A1989 water damage / missing PP3v3_S5 / Stuck 20v 0.11 amp

[juyoung165]

The device is a MacBook A1989 that experienced liquid damage. Initially, it was recognized in DFU mode, and a REVIVE operation was successful (although the display and keyboard Caps Lock were non-functional, the CPU VCore was present). However, after cleaning the board, it started drawing only 20V at 0.11A, and DFU mode stopped working.

Upon inspection, I found a short on the PP1V8_G3S line, which was resolved by removing U6400 and U6450. Despite this, DFU mode and other functions are still non-operational, and both PP1V8_S5 and PP3V3_S5 are missing.

Suspecting a PMIC failure, I replaced it, but the symptoms remain unchanged.

 

[2informaticos]

First of all, welcome to the forum!

Possibly some components ripped off in the cleaning process.
Corroded components can come out of board really easy.
Also may have corroded traces, or solders under some BGA chips.

 

[juyoung165]

I double checked corroded area but it seems have no problem.

I want to know why PP1V8_S5 and PP3V3_S5 have no voltage. What should I have to check? Please let me know anything I have to check.

and I found T2 chip is 36.4~37 degree. Is this normal?

 

[2informaticos]

G3S voltages are controlled by PMIC and T2.
Sometime can be enabled after DFU restore.

You may have corrosion under some BGA chips.
Did you try external switch method to enter DFU?

 

[juyoung165]

What do you mean external switch method ??

I tried force_dfu pin pull down to get into DFU but no luck.

Also I tried using option, command, shift , power button method but also not work.

I wonder if the T2 is bad or not

 

[2informaticos]

"I tried force_dfu pin pull down"
???

DFU Mode Restore (Macs) - LogiWiki

We have Apple MacBook and iPhone Diode readings and general fault finding information compiled by the leaders in this area

logi.wiki

 

[juyoung165]

Sorry for the confusion, I’ve done RE032 before.

 

[2informaticos]

Do you get expected SLPS2R and AWAKE voltages?

 

[juyoung165]

Sorry for bothering you, but could you let me know the full name of the line you need? I’ll measure it and get back to you right away.

 

[2informaticos]

Mentioned voltages are available at the coils around U7800.
For example, missing 1V8_SLPS2R will not allow entering DFU mode.

 

[juyoung165]

PP1V8_SLPS2R, PP0V9_SLPDDR, PP1V1_SLPS2R, PPVDDCPU_AWAKE, PP0V82_SLPDDR, PPVDDCPUSRAM_AWAKE

These are all present.

PPVPCORE_S5, PP1V_PRIM, are missing.

 

[2informaticos]

Then it should enter DFU.
Be sure to follow the steps in mentioned link.

 

[juyoung165]

I tried but no luck, I also checked SOC_DFU_STATUS if it is high, but no luck.

 

[2informaticos]

Something happened in the cleaning process, if DFU was available just before that.
You've damaged some component, trace, or solders under BGA chips.

 

[juyoung165]

can be the thunderbolt control ic can be a problem?

Or the T2 chip is faulty?

 

[2informaticos]

Thunderbolt is not involved.
DFU communication is done directly through U3100.

 

[juyoung165]

I removed SOC Rom chip to force the DFU mode, but it is not working.

I checked the SOC_DFU_STATUS, and it stays at 1.8V for 5 seconds before looping back to 0V.

 

[2informaticos]

"I removed SOC Rom chip"
???

Erase it, do NOT remove.
Don't forget to make backup first.

 

[juyoung165]

Even after erasing, the symptoms remain the same.

 

[juyoung165]

Then are there nothing to check with this anymore?