820-00281 throttling

[Sr. Robot]

Hello, i have a 820-00281 that throttles very fast. I compared it to another Mac with the exact same specs and it throttles to about 30% of CPU capacity in matter of minutes while the other one lasts hours and only gets to about 70% throttle.

I changed thermal paste, changed the copper plate, tried with an external OS. The battery works fine, adapter is 87w OEM. There are no other software running in the background. Fans run at max.

All temperature sensors are all right except for the CPU ones which go for about 90 C

 

[Sr. Robot]

I noticed the touchbar wasnt working. PP1V8_S0SW_DFR was shorted to ground by C4471. Replaced C4471 and now the mac doesnt seem to be throttling anymore but the touchbar still doesnt work (tried known working one). PP1V8_S0SW_DFR is pulsing from 0.4v to 1.8v

 

[2informaticos]

DFR_DISP_PWR_EN is stable?
Just in case, change U4404.

 

[Sr. Robot]

Now i have stable PP1V8_S0SW, but still no touchbar.

i get PP5V_S0_T139 and PP3V3_S0SW_DFR

 

[2informaticos]

Compare J4401/2 readings in diode mode and voltage with good board.