Question Fan with 3 black wires. Which is which ?


Feb 25, 2016
I have recently bought a 120 mm fan in bulk from segotep, nothing fancy, to make a soldering fume extractor. It has a 3 pin connector and a 4 pin adapter but all the wires are black, one having white stripes on it. Could anyone tell me which is which or help me find a way to find that out myself ?
Thanks in advance!


That pinout link helps. Pay special attention to how the connector is oriented when you look at it. Note in the drawing that the holes are facing you, and the BOTTOM of the connector has two ridges running along it - you can just see the front tips of those ridges.

BIG OOPS! That first drawing shows the wire colours as Yellow on Pin #2 in the middle, and Red on Pin #3 on the nearer edge. Those two colours are REVERSED! You can see the correct colour arrangement in the next drawing down that shows a 3-pin female connector plugging into a male header. On a standard 3-pin female connector, the BLACK line on one edge is power supply Ground, the RED line in the MIDDLE is power supply +VDC (12 VDC for full speed) and the YELLOW on the other edge is the fan motor's speed signal being sent back to the mobo header. If you are making a custom fan box, ignore the one that should be Yellow - just tape it up and do not make any connection to it. The speed signal is never used for speed control of such a fan. Control is solely by changing the fan supply voltage from 12 for full speed down to about 5 or 6 - less can cause the fan to stall.