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Late 2011 model, A1278 / 2.4 GHz i5 or 2.8 GHz i7 processor.

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Liquid damage, how do I diagnose?

I am trying to repair a late 2011 Unibody MacBook Pro A1278 that my wife spilled soda on. I have it all apart and plugged the charger into the magsafe bd and I am getting a very faint green light most of the time (sometimes no light). This is with the magsafe bd unplugged from the logic board.

When I plug it into the logic bd it acts the same. I have tried cleaning all that I could with isopropyl alcohol and a toothbrush and don't see any signs of corrosion. I'm not getting any power or anything though. I have tried powering on using the power pads too with the keyboard disconnected and still nothing.

What would the next step be in diagnosing? What voltage should I be getting out of the magsafe board? What voltage at the power pads? And does anyone have a schematic for the model A1278 Logic Board?

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3.42 volts on one of the power pads, the other one is ground so 0.

on the magsafe socket on logic board with battery disconnected and green steady light:

1- 3.4v

2- 0v

3- 0v

4- 16.96v

5- 16.96v

In your case an issue prevent the sense line (faint green light) to tell the magsafe adapter to give full power to the power rails so maybe your readings may be less.

Schematic of your board should be available online but you need to do a little google search with your logic board ID like K19 or 820-2879 and you'll also need the boardview file of your logic board to locate the ICs on the board. Check this thread maybe you'll find the needed infos there:

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Faint Green light means part of the one wire circuit is damaged.

You need a 3.42v from the G3H_PP3V42 and 3.3V from the ACOK line from u7000.

Then these must pass through the logic gate to enable the bright green light.

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