820-2577 Fan pinout

XooP

New member
Got this Mac Mini today with a ripped of fan connector, not on the logic board but from the fan wires. I have taken the connector of an old A1278 fan but I can't tell which pin goes where.
I have tried some different places now an got the fan to spin but I don't know if tach and controller pins are correct.
The fan spins high all the time now. The hard drive is also missing one of the thermal sensors (the one not connected to the SATA plug). I know this could be the fan issue as well as I have only taken a sensor from an old iMac to try. Can I replace the sensor with a resistor for testing?

I know I could just buy a new fan and thermal sensor but I would like to verify that everything works before ordering.
 

XooP

New member
Sorry, found the fan pin-out now. I just remembered that I have a running 2012 mini :)
Still need help with the thermal sensors.
 

XooP

New member
Hmm, strange. Now the fan doesn't spin at all. Did the pin-out exactly as the other Mac Mini. In ASD all temperature readings are okey, so the old iMac sensor probably works as it should.
 

XooP

New member
Just put in the fan from the 2012 Mini and the fan spins like crazy. ASD also says "Motor is spinning faster than it should".
 

XooP

New member
Just an update here. It seems the circuit for controlling the fan has a defect of some sort. I have downloaded SMC fan control and whatever I do the fan runs full speed, I can't control it at all.
I'm really struggling finding schematics and boardview files for this motherboard as well. Do anyone know if the fan is controlled by the SMC or should I look elsewhere?
 

dukefawks

Administrator
There are no files for this. All fan control is the same on Apple boards. Just look at how it works on a 2915 board. Could be the feedback trace, so SMC is not seeing the fan tacho and gives it full PWM signal.
 
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