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PPBUS is 12.28V and 3V3_G3H_RTC is 3.38V.

This one has me stumped, though it looks like it should be an easy fix! Customer brought in an A1989 with a bit of liquid damage, which I cleaned up. It starts up and runs off a charged battery but does not recognize the charger on any of the 4 ports. Without a battery, all USB-C ports show...

This liquid-damaged Air has no trackpad and no keyboard. I need help troubleshooting. I already tried a known-good trackpad cable and a good keyboard without success. A known-good logic board in the same topcase shows functional keyboard & trackpad, so the topcase and daughter board should be...

Update: it turned out that the 3V8_AON rail itself was fine but its power control chip was failing. I replaced U5700 and 3V8_AON is stable now. The machine is starting up now and I'm troubleshooting it.

I do hear a clicking sound from the logic board when PP3V8 is enabled... possible culprits U8100/U7700?

Thank you. I also seem to have an issue on the PP3V8_AON line. The rail shows 3.8V for a moment, then drops to 0V, and continues cycling. Compared to a good board I get about half of the diode mode reading on this rail, but no short. I removed the 3 sense resistors R5800/5820/5840 and I get...

It's clear that I have one bad CD3217 on the board. Questions: 1. Can I replace a single CD3217 from a donor board, or do I need to swap all three? 2. Can the donor board be from a related model such as the 15" Air (A2941)?

To clarify, I did have LC320 connected, but off the board. I also connected the FB and BIAS line. But you're right: there was a damaged resistor in the feedback resistor divider. The circuit is correctly producing 5.2V now.

I found the culprit (it was UP700) and removing it removed the short. Now, however, I'm afraid to put LC320 back into the PP5V_S2 circuit because the step-down converter produces 12V (measured at P5VS2_SW) instead of 5.2V. I already replaced UC300 but the output is still nowhere near 5V.

Operating without an IR camera here, so will need to manually remove components powered by PP5V_S2 to find the short.

This is my first board with the M2 architecture. This 2022 Air arrived with liquid-damaged USB-C port connectors and a few small spots of corrosion on the logic board. After cleaning, I found a short on LP800 and removal of the backlight controller UP800 removed the short. Now the board sits at...

I removed U6400 and C6103 but the short persists (around 70Ω now). Voltage injection produces less than 0.1A current flow, so no heating up. But I already know that the only component left is the T2 chip... internal damage probably keeps SPKRAMP_INT_L low which sends a continuous interrupt...

SPKRAMP_RESET_L: 0.40 SPKRAMP_INT_L: 0.005 Looks like SPKRAMP_INT_L is indeed shorted to ground (5Ω in resistance mode). This is a 1.8V line, correct? Inject 1.8V and see if the audio amp U6400 heats up?

No change after DFU Restore. Another new observation: the right speaker does not work, even after trying several audio daughter boards, cables, and speakers.

Already performed a DFU Revive but will try a Restore as well.

Yes

Without battery: PP3V3_G3S = 0 with PP3V3_G3H_RTC = 3.3 and PP3V3G3S_EN = 0 PP1V8_G3S = 0 with PP1V8_SLPS2R = 1.8 and PP1V8G3S_EN = 0

Yes, both ports are the same.

Just discovered that with only the charger connected, PPBUS is at 12.6V but the board is missing PP5V_G3S. As soon as I plug in a battery, 5V G3S appears and the machine starts up.

Yes, battery is charging fine.