Macbook 820-00850 20V 54mA No Power

[Comp_Pro]

Hello,

I'm trying to diagnose this board with no power.

The board was originally brought in for water damage. Corrosion was not very bad and the board was successfully repaired by a quick ultrasonic cleaning. All corrosion was very surface level and no solder repair was needed at all. No oxidized components can be seen. Customer took the laptop home and it worked fine until it was brought back for warranty. Customer was watching youtube when it suddenly shut down. Customer says last time she tried turning it on it would turn on after a very long while but gave some kind of error. During my own testing I THINK i saw the board try to power on once but have not been able to replicate the customers claim that it would sometimes try to turn on after a long while of waiting

I tried DFU restore but got error 9xFCA (4042) "Gave up waiting for device to transistion from DFU state to DFU state".

I am unsure of the most efficient workflow to test voltages on these boards so I went off the sequencing diagram from 820-01598.


Current consumption

Starts at 5V .245A when plugging into charger-seems normal
Then transitions to 20V 0.054A and just sits there, no boot.
On occasion the current "dips" and it seems like the board trying to boot.
It will go: 20V 0.00A then 20V 0.035A then 20V 0.075 then it will go back to 20V at 0.054A like at the beginning and sit there again. The cycle repeats every 15 seconds or so.

Same behavior on all ports.

Sequencing Diagram


PPBUS_G3H 12.59
PP3v3_G3H 3.37
PP3V3_G3H_RTC 3.38
PP5V_G3S 5.15
PP3V3_S5 0V
PP5V_S4 0V

PP1V8_SLPS2R 1.8
PP1V8_AWAKE 1.8
PP1V8_SLPS2R_PMUGPIO 1.8
PP1V1_SLPS2R 1.1
PP0V8_SLPS2R 0.79
PP0V82_SLPS2R 0.82
PP3V3_AWAKE 3.36
PPVDDCPUSRAM_AWAKE 0.80
PP0V9_SLPDDR 0.9
P1V1_SLPDDR_SOCKET_EN 1.1
PP1V1_SLPDDR 1.1
PP1V2_AWAKE
PPVDD_CPU_AWAKE 0.75
PMU_SYS_ALIVE 1.78
PMU_ACTIVE_READY 1.78
PMU_COLD_RESET_L 1.79
PMU_PVDDMAIN_EN 3.38
P3V3MAIN_PGOOD 3.25
PP3V_G3H_RTC 3.00
PMU_CLK3K_PCH (unkown)
PCH_RTC_RESET_L 3.00
P5VG3S_EN 3.38
PP5V_G3S 5.15
P3V3G3S_EN 1.8
PP3V3_G3S 3.38
P1V8G3S_EN 1.8
PP1V8_G3S 1.8
P5VG3S_PGOOD 1.78
PMU_CLK (unkown)

Any help is appreciated!

[reformatt]

Re: Macbook 820-00850 20V 54mA No Power

Ultrasonic cleaners wipe away all the evidence of where the liquid was, and they are your biggest clues into diagnosing faults. Take photos of the areas affected before any cleaning as you may need to come back to that as you are now. Ultrasonics are used to clear off all your fluxes etc, not to 'fix' a board.

Pay attention to any areas the liquid got to for corroded end caps to passive components. Look for discolouration etc under the microscope. I often find the pad is corroded once you take that component off. Additionally, ultrasonics don't remove crap under BGA's either so often need a reflow with flux (or worse case, a reball).

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

Hello, thanks for the reply.

I did check ahead of time for any corrosion on the board but found nothing except a few traces of residue. It was very light and none of the components were oxidized and there was no build up.

It appears to be at least partially alive since it will show up in DFU mode on another macbook, just won't go through the entire procedure unfortunately.

[reformatt]

Re: Macbook 820-00850 20V 54mA No Power

Check the power sequence. You're missing PP3V3_S5 so it's something before that. SSD voltages present? T2 chip needs to communicate with the NAND's in the sequence.

https://logi.wiki/index.php/CD3217_a...er_on_Sequence

[Stephen]

Re: Macbook 820-00850 20V 54mA No Power

Sounds like something I was working on myself. I may have wnt to see what he finds as well.

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

Sorry for the late reply guys, I had to shelf this one for a while as I have tons of other work this week.

I will be going through the power sequence diagram tomorrow. For now I did some quick measurements before leaving work and found the following.

PP3V3_s5 as mentioned before is missing. No short here. Diode mode measures 0.315
PP1V8_S5 is also missing. Diode mode 0.411.

PP1V8_SSD0=0V diode mode 0.306
PP0V9_SSD=0V diode mode 0.134

So looks like the SSD voltages are missing. I installed a button at PMU_ONOFF_L and observed PP3v3_s5 while pressing the button to see if there was any kind of peak but there's absolutely no reaction. Same goes for the current draw, no change at all. I noticed on ocassion the voltage at PMU_ONOFF_L dissappears. This is sourced from the PPVRTC_G3H if I'm not mistaken, however this is only sometimes and does not appear to be linked to any particular action that I'm doing while testing the board.

I'll get some more thorough reports tomorrow. In the meantime if you can offer any info based on these measurements do let me know. Thanks!

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

Okay guys here is the measurements I took.

I went from PP3V3_S5 all the way to the beginning of the power sequence diagram. Since this chart is for a different board I labeled all the rails I couldn't find here as "N/A". I also put any odd readings in bold.

