Apple makes no guarantee of successful operation of Apple equipment when it is used outside of the equipment specifications -- including its operation in a foreign country with different voltage levels, etc.
Even though a piece of equipment may APPEAR to function correctly when operating outside of the specifications, unexpected results may be encountered due to additional variables. These variables include the number of peripheral cards installed in the system, and fluctuations in line voltage.
Such variables make it impossible for us to guarantee that, for instance, a domestic Macintosh II will correctly function at 85-90 volts in Japan.
Other Helpful Resources
Apple Spec Database:
http://www.info.apple.com/applespec/.