MacBook Pro 2019 A2159 (2-port) wont boot

[Eniaro]

Hi Noob here kinda I have a MacBook Pro 2019 A2159 (2-port) wont boot

Trackpad clicks.

Plugging in a genuine USB-C charger and any other charger = 20V and charges all the way.

Plugging in a Dell USB-C dock (WD15 docking station: is capable of outputting 19.5V/3.34A)
or
Dell USB-C monitor causes the voltage to cycle endlessly between 5V and 19V (Dell P2419HC: has built-in power delivery, capable of outputting 20V/3.25A)

The Caps Lock button doesn't illuminate.

Holding the power button (fingerprint scanner) for 10 seconds stops the trackpad clicking temporarily, but it starts clicking again after 3 seconds.

If I open the lid slightly, the trackpad stops clicking.

The keyboard backlight is not working.

The Touch Bar is not displaying anything.

Resetting the SMC and PRAM, as well as fully discharging the battery, has not resolved the issue.

I've replaced the display. ( Original had a small crack on lower right corner)

I've even bench-tested the logic board with nothing attached, plugging in a genuine USB-C charger and any other charger = 20V but the same 5/19V loop cycle when connected to a USB-C hub or monitor.

No physical components are visually damaged


I'm at a loss as to where to start troubleshooting this problem any help will be appreciated

 

[2informaticos]

First of all, welcome to the forum!

Work with the MLB alone on the desk, using original 61/87W charger.
Do not connect anything, apart of charger (no battery).
Just check the voltage on big coils.

 

[Eniaro]

Thank you.
I don't repair Macs that often but there has been an uptick lately and most of my repairs have been exploded caps so this level of troubleshooting is new for me.
I have been using the Apple 87W, (I included the dock information in case it provides any information that could be helpful)

All coils measure 0.01v
To make sure I'm doing the right thing I included a photo

 

[2informaticos]

If USB-C inputs switch to 20V, then PPBUS_G3H and 3V3_G3H_RTC are both present.
Check their exact voltage anyway.
Also check all G3S and SSD voltages.

 

[Eniaro]

@ the USB-C voltage goes from 5v to 20v like normal

PPBUS_G3H: 12.58V (measured at @ CD761)
PP3V3_G3H_RTC: 3.312V (measured the same everywhere)

I'm not quite following when you say all G3S and SSD voltages...

I2C_SSD_SCL: 1.797V (measured at @R2523)
I2C_SSD_SDA: 1.797V (measured at @ @R5230)
P3V3G3S_SS: 2.889V (measured at @ @U8200 & C8200)

Edit: while testing everything in Board Viewer that lists G3S
PP5V_G3S_VCCIOPVCC: C8143 appears to be shorted

Edit 2 can I use: Schematics says 10UF 20% 10V X5R Cerm 0402-7, on hand, I have 0402 10uF 6.3V 20% X5R can I use it for testing?

 

[2informaticos]

Good enough for test.

 

[Eniaro]

Replacing C18143 with 0402 10UF 6.3V
PP5V_G3S_VCCIOPVCC to measure 5.102V
P3V3G3S_SS
The USB-C meter is now 20.14V and 0.25A before it was 0.00 amp
CPU gets warm at about 40°C

Does this indicate its back to life being a noob it would be a pain to reassemble and it still doesn't work

 

[2informaticos]

Check voltage on the big coils from CPU area.
You can also connect an external monitor for test.
An USB-C test tool is also helpful.

 

[Eniaro]

USB-C 87W: 20.16V 0.28A when CPU gets warm. 20.16V 0.00A when CPU does not get warm
USB-C monitor cycles 5v > 20v >off > 5v> 20V > off> repeat

 

[2informaticos]

When CPU gets hot, you should have voltage on more coils near CPU; apart of RAM's one.
This board is not complicated to put back in case and test...

 

[Eniaro]

So I put it back together, the system has improved, however, there is no display, and the USB-C monitor (with USB-C meter) shows 5v then 20v then off the monitor sees MacBook for a few seconds then off... endless loop.

with just the 87w charger there's no 5v>20V loop

also, the fan spins as well

 

[2informaticos]

Is it recognized in DFU mode?

 

[Eniaro]

Took some serious tries to get it to DFU mode but it did, I am not sure if it's a 1d10t (me) issue or the system itself
I tried "revive" & "restore", during the process, the display remained blank eventually my host mbp displayed a lock... but the A2159 still has nothing on screen

Edit 2: I just noticed the 5>20V endless loop connected to the USB-C monitor only occurs when the battery is disconnected but when the battery is connected it cycles and then maintains 0.95 amperage

 

[2informaticos]

Check diode mode to ground on all secondary power rails (big coils).
BTW, good enough to check ONLY one pin of the coils.

 

[Eniaro]

my noobness is about to show here...
Red to ground and Black to coil pin?
Am I checking for open or short?

 

[2informaticos]

Ideally, compare with good board.
Short, or open, both are bad; we suspect short somewhere.

Reference table exists on Internet.

OpenBoardData Project

 

[Eniaro]

I didn't get to inspect the rails yet,
I noticed L2950 had a crack in it and tested it for short, and thinking it was a cap, removed it. While removing it, it completely disintegrated. I don't think this was the issue but I have to suspend troubleshooting until I find a replacement. The only "donor" board I have is an 820-00430 which was given to me I don't know if it has parts I can use

Edit does anyone know where I can find L2590 (0.68UH-20%-6.1A-0.020OHM 1210)

Edit 2: will this work?
TDK TFM322512ALMAR68MTAA

 

[2informaticos]

The board can boot without that coil.
You have time to find a replacement coil, once you've got the board booted first.