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Mid 2010 Model A1278 / 2.4 もしくは 2.66 GHz Core 2 Duoプロセッサ

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0.5V on PPBUS_G3H after water damage, green light but won't start

Hello, I am working on a 820-2879 MacBook Pro 2010 13" on which water has been spilled. I cleaned the entire board with alcohol. I measured the PPBUS_G3H rail when the charger is plugged and I get 0.5V, I am getting that this is not normal since it should be around 12.6V. But I can't find any defective component, they all look OK from a visual point of view.

I am not sure where to start looking for. Got any idea ?

Thanks in advance

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Low PPBUS voltage will either indicate a short to ground, or a bad charging IC, where it is not producing more than 0.3V-0.5V.

Check for a short on that line first, and also feel the charging chip, to see if it gets hot, if it is shorted (will be U7000 in schematic and board view). If there is a short, or the chip is getting hot, remove the chip first to see if there is no longer a short.

If there is no short, I always replace the charging chip first, since this produces PPBUS_G3H (as long as it is getting required inputs, etc). Most of the time, the charging chip will be causing the issue.

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You have a short to ground on PPBUS_G3H that's why is so low. To solve this one you need proper schematic and tools for micro soldering.

Look for caps with corroded traces remove them and check every time if the line is still shorted using continuity mode on your multimeter.

For more hints or visual clues watch Louis doing this

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JPL さん、ありがとうございました！
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