820-00165 S0 rails pulsing

BCN_Techs

Member
Got this board, no liquid damage.


Green/orange light, fan try to spin and s0 rails pulsing. ALL SYS also pulses. Already checked all traces on U6100 and resistors on SPI Bus Series Termination and all are ok. No visible damage.


My guess is U6100 but i dont have medusa for now. Anyway to check if there is something else or it is defenitly EFI?
 

2informaticos

Administrator
Staff member
To suspect SPI, you should get pulse at PLT_RESET_L first.
Do you get pulse at pins 7 & 3 of U1950?
VCORE pulsing too?
 

BCN_Techs

Member
Yes, PIn 7 and 3 are pulsing up to 3.3. and Vcore is also pulsing to 1.05V.


P.S. when i measure pin 7 on U1950 sometimes fan spins and but there is no image. :S


Same happened when measered PLT RESET, but when not starting PLR doesnt pulse
 
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2informaticos

Administrator
Staff member
"will buy chip "
What chip???
Don't you have normal programmer to flash U6100, once removed from MLB?

Solder back U8130 (after changed U8005) and try again.
 

BCN_Techs

Member
i dont have programmer, because i dont have many efi issues macs. Usually i buy clear efi and never had problem with that.


P.S: Soldered back U8130 and nothing happens now.


Main S0 rails pulsing, without U8005 fan spins (just spins)
 
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2informaticos

Administrator
Staff member
Shouldn't be BIOS; PLT_RESET_L is required before PCH accesses U6100.
Board stays on w/ U8005 and w/o U8130?
 

BCN_Techs

Member
PP1V05_S0SW_PCH_HSIO short disappeared, seems that U8005 was soldered bad. Now With and without resistance to ground - 450 Ohms

and like before: with u8005 no fan spin without fan spins.
 
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BCN_Techs

Member
Yes, smc by pass first make fan spins for 1 second than stops, and than fan making "clicks" trying to sping but not spinning.
 
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