Need magic to clean strings from unconvertible UTF8

Hi,

somehow there have unconvertible characters sneaked into my DB.
Very probaply they came in via Imports from MS-Access.

Access doesn't complain but when I try to export stuff with pgAdmin to
csv I get an error that some char is not representable in the local charset.

I can find the problematic rows.
How could I delete every char in a string that can't be converted to
WIN1252?


Regards
Andreas