If the database contains blobs the plain text dump doesn't work. Actually I use the following commands to dump and restore my databases:
export dbname=mydb
pg_dump $dbname -b -Fc -f /tmp/$dbname.dmp
pg_restore -d $dbname -v -O -Fc /tmp/$dbname.dmp >& /tmp/$dbname.log
and so I don't see how to process the dump file with 'iconv'.