820-4924 Pulsing voltages not turning on

ytesfay80

New member
The customer said this board was put to sleep and ever since then it hasn't turned on. There looks to be no liquid damage after inspecting the board. I get a green light when I plug in the charger but nothing comes on nor does the fan spin(which is common for these 2015's).

I unplugged all the external components(kbd,tpad,screen, etc) except for the dc-in board and I plugged in another one to make sure that wasn't the issue. Here are some voltages I get with no components plugged in
PP5V_S5 - 5.04v then every 3seconds it goes to 5.17v
PP5V_S4 - 0v then pulses to 5.17v
PP5V_S3 - 0v then pulses to 5.17v
PP5V_S0 - 0v then pulses to 5.17v
PPVCC_S0_CPU - 0v then pulses to around 1.7v
PPBUS_G3H - steady 12.58v
PP3V3_S5 - constant 3.36v
PP3V3_S3 - around 0.08v then pulses every 3seconds to 3.32v
PP3V3_S0 - around 0.4v then pulses to 3.32v

Pin 1 of U1950(ALL_SYS_PWRGD) - 0v then pulses to 3.35
Pin 2 (CPUVR_PGOOD_R) - 0.08 then pulses 3.3v
U6100 and the traces look perfectly fine.
I checked about 10 spi termination resistors and they all measured the proper resistance. All the areas are spotless so I don't think there was any liquid damage causing this.

I tried booting in smc bypass mode without the battery plugged in. After doing it the fan will spin for like half a second then stop and every few seconds it will keep doing the same pulse.
 
Last edited:

ytesfay80

New member
I put another u6100 and it still pulses and does the same fan issue in bypass mode.

Is there any other components that I can try replacing to solve this?
 

ytesfay80

New member
Yes.
PPVCC_S0_CPU - 0v then pulses to around 1.7v.
The only thing I have is their word. There is no liquid damage as I can see.
 
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