For future reference

Output: 10VDC 850mA

Conector: Outer Diameter 5.5mm; Inner Diameter 2.1mm

Polarity: Centre Pin Negative

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So, yes, a Genesis AC adapter works just fine (identical connector, and almost similar output), but I don't recomend using a Famicom on the Genesis/MD, the mA output is too low (Genesis needs 1200 mA)