820-00165 10 second fan spin then sometimes boots

No-Clean

Member
Board was worked elsewhere, came in not working, looks like SMC was replaced or reflowed and had some corrosion around R8020, I found PP3V3_SUS had a very low impedence, replaced C1204 and all good there, U1950 also had some corrosion I replaced it, also replaced U1900 as it had some corrosion.

Now board starts up, fan spins for about 10-12 seconds, stops then starts up again and most times it stays on fine, some times after the initial fan spin it just hangs, when that happens I found that checking voltage on SMC_RESET_L makes the computer start up, but not always works.

I don't recall this board having that 10 second initial fan spin.
 

2informaticos

Administrator
Staff member
You still have something affected by corrosion.
Clean, or remove J6100.
Check all SPI Bus Series Termination resistors and their solders/traces.
You can also try known good working clean ME BIOS.
 
Last edited:

No-Clean

Member
Removed J6100 and cleaned the pads, SPI resistors good, clean ME BIOS and still same thing, could this be related to SMC since it was either replaced or messed with before?
 

No-Clean

Member
Board tries to start it gets as high as 0.200a then eventually comes down to 0.070, fan keeps spinning but no startup, this is with just a good know LCD connected.
 

No-Clean

Member
I can see a little heat in the bottom left corner of U3900, but when I check all rails related to area of the chip I cannot find any shorts
 

2informaticos

Administrator
Staff member
"Do you get VCORE and PLT_RESET_L, when board stays on? "
Please post usefull measurments.

Are you sure SMC is correctly soldered?
Try to reflow it...
 
Top