820-00165-A - PM_SLP_S4_L missing

[Atomrepair]

This macbook came in with no signs of current or past corrosion anywhere to be found. Board looks as new.
History: machine would sometimes shut down and work again for a while when started up again.
Later, it only worked in safe mode, up until the current state: it wont power up at all.

no fan spin
green light functioning normally (starts green, then orange)
using original charger.
Everything but I/O pcb and its flatcable disconnected

	Voltage	Resistance to ground
PP3V42_G3H	3,4
PPBUS_G3H	8,6
PPVRTC_G3H	3,3
PP5V_S5	5
PP5V_S4RS3	0	22k
P5VS4RS3_EN	0	98,5k
PM_SLP_S4_L	0	100k
SPI_MLB_CS_L	3,32
SPI_CS0_R_L	3,3
PP5V_S0	0	63k
PP3V3_S5	3,3
PP3V3_S4	0	33k
PP3V3_SUS	3,3	548k
PP3V3_S3	0	184k
PP3V3_S0	0
PP3V3_S3_EN	0
SMC_RESET_L	3,36
SMC_BC_ACOK	3,3
SMC_ADAPTER_EN	3,4
S5_PWRGD	3,36
ALL_SYS_PWRGD	0
S4_PWR_EN	0
PM_SLP_S5_L	0
PM_S0_PGOOD	0	0.L (same for 2 donor boards)
PPVCC_S0_CPU	0

I've checked U1900, U1950 and the SMC - the IC's, traces towards them and surrounding components look fine and clean.

Ive also checked all U6100 pins with my scope. All but GND are sitting at ~3.3V (flat line)

What to do?

 

[JohnB8812]

Resistance to ground on CPU VCore?

 

[TCRScircuit]

This is going to suck. PM_DSW_PWRGD and SMC_DELAYED_PWRGD present? Your issue isn't no PM_SLP_S4_L. It's PM_SLP_S5_L missing that is causing all your issues. Any pulse on PM_SLP_S5_L when first turning it on?

 

[Atomrepair]

JohnB8812 : PPVCC_S0_CPU_PH1 = 7.5 Ohm to gnd

TCRScircuit : PM_DSW_PWRGD - 3.4V
SMC_DELAYED_PWRGD - 0V and 100kOhm to gnd
PM_SLP_S5_L does have a ~3.2V pulse when first hooking power up. the pulse lasts about 80miliseconds, if that matters.

 

[TCRScircuit]

OK, this could be dead SMC, dead CPU, Corrupt ROM etc... SMC_DELAYED_PWRGD is low because the CPU isn't talking to the SMC to send out PGOOD. Your sure you have pp3v3 and pp5v_S5 correct?

 

[Atomrepair]

Doesn't hurt to double-check..
They're both present: PP3V3_S5 at 3.3V and PP5V_S5 at 5V.

 

[2informaticos]

Solder an wire to SMC_ONOFF_L and touch the ground with it.
Then look if PM_PWRBTN_L and PM_SLP_S5_L react at the same time.
Is PM_RSMRST_L high?

 

[Atomrepair]

PM_RSMRST_L is high. No time to do further testing right now, will check back later!

 

[Atomrepair]

2informaticos : with SMC_ONOFF_L shorted to ground, PM_PWRBTN_L is pulled down to ~300mV
PM_SLP_S5_L gives a ~80ms 3.2V pulse, just as it does when connecting the magsafe.

I don't know what this is telling me, other than that the power button press is being responded to.

 

[2informaticos]

So SMC sends power button signal to PCH and this one respond with PM_SLP_S5_L.
That means S4_PWR_EN pulses, and voltage on R8000.
PM_SLP_S4_L should pulse, as PM_SLP_S3_L too.
Also check for pulse at L7520.
In fact all secondary coils should pulse at the same moment; the ones from CPU maybe not.

 

[Atomrepair]

R8000 pin 1 and 2	pulsing
S4_PWR_EN	pulsing
PM_SLP_S4_L	pulsing
PM_SLP_S3_L	pulsing
L7520 (PP5V_S4RS3)	pulsing
L7630	pulsing
L7430	pulsing
L7560	~3,3V
CPU coils L7310 and L7320	no pulse
L7701	no pulse

 

[2informaticos]

Dou you get only one pulse, or cycling every 5s?
ALL_SYS_PWRGD pulses too?

I have one 00165 here with one pulse only.
I tried another BIOS dump (clean ME) and the board stays on. However doesn't work yet, no USB activity.
Should have something more, I only commented as seems that BIOS is involved somehow in starting too...
Just for test, I tried again its BIOS and got again one pulse only. Tried another BIOS, one pulse too.
Reflased the clean ME dump and board stays on again.
This one was liquid damaged and SMC was changed too.

 

[dukefawks]

CPU Vcore not coming on is worrying. Is ALL_SYS pulsing?

 

[Atomrepair]

dukefawks - ALL_SYS_PWRGD pulses once when I connect the charger or short SMC_ONOFF_L

2informaticos - I've only checked ALL_SYS_PWRGD and PM_SLP_S5_L, both will only do a single pulse like your board. I can try looking at the BIOS if there's nothing else left to do, because I have no BIOS programming experience beyond flashing mostly older windows laptops.

 

[dukefawks]

What is resistance to GND on CPU Vcore?

 

[Atomrepair]

8.5 Ohms on both L7310 and L7320

 

[dukefawks]

BIOS is the only thing that is left now.

 

[Atomrepair]

Alright, I guess this will be my first apple BIOS job. Time for some experimenting on donor boards.. will report back later..

 

[Atomrepair]

I've taken the U6100 off the board and read its contents. File can be downloaded here. I compared it to a clean ME 820-00165 bin I found online, it looks about the same, but there are differences. I dont know if I can tell whether something is messed up by looking at this.

Not sure how to proceed. Do I need to replace only the ME region with a known good one?
ME Analyzer says firmware version for this BIN is 10.0.35.1012

ps: I tried to link to the bin file below, but the board stripping part of the link. Now I can't remove the link at all. If i take it out, it wont let me save the post.. feel free to ignore.

 

[dukefawks]

Just flash any 00165 file. Bad ME will not affect it turning on. Once it works we can fix the ME.