"Yellow light from power adapter and buzzing noise." için yanıta similar problem started on my iBook about a week ago. initially, the charger light ring would cycle between orange and yellow while the buzzing occurred. at the time, the AC was registered but the battery would not charge. today, the AC no longer registered. after pulling the case apart and looking more closely at the DC-in board, it appeared that one of the three power contacts just burned itself out.