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During testing, this board has decided to shut down. I'm now stuck with 5V on USB-C, PPBUS of 12.3V, and no shorts on the big coils. 3V8_AON rail is stable at 3.8V but the outputs of both PMUs fluctuate wildly. No obvious shorts on any of the PMU outputs. What's the best way to troubleshoot why...

IPD_PWR_EN_GATE: 1.8V PP3V3_S2SW_IPD: 3.3V PP5V_S2SW_IPD: 5.2V PPBUS_AONSW_TPAD: 12.4V PP1V8_S2SW: 1.8V

Just discovered another tiny bit of corrosion around one of the CD3215s (UB300). I reflowed it with flux. Now I get 20V on all ports and the machine charges the battery.

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