>>445
自分でやれば1万円ちょっと

https://jp.ifixit.com/Store/Mac/iMac-Intel-27-Inch-Late-2012-Early-2019-Power-Supply/IF174-014?o=1

https://jp.ifixit.com/Guide/iMac+Intel+27%E3%82%A4%E3%83%B3%E3%83%81+EMC+2546%E3%81%AE%E9%9B%BB%E6%BA%90%E3%81%AE%E4%BA%A4%E6%8F%9B/15722