Summary
There is a bunch of conflicting information around relating to these fan extender boards, and at least two different types that look very similar. Note the position of LEDs and components on this board.
I was concerned about plugging the 12v input in backwards, and ended up needing to find out the hard way, which wasn’t actually hard and didn’t release any magic smoke.
Adding this to the search result noise for completeness.
RAMPS RRD Fan Extender Expansion Module – NOTES 3D Print Model
