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what would you do sir if you ware in my place with such issue? Would you replace the chip only or replace the chip along with the buck converters+

Thank you for your reply, do you know what could cause this issue? I mean, even if I replace it with a new one without first taking care of the main issue, then it will destroy the new one as well.

Dear sir you are right after that I removed it. I see that pin 2 of L7520 still shorted to the ground. I assume that U7400 most gone bad. Do you know where I can buy this chip? because I couldn't find it on ebay and Alibaba.

when I inject voltage to the PP5V_S0 it gets warm and when I removed it the short is gone ( according to the multi meter)

I found it. The L7520 has gone bad. I'm wondering if I could use L7820 of a 820-3437 board? The specification of L7520 is: 2.2UH-20%4.8A-0.105OHM The specification of L7820 is : 2.2UH-20%-2.0A-0.10OHM 2.2UH-20%-2.0A-0.108OHM

Thanks a lot for your replay. is the pin 1 of C7552 a good spot to inject voltage? I put the current at max and begin with 0.5 volt. is this the correct way?

PP3V3_S5 changes rapidly between 1 volt and higher and 2 volt and higher. it's not steady even for a second and the resistant to the ground on PP5V_S0 is only 5.3 ohms and in diode mode it's 0.008.

R7120 14.76v F7140 8.59v

no liquid damage nothing it was updating OSX all of the sudden turned off and does nothing, yes I get 3.32v on PP3v3R3v0_AON. I thought that if the led lamp is on means that the board is powered on,

the little led lamp on the board lights up but and that's it, no image no sound.

Thank you Sir for explanation, p S5_PWR_EN is present S4_PWR_EN is present P3V3S3_EN is present S5_PWRGD is present Q8150 pin1 VMON_Q1_BASE0,78v pin3 0.11v pin4 0,11v pin5 VMON_Q2_BASE 0.00 pin6 S0_PGD_C 3,27v pin7 VMON_Q3_BASE 0,70 pin 2 and 8 are unconnected according to the schematic but I...

yes sir these voltages are present. Could you please explain a little more about the involved voltages in ALL_SYS_PWRGD geberation+

Pp3v3_s3 pp1v8_s3 pp1v2_s3 pp3v3_s0

ALL_SYS_PWRGD is 0,111v

I tried to bypass smc by holding the power key for 10 second and connect the charger ( while keep pressing the power for the next 10 second ). the board didn't power on but the light on the charger is back

all of the sudden the light on the charger is gone and System_Onewire is dropped down to 0.8v but SMC_BC_ACOK is present 3.4 SMC_RESET_L is. 3.37

yes I did. tried to bypass the SMC but the charger light changes from amber to green and again amber but the fan doesn't spin. the fan is known working one and also there is no USB activity.

I've replaced the U8000 and pin1 PP3V3_S4_FET_R 3.02v pin2 PP3V3_S5 3.32V pin3 PP3V3_S4_FET_R 3.02v pin4 PP3V3_S5 3.32V pin 6 S4_PWR_EN 3.32 I've replaced the U8050 but nothing's changed I get pin1/3 PP3V3_S4SW_SNS_FET_R 0.3v pin 2/4 PP3V3_S5 3.32v pin 6 SMC_SENSOR_PWR_EN 0 I tried to bypass...

Pp1v05_sus 1,05 pp1v8_s3 1,80 pp1v5_s0 1.50 pp1v5_s0sz_audio_adh 1,5 pp3v3_sus 3.32 pp3v3_s4 39.6 mili volt pp3v3_s3 3,28 pp3v3_s0_fet_r 3,28 pch_hsio_pwr_en 2,55 s5_pwr_en 3.4 s4_pwr_en 3.328 usb_pwr_en 3.28 pm_slp_s4_l 3.28 p3v3s3_en 3,28 p1v8s3_en...

thanks for your replay, PM_SLP_S3_BUF_L = 3.30 P5VS0_EN = 3,30 P3V3S0_EN = 3.30 P1V05S0_EN = 3,30