PP3V3_S5 0v 0.317 DIODE MODE
NAND_RESET_L N/A
SSD0_OCARINA_RESET_L 0.03
NAND_WP_L N/A
P2V7NAND_PGOOD N/A
P2V7NAND_EN N/A
NAND_DISCHARGE N/A
PP0V9_SSD 0V 0.134 DIODE MODE
PP1V8_SSD 0V 0.306 DIODE MODE
SSD0_OCARINA_LPB_L CANT ACCESS NO TEST POINTS
SSD0_OCARINA_PFN 0.23V 0.412 DIODE MODE
SSD_OCARINA_WP_L 0.07V 0.488 DIODE MODE
SSD_VR_P2V7_EN 0.01V 0.368 DIODE MODE
SSD_PMU_RESET_L 1.8V
P5VG3S_PGOOD 1.76V
PP1V8_G3S 1.8V
PP3V3_G3S 3.38V (this one occasionally restarts at the same time current changes at charger ammeter)
PP5V_G3S 5V
PCH_RTC_RESET_L 3V
PP3V3_G3H_RTC 3v (CHART SAYS PP3V3_G3H but one found on board ends in RTC)
P3v3MAIN_PGOOD 3.33V
PP3V3_G3H 3.36
PMU_VDDMAIN_EN 3.38V
PMU_ACTIVE_READY 1.8v
PMU_SYS_ALIVE 1.78V
PMU_COLD_RESET_L 1.79V
PPVDDCPU_AWAKE 0.75V
PP1V2_AWAKE 1.19V
PP1V1_SLPDDR 1.1V
P1V1_SLPDDR_SOCFET_EN 1.1V
PP0V9_SLPDDR 0.9V
PPVDDCPUSRAM_AWAKE 0.8V
PP3V3 AWAKE 3.36
PP0V82_SLPS2R N/A
PP0V8_SLPS2R 0.82V
PP1V1_SLPS2R 1.1V
PP1V8_SLPS2R_PMUVDDGPIO 1.8V
PP1V8_AWAKE 1.8V
PP1V8_SLPS2R 1.8V
PP3V3_G3H 3.37V
PP3V3_G3H_RTC 3.38V
CHRGR_EN_MVR 5V
PPBUS_G3H 12.27V


I assume that the fact that PPBUS_G3H is at 12.27 is a little low further shows some kind of an issue correct? Would greatly appreciate any help. Thank you!

[mon2]

Re: Macbook 820-00850 20V 54mA No Power

I assume that the fact that PPBUS_G3H is at 12.27 is a little low further shows some kind of an issue correct?

Yes, it is low. SMC is a suspect. Check the voltage to ground of the SMBUS lines.

https://logi.wiki/index.php?title=PPBus_G3H

The MacBook Pro series uses a 3S2P battery so on the charger it has a PPBus of 12.6V (12.2V before SMC boosts).

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

UPDATE:

While investigating the missing SSD0_VR_P2V7_EN line at U9080 I found that the output of this chip, PP2V7_NAND_SSD0, is missing and perhaps shorted to ground. The diode mode reading here is about 0.050. However the short is only 70 ohms to ground which at 2.7V is only about 30 milliamps. So perhaps this is only a MOSFET or gate somewhere turning on? What's odd is that this "short" disappears sometimes. When I removed L9080 and L9081 to isolate the issue the diode mode reading went to 0.340. After re-installing these coils and re-applying power the short re-appeared and went back down to 0.050 on diode mode. Basically at some point the short disappears and the line goes back up to 0.340 but when I apply power to the board the reading goes back down to 0.050. I also can't reliably recreate this issue by injecting power from a power supply. The only way I can reliably make the short re-appear is by applying power to the actual board. I'm not sure if this may be normal behaviour from the nand chips or if it's an actual shorted component. I'm also not sure what it is that makes the short go away. Discharging the line to ground does not make the short go away, it only does so when it wants. But applying power the board reliably makes the short re-appear every time. Maybe I should remove the nand chips to try and isolate the issue?

mon2 I will check those lines. Thanks.

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

Anyone?

[mon2]

Re: Macbook 820-00850 20V 54mA No Power

Very good diags on the power rail buck regulator.

Measure the voltage to ground of SSD0_VR_P2V7_EN_R.

Also measure SSD0_VR_P2V7_EN.

What is the measurement?

The switching mosfets are internal to U9080 and suspecting that this buck regulator is defective. The diode readings, to me are too low.

PS: Craving for some of your deep dish pizza but then again, it is dinner time

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

Hello, thank you for taking the time to respond and I apologize for the delay to reply back. Since It's been busy here I had to shelf this one for a little while. Today I had some free time so I went back to it.

Voltage to ground on the enable line is 0.357 on both sides of the resistor R9082. It definitely seems however that the short is on the output side of coils L9080 and L9081. The low reading is on the output side of these coils when they are removed from the circuit.

Shorted NANDs? Unless it's a shorted cap somewhere on this line. However I find it very odd that the short only appears when I try to power the board and then disappears. As mentioned in my previous post, I'm not sure what behaviour it is that makes the short dissappear but what makes it appear is attempting to power on the board. The short cannot be made to appear if I inject voltage to this line either, it has to be when I try to power the actual board by plugging in the charger. Very odd and this is what makes me wonder if this type of reading may be normal and due to a logic gate of some sort turning on somewhere inside the SSDs. After all at the 50 ohms or so that the short reads, that's only about 30mA of current.

That said I do think most likely we have shorted NANDs. Would you agree? I've read around about people replacing these but I haven't done it myself. I've read these don't have to be programmed like an iPhone NAND? Is that true for all macbook NAND chips of this type? Can someone point me towards a source?

Thank you!

PS: Mon2, you are welcome to have some deep dish! Many good little hidden gems around the city that sell great pizza. However, don't forget to try our REAL main pizza which is tile cut tavern pizza! Deep dish is kind of our "Side B" pizza, though it too is very delicious.

[Comp_Pro]

Re: Macbook 820-00850 20V 54mA No Power

bump. Anyone?