820-00165 PM_SLP_S5_L missing, all rails pulsing twice on power on

[dudipupan]

Hi,

i'm currently working on a MBA2017 820-00165.
Here some Voltages of the rails:

PPBUS_G3H: 8.6V
PPVRTC_G3H: 3V
PP3V42_G3H: 3.4V
PP3V3_S5: 3.3V
PP5V_S5: 5V
PP3V3_SUS: 3.3V
PM_DSW_PWRGD: 3.3V
SMC_DELAYED_PWRGD: 0V
PM_SLP_S5_L: 0V

All rails are pulsing twice when i connect the magsafe (inlcluding CPU_VCORE 1.8V).
I haven't found any short to ground on the board.

Thank you so much
best regards

 

[dudipupan]

After swapping U6100 i got a fanspin but no display and no USB activity. I will try to flash a new BIOS

 

[dudipupan]

After reflashing BIOS i got still no display or usb-activity...

 

[2informaticos]

Any history available?
Check all SPI Bus Termination resistors and their traces.
PLT_RESET_L comes up?

 

[dudipupan]

No, unfortunately no history available. Looks like SMC was replaced or reflowed.
PLT_RESET_L is stable 3.3V

 

[dudipupan]

SPI Bus resitors and traces seem to be fine.

 

[2informaticos]

May be waste of time, if board was meesed up for someone else before.

Check all voltages from page 11.
You sould try to solder known good SMC.
Once removed, check all its traces and pads.