Chosen Solution
I just received this A1278 EMC2419, MLB# 820-2936. I have very little history on it other than: MacBook stopped powering on, previous owner said they replaced: BatteryMagSafe chargerDC-in board I can confirm the Chinese battery is new, the charger was still in plastic, but the DC-in board showed corrosion despite looking otherwise brand new and having a 2015 date stamp. The MacBook doesn’t respond to the power button, or to shorting the power pads. the MagSafe illuminates green with or without battery connected, and the battery level indicator is non-responsive unless the MagSafe is connected. I have attempted SMC reset, though I cannot be sure it has completed. I’ve shorted the pads at R5001 (omitted) which according to the internet will pull SMC_RESET low. That didn’t have any apparent effect. I set my SPI programmer with SOIC8 clip on the EFIROM, to attempt a reflash there, and strangely enough, the MagSafe turns orange when my programmer is connected and powered on. I’m unsure if that means the battery is charging, or that the SPI programmer is drawing current and tricking the MagSafe. Due to the precarious nature of equipment and connections, I’ve not yet attempted an SMC reset while the MagSafe was orange. I have the schematic and the board view, though i’m not electrical engineer. I’ve followed V+ lines from both the battery and the DC in. all resistors test ok, all fuses are good. I’m showing 11.99VDC at each rail from the battery, at the connector. Can anybody point me in a direction? PP3V3_S5 points:
PP5V_S5 points:
Sounds like you have the schematic and board view for this. Check out the power aliases page, check all G3H and S5 power rails whilst just the charger is plugged in (battery is probably bad if it looks really cheap). If any rails are missing, not steady or not what they should be according to the schematic, look into it. If DC in voltages are reading at 16V or over and is lighting up, the DC jack is fine. You can’t get these new anymore, so it usually has flux on the PCB where a new charger port has been soldered on (probably not corrosion). Leave the SPI ROM alone for the moment, this will be fine unless it has been damaged, reprogrammed or replaced by someone else. Usually if this is bad, the fan will spin but it won’t chime, very rare for it to be dead from a bad SPI ROM (also, they rarely corrupt without cause). Check out main power rails and look into this further.
