to treat the MDA as a DH if the runway had a PAPI/VASI or if the runway had a precision approach even if we were not flying that approach. Those authorizations have gone away.