820_3787-a no p5vs4_en

[PPVCC_S0_CPU]

Its a previous repair attempt,
ppvrtc is present
pp5v_s5 and pp3v3_s5 are present
ppbus_g3h is 12.56
adapter en and bat_low and pm_dsw_pwrgd is there.
pp3v3_sus is 3.3v.
checked resistors around u6100 and they look fine.

pp5vs4 comes for few seconds when adapter is plugged in and then it goes to 0


Followed enable pin(4) of u7501 and checked for pm_slp_s5_l and its 0 volts and same goes for smc_s4_wakesrc_en .
i have replaced u7501 just to be sure that its not pulling enable signal low but the result was same. So i removed u8170 and measured pins without it and there was 5 volts on pin 4 which is s4_pwr_en, as far as i know there shouldn't be anything on pin 4 if u8170 was missing

and p5vs4 comes without u8170 and it stops when i put it back

any ideas what i should do next

 

[PPVCC_S0_CPU]

Did you try to start in SMC bypass mode?
Are you using original Apple 85W charger?

yes i am using original 85w adapter.
can you tell how to start in smc bypass mode?

 

[2informaticos]

Press power button, connect charger and maintain pressed 5-10s...
You can use SMC_ONOFF_L pads when board is alone on the desk.

 

[PPVCC_S0_CPU]

​

You can use SMC_ONOFF_L pads when board is alone on the desk.

​​​​​​Thanks, i will try it tomorrow.
i also noticed that all pins of u6100 are on 3.3 volts except the gnd.

 

[PPVCC_S0_CPU]

Its Its not working on smc bypass mode, i removed u6100 and fans started spinning and all power rails comes up.
i can see light in usb mouse when its plugged in

 

[2informaticos]

Try new BIOS, with clean ME...

 

[PPVCC_S0_CPU]

Try new BIOS, with clean ME...

I will try it on Monday, i measured resistance to ground on cpu vcc rail and it was around 0.7 ohms and it gives 0 volts drop on diode mode. Is this normal?? I tried removing 3 chips for cpu vcc and powered it, the fans starts spinning too(didn't removed u6100 this time) but when board is powered without u6100 cpu vcc shows 1.7 volts.

 

[2informaticos]

CPU VCORE has very low values...