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820-00165 not starting, all S0 rails pulsing

N

Narek

Member
I'm working on 820-00165 which as customer says has died after plugging headphones to the jack. He turned it on after that, but computer went off while loading system. Board is perfectly clean, no corrosion, no liquid, no burnt components. After plugging charger in, there is green and orange light, but no fan spin.

- PPBUS is stable 8,59v,
- I have all S5 rails.
- PM_SLP_S4_L and PM_SLP_S3_L are pulsing, the same ALL_SYS_PWRGD and S0 rails - I get CPU VCORE and PP_1V05_S 0 for half a second, then second time and later no pulse.
- current sense resistors are ok
- no corrosion on J6100
- I have removed U6410 - no results,

Nothing gets hot, CPU and PCH have good resistance. I have tried known good BIOS, but it gives no difference. In SMC bypass mode fan spins once and stops.
 
2informaticos

2informaticos

Administrator
Staff member
If board is clean, can be CPU problem.
However, check all SPI Bus Series Termination resistors and their traces.

Check for pulse at CPU_VCCST_PWRGD and PLT_RESET_L.
 
N

Narek

Member
CPU_VCCST_PWRGD is pulsing to ~1v,
PLT_RESET_L is pulsing to ~3,3v

it pulses only twice, and later nothing happens.

SPI resistors are ok.
 
N

Narek

Member
Everything can happen with electronics, but in this case it's hard for me to believe that headphones have killed CPU. Ok, PCH is related to audio, but anyway if it would be CPU/PCH they would die permanently. Customer claims that computer has started after that but shut down while loading system.

@piernov, thank you for the link. I will follow these steps and report.
 
Last edited:
N

Narek

Member
I've checked everything you have mentioned about twice pulsing in LogiWiki, no described causes found on my board. But something interesting happened: I decided to reflow the SMC, just in case. After that board started, I had two short fan spins, then nothing, but CPU VCORE was present all the time, stable 1,8V. I thought it's BIOS I have used just for testing (known good for this board), so I flashed it with original one. This time I got RTC reset (fan spin-stop-spin) and it was working like this for about 15 seconds, CPU got warm. Then it turned off. I've replugged charger, there was no fan spin this time but CPU VCORE and other S0 rails were present again, CPU got warm. Now it's dead again, only twice pulsing..
 
2informaticos

2informaticos

Administrator
Staff member
I recently had 00165 with same symptom.
Tried BIOS, no change.
Tried SMC reflow, still the same.

I then remove U8130 and board stays on.
I resoldered U8130 and board started working good.
No corrosion found close to U8130 and also had goos solders.

I can only suppose crap accumulated underneath CPU chip (PCH area).
Reflowed that area, just in case; machine still working good.
 
N

Narek

Member
U8130 on this board looks perfect too, as well as traces. But I removed it and it made no difference. I've USC'ed the boad, no effect..
 
2informaticos

2informaticos

Administrator
Staff member
This sympyom is a nightmare.
Many times CPU internal fault.

Try to start in SMC bypass, just in case...
 
N

Narek

Member
In SMC bypass mode fan spins twice on high speed then stops and nothing happens, S0 rails are not present.
 
G

grmacs

Member
I've posted on another thread but I'm having the EXACT same problem. I've also done pretty much everything you have... frustrating.
 
G

grmacs

Member
Not yet. Frustrating that these boards can run with 3 sheets of garbage and junk on the board and ya get a clean one and can’t fix it haha
 
G

grmacs

Member
I’m going to try to USC mine to see. May try swapping the smc as a last effort. I’m guessing both are long shots
 
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