MacBook Pro A2289 TouchBar (820-01987-A) - No power / No image

[GeniusPlace]

Hello community !
I have a MacBook Pro A2289 TouchBar that initially had a screen replacement issue. Being the king of small tests, I wanted to test to see if an A1708 screen could potentially work on this model. #BadIdea

Currently, the motherboard (820-01987) partially supports the 20V load. That is to say that the USBC-A takes 20V directly without going through 5V. And the USBC-B goes through 5V then 20V. The 2 charge ports are in 0.5A unstable, and are close to 10W but always drop down to approximately 1W unstable.

This Macbook doesn't turn on any more (on the other hand the trackpad which reacts randomly to the click). Have you ever encountered this type of failure on this model ?

So, while testing the voltages, I unsealed a few issues with the circuits, and I'm wondering if you could help me find where the problem is coming from ?

- P5VG3S_PGOOD - 1.76v instead of 5v
It is important to specify that the voltage is not stable. This decreases slightly every second to drop to 0v after about 3 seconds. Then back to 1.76v, etc ...

- PP3V3_S5 - 0 instead of 3v3
- PP1V8_S5 - 0 instead of 1V8
- PPVPCORE_S5 - 0 instead of 0.7-1V
- PP1V_PRIM (PCH POWER) - 0 instead of 1V

- PP1V8_S3 - 0 instead of 1V8
- PP1V2_S3 - 0 instead of 1V2
- PP1V_S3 - 0 instead of 1V
- PP1V2_S0SW - 0 instead of 1V2
- PP1V_S0SW - 0 instead of 1V
- PPVCCIO (CPU GFX) - 0 instead of 0.95V
- PPVCC_S0_CPU - 0 instead of 0.55 - 1.5V
- PPVCCSA_S0_CPU - 0 instead of 0.55 - 1.15V
- PPVCCGT_S0_CPU - 0 instead of 0.55 - 1.5V

All other voltage are normal.

Do you have a solution?
thank you in advance for your help

 

[2informaticos]

First of all, welcome to the forum!

Be aware of wrong assumptios!!!
"P5VG3S_PGOOD - 1.76v instead of 5v"
Don't make confusion between signal name and its nominal voltage.
The above mentioned signal is not a power rail; is just used to indicate a proper working state of 5V_G3S power supply.
It has correct voltage, being pulled-up to 1V8_G3S.

A1708 LCD assembly can be used for test.
However, no reason for video test yet, as you don't get CPU core voltage.
"PPVCCSA_S0_CPU - 0"
Many other voltages must come on before CPU gets core voltage.

"initially had a screen replacement issue"
What's the full history?

The MLB can be tested alone on the desk, without LCD connected; nor even external monitor is needed.
Connect charger (no battery) and check for voltage on the big coils.

 

[GeniusPlace]

First of all, welcome to the forum!

Be aware of wrong assumptios!!!
"P5VG3S_PGOOD - 1.76v instead of 5v"
Don't make confusion between signal name and its nominal voltage.
The above mentioned signal is not a power rail; is just used to indicate a proper working state of 5V_G3S power supply.
It has correct voltage, being pulled-up to 1V8_G3S.

A1708 LCD assembly can be used for test.
However, no reason for video test yet, as you don't get CPU core voltage.
"PPVCCSA_S0_CPU - 0"
Many other voltages must come on before CPU gets core voltage.

"initially had a screen replacement issue"
What's the full history?

The MLB can be tested alone on the desk, without LCD connected; nor even external monitor is needed.
Connect charger (no battery) and check for voltage on the big coils.

Thank you for your response and for taking the time to help me.

This macbook arrived with a broken screen. Initially, the Macbook allowed us to have a signal on an external monitor, so it would turn on.

I wanted to test an A1708 screen out of curiosity and then replaced the screen with a functional screen with a good reference (A2289). Finally, I noticed the problem described above.

As you asked me, here are the voltage's coils :

L8100 0.00v
L8102 0.00v
L7210 0.00v
L7220 0.00v
L7702 0.00v
L7420 0.00v
L7410 0.00v
L8410 0.00v

L7030 (CHGER_LX1/LX2) voltage variable 0.03 - 3.9/4.00 - 12.1v
L7670 (P5VG3S) voltage variable 1.9 - 3.3v
L7690 (PP3V3G3H) voltage variable 0.01 - 3.3v

 

[2informaticos]

Did you disconnect the battery, before touching LCD connector?

