Background

This story is about my proudest repair from my roughly 6 years working in IT. Interestingly enough it occurred at around my 3 year anniversary, sometime in 2018! It was the culmination of a months long effort to teach myself to repair macbook motherboards(1). My interest in this pursuit was piqued when I saw how many broken motherboards we turned away, and I had become aware that it is possible to repair them by watching Louis Rossmann(2) videos on YouTube.

While this story is not the first motherboard I was able to repair, it is the first repair that I feel was entirely due to my own skill, and at no point was I in doubt of whether it was possible.

The Story

This all begins when, naturally, the customer brought in their broken computer. It seemed to charge just fine (when they plugged in the adapter the charging light would go from green to orange, indicating charging), but the computer just wouldn't turn on. The technician checking in the computer poked around a little but couldn't find anything, so they checked it in for me to take a look at it later.
When I got around to looking at it, the first thing I tried was resetting the SMC(3), which is often the culprit when a computer will mysteriously not turn on. Sadly, no dice this time around.
Next up in troubleshooting is to test each power rail to make sure they're all working. Power rails in computers honestly work kinda like highways, except they deliver power rather than vehicles. Computers have several different power rails for different voltages, since different components need higher or lower voltage. If one of these rails doesn't exist for some reason, your computer is NOT going to be happy. In fact, it might not even turn on at all, just like this one! One can test these power rails by removing the motherboard from the rest of the computer, attaching the charger, then using a multimeter to test what voltage the motherboard reads at test points for each power rail. These test points can be located using a boardview (like Google Maps for a motherboard, it shows you the names of each tiny component on the board, since the board is too compact for street signs), and the schematic, which is like the atlas for the board, showing you technical information on each component and details on how they all interact together, to assist in troubleshooting.
So, I took the motherboard out, plopped it on my desk, and started poking it. The very first rail to try is PPBUS_G3H, which should be present at all times, even when the computer is off. Almost immediately, I noticed that the area of the board I was testing was hot to the touch! I started feeling around a bit until I was nearly burned by the problem component! The culprit was a tantalum capacitor that was part of the circuitry in charge of the 3.3V and 5V rails, and there was a giant "CRITICAL" right next to it on the schematic. When I looked closer at it on the board, I even noticed that there was a gigantic crack in the thing.
That would do it!
I disconnected the power right away, then popped into the parts closet to dig around for a donor board(4). Sadly, I didn't find a donor board that exactly matched the one I was working on, but I did find a donor that was a year newer or older (I can't remember anymore, but they weren't the same) and took it back to my desk to see if it could fly. I pulled up the donor boards schematics, found the page that gave the information on the 3.3V and 5V rails, and soon discovered that the capacitor on the donor board matched the one my broken board needed! Score!
I identified the donor component on the donor board, made sure I knew the polarity of both capacitors (very important. If you do this wrong it might even break worse), and carried them both over to the soldering station. I swapped them out using a heat gun(5), tweezers, and a little flux(6). The process went seamlessly. After the boards cooled down, I stuck the donor board back on the shelf, cleaned up the spare flux from the board I was working on, slapped it back in it's computer, and it worked perfectly!

The entire repair took about 30-45 minutes from start to finish, and at no point was I confused on what to do next. It was such an empowering moment for me; it really served as evidence that if I want something bad enough and work at it hard enough, I really can figure it out!