Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

[salopian]

Hello. I would need some advice please.

My son's MBP suddenly stopped working and is now only getting the green-then-orange light on Magsafe and no fan spin.
He brought the MBP into the house (22 deg C) from a very cold conservatory (-3 deg C) and turned it on straight away. The Mac suddenly died a few minutes later.

I examined the logic board and couldn't find any signs of water damage, corrosion, blown up components etc. Nothing was ever spilt on it, and the logic board looks immaculate.

I have already replaced the logic board with another one, but I am now really interested and curious to learn as to WHY this MBP failed (temp difference resulting in condensation? something else?).

So, my measurements are like this:

PPBUS_G3H 12.55V
PP3V42_G3 3.39V
PPVRTC_G3H 3.34V
PP5V_S5 5.02V
PP5V_S4 0 V (missing)
PP5V_S0 0.37V
PP5V_S3 0.37V
PP3V3_S5 3.34V
PP3V3_S4 0V
PP3V3_S3 1.78V
PP3V3_S0 1.78V
S4_PWR_EN 0V

I then checked the enable signals @ U7501

SMC_PM_G2_EN 3.39V
S5_PWR_EN 3.39V
P5VS4RS3_EN 0V (missing)

…and then concluded that the PM_SLP_S4_L is missing
PM_SLP_S4_L 0V (missing)

Then I checked the inputs for the system power management:

PM_PCH_PWROK 0V (missing)
SMC_ADAPTER_EN 3.36V
PM_RSMRST_L 3.3V
PP3V3_SUS 3.34V

All CPUs 11 prerequisites for PM_SLP_S4_L are OK.

I then checked the PCH PWROK Generation @ U1950:

ALL_SYS_PWRGD 0V (missing)
CPUVR_PGOOD_R 1.78V
SYS_PWROK_R 0V (missing)
PM_S0_PGOOD 0V (missing)
SMC_DELAYED_PWRGD 0V (missing)
PP3V42_G3H 3.39V

The only thing that I didn't measure (as I don't have a scope) is SYSCLK_CLK32K_RTCX1 i.e. clock frequency (the voltage is 0.43V on U1900, if that means anything).

And this is where I got stuck….where should I go next with troubleshooting?
Did I miss something along the way?
Sorry, I am a complete newbie who's just trying to learn out of curiosity as I find this very interesting…

Any advice would be greatly appreciated.

Many thanks

[dellxps15]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

check resistance in omh on cpu coil

[piernov]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

PP3V3_S3 1.78V
PP3V3_S0 1.78V
CPUVR_PGOOD_R 1.78V

That doesn't sound right. I don't see how there can be leakage on both PP3V3_S3 and PP3V3_S0 here.

Anyway when SLP_S5#/SLP_S4# are missing, first thing is to check if they are pulsing when plugging in Magsafe using the oscilloscope (most multimeters are too slow to catch it).
If not then go through the power sequence https://logi.wiki/index.php/G3_to_S3..._and_Broadwell
If it's pulsing then it's not actually missing and the issue is not in that first part of the power sequence.

[salopian]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

That doesn't sound right. I don't see how there can be leakage on both PP3V3_S3 and PP3V3_S0 here.

Anyway when SLP_S5#/SLP_S4# are missing, first thing is to check if they are pulsing when plugging in Magsafe using the oscilloscope (most multimeters are too slow to catch it).
If not then go through the power sequence https://logi.wiki/index.php/G3_to_S3..._and_Broadwell
If it's pulsing then it's not actually missing and the issue is not in that first part of the power sequence.

Oh, so sorry, you're right! I've written down the wrong measurement.

PP3V3_S3 is 0.19V, not 1.79V

Will try to get an oscilloscope and also go through the power sequence as suggested.

Many thanks!

[salopian]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

check resistance in omh on cpu coil

Resistance to ground in diode mode:

L7320 0.001
L7310 0.001

Resistance to ground in ohms:

L7320 1.8 ohm
L7310 2 ohm

I guess these are the cpu coils?

Thanks!

[dellxps15]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

u had the same exact voltage like i had on same board. it's cpu is in short. ofcourse u can try with 1 volt and see if cpu is getting hot or some caps, but dont go to high with voltage, u can damage cpu. go around 1 volt and see if cpu or caps emosfet get hot, maybe ur lucky and it's just one mosfet or capacitor near it

[salopian]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

So high chance this board is not repairable due to a dead CPU, oh Apple....

Where would be the best place to inject the voltage? At one of these CPU coils?

Thank you so much for your help, really appreciated.

[dellxps15]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

inject 1 volt on the coil (cpu side) without cpu heatsink. chech carefully if cpu or mosfet or caps around it get a bit warm.
on my board it was the cpu getting warm.

[dellxps15]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

look at the attached picture; check the red markez zone for getting warm and that side of cpu too.



edit: i did edit the previous post but dunno why i did a new post. sorry for that

[Eleways]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

Hi

I've a similar problem, my A1502 it's dead too, but the led does't light on.

