Hello fellow Badcappers,
I have a problem with stubborn Surface Pro 7. I narowed it down to disappearing SLP_S4# (gone after around 200 ms).
Everything else works as it should (the whole power on sequence succesfully finishes, all the voltages are present) until this signal goes missing - with it missing the AND gate causes ALL_SYS_PWRGD to go back low and this makes VCCIN drop to 0 V as well. Interestingly the SLP_S4_DRV# signal from SAM is still present for a second, even after SLP_S4 is no longer there. I wonder what could either cause PCH to stop sending the signal or what could deassert the signal after such a short time (before even attempting to read the bios).
It doesn't seem to be caused by a bad bios because there's not enough time to even show any activity on the CLK signal for the flash.
Also, SLP_S3# is still present for additional few seconds even after S4 is LOW.
Does anybody have any tips on what to check / probe? Thank you so much.
I have a problem with stubborn Surface Pro 7. I narowed it down to disappearing SLP_S4# (gone after around 200 ms).
Everything else works as it should (the whole power on sequence succesfully finishes, all the voltages are present) until this signal goes missing - with it missing the AND gate causes ALL_SYS_PWRGD to go back low and this makes VCCIN drop to 0 V as well. Interestingly the SLP_S4_DRV# signal from SAM is still present for a second, even after SLP_S4 is no longer there. I wonder what could either cause PCH to stop sending the signal or what could deassert the signal after such a short time (before even attempting to read the bios).
It doesn't seem to be caused by a bad bios because there's not enough time to even show any activity on the CLK signal for the flash.
Also, SLP_S3# is still present for additional few seconds even after S4 is LOW.
Does anybody have any tips on what to check / probe? Thank you so much.
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