As always for T2 machines, try DFU mode.
More information available here:

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

Follow exactly the tutorial steps.

Write directly into reply box, instead of clicking Reply button.
No reason to quote an entire post, visible few centimeters above.
Please, maintain the forum aesthetic...

 

[GeniusPlace]

Yes, we disconnected the battery before touching the LCD connector.
I tried DFU mode (Normal and Deep Dive), but no results. Still no screen, no power, no fan

What do you think of the above results for the coils ?

 

[2informaticos]

Don't touch L7030; it is not connected to PPBUS_G3H.
Check if get steady voltage at F7000 and R6934.

Did you complete DFU revive, or machine is not recognized in DFU?

 

[GeniusPlace]

Battery disconnected, and USB-C cable connected :

F7000 (1 and 2) give 12.3v
R6934 (1 and 2) give 3.3v

About DFU, the macbook is not recognized. No "DFU image" appear on the app "Apple Configurator 2", No apple logo on the defective macbook, nothing :/

 

[2informaticos]

Check if all AWAKE and SLPS2R voltages come on.

 

[GeniusPlace]

Here are the voltages :

PP1v8_AWAKE : loop from 0v to 1v8
PPVDDCPU_AWAKE : loop from 0v to 0v7
PPVDDCPUSRAM_AWAKE : loop from 0v to 0v8
PP3V3_AWAKE : loop from 0v to 3v3
PP1V2_AWAKE : loop from 0v to 1v2

PP1V8_SLPS2R : loop from 0v to 1v8
PP1V1_SLPS2R : loop from 0v to 1v1

 

[2informaticos]

That explains no DFU connection.

Do you have stable voltage at F7000 and R6934?

 

[GeniusPlace]

Yes, both are stable. No loop, no variation

 

[2informaticos]

Check for short on all other coils of U7800; not AWAKE, nor SLPS2R related.
Also check on all big coils and other secondary supplies; look in pages 69 & 73/4/5.

 

[GeniusPlace]

About U7800, it seems all coils are ok. About voltage,
- L7815/L7814 : loop from 0v to 1v1
- L7816/L7815 : loop from 0v to 0v9
- L7813 : loop from 0v to 1v8
- L7823 (no stuff) : loop from 0v to 0v1
- L7806/L7807/L7808/L7809 : loop from 0v to 0v75
- L7811/L7812 : loop from 0v to 0v82
- L7810 : loop from 0v to 0v8
- L7824 (no stuff) : 0v8 stable
- L7821/L7822/L7820/L7819 : 0v


U7710 : All pins are 0v
U8100 : All pins are 0v

U8200 : pin 1/3 : 3v2 stable. All other pins are 0v
U8220 : pin 1 : 3v3 stable. pin 3 : 1v7 satble. All other pins are 0v
U8207 : All pins are 0v
U8208 : All pins are 0v
U8250 : pin 2 : 3v2 stable. All other pins are 0v
Q8251 : pin 5/6 : 3v2 stable. All other pins are 0v
U8213 : pin 1/3 : 0v5 stable. All other pins are 0v
U8290 : pin 3 : 3v3 stable. All other pins are 0v

U8400 :
- pin 21 : 10v7 stable
- pin 13 and 14 0v9 stable
- pin 11 : 12v16 stable
- pin 9/10 : 12v3 stable
- pin 1/2 : 0v09
- All other pins are 0v

 

[2informaticos]

Posting 0V on some power rails doesn't help to much.
In such case, you sould check diode mode to ground; switch to ohm scale, for very low values.

