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820-00165 with all power rails but no POST

S

sekidata

Member
This 2015 Air board generates all power rails, Vcore, ALL_SYS_PWRGD, and PM_SLP_S4_L. Fan spins but does not POST, chime, or start up. The only abnormal signals I noticed are SMC_PROCHOT = 3.4 and CPU_PROCHOT_L = 0. Any ideas?
 
S

sekidata

Member
Tried a known good BIOS chip (clean ME region). No improvement. Fan spins, then stops, then continues spinning without POST.
 
2informaticos

2informaticos

Administrator
Staff member
Check all SPI Bus Series Termination resistors and their traces.
Inspect board for corrosion.
Check it outside of shell, only charger and USB device for test.
Do not connect LIO flex, nor SSD and airport card.
 
S

sekidata

Member
Close inspection revealed a tiny speck of corrosion on one corner of the SMC. Anything I can do to the SMC that doesn't involve replacing or reballing it?
 
2informaticos

2informaticos

Administrator
Staff member
Reball is necessary, always when corrosion is detected close.
You can try reflow, may just help temporary; just to detect the issue.
 
S

sekidata

Member
Ok, I did a reflow with flux and the board starts up and works now. Will test long-term to see if the issue is fixed.
 
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