These are my measurements:

PPBUS_G3H 12.55V
PP3V42_G3 3.4V
PPVRTC_G3H 3.4V
PP5V_S5 0V
PP5V_S0 0.39V
PP5V_S3 0.15V
PP3V3_S5 3.4V
PP3V3_S4 0V
PP3V3_S3 0V
PP3V3_S0 0V
S4_PWR_EN 0V

SMC_PM_G2_EN 0 V
S5_PWR_EN 0 V

SMC_ADAPTER_EN 0 V
PM_RSMRST_L 0 V
PP3V3_SUS 0 V

CPUVR_PGOOD_R 0 V

PP3V42_G3H 3.4V

Anyone can help me to understand what's the problem? I'm not able to find a solution.


Thanks!!

[mon2]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

hi.

1) Is your logic board also 820-3476-A ? Please confirm by searching for these markings on the PCB.

2) Assuming yes, the PP5V_S5 rail is created by U7501 pin # 29. Check for this rail @ C7505.

3) Confirm the enable for this rail - check the voltage on pin # 4 of U7501.

4) Voltage on pin # 5 of U7501 ?

[jeusith]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

Hello guys, greetings from Mexico and a Happy new year to all of you!


I'm having trouble with a 820-3476-A that suddenly decided not to power-on (no liquid damage or anything like that).

I'm seeing similar symptoms as the ones described on this thread (No power, but charger light is present), also, I can hear a clicking noise on the board, which seems to be coming from Q7520 (I assume that's where the noise comes from, since after inspecting under a thermal camera, temperature pulses can be seen at the same rhythm of the noise).

I also took some measurements following mon2's advice:

PP5V_S5= Oscillating between 1.5V - 5V

U7501-Pin 4= Oscillating between 0-0.14V

U7501-Pin 5= 0V

Any clues? I might lose my job if I don't manage to fix this MacBook

[mon2]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

What is the voltage to ground of PPBUS_G3H?

Is it also power cycling?

[jeusith]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

What is the voltage to ground of PPBUS_G3H?

Is it also power cycling?

PPBUS_G3H is a steady 12.57V

[reformatt]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

PP5V_S5 is a LDO output on U7501 and should be a stable 5V (as is pin 22 which should be 3.3V). This chip is fed from PPBUS_G3H, so check it on pin 23 for voltage and stability. Then check resistance to ground for pin 22 and 29. LDO's don't provide much current, so it doesn't take much for them to shut down as they are just linear regs.

You will only get PP3V3_S5 enabled if SMC_PM_G2_EN is high.

[jeusith]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

PP5V_S5 is a LDO output on U7501 and should be a stable 5V (as is pin 22 which should be 3.3V). This chip is fed from PPBUS_G3H, so check it on pin 23 for voltage and stability. Then check resistance to ground for pin 22 and 29. LDO's don't provide much current, so it doesn't take much for them to shut down as they are just linear regs.

You will only get PP3V3_S5 enabled if SMC_PM_G2_EN is high.

U7501:
Pin 22 = stable 3.3V / Resistance to ground ≈4MΩ
Pin 29 = cycling between 1.5-5V / Resistance to ground ≈2MΩ
Pin 23 = stable 12.57V

[reformatt]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

Are you doing this with board removed or still in the laptop? Only other place PP5v_S5 goes is the trackpad. Try disconnecting it from J4800.

This LDO output is limited to 100ma. So it's either an active short or U7501 is U/S (unlikely).

[jeusith]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

Are you doing this with board removed or still in the laptop? Only other place PP5v_S5 goes is the trackpad. Try disconnecting it from J4800.

This LDO output is limited to 100ma. So it's either an active short or U7501 is U/S (unlikely).

The board is removed from the laptop, so the Trackpad was disconnected while taking measurements.

The owner of the macbook tells me that a while ago, he had a similar problem (no power and he heard a clicking noise) he took it to another shop and they had his logic board replaced.

Before replacing the logic board on the other shop, he says, the OS was reporting the battery 'was in bad condition and that it needed to be replaced soon'.

After the logic board was replaced, this message about the battery never showed up again and he assumed it magically fixed itself

Could it be that the battery somehow damaged U7501?

[reformatt]

Re: Macbook Pro Retina 13” 820-3476-A (A1502) - missing PM_SLP_S4_L

Not likely. These boards should boot on the bench without a battery connected BTW. They may have swapped the entire lower case with battery I suspect. Broken screen on these results in a donor machine, since the displays are still seriously expensive. They were only made for a limited time, which is why they are like hens teeth.

What is the resistance to ground of PP5V_S3 (at L7520). You should also measure all sub-rails too, just go around each coil and measure resistance to ground. Check L7630 just to make sure you don't have a dead PCH.