MacBook Pro A1708 VERY slow

[alexity]

Hello

I'm 40, french IT guy, my wife have a MacBook Pro F-keys i5 13-inch Mid-2017 wich is VERY slow, fan don't turn at full speed, airport and motherboard sensors indicate 128 degrees
I tried to unplug the screen, the webcam, reset SMC... without effect

I've watch many videos about sensors issues, but all of the videos talk about fan turning at full speed which is not my case
do you have any idea ? what is wrong?


Motherboard number: 820-00840

regards

Alex

[mon2]

Hello. Unit is running very slow because the logic board is being throttled on the CPU speed due to the (false?) readings of your sensors. The sensors appear to be 'stuck' as they operate using the 2-wire I2C / SMBUS interface which consists of the SCL & SDA lines. Review the schematic and locate the thermal sensors onboard. They operate in a group or cluster using the same 2 lines. Remove all power. Remove the battery. Meter in resistance mode.

Measure the resistance to ground of the SCL line. What is the measurement?

Repeat with the SDA line. What is the measurement?

We are checking if the ESD transient diode is damaged which will cause the entire network of sensors / devices that are called I2C slaves from operating. The logic board 'assumes' the temp is 128 degrees due to the true readings being unavailable -> slow down the CPU. This is first theory.

Try to disconnect the trackpad cable to see if the results are any different. The trackpad cable may be integrated with the keyboard cable but not 100% sure at this time so review the youtube videos. That is, sometimes the removal of the keyboard cable will also remove the trackpad interaction. Either way, proceed with extreme care as the connectors and parts are quite fragile. If in doubt, stop and ask with questions posted on this forum. Can review the actual schematic once at the office but the above is a general guidelines to get you started.