A federal judge has refused to alter a jury’s $675,000 judgment against a Boston University graduate for illegally downloading music. US District Court Judge Rya W. Zobel ruled Thursday that jurors properly weighed evidence in 2009 before determining that Joel Tenenbaum violated copyright laws and in setting the amount of the fine, and so there is no reason for another jury to hear the case. Zobel also found that the judgment did not violate Tenenbaum’s due process rights. Tenenbaum had already appealed the jury’s verdict, but a higher court ruled that he must go through the proper process in asking Zobel to consider having another jury hear the case before the appeal could proceed.