Quote Originally Posted by Zach View Post
It's definitely first party. An actual Nintendo brand NES AC adapter. And I'm fairly sure I've used a few different NES adapters over the years, just grabbing whatever was available when I wanted to hook up the SFC.
The two consoles don't even use the same style of power connector, and the NES adapter has no bridge rectifier, so it outputs AC instead of the needed DC.
Something is definitely strange about your setup.