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2,2 GHz (Turbo Boost bis zu 3,4 GHz) oder 2,5 GHz (Turbo Boost bis zu 3,7 GHz) Quad Core Intel Core i7 Prozessor mit 6MB geteiltem L3 Cache.

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Logic board? I/O board? Both?

The Mac was connected, via USB, to an external circuit running on A/C power, and an isolation transformer was not used when it should have been. Result: dead Macbook. No indication of any activity at all when power key is pressed or held. The SSD was fine, and has been moved to another machine…but I’d like to salvage the laptop if I can.

I’m prepared to swap in a new logic board, but do you have suggestions for determining if the problem is the logic board? the I/O board? both? Something else? TIA

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The first thing I would recommend trying is an SMC reset. In addition to resetting the SMC this will help you determine that the power button is still functional (if the MagSafe 2 LED light changes from orange to green during the SMC reset you know the keys pressed are sending a signal). If it doesn’t power on after an SMC reset, then you’ll need to do some troubleshooting to isolate which components are preventing power on. Assuming you are using the correct charger wattage (85 W for the 15-inch model), your model should be able to run with the battery disconnected and the charger connected. By disconnecting the battery and attempting to power on with just the charger connected you can rule out the battery as a cause of power on issues. If the system still does not power on, you’ll need to isolate further. Although I doubt it would be preventing power on you can disconnect the I/O board by following this guide. You can continue to disconnect various components from the logic board, testing if able to power on afterwards in each case, until you have isolated to just the logic board (and maybe some other component like the fan or display to verify power on). If the system still doesn’t power on when just isolated to the logic board we can be pretty confident the issue either lies there or in the MagSafe 2 board. You can test the MagSafe 2 board by using the readout pins and a multimeter to confirm it’s passing the correct DC-In voltage. You can also try an SMC bypass to see if sensors on the logic board are preventing power on. To perform an SMC bypass, disconnect the battery, hold down the power button for 10 seconds, connect a charger while still holding the power button, wait 10 more seconds, then release the power button. If the bypass is successful the machine will power on with the fans spinning at full speed. Hope this helps!

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Thanks a lot, Zachary! SMC reset steps. SMC bypass steps, had no effect, though indicated keys were working. I/O board, battery do not seem to be the issue. I think it's likely to be the logic board. I appreciate your suggestions!

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Joel Black wird auf ewig dankbar sein.
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