Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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Water Damage, Logic Board appears Boot?

June 2014 Manufacture date


S/N can be seen in the picture.


Daughter spilled Vinegar+water solution on keyboard. She may or may not have properly powered it off immediately.


-Power button causes no response, no boot

-Attaching the charger cable gives me the 'AHHH' and the fan and HDD spool up; no screen ----Originally the HDD would not spool up, and I replaced it with a new one (sans OS). So the original HDD is confirmed bad. But still have the same root issue with a new one.

Done so far:

-Disassemble and clean logic board with isopropal+toothbrush under a nice microscope.

-Inspected each component for signs of shorting & found none; There was some light corrosion, but not significant (I think based on low experience). In viewing the picture of the logic board, I saw a bit more corrosion at the battery connector that I have since cleaned up. Did not include a pic of the back side of the board because it looks pristine.

-Tried the RAM switch/re-try with 1 chip at a time.

Logic Board Pic

Block Image

Next Steps

I have good technical capability, but know very little about Macs. I'd appreciate it if anyone could advise the proper next steps to debugging this. My plan for tomorrow otherwise:

-Have not removed the keyboard yet, but it looks like power button is a part of that component. Also looks like 100 screws holding the keyboard lead frame must be removed to replace it...don't see any visual indications of problems.

-Soak logic board in water to ensure cleanliness



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john, with your serial number your computer comes back as a 2.5 GHz Core i5 (I5-3210M)

Intro Date: June 11, 2012 Disc Date: None

Order No: MD101LL/A Model No: A1278 (EMC 2554*)

Subfamily: Mid-2012 13" Model ID: MacBookPro9,2

Std RAM: 4 GB Std VRAM: 512 MB*

This will make a difference if you are having logic board issues. Looks like your board is a 2.5 GHz Core i5 (I5-3210M)

Intro Date: June 11, 2012 Disc Date: None

Order No: MD101LL/A Model No: A1278 (EMC 2554*)

Subfamily: Mid-2012 13" Model ID: MacBookPro9,2

Std RAM: 4 GB Std VRAM: 512 MB*

Std Storage: 500 GB (5400 RPM) Looks like your board is a 820-3115-B


Thanks oldturkey; logic board number confirmed to 820-3115-B. I should have checked the S/N. (But interestingly, we did order the 'Core i7 2.9GHz version, but apparently received the 2.5Ghz Core i5)


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Well, I was looking forward to getting the Multimeter out, but replacing the keyboard was the answer (as Louis points out on YouTube, it is a primary suspect). Interesting for someone later, maybe: I had to drill out 10 of the PH000 screws holding down the keyboard backing metal sheet. No big deal.

Ordered this keyboard from amazon, and it functionally works, but the screw holes don't line up in 10 locations,so some of keys are not rigid enough.

Thanks for the help Louis and OldTurkey

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congratulations--great news! Don't forget to 'accept' the answer that helped you ;)


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This is an 820-3115 board. If it is a board issue, find a schematic and a boardview online for an 820-3115 board. Yes, I know, not easy to find, but same thing if you go to college. Class with professor for a semester is $400, textbooks $1500!!! Same thing here, except professor is FREE!

First question here is real important, what does no boot mean?

a) No boot means it turns on, chimes, you see the white screen, but never get to anything.

b) No boot means it turns on, chimes, you see NOTHING on the screen. No image and no backlight, and screen doesn't "blink" on and activate.

c) No boot means it turns on, chimes, you see a picture on the screen but no backlight. Screen "activates", like the ink is settling inside whenit turns on.

c) No boot means it turns on, doesn't chime, you see nothing on the screen.

Also the lighting in that picture sucks, something with less glare would help me point out the corroded vias to you.

I have guesses as to what is wrong but they will require some more information on your part.

If it ever does stop turning on, measure the following.

Once you've done that, it's time for homework. Measure the following voltages using a basic multimeter. You can look for where they show up on the schematic, then use the boardview software to find components to measure from.

a) Measure PPBUS_G3H voltage. Should be 12.6.

b) Measure PP3V42_G3H voltage. Should be 3.42v,

c) Measure PP5V_S5, should be 5v.

d) Measure PP5V_S3, should be 5v.

e) Measure PP3V3_S5, should be 3.3v.

f) Measure PP3V3_S3, should be 3.3v.

We will move on from here. There so many things to check, the idea here is to narrow it down to find the problem region and focus on it. This is easier in real time, but forum format can do.

In all honesty; if you actually do want to get into board level repair, I can walk you through a good portion of this if the board is fixable. However, if you look at this like "%#*@... a good multimeter is fifty bucks and schematics & boardviews cost $20, nevermind", give this to someone else. You'll need tools to measure what is present and the documentation so you know what you're looking at or else this is all just guessing.

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Sorry for the delayed response guys, I was expecting an email alert and didn't get one.

I'll take option B for my 'no boot' situation.

I will be working on this tomorrow; first step is a reassembly with a new HD and keyboard.

It is a nice computer and would prefer to fixit. It is cold outside, so I might as well give it a go. I will report back in late tomorrow night with some results.



Slightly better pictures


I will just add the comment that Louis just helped me fix THIS EXACT board last night with a similar strategy as you have here. It was my first MacBook Pro board repair as well. It was actually really, really fun. You'll need a dead donor board to harvest components off of when you find the problem. These are on alibaba. I also found his videos enormously helpful.

and his one on the SYS ONEWIRE circuit video as well.


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John will be eternally grateful.
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