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yes, PPBUS_AON and 3v8_AON are stable at 12.4v and 3.8v. Is there a way I can test for a faulty M1 CPU? I’m happy to buy new U8100 and U7700 but not if the cpu is dead obviously. Seriously, thanks again for your time and help, i really appreciate it.

What do you mean by secondary power supplies? Will they be on the power aliases page or somewhere else? I cannot enter DFU because 1v2_s2 is unstable so if I bridge 1v2_s2 to SOC_FORCE_DFU there isn't any stable voltage to pull it up. Also, I just found that PMU_CRASH_SLAVE_L is pulsing if that...

Will not enter DFU mode, PP1v2_S2 unstable and pulsing along with other PMU LDOs. Do you think this M1 CPU is dead? Or should I order some PMUs to test? PP5V_S2_MAIN is unstable too, would that cause PMUs to create unstable LDOs?

Have not had the chance to try DFU mode yet, but I don't think it will work. This issue seems very similar to https://boards.rossmanngroup.com/threads/a2442-820-02098-after-liquid-damage-for-data-revovery.65208/#post-110842 Looks like possibly dead M1 CPU ☹️ Why do I always get the dead...

Ill try to get into DFU tomorrow following https://logi.wiki/index.php/DFU_Mode_Restore_(Macs)#NO_DFU_Mode_Troubleshooting

I tested every power rail on pages 137-141 and these are what I came across as potentially odd. PPVDD_SOC_S1 is 0.64 vs openboarddata 0.130 is that cause for concern? Is this M1 CPU fried? Could this still just be faulty U8100/U7700? If 3v8_AON powers U8100 and U8100 outputs 3v3 that would make...

I was thinking, could it be some sort of short protection on another secondary rail? What are the odds of dead but pulsing PMUs vs shorted secondary rails tripping protection? Does the PMU generate 3v3_AON? Looks like it does in the schematics but just verifying.

Yes, I just used a different test point to confirm, I know it's weird but 3v8 is stable while 3v3 is bouncing all around

Are these other rails pulsing due to 5V_MAIN being unstable?

Are these the LDOs you are referring to? U8100 PP1V8_S2SW_CLVR_VDDC1_LDO - unstable PP3V3_AON - unstable PP0V8_S2_CLVR_VDDDIG - unstable PP1V8_AON - 1.8v PP1V2_AON - 1.2v PP1V5_AON_VCORE_MPMU - 1.5v U7700 PP0V72_S2_VDDLOW - unstable PP1V2_AWAKESW_BLC - 0v PP1V8_AON_SPMU - 1.8v PP1V2_AON_SPMU -...

I have a liquid damaged 820-02098 M1. No corrosion around CD3217 areas. Corrosion is located from UR500 to C8012 if that helps. UR500 was the worst and has been removed due to creating a short, waiting on replacement but the board should still work without once fixed, correct? PPBUS_AON - 12.4v...

I measured the board in diode mode, black probe ground, and just the board with nothing connected. You are correct that it should not be 12v on one side and then short on the other, most reasonable explanation is I misread a reading or used the wrong pin. U9080 was shorted though and was taking...

Actually, never mind on that 150 ohm reading, it's getting normal resistance now. I think it could have just been drained caps on SSD0? U9080 does not get SSD0_PMIC_VR_P2V5_EN, looks like that comes directly from U9000 and(?) U7800 through R9618.

R5460 was not on this board and its pads look factory, I still get 12.35v on PPBUS_G3H_SSD0 though but no voltage on PP2v5_NAND_SSD0. The whole area around U9080 looked fine except for U9080 itself. Had a slight bulge in the chip and a small burn mark right outside the chip (near pin 21 and 22)...

Yes, no power just plain board on desk. U9080 had a dead short to ground, replaced it and now short is gone. Not sure how that is possible but it fixed the short on PPBUS_G3H_SSD0. PPBUS_G3H is still 12.35v though, and DFU has the same error.

Well, looks like that wasnt it. Short is gone but still no PP2v5_NAND_SSD0. Will post updates later.

PP2v5_NAND_SSD0 is ~50 ohm to ground, and known good is ~100k. Checked PPBUS_G3H_SSD0 and it has a 0 ohm to ground. Looks like U9080 is bad based off thermals, there is also a small bump on the chip only visible at certain angles. I think this is the issue and I should have checked for a short...

Hello, back again with a funky one. I have an 820-01987 with no signs of liquid damage that sits at 20v 0.00a. When plugging the board into another MacBook it is instantly recognized as being in DFU mode every time it is connected. I have tried reviving and restoring multiple times and it always...

Look like you are right, all RAM chips are fried. They all have 15ohm to ground but at least the short is gone on the board so maybe I can source some replacements somewhere. Thanks for all your help, this is pretty much resolved.

Forgot to attach photo of something I noticed on the underside of the bad RAM module. The black mark is inside the chip and connects with the pin that attaches to PP1v1_S3. I don't see that black 'burn' spot on any of the other 3 RAM modules. Just posting for anyone who is curious or for future...