Different database encodings


it´s me again with another problem. I have a second database with encoding
sql_ascii. At this database I send queries by DBIx::SearchBuilder. Now I have
the problem with umlauts. I can´t search for umlauts and I get the words back
without umlauts. That´s not fine.
When I make a search to the logfile of postgres, it tells me, that DBIx checks
the database-encoding with the sql-query "select getdatabaseencoding();"
Does it change there anything at the encoding from my sqlascii-database?
Or can´t it read sql_ascii?
Can I tell the SearchBuilder to change his encoding to sql_ascii or who of
the system don´t understand it?
Is it generally possible with RT and DBIx::SearchBuilder to work with a
sql_ascii-database or only with unicode-databases?

Thanks for help,