A2289 won't power on

[sauce]

Hi,

I bought a faulty A2289 for myself.

The USB-C meter was stuck on 5V.

After remove the board the U3100 was corroded and also around but quite light.

So I clean the U3100 and see R2834 in bad condition and its value was not good.
I replace it and not the USB-C meter shows 20V, the fan is spinning, CPU is hot but nothing else no picture.

The USB-C meters shows a very low current with all connected. It starts at 20v few mA and then stays at 20v 100mA.

How mush current the board is supposed to take without nothing connected only the usb-c meter ?

No voltage on L7210, L7220, L7410, L7420 and L7702.

Thank you in advance.

[mon2]

Remove all power. No battery. Measure the resistance (ohms) to ground of each inductor that is missing the correct voltage to ground. Post each measurement.

[sauce]

Here are the voltages at 0v with resistance to ground.

PP1V_PRIM 0V 112.9ohm
PP3V3_S5 0V 66.2Kohm
PP1V8_S5 0V 1.6Kohm

No direct short on any inductors.

These voltages are taken only with USB-C meter plugged.

If I plug everything back these voltages are present !
I don't know if it's normal.

[sauce]

Very strange these 3 voltages (PP1V_PRIM, PP3V3_S5, PP1V8_S5) are present few seconds after I plug the USB-C meter, are stable, but return to 0v after 10 seconds.

[mon2]

After the 10 seconds, does the logic board power up again and repeat this ON / OFF cycle? If yes, this is power cycling.

[sauce]

No once these voltages are lost the USB-C meter show at 20v 100mA.

I was thinking the corrosion was near U2890 too maybe the chip is fried ? Or need to be program again I saw there was bin files for this chip ?

But how can we program such chip ? And we just need to program it with original bin found on badcaps ?

[sauce]

I try to re-program U2890 but still the same problem.

[mon2]

If you have 20V on the Type C meter, then the CD3217 are working and so is the TBT firmware that is held inside of U2890. The issue is after this power delivery contract of 20V is negotiated, something else is failing after 10 seconds. The main bios should be inspected next. Trying to locate the device in the schematics.

[mon2]

Confirm that the charging port itself is clean and without corrosion. Apply IPA (alcohol) onto the pads or better if tested with a fresh / known good port. We have seen this issue in the past. The charging port is the small and replaceable board with the 2 x Type C connectors. Do rule this out as a suspect.

Avoid This Mistake: MacBook Pro A2289 2020 No Power Repair (youtube.com)

[sauce]

I tried with brand new charging port still the same.

Very strange issue.
For now the only suspect thing is the quite low voltage of PPVDDCPU_AWAKE 0.54V.
Is it normal ?

[mon2]

Yes, appears to be lower than normal range. What is the resistance to ground for this rail ?

[mon2]

Also, from logiwiki :

PPVDDCPU_AWAKE 10-15 Ohm ; resistance to ground on a good device

reference:

CD3217 and T2 Power on Sequence - LogiWiki

[sauce]

PPVDDCPU_AWAKE 10.2 ohm

Everything I an checking is OK and we can find diode readings on openboarddata and all readings are fine too.

I force DFU and my hackintosh I made this evening because I don't have any macbook can see the board in DFU mode but when I try revive or restore I have 4042 error.

I also have a thermal camera but even with good SSD voltages I don't see any heat from SSD.

Is a board only connected to usb-c meter is supposed to run ?

[mon2]

DFU error 4042:

https://boards.rossmanngroup.com/thr...2-error.64310/

[sauce]

So DFU revive or restore :
- without charger => error 4042
- with charger plugged before USB => error 9

[mon2]

Test with a quality usb 3 rated cable. Are you using Sonoma as the host ?

[sauce]

Yes it is Sonoma.

[sauce]

I give up.

Thank you very much for ypur help.
I think i have a dead ssd ou cpu.