2019 Macbook Pro A2141 / 820-01700-05 / No water Damage / Does not Boot / no DFU

[zeydullak]

Hi there,

I need your advice on troubleshooting the cause of failure The purpose is to get the data from the Macbook. The MacBook was very dusty. Here are the symptoms and measurements.

Macbook On Battery / Without Batter Connection --> all 4 USB-C ports shows the same --> 5.15v 30 mAmps - just stable, no jumps.

Removed the Board and it was dusty, cleaning with high-pressure air without damaging component but did not applies any isopropyl to check it under the microscope. While observing the board, saw that U5620 has greenish corrosion on the right side of it. I see damage near pins 2 and 3 of U5620.

Then I observed greenish corrosion on R9012, R9010, and C9002. See the attached picture. Cleaned the area using Isopropyl alcohol. Please check the attached pictures.

Information about some Power Lines:

PP5V_S4_T_USBC - 0v
PPDCIN_TA_G3H_F - 5.1v
PPVBUS_USBC_TA - 0v -
PP3V3_G3H_RTC_X - 0v (primary power for CD3217 missing)

PPBUS_HS_3V3G3HRTC_X - 0v
PPBUS_G3H - 0v (we need to check the Charger Chip - U7000)
PPDCIN_G3H - 5.1v
F7000 - 0v on pin_1
F7001 - 0v on pin_1

I am again lost. Now I removed the U5620 and did measurements and waiting for your advice. Thank you.

regards,
Zeyd

 

[2informaticos]

Start checking diode mode to ground at L6960 and F7000.
If good, post U7000 basic voltages; P_IN, AUX_DET, VDDA/P, EN_MVR, AUX_OK.

 

[zeydullak]

Diode Mode Testing for Shorts:

L6960 - No shorts
F7000 - No shorts

Basic Voltages on U7000
P_IN --> 5.1v
AUX_DET --> changes between 1.0v-1.2v / not stable
VDDA --> 5v
VDDP --> 5v
EN_MVR --> 0v (nothing)
AUX_OK --> NC_CHGR_AUX_OK Could not find this signal on board schematiccs. is it possible something is not matching with the documentation?

Regards,
Zeyd

 

[2informaticos]

"L6960 - No shorts
F7000 - No shorts"
Can you post the readings?
Not only short means bad!
Post the readings on both ways; red probe, also black probe on ground (reverse way).
You may need to change U7000.

 

[zeydullak]

Just an update --> the chip U5620 is not soldered back to the board. I am not sure if it is damaged or not. Waiting for further advice on this. Thank you.

 

[2informaticos]

Resolder U5620 and its traces and related resistors.

 

[zeydullak]

Here they are:
L6960 --> 0.740v
F7000 --> 0.275v

Thanks.

 

[2informaticos]

"also black probe on ground (reverse way)"

 

[zeydullak]

The black probe was on the screw hole and the red probe was connected to the side of L6960 and F7000. Should I change it, but the RED on the ground and Black probe on chips?

 

[zeydullak]

Put back U5620 on the mainboard and the USB-C meter is 5.15v 30 mA - stable.

 

[zeydullak]

I connected the mainboard to USB-C power and tested it. I do not know if this is correct approach or not.
Black probe on the ground and red probe on the side of elements.
L6960 --> 0.860v
F7000 --> 0.860v

Thanks.

 

[2informaticos]

Normal way to check in diode mode, is RED probe on ground.
Reverse way (BLACK probe on ground) is rarely needed; but necessary in this case!
Now I'm not sure which readings did you post.

 

[zeydullak]

Sorry for making some mistakes.

Diode Mode - Black Probe on the ground (Reverse way) :

L6960 --> 0.505v
F7000 --> 0.048v

Diode Mode - Red Probe on the ground:

L6960 --> 0.417v
F7000 --> 0.048v

Please check the above measurements. Thanks.

Regards,
Zeyd

 

[2informaticos]

0.048 is really bad value for PPBUS_G3H.
Check if you get the same value on a big coil.

 

[zeydullak]

I did reverse and normal diode mode testing between ground and Test Point --> TPC5X7 (PPBUS_G3H main connection) --> I got 0.053v. Is this the correct point to make a test? basically, Multimeter cannot push enough volts from the ground to the PPBUS_G3H coil. Am I getting it correctly?

I also attached 2 pictures of diode mode testing using different Multimeters. Let me know what you think about this.



Thank you
Zeyd

 

[2informaticos]

Check if you get similar reading on any big coil; like L7600/60, L9080, L7701, etc...

 

[zeydullak]

Sure. here are they:

L7600 --> 0.530v
L7660 --> 0.599v
L9080 --> 0.501v
L7701 --> 0.122v
L8102 --> 0.044v
L7410 --> 0.006v
L7420 --> 0.006v
L7211 --> 0.002v
L7221 --> 0.003v
L7331 --> 0.003v
L7330 --> 0.017v
LA750 --> 0.009v
LA850 --> 0.054v
LA860 --> 0.039v
LA870 --> 0.040v
LA950 --> 0.038v

There are voltage drops. Thanks.
Zeyd

 

[2informaticos]

Check in diode mode (ohm scale, or buzzer) between PPBUS_G3H and any coil with similar reading; like L8102, LA850/60/70 and LA950.

 

[zeydullak]

Please see the measurements:

L8102 --> 52 Ohm
LA850 --> 65 Ohm
LA860 --> 27 Ohm (Multimeter Beeping Like Beep Beep Beep)
LA870 --> 27 Ohm (Multimeter Beeping Like Beep Beep Beep)
LA950 --> 0.079v - this is switching from Ohm to V

Regards,
Zeyd

 

[2informaticos]

If you checked correctly, then no high-side MOSFET shorted.
I hope last readings are taken between coils and PPBUS_G3H, not referred to ground.
In such case, you can try voltage injection method.
As is not pure short, a thermal IR cam can help you.