It's recommended that you use the original Japanese AC adaptor that came with the Famicom, Disk System or accessories when playing in the United States or Canada. To do so will require a step-down converter.

The Japanese AC adaptor has the following specs:

AC-Adaptor

MODEL HVC-002

AC100V 50/60Hz 18VA

DC10V 850mA

+ ------ C------- -
 

The Japanese Famicom AC adaptor is equipped with the same prongs, and nearly the same input voltage (AC 100V) as AC adaptors used in the United States and Canada. The proper output voltage is DC 10V, 850mA.

Never use an NES AC adaptor with your Famicom. Most adaptors transform the electricity from AC to DC. The NES adaptor takes the input voltage down but still puts out AC, which is potentially harmful to your Famicom.

To prevent from overheating and damaging your Famicom, it's highly recommended that you use a step-down converter. Japanese electrical outlets output 100V, which is what the Famicom AC adaptor is made to input. United States and Canadian electrical outlets output 120V. Step-down converters that will convert the electrical outlet output to 100V are available online and in stores.

www.voltageconverters.com