Ok, thanks!
I have used iconv to convert text from UTF-8 to ISO-8859-1.
First for forum table of db.
iconv -f UTF-8 -t ISO-8859-1 forum_table.sql > ok_forum_table.sql
And now character and text in forum table is ok (and are show ok in board index).
But when i try to convert the posts table also, i have this error.
iconv -f UTF-8 -t ISO-8859-1 posts_table.sql > ok_posts_table.sql
iconv: illegal input sequence at position 1719812