Macbook Air A1466 820-000165 Fan allways on 6200rpm

[Mannislav]

Hello, i have a Macbook Air A1466 820-000165 where the fan is constantly running 6200rpm, as soon as i hit the power button.
I already tried a different fan, reset of SMC and PRAM. No difference.
So i measured the voltage on the connector
1:5V PP5V_S0
2:1.6V TACH
3:4.6V Motor Control
4:0V GND

I checked HW Monitor temperatures are in the normal range, no missing signals.

What can i check next?

[mon2]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Measure the voltages on the following:

SMBUS_SMC_3_SDA
SMBUS_SMC_3_SCL

and post the readings.

[Mannislav]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Thank you for the fast reply. Both signals are 3.3V

[mon2]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Review this thread:

https://www.badcaps.net/forum/showthread.php?t=93255

[piernov]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

fan is constantly running 6200rpm, as soon as i hit the power button.

after 10 seconds the fan spin starts to rise and reaches maximum speed

Completely different problems.

[mon2]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Focus on mosfet @ Q6060. Apply flux and reflow it.

Confirm the resistance and presence of R6061.

Confirm the connections in this area to the fan connector.

[Mannislav]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

I already found that thread and switched with a known good one.
Resistance of the Resistors in this area are right.
Then i reflowed it as best as possible with the connectors nearby, but no difference.
I also measured from SMC_FAN_0_CTL to R6061 using a testpoint on the backside near C7601 and i get 400/500KOhm depending on which side of the resistor i measure. But reading the schematics there should be no resistance, since it is a trace on the board. Or am i thinking wrong?

[reformatt]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Confirm prescence of fan tach using a scope to the SMC. If it’s missing, fan will be driven at full speed.

[mon2]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Try another fan.

[Mannislav]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

I already tried another Fan. I have no scope to Check tach but with mac Fan control it displays RPM Signal.

[heruhaerudin873]

Re: Macbook Air A1466 820-000165 Fan allways on 6200rpm

Fix,change mosfet