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The long-awaited refresh of the popular MacBook Air, featuring Intel's Core i5 processors, an updated Retina Display, and numerous other changes and updates. Released November 7th, 2018.

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Liquid Spill - Voltages to check on the logic board

Laptop won’t turn on. I have cleaned the logic board, no corrosion marks on the logic board. I have checked the voltages and this is what I find.

Input from the charger connector: 21V

PPBUS_G3H: 13.3V

PPBUS3V3_G3H: 3.4-3.5V

The entire logic board becomes hot when I connect the charger. All the large caps heat up and it gets hot especially around the CPU area, not sure if this is normal. But not of the caps look burnt out.

Are these voltages right or are they too high? Not sure what to check next. Any guidance will be appreciated.

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You have a short within the logic board or connected part which is messing up the logic board.

What happens when you power the logic board by its self?

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Yes I have connected the logic board by itself while measuring these voltages. Are these voltages as expected or are they high? I’ve been looking at the schematics and board view but it does not tell you what the voltage on PPBUS_G3H should be. From some board repair videos I watched, it is usually 12.6V but those were on older models so I’m not sure if it will apply to the A1932 Logic board as well. Do you recon the buck converters with PPBUS_G3H output is not functioning correctly?

Also all inputs to the SMC are at 1.9V and the all system power good signal is at 1.9V as well so assuming the SMC is functional


@simeonthomas2 The voltages you posted are normal. How many amps is it drawing? Are you sure it is not in DFU mode. I have seen this model board heat up before after a failed process in DFU.


Thanks Chris and Dan.

Chris are you suggesting that I try to restore the OS by booting in DFU mode? Or do you mean something else? How do I check if it is DFU mode? I will check the amps a little later and keep you posted.


@simeonthomas2 You would need to connect it to another mac to see if it is in dfu mode. I didn’t mean try and restore the OS. It most likely isn’t in dfu mode however I have seen this happen after a liquid spill.


Thanks Chris, I will give that a shot. Now to find another MacBook. Will it work with an older MacBook Pro(Without T2 chip) as the host?


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