mac 1706 fan not working damage U5860

[reset1986]

Hi everyone, I have this Mac that had flaxgate problems, it was repaired, I noticed that the fans were running at maximum, I inspected and found the u 5860 torn away, recovered the chip on another main, I rebuilt the tracks, but now the fans don't turn really, if I unsolder it the fans go to max and the Mac is very slow, could I bypass this sensor? I attach the diagram+brd thanks

[mon2]

I think the best suggestion is to review the reworked areas. If the Mac is slow, then the sensor is not being properly detected so the CPU speed is being throttled. It is also possible that the fan is not properly spinning so the CPU speed is being throttled. U5860 has its own I2C bus address. Was the replacement part 100% the same as the original? The I2C node address for this thermal sensor is defined by the A0/A1 strapping pins. Can you confirm the connections are present for A0 to ground. A1 is floating. If not, then the I2C address will be something else and this condition will also cause the sensor to be found and then the CPU speed will be...throttled.

You can attempt to run diagnostics on the logic board which should offer clues on which sensor (most likely this one) is not being detected.

[reset1986]

I think the best suggestion is to review the reworked areas. If the Mac is slow, then the sensor is not being properly detected so the CPU speed is being throttled. It is also possible that the fan is not properly spinning so the CPU speed is being throttled. U5860 has its own I2C bus address. Was the replacement part 100% the same as the original? The I2C node address for this thermal sensor is defined by the A0/A1 strapping pins. Can you confirm the connections are present for A0 to ground. A1 is floating. If not, then the I2C address will be something else and this condition will also cause the sensor to be found and then the CPU speed will be...throttled.

You can attempt to run diagnostics on the logic board which should offer clues on which sensor (most likely this one) is not being detected.

I checked the connections again and they all seem correct, A0 to ground, A1 not connected, I recovered the spare part from a 820-01949 board, looking at the diagram this is U5850 TMP461-S, could this be the problem? The diagram instead of my sensor gives me TMP461 without the final s

[mon2]

According to the 820-01949 schematics, the I2C bus address for U5850 is the same so this should have worked ok.

Carefully measure the voltage to ground of:

SMBUS_SMC_3_SCL
SMBUS_SMC_3_SDA

Each should be ~3v unless one of the lines is stuck. If stuck, the sensor cluster cannot be pinged and will cause the CPU speed throttling.

[reset1986]

According to the 820-01949 schematics, the I2C bus address for U5850 is the same so this should have worked ok.

Carefully measure the voltage to ground of:

SMBUS_SMC_3_SCL
SMBUS_SMC_3_SDA

Each should be ~3v unless one of the lines is stuck. If stuck, the sensor cluster cannot be pinged and will cause the CPU speed throttling.

I carry out measurements and update, I noticed that the SMBUS_SMC_3_SCL and SMBUS_SMC_3_SDA line between u5860 and u5850 measure 8 ohm and 3 ohm on the common points, if I disconnect the flat trackpad the fans start to spin quickly and the Mac slows, if I connect the fan remain still

[mon2]

Requested the voltage of the SMBUS lines but it appears the trackpad sensors are absent when removed so the fan spin is high and CPU speed is throttled.

Run the diagnostics to check which sensors are failing.

[reset1986]

Requested the voltage of the SMBUS lines but it appears the trackpad sensors are absent when removed so the fan spin is high and CPU speed is throttled.

Run the diagnostics to check which sensors are failing.

here SMBUS_SMC_3_SDA 3.3 v SMBUS_SMC_3_SCL 3.3 v all connected track, battery etc, when turned on there is no rotation of the fans, I ran the diagnostics and it is without errors, the fans started to turn first the right one then the left one, but when I turn it on the fans remain stopped, I don't think it's normal, can I check something else? thanks

[reformatt]

The fans only spin on these models when needed. If you boot and hold D the fan will be spun up and tested for tach etc during the test.

It's rare to see a fan not spinning on an Intel machine though, as they do run very hot. That's why Apple ditched Intel CPU's in their MAC's.

[reset1986]

The fans only spin on these models when needed. If you boot and hold D the fan will be spun up and tested for tach etc during the test.

It's rare to see a fan not spinning on an Intel machine though, as they do run very hot. That's why Apple ditched Intel CPU's in their MAC's.

thanks, so when it turns on is it normal to see no rotation?

[mon2]

Correct. Perform the pram reset.

https://www.reddit.com/r/macbookrepa...lem/?rdt=34512

[Stephen]

I was going to say that fan spin is not instant on these models. It needs to turn on when it gets hot, Intel chips run hot and are crap now compared to the M series chips. Hopefully you fixed it and don't need to do anything

[reset1986]

I was going to say that fan spin is not instant on these models. It needs to turn on when it gets hot, Intel chips run hot and are crap now compared to the M series chips. Hopefully you fixed it and don't need to do anything

thanks, yes indeed the CPU does not heat up, in the diagnostics the fans work and do not cause problems,

[Jose_elec]

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