My brother has a Sony STR-DE915 receiver that has a subwoofer out that is no longer working. I've tested the jack and there is indeed no voltage at all. Removing the cover revealed no obvious problems (I'm not an electrician but I know a little). Has anyone else experience a similar problem? This receiver is up in years now. I is being used with an Awia subwoofer with an Auto power option. About how much would repair cost?