NOTE: Close-up images of this repair were taken using a cheap USB microscope. As a result, they are very poor quality.
I purchased this one on eBay in October 2017 for $250. It was described as “MacBook does not power on or charge”. It was sold with all components intact, and the genuine MagSafe charger included. These are very important factors. Many times people remove the SSD in order to protect their privacy, but regrettably, the SSD is a very expensive component to replace. I have zero interest in other people’s data and always erase the drive as soon as I get them. If I buy a Mac with the SSD removed, I have to factor its replacement into the cost of repair. The inclusion of the charger was another positive thing. I always resell with a charger included, so if I buy a MacBook without one, that’s an additional cost.
As soon as it arrived, I connected it up to the power, and as expected, it was completely dead. No green light on the charger, no power, nothing.
So before I begin any form of diagnostics, I always like to give the logic board a visual inspection. In many cases the problem is nice and obvious, which saves me from having to run any mentally taxing diagnostics.
I popped off the back cover, and at a glance the inside looked very tidy. The circular water-damage indicators were still white, so there was no significant water spill.
Once I flipped over to the hidden side of the logic board, the problem was staring right at me. There was a bit of green gunk around the capacitor C2428, but there was an absolute forest of snot around U7600, which is the important part of the 1.05V power supply.
I immediately set to work replacing these components. I poured on a mound of flux, then removed U7600, as well as the surrounding resistors and capacitors using my hot air station.
I removed all of the excess solder using some solder wick, then cleaned up the general area with some alcohol. The traces for pins 2 and 3 of the U7600 didn’t look good at all, so I pulled out the trusty multimeter to check continuity. As suspected, the test points had become so badly corroded, they had broken the continuity of the trace. So it was time to get creative. I would need to repair the break using some wire.
I grabbed a donor board and replaced all of the removed components with “new” ones, in readiness for the next stage of the repair. I also replaced the corroded C2428 capacitor. This one had no trace or pad damage, so was a simple removal and replacement.
Using a surgical scalpel, I very carefully scraped away at the damaged traces. I scraped off the coating (and some rust) to expose some lovely, virgin copper. This would give me the base point for soldering my wire.
I grabbed some fine, enamelled wire, then using my finest soldering iron tip, I carefully soldered the first wire to the exposed part of the trace coming from pin 2 of U7600. I then bent the wire up to pin 2 of R7604 and pin 1 of R7605 and C7604. They are all in a line, making the process nice and easy, and giving me a nice, big area to solder to. It was very fiddly, especially using a cheap USB microscope, meaning I had to check my work up on a screen, rather that looking down into a proper optical microscope.
I trimmed the first wire to length using my scalpel, then repeated the process for the pin 3 trace. This wire went to a nice, fat capacitor (C7981), so it wasn’t too difficult.
I connected up the DC power supply, attached my MagSafe charger and… success! The green light came on and the fan started spinning away – my favourite part of any repair. I connected up the LCD, and the SSD, and to my delight, it booted into an operating system.
So I dismantled it once again, then cleaned the board in my ultrasonic cleaner. Once cleaned, I dropped it into an alcohol bath, then popped it into a fan-forced oven on 80ºC for 25 minutes.
In order to protect the new repair, I added some conformal coating to protect from any bumps or future oxidation.
I reassembled the MacBook, erased and tested the SDD, then installed a fresh operating system. I ran the Apple Service Diagnostics, as well as a few of my own diagnostic processes. I tested all in/out ports and I also throughly cleaned all exterior surfaces. The battery had a pretty low charge cycle count, and it was still holding 85% of its original capacity, so I saw no need to replace it.
I already had all of the repair parts in stock, so there were no additional costs incurred (other than my time). I listed the MacBook on eBay for a 7 day sale, and recorded a very tidy profit!
Even though this logic board was not obviously exposed to water, the cause was definitely “liquid damage”. There was a fair bit of dust on the board, and it was possibly some condensation held within that dust, combined with the electrical current that caused the corrosion. MacBook Airs are a very compact unit, with no air filtration to speak of. Had the board been cleaned and the MacBook stored in a dry location, the damage would probably not have occurred.