A1466 820-00165 intermittent shutdown

[cruiser_]

hi there,

Got this macbook after liquid damage. Nothing major, cleaned and reflowed what was suspect. Now, the laptop turns on and boots up but shuts off intermittently - sometimes after a few minutes, sometimes after a few hours.
Can be immediately started from keyboard right after. Plug stays orange during this time. No battery.

Gives shutdown cause -128.

Seem to work fine in SMC bypass.

Same shutdown happens with disconnected TP/KB/KBLED/CAM.

Observations:
- SMC_RESET_L - when pulled down - plug goes orange/green and 'shutdown cause is 0'. I suspect then that the shutdown is not SMC_RESET related, since in the intermittent condition the plug stays orange
- PP3V3_S5_AVREF_SMC - stable over time
- PP3V3_SUS goes down a few seconds after KBLED goes off
- removed U8130 - if PM_RSMRST_L is brought to GND (or even measured with multimeter) it shuts down the same way (with shutdown cause -128)
- PP1V05_S0_PCH_VCC* - 5 seconds after KBLED goes off, this goes down
- ALL_SYS_PWRGD & SMC_SENSOR_ALERT go down after - but I am not sure whether it is the cause or the effect.

When it is fully booted up:
- sensors that are suspicious are inlet/air temp (I think its expected, since the board does not have the 'measuring' transistor in place) and flipping PECI SA (0/65)
- CPU is throttled to 0.9 (sometimes to 1.4) - in SMC bypass it's 2.6/2.7.

Appreciate your help on this one!

[mon2]

Re: A1466 820-00165 intermittent shutdown

Is it stable with the SSD ?

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

yeah, when it runs it runs ok, albeit slow. put vanilla fresh monterey on it, no bother.

same shutdown happens also without SSD - just the USB installer.


It sort of looks as if PCH was getting cut off - with SMC not having a chance to react/record.
But then why would SMC bypass make it work just fine?
What inputs exactly SMC bypass ignores?

[dellxps15]

Re: A1466 820-00165 intermittent shutdown

wich area get liquid on it ? -128 is like bad cpu power or bad gpu power or bad memory power.

check very carefull the area it had liquid spill for missing track. was corrotion just occurred ot it was a really bad situation ?

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

Nothing 'eaten' away, so I guess a relatively fresh one. Don't know full history.

Corroded J6100, elements around U8130 (3.3V SUS detect), U6100 (SPI), U1900 (RTC) as far as I remember. Some smaller chips that looked dirty also cleaned and reflowed.

[mon2]

Re: A1466 820-00165 intermittent shutdown

Known good but official power adapter ?

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

Yup, original OEM 45W adapter.

wich area get liquid on it ? -128 is like bad cpu power or bad gpu power or bad memory power.

why would it run fine (now at 2h counting) in SMC bypass?

[mon2]

Re: A1466 820-00165 intermittent shutdown

In SMC bypass you are requesting for the sensor feedback to be ignored.

https://logi.wiki/index.php/SMC_Circuits

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

In SMC bypass you are requesting for the sensor feedback to be ignored.

https://logi.wiki/index.php/SMC_Circuits

I surely know of that page

"several SMC features are disabled (sensors in particular),"

what are those 'several' features and which sensors could potentially lead to the board shut down?

[mon2]

Re: A1466 820-00165 intermittent shutdown

https://boards.rossmanngroup.com/thr...ss-mode.43930/

Kinda feel like a junior Piernov by cutting & pasting like that but that would make him of Yoda's age.

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

"Other ones will block the board after some S4/S3/S0 voltages try to appear."

it would be great to have a list of inputs/signals showing which cause mere sensor values reading woes, throttling, board non-start, board shut-down 'gracious' and board shut-down 'suddent death'

So we have
1. *_ISENSE ones
2. *_VSENSE ones
3. ALERT_L ones (including CPU temps) - getting in as SMC_SENSOR_ALERT_L.
4. PCH_SM*/CPU_VID* ALERT_L ones

Any guess as to which does what? Some lead to 'gracious' SMC shutdown (shutdown cause 0) while some are more 'violent' (shutdown cause -128).

What would be the recommended strategy to getting to the bottom of these?

Soldering cables, setting up a 1-ch oscilloscope, recording it on a camera is waaay too tedious :|

[dellxps15]

Re: A1466 820-00165 intermittent shutdown

J6100 still in place or removed ?

[piernov]

Re: A1466 820-00165 intermittent shutdown

it would be great to have a list of inputs/signals showing which cause mere sensor values reading woes, throttling, board non-start, board shut-down 'gracious' and board shut-down 'suddent death'

Just gotta ask Apple for the SMC firmware source code… Or you can work it out by messing with the sensors one by one and seeing what the result is.

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

Unfortunately I do not have a 'real' oscilloscope with a few channels to get the timing/dependencies accurately. I am just surprised that someone has not gotten through this route yet.

Jokes aside though, with such an intermittent issue at hand, what would you recommend to do in order to get this case more 'manageable'?

Random poking with a stick to see where a cold joint is? removal of sensor-related chips? freezing parts of the board?
I'm doing this for my own 'fun' so no, I won't throw it away or give it back to a customer

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

J6100 still in place or removed ?

still in place

[dellxps15]

Re: A1466 820-00165 intermittent shutdown

asd gived u some error ? cpu igpu mosfet zone looks clear ?

best way to spot problem is to know wich zone got bad liquid damage....

last day i was working on a 13 inch with no working wifi.... j connector looks almost clear and all voltage present.... voltage for wifi signal was not getting low. many people reporting to a bad pch. when i decided to compare j pins with a working board i found out enable pin for wifi was not properly attached...

so know the bad zone give u 99% of possible fix

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

asd's only error was lack of battery.

however... based on the recommendation, I looked again at the areas I worked on before... Q8150 - fully re-soldered, looked to have dodgy connection to ALL_SYS_PWRGD. Vicinity of the chip had some crap on a pad that has PP5V_S0 - cleaned up.

And lo and behold, laptop is running for a few hours now! Could be it or just the fact that the board was heated up severly?

How could possibly ALL_SYS_PWRGD (or PP5V_S0) woes lead to a recovery, _especially since_ the macbook worked fine in SMC bypass?
ALL_SYS_PWRGD is needed for a CPU_VCCST_PWRGD signal, which goes to SMC. Could it be possibly ignored?

What gives?

PS.
already started going through SMC code with Ghidra, decompiled quite fine

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

darn... spoke too soon

it shut off after more than 4 hours! shutdown cause -128

what the actual heck?

[dellxps15]

Re: A1466 820-00165 intermittent shutdown

if u have ssd wit installed osx for air install some app that read all temperature and value, so u could find wich sensor is bad.

[cruiser_]

Re: A1466 820-00165 intermittent shutdown

sensors that are suspicious are inlet/air temp (I think its expected, since the board does not have the 'measuring' transistor in place) and flipping PECI SA (0/65)

I had iSMC output the values and sent over netcat to another computer constantly. Didn't capture anything off - voltages, currents, temperatures all check out but above.