I have a Yamaha CR-450 that was fully recapped and worked perfectly for about 4 months while I owned it. I sold it to my aunt to use in her shop and it only lasted 3 months until it started blowing power fuses. When I picked it up to take home and look over, I noticed my cousin had wired some extra outside speakers into it in series. The night it stopped working he had it turned up 3/4 for 3 straight hours. The issue it has is consistent blown power fuses upon turn on. I checked all solder joints and tested each diode directly after the transformer. Can someone recommend where I should look next? Thanks!