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Hi there! I have a question regarding a MacBook Pro A1278 from a customer. The customer said the macbook did not start from one to another day after having the famous big cross at his battery saying it needed to be replaced for months now. The customer tried different chargers all to no success. What i have tried: 2 Different chargers, of wich 1 is brandnew. Old DC-In board does the same as a brand new DC-In board, they both show up (with or without internal battery connected) as a faint/dim green light. Disconnected everything, swapped memory etc, it keeps faint/dim. All ram resets possible, nothing. Now what we do know is that the battery is faulty but even without the battery attached on the logic board it does the same, it shows no life whatsoever in any way possible. I do feel that there was alot of dust on the bottom side, i cleared it all but but it seemed quite alot. Also, a few screw points seem to be a little brownish, it almost seemed like water spills corrosion but i could not find any white residue anywhere on the logic board itself. Anyone that might have another idea or will this probably be a logic board that died here? Thanks in advance!
If you don’t get a steady green light on the magsafe tip it’s because the charger sense circuit gets an error from the logic board who don’t give the OK needed to the charger to send the adequate voltage to power on the machine. Check the voltage on one of the two power pads near the logic board keyboard connector. You need 3.42 volts on one of the two pads. If the logic board is still in the machine, disconnect the keyboard cable before checking the voltage on the power pads because a faulty top case can give you wrong voltage reading. One of the pad is ground so 0 volt and the second pad is G3Hot so 3.42 volts. To troubleshoot the logic board circuits you’ll need the board schematic and the boardview file to identify the components you want to measure on the board. No green light or faint green light means that the “Onewire circuit” is faulty and doesn’t provide the 3.42 volts needed to get the steady green light and adequate communication from the SMC to the charger. Also a good visual inspection of the board could help to identify a faulty, corroded or missing component. I use a microscope 10x to 20X for close up view. Pay attention to areas affected by liquid spill. more info
The first thing I would do is drop in a fresh battery and run diagnostics again. Next drop in a hard drive with 10.7.5 on it and a new HD/IR cable. Lastly. get a flat rate repair from Apple.
