820-3115 randomly shutdown

Yoel Ren

Member
customer brought it in, no liquid damage, I got green light on charger
it can turn on, normally, after a few minutes of use, it will suddenly shut down
tried with booting from usb drive, still sudden dead
after a bit of testing and trying, its life slowly lessened, it will only boot to login screen, and then poof dead
after that, it only boot to apple halfway and then dead, and after that, it can't even be turn on anymore
I have tried reballing smc, still the same

is this pch problem ?
 

2informaticos

Administrator
Staff member
Check if starts in SMC bypass mode first.
If not, post some voltages and signals for power on sequence.
Don't forget to check resistance between pins 17/18 and 27/28 of U7000.
 

Yoel Ren

Member
smc bypass does nothing
17/18 : 3 ohm
27/28 : 20 ohm
compared to working board, seems normal

ppbus_g3h 12.6v
pp3v42_g3h 3.42 v
ppvrtc_g3h : 3.3v
pp5v_s5 : 5v
pp3v3_s5 : 3.3v
pp5v_s4 is 0.6v
if s4 doesnt even come, no need to check pp1v8_s0 stuff etc right ?

if i smc_on_off_l , pm_slp_s4_l doesnt go low
i have pm_slp_s3_l
processor is getting warm, fan ocassionally twitching

update : i have all_sys_pwrgd at 3.3v, but keep cycling on and off every few second
 
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2informaticos

Administrator
Staff member
If you get ALL_SYS_PWRGD, then you must get some S3 and S0 voltages; maybe not VCORE.
So check if VCORE pulses at least.
Check if board stays on without RAM.
 

Yoel Ren

Member
PPVCORE_S0_AXG 0V, doesnt even pulse..
PPVCORE_S0_AXG resistance to ground is 2.6 ohm, is that normal ?
i don't know what do you mean by board stay on, it doesnt even turned on, or do you mean the green light ?

by the value of the voltage, can i assume at least the smc is not the problem ?
 
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2informaticos

Administrator
Staff member
AXG and VCORE are very low values as normal for Ivy Bridge CPU.

"pm_slp_s4_l doesnt go low"
Must stay high when board is turned on.
It should go off if you maintain power button pressed 4s.

"i have pm_slp_s3_l"
So secondary power supplies controled by this signal can be on; check that.
 

2informaticos

Administrator
Staff member
""i have pm_slp_s3_l"
So secondary power supplies controled by this signal can be on; check that."
Which is the exact level of PM_SLP_S3_L?
Check all the secondary power supplies enabled by this signal.
 

Yoel Ren

Member
this customer change battery before, but come back after 1 week for sudden shutdown issue
he doesnt want to wait anymore so i refund him his money, got a little mad because its completely dead now,
you can closed this thread, but i just want to ask, how do you prevent or handle situation like this ?
 

2informaticos

Administrator
Staff member
You need different voltage readings to diagnose the board.
Could be a problem generated by fake chinese battery...
 
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