Yakuza

I've got a Lynx II that's been broken ever since the AC adapter has been connected to the audio/headphone port. It's completely dead, that is: - When I plug in a game and press 'on', a squeeky noise comes from one of the components on the motherboard. Otherwise, nothing happens. - When I plug in a game and connect a wire from the adapter minus to the exterior of the headphone connector, the powerled and backlight turn on and the speaker gives some distorted sound. The sound is not there all the time, but just for a second or so. This happens twice. Also, the three diodes marked 'D11' become very hot up to the point in which I recon the board/components cannot take it any more (after which I unplug the adapter). Does anybody know what to do? I've seen people with the same problem, but nobody ever seems to actually repair the thing. I've got all the tools (and soldering experience) to do the job, but I don't know where to start. Any info is very much appreciated. Oscar. P.S. Buying a new motherboard is not an option.