I was lucky :-)
It seems the guys at Sega just replaced the 470µF capacitors shown in the reference setup for the TDM2822M dual amplifier with 47µF ones. Other people have had problems with these too, so I just pulled them off and put standard 47µF 50V ones in as a replacement. I just had a couple of them in my big box. But first some more info.
As you have to open up your Game Gear, you’ll have the pleasure to meet an especially nasty security bolt.
And here is a closeup of said bolt. Be sure to NOT put it back when you’ve managed to get it out. Keep it as a sign of your victory over some sick bastard who thought this to be a neat idea.
So basically all that had to be done was to remove the two dried out electrolytic caps labelled C5 and C7 and put suitable replacements back in. I happened to have 47µF 50V caps in my big box.
The fixed board in all its beauty
And the complete Game Gear
Finally 2 videos, one showing the sounds of ‘columns’ on my scope, the other one is the intro of ‘Sonic the Hedgehog 2′
To sum it all up, it was fun and much easier than expected :-)
A manual for fixing other Game Gear problems is here.