Starting March 3, Microsoft Japan will no longer service first generation original Xbox consoles (not Xbox 360s). This includes Xboxes that are under warranty as well as out-of-warranty consoles.
Microsoft Japan, however, is offering an upgrade to those owners with still-under-warranty first generation Xbox consoles in need of repair: Swap that busted console for an Xbox 360 free of charge.
It is possible to troubleshoot any Xbox problems via the Xbox.com support site as well as find out how to exchange that in-need-of-fixing first-generation, under-warranty Xbox for an Xbox 360.
初代 Xbox の修理サポート終了に関するお知らせ [Xbox.com]