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[820-00165] Missing S4_PWR_EN / PM_SLP_S4_L is low

smiba

smiba

New member
Hi

I got a 820-00165 board here with a previous attempt at a repair ("Reflow the SMC and BIOS") that was not done by me

Power lines:
5V_S5: OK
3.3V_S5: OK
PPBUS_G3H: OK (8.62)
3V42_G3H: OK
PPVRTC: OK and not short
PM_DSW_PWRGD: OK

PCH_CLK32K_RTCX1: ~32Khz signal, 49/51 duty cycle

PCB_CLK24K_XTALOUT/XTALIN is not there though, not sure if it has to be in a non-S0 state?

Anyways I did manage to let it have a 1-2 second fan spin one time when I was just plugging it in while working on it. So its not fully dead, but I smell corrosion, a bad solder joint or a part thats dying

Any ideas?
 
larossmann

larossmann

Administrator
Staff member
I wouldn't trust the reflowed SMC or BIOS. You don't now what temp was used or for how long. Also as per duke's advice from another thread, start dodging these destroyed pre-worked boards. See if they knocked any resistor off, and as usual the SPI ROM termination resistors next to the BIOS & their traces to the resistors under the CPU.
 
smiba

smiba

New member
Gurmon said:
Is S5_PWRGD present ?
Click to expand...

Yup

larossmann said:
I wouldn't trust the reflowed SMC or BIOS. You don't now what temp was used or for how long. Also as per duke's advice from another thread, start dodging these destroyed pre-worked boards. See if they knocked any resistor off, and as usual the SPI ROM termination resistors next to the BIOS & their traces to the resistors under the CPU.
Click to expand...

Will check it out!

I actually just thought I fixed it by resoldering the slightly messed up looking solder joints of the spi chip because it kept a fan spin numerous attempts after doing so. However it stopped working again after I got it back in its casing. Too bad
 
smiba

smiba

New member
This board is still making me go crazy after 4 weeks. All termination resistors are OK and all traces are in tact (At least, to the furthest point I can measure without doing some magic BGA probe underneath the CPU :p)

I just was about to give up after re-soldering U1900 because the solder connections have been touched by someone else before, until it actually turned on again! A full fan that kept on spinning. However after disconnecting the power and re-connecting it it once again stopped working.

How often does U1900 die?
I know when replacing the U6100 BIOS SPI from a broken motherboard the the ME region gets messed up, but would it be good enough to verify if it actually was the chip? I just need it to pass S4 to make sure. A chime is the next goal

EDIT: I'll just see if replacing U1900 changes anything. At this point I'm forced to replace something because just staring at it won't fix it
 
Last edited:
smiba

smiba

New member
Replaced U1900: No Luck
Replaced Crystal: No Luck
Resoldered SPI chip: No Luck

Maybe corrosion underneath CPU or dead SPI Rom?

WIll check with scope at a later moment if there is any communication going on
 
smiba

smiba

New member
U1950 looks good, Pin 8 has contact with the 3.42V supply.

I grabbed my oscilloscope to check the SPI chip and there is no communication. At no point the SPI_MLB_CLK signal carries any clock and MOSI/MISO does not have any I/O activity.
All the signals get pulled-up though after ~1 second of connecting the charger though.

PCH_CLK32K_RTCX1 has a ~32Khz signal (32.7Khz if I can trust my oscilloscope, which I don't since its a cheap digital piece of crap. Point being the clock is there)

Any chance reballing the SMC will fix this? Or can I better just give up and call it dead?

Thanks for your help as always
 
smiba

smiba

New member
Replaced the SMC but it did not solve the issue

I hate this one so much because it actually turned on a couple of times and got my hopes up

Any other idea or just dead board?
 
D

dukefawks

Administrator
It is a corroded trace/pad/resistor somewhere. Sometimes you just cannot find it and it is just a time waster.
 
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