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在2017年6月,Apple更新了13寸的MacBookair,他换上了更新更好的Intel Core i5处理器,让性能和电池续航时间提高。

Troubleshooting a Fan that's Always at Full Speed.

... Continuing from a bunch of previous questions we are now at the final issue of a fan that is always at full speed even in sleep mode. Attached are a host of reports from various fan control apps. It has to be an issue with a sensor but we cannot find it after testing voltages (Likely missed one as we are still learning). Unit initially came in for a non charging issue which we have now fixed (Solved) Charging issue (Fading Green Light Only)).

@oldturkey03 Maybe related: Why is there a 'Jumper' wire? For what purpose?

No output Knock on effects from a Faulty TBP & still appears on apple diagnostics

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CoconutBattery (For @danj)

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Any ideas appreciated & donations are always welcome :)

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@livfe check your FINSTACKSNS_ALERT_L line since that is the temp sensor line for the Finstack Temp, so from the thermal sensor to the SMC (which then goes into protection mode and ramps up the fan if it reports High). Since TG Pro shows it to be "Exhaust" I would expect this to be an issue with the air (Thermal) sensor on the I/O board (or cable/connector). You also want to check U5800 (since you do have the schematic you know where to find it;-) if a different IO board/cable does not resolve it.

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@oldturkey03 Swapped out the I/O Board and the cable for another and the fan is still running high..... tomorrow to look into the other things. Thanks for the tips!

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@livfe you know that will all lead you right back to the SMC. Errors like this are the most frustrating to troubleshoot. Best of luck to you and hope that this MBA is going to work out for you soon.

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@oldturkey03 We should just replace the SMC and see if that solves it? Anyone interested to have a 'working holiday' out here? lol

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@livfe if nothing else check R5210 and see if you got something as simple as a failed resistor. Thanksgiving Turkey at your place :-)

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@livfe - The fan has a tachometer measuring the fans speed (the sensor). So the fan or the wiring to the logic board as well as the bias control logic which alters the fans power is where I would look.

I would start with replacing the fan, then check the connector and a test point for each of the tach lines to make sure the connector interface was working, then check the solder joins and the dual MOSFET circuit which controls the voltage.

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Great help. We will check this and update as and when!

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