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Macbook pro 820-4924 not turning on

I

ielectron

Member
Hi we get macbook pro A1502 13" mainboard 820-4924 laptop want turn on. I get in green light and than orange light no reaction on power button.
nothing is geting hot.
without battery laptop takes 0.30A
with battery around 1,8 A
I reflow SMC but didn't help,
PP_BUS_s5_hs 12,89V
CPUVR_PHASE1 0,00V resistance 0,32Ohm

CPUVR_PHASE2 0,00V resistance 0,31ohm
SMC_ADAPTER_EN 3,39V present
PP5V_S4 is not shortedget pulse once connected charger

Any idea ?
Thanks
 
A

aprendiz

Moderator
Any history? dropped? water damage?

PP_BUS_s5_hs 12,89V this is high, should be 12.56V.

resistance betweens pins 17/18 and 27/28?
 
I

ielectron

Member
the cpu is physically broken, i guess the smaller dye on the chip is for the chipset part? cause that part is not even covered by the heatsink. i thought that is the gpu part of the i5 but the integrated gpu must be covered by the heatsink.

Do u have experience replacing the CPU? can i just solder the same numbered cpu in there? is there anything to look for?

Also how come that dye is cracked? was it caused by a short inside the chip, or maybe someone forced it before? though i dont see any tempering with the board , the heatsink is not bent.
 
D

dukefawks

Administrator
Don't bother unless you have a free CPU on a donor board. Buying these reballed from China is a waste of time and money.
 
D

dukefawks

Administrator
A Chinese CPU picked from the trash? Who knows if that is good? ME region will need fixing if you are lucky and it will work.
 
I

ielectron

Member
I replace CPU on this laptop,
orange and green light present
PP_BUS_s5_hs 12,75V with disconnected charger
PP_BUS_s5_hs 13,15v with connected charger
CPUVR_PHASE1 1,87V
CPUVR_PHASE2 1,87 V
P5VS3_VSW 5,14V
I get reaction on power button CPUVR voltage shuts off and turn on looks like laptop wants boot up but no display no chime.
I didn't fix ME region yet, should laptop boot up anyways without changing it ?
I connected mouse to USB ports and it blinks for a less than sec,
Thaks
 
Last edited:
D

dukefawks

Administrator
As I warned you! There is no way to know if the CPU is good, no way to know if it is soldered correctly and no way to know is there is more things wrong on this board. With this many variables this is hopeless.

Yes it should boot without fixing the ME.
 
I

ielectron

Member
any other thoughts than faulty CPU ? soldering was perfect. is it possible that the PP_BUS_s5 is causing issue ? Where you are getting CPU from ? I seen that you are replacing it.
 
D

dukefawks

Administrator
I do not replace CPUs. I have done maybe a hand full in 10 years and pulled them from donor boards with known good CPUs. Your PPBUS is fine, this is a CPU issue or pretty much anything else is possible. Dead CPU is just the end.
 
I

ielectron

Member
so after a week we get macbook with good CPU I swap CPU to see it actually Chinese CPU is faulty and it is exactly same issue.
CPU was OK and this fitted now is 100% ok
everything is exactly the same
orange and green light present
PP_BUS_s5_hs 12,75V with disconnected charger
PP_BUS_s5_hs 13,15v with connected charger
CPUVR_PHASE1 1,87V
CPUVR_PHASE2 1,87 V
P5VS3_VSW 5,14V

Any ideas ?

I swap also BIOS from working board but no luck.

Just to remind board wasn't liquid damaged , I didn't noticed any physical damages on the laptop except crack on CPU.

Thanks
 
D

dukefawks

Administrator
Cracked CPU may have been due to an impact damage and traces can be damaged anywhere on the board. Please stop wasting time on a trash board like this.
 
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