 

[GeniusPlace]

Sorry, I don't yet have the basics reflex. Here are the ohm :

About U7800 :
- L7815/L7814 (427 ohm) : loop from 0v to 1v1
- L7816/L7817 (037 ohm) : loop from 0v to 0v9
- L7813 ( 1135 ohm) : loop from 0v to 1v8
- L7823 (no stuff, 1700 ohm) : loop from 0v to 0v1
- L7806/L7807/L7808/L7809 (009 ohm) : loop from 0v to 0v75
- L7811/L7812 (023 ohm) : loop from 0v to 0v82
- L7810 (158 ohm) : loop from 0v to 0v8
- L7824 (no stuff, 746 ohm) : 0v8 stable
- L7821 : 0v, 087 ohm
- L7822 : 0v, 087 ohm
- L7820 : 0v, 073 ohm
- L7819 : 0v, 093 ohm


U7710 : All pins are 0v
- pin 1 (0 ohm), 2 (1305 ohm), 3 (OL), 4 (1307 ohm), 5 (OL), 6 (1308 ohm), 7 (1557 ohm), 8 (1554 ohm), 9 (OL), 10 (031 ohm), 11 (970 ohm), 12 (OL), 13 (015 ohm), 14 (015 ohm), 15 (668 ohm), 16 (000 ohm)
U8100 : All pins are 0v
- pin 1 (330 ohm), 2 (316 ohm), 3 (342 ohm), 4 (OL), 5 (801 ohm), 6 (OL), 7 (0 ohm), 8 (1985 ohm), 9 (325 ohm), 10 (0 ohm), 11 (482 ohm), 12 (012 ohm), 13 (317 ohm), 14 (1040 ohm), 15 (OL), 16 (1338 ohm), 17 (OL), 18 (1863 ohm), 19 (OL), 20 (1333 ohm)

U8200 : pin 1/3 (1364 ohm) : 3v2 stable.
All other pins 2 (1362 ohm)/5 (002 ohm)/7 (1952 ohm) are 0v
U8220 : pin 1 (1360 ohm) : 3v3 stable. pin 3 (1130 ohm) : 1v7 stable.
All other pins 2 (1466 ohm)/ 5 (713 ohm)/ 7(OL) are 0v
U8207 : pins are 0v
- pin 1 (672 ohm), 2 (OL), 3 (319 ohm), 5 (585 ohm), 7 (OL)
U8208 : All pins are 0v
- pin 1 (799 ohm), 2 (1340 ohm), 3 (319 ohm), 4 (OL), 6 (428 ohm)
U8250 : pin 2 (402 ohm) : 3v2 stable. All other pins 1 (700 ohm)/3 (544 ohm) are 0v
Q8251 : pin 5/6 (OL): 3v2 stable.
All other pins 2 (1337 ohm)/3 (720 ohm) are 0v
U8213 : pin 1/3 (013 ohm) : 0v5 stable.
All other pins 2 (1340 ohm)/5 (OL)/ 7 (OL) are 0v
U8290 : pin 3 (1360 ohm) : 3v3 stable. All other pins 1 (1544)/2 (1464)/5 (1388 ohm)/7 (1540 ohm) are 0v

U8400 :
- pin 3 (0 ohm), 4 (680 ohm), 5 (0001 ohm), 6 (0013 hom), 8 (1985 ohm), 12 (0001 ohm), 15 (923 ohm), 16 (924 ohm), 17 (1040), 18 (0023 ohm), 19 (0001 ohm), 20 (730 ohm), 22 (0001 ohm) are 0v
- pin 21 (OL) : 10v7 stable
- pin 13 and 14 (OL) : 0v9 stable
- pin 11 (OL) : 12v16 stable
- pin 9/10 (OL) : 12v3 stable
- pin 1/2 (OL) : 0v09 stable

 

[2informaticos]

No need to check all chips pins.
I expected the values on the output pins.
BTW, my error about page 75; no need to check it, yet.

However, from your readings, seems to have very low resistance to ground at 5V_G3S.
Post the exact ohm value to ground at L7670.

 

[GeniusPlace]

As I begin, I didn't know what to give you exactly
In this case, it is better to be too complete than not enough haha

About the L7670, the exact ohm value is 0012 ohm.

 

[2informaticos]

That is really low value for 5V_G3S power rail.
You can try voltage injection method.
Start with 3V and slowly go to 5.5V (if needed).
May need time injecting around 5V and thermal camera can help you.
Not sure if you can detect something heated just with fingers; as the ressistance is not very low.

 

[GeniusPlace]

It seems that the components R8444 and R8445 are faulty because the temperature is very high and their diode value is OL.
I'll replace them and check what's going on

 

[2informaticos]

A resistor cannot generate short to ground, or low resistance value!!!

What is the exact resistance to ground at PPBUS_G3H and C8440/41?