820-01814 - MacBook Pro - PPBUS_G3H power cycling

[mccafe]

Hello guys,

I have a 820-01814 (using 820-01041 schematic) and found that PPBUS_G3H is power cycling. It measures 10.9 volts most of the time, but in short 3-4 second bursts it holds at 12v and in some cases 13v - battery connected. It stays 12.3 volts or sometimes 13 volts when battery disconnected. I have disconnected all parts such as trackpad, keyboard, Touch Bar, etc.

With a known good working battery, PPBUS_G3H measures 12.3 volts and in short bursts every now and then it measures 13 volts.

Diode mode:
PPBUS_G3H - 0.377

Charger shows 20v - 0 amps. Unable to connect to Apple Configurator 2 - tried many different cables, Macs, etc.

Edit: Most of the time charger shows 20v - 0 amps, sometimes it shows 0.43 amps and then cycles back to 0.

 

[2informaticos]

Check diode mode to ground on all big coils; don't forget L9080/580.
Compare readings with good board, if possible.

A1990 - 820-01814.rar

drive.google.com

Also check at all small coils around U7800.

 

[mccafe]

Hello, just coming back to this. Unfortunately I do not have a good board to compare it with, but here are my readings.

L9080 - 0.011
L9580 - OL (No SSD here)

CPUGT_SW
L7410 - 0.003
L7420 - 0.003

CPUCORE
L7211 - 0.001
L7221 - 0.001
L7231 - 0.001

L7330 - 0.011

GFXIMVP_PHASES
LA340 - 0.00/0.01
LA640 - 0.00/0.01
LA650 - 0.00/0.01

LA350 - 0.011
LA300 - 0.120

U7800 Area
L7821 - 0.032
L7822 - 0.032
L7813 - 0.400
L7817 - 0.030
L7816 - 0.030
L7814 - 0.300
L7815 - 0.300
L7806 - 0.010
L7811 - 0.020
L7812 - 0.020
L7810 - 0.200

 

[2informaticos]

"L9080 - 0.011"
This is a big problem.
Very likely dead SSD.

CPU and GPU core give very low values as normal; however, not sure the real values.

 

[mccafe]

Hello, judging by the thermal cam, yes it sounds like you are right. The boot process is stuck around T2 / SSD. I will mark this one as unrepairable. Thank you.

What are the normal values for L9080 approximately?

 

[2informaticos]

I got 0.400 in diode mode for 01041 board.
0.350-0.450 should be a good range...

 

[mccafe]

And a low resistance on the SSD power rail would cause the DFU revive error, right?

The operation couldn’t be completed. (AMRestoreErrorDomain error 6 - Failed to handle message type StatusMsg (Operation failed)) [AMRestoreErrorDomain – 0x6 (6)]

 

[2informaticos]

Very likely.
T2 has a dedicated partition on the SSD; which can't be accessed in this case.