I have a 2011 mac mini that has full speed fan all the time. I have checked the fan in other mac mini and it works correctly. I have checked pin 2 (near gnd in the fan connector) and it is always 3.3v, no pwm. I do not know which element generates that pwm for the fan, nor where is that component. I have tried to follow the track that goes out from the connector but i have found nothing. Anyone with the schemes may help me? please. it seems there are no missing components on the board. thank you
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=== Update (05/26/2022) ===
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Hello, i do not know if my smc chip is broken or not, what i know is that in the fan connector i have 12v in pin 1, tacho is measuring correctly in pin 2, pin 3 is always 3.3v and pin 4 is gnd. The problem is that the pwm that controls the speed of the fan is not existent, pin3 is always at 100% so 3.3V all the time. I do not know what chip generates the correct pwn to control the speed. I tried to follow the track that goes to the pwm but i got lost.
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Does anybody have the electric circuit of the pwm? or tell me what chip is the smc? i cannot identify it in the motherboard.
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I run the diagnostic and i got ( 4MOT /1/140000003: exhaust-6262) the number after Exhaust is the revolutions of the fan so that means nothing, it is maximum speed. There is no speed control because there is no pwn, just a 3.3v signal.
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If could see the electric scheme maybe i can identify if it is the smc chip that is broken or maybe some capacitor or resistance.
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Macfan software shows the speed of the fan and all the temperatures, everything is ok but the fan speed that has no control regulation.
I have a 2011 mac mini that has full speed fan all the time. I have checked the fan in other mac mini and it works correctly. I have checked pin 2 (near gnd in the fan connector) and it is always 3.3v, no pwm. I do not know which element generates that pwm for the fan, nor where is that component. I have tried to follow the track that goes out from the connector but i have found nothing. Anyone with the schemes may help me? please. it seems there are no missing components on the board. thank you