Chosen Solution
Hey guys, After having completely removed the logic board from my MacBook Air (13’, mid 2012), washed it and re-assembled the components (following a water damage), I managed to turn it on, and it worked normally. However, since I switched it off, it is impossible to turn it on again. The battery is fully charged, the Magsafe led is green, but I don’t hear any noise from the inside, so the ventilators don’t seem to work. I also reset the SMC, but it didn’t change anything. So, before I throw it to the trash, I would like to try to identify the problem, i.e. the component which is working bad or not working, and possibly replace it. To sum up, I’m looking for a complete procedure which is able to determine if each component get power, and if this component “seems to be able to work”, by using basic electronics tools (as multimeter). Thanks a lot !
I’m afraid there’s not such a unique step by step procedure for everyone. You need to use your brain, schematics, board view and at least a multimeter to go through all Macbook’s power lines and identify where the problem might be. In case the board doesn’t work inside the macbook, first thing try if it does when outside the mac, in order to rule out possible shorts present in other machine components. If it doesn’t and you have a green light from the charger you can avoid checking the onewire circuit and jump straight to PPBUS. From there, you have to check all power lines, voltage and current sensing until you find some hint. Since yours was a liquid spill on the board look for burnt components or the likes with a good light source and some magnification, you’ll probably find some visible hints to start with.
This might sound kind of weird but see if it will boot without the track pad connected. It can control the SMC so if it is damaged it can be constantly sending the reset SMC command therefor preventing the system from booting.
