logicboardpower
I'm trying to locate the power-on jumpers on the logic board of mid-2013, 13" MacBook Air. Similar to this question, but for the newer model MacBook Air.
I have disassembled and cleaned all components after I had a liquid spill. Computer seems to be charging ok now; previously was not. I suspect the keyboard is damaged but want to start computer to run a systems check.
I think you're out of luck. From iFixit, here's the logic board from the original MacBook Air:
And here's the logic board from a 2012 MacBook Air:
Unlike desktops, which typically use standardized parts, laptops use fairly specialized components, and on top of that, Apple tends to iterate its designs fairly aggressively even within models with similar outwards appearance to achieve better cost or performance (e.g. smaller logic boards means more space for the battery). Because of this, most Apple components beyond hard drives and RAM are only interchangeable with those of the exact same generation.
There are two possible causes these symptoms:
Faulty Battery
Bad SMC Chip (Logic Board)
Faulty Battery. As the OP described, once the battery was disconnected, the machine booted fine. What could be happening here is that the battery life has degraded to the point where it will not hold a charge above the threshold to power on the device.
If you can power the MBA in this manner, try resetting the SMC then reconnect the battery. If it continues to fail, you probably need a new battery. If you already know how to open the MBA and disconnect the battery, you are halfway to replacing it. If you're not sure, ifixit.com has an excellent tutorial.
Given that the OP's machine is a 2012, it would mean the battery is pushing 5 years now which is around the EOL for this battery. It's time for a replacement. I recommend getting one with at least a 18 month warranty.
Faulty SMC. There is a possibility that the SMC (chip) is faulty. The first thing to attempt to diagnose it would be to run Apple Hardware Test (AHT). Hold the D key while booting from a powered off state with the AC adapter connected.
It may come back with "no errors" so the positive diagnostic test would be to attempt with a known "good" battery. If it continues to fail after the battery is replaced, there's a high chance than the SMC is bad. It's time to take it in for service.
Best Answer
They are located just above the airport card. A small flat head or T7/T8 bit should work for bridging them.
You can see them in step 17 of iFixits Logic Board replacement guide:
Power Pads highlighted with a red square along the top edge of the Mac, picture courtesy of iFixit
Something to keep in mind is that a damaged or faulty keyboard could prevent a Mac from starting if the power button is always registering a press. If I were troubleshooting this I would first try to short it using the power pads. If that didn't work after a couple of attempts (the flat ones are more difficult to short) I would disconnect the keyboard's flex connection (to the right of the battery connection) and attempt it again.
Obviously, always use caution when working inside of a Mac that has power supplied to it.
Good luck!