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Model A1502 / 2.6 GHz (Turbo Boost up to 3.1 GHz) or 2.8 GHz (Turbo Boost up to 3.3 GHz) dual-core Intel Core i7 processor with 4MB shared L3 cache.

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Only boots after long disconnection from any power source

Hi all.

I received this A1502 Mid 2014 with a weird behaviour. Once it boots, everything works perfectly. Once it's been shut down, it takes hours and disconnection from battery and charger in order to boot again. It behaves ok if it just restarts. The problem only occurs when the machine shuts down.

  • Battery is ok
  • Charger is ok
  • Same behaviour with logic board removed from the chassis (only fan and power board remain attached). This means it's not the I/O board, not a faulty keyboard.
  • I'm pretty sure the SMC chip has been reworked, to no avail

Any help is appreciated. Thanks.

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I would run the onboard diagnostics if you can, Apple messed up the firmware with the newer macOS’s so it might not load.

As far as SMC, it’s more likely one of the sensors has failed or is not communicating to SMC correctly. What you are encountering is a latched SMC condition. What happens is when SMC thinks the system is in damaged it set a latch so the system won’t turn on again without first clearing the latch condition. To do that all you need to do is disconnect the battery and with nothing connected press and hold the power button for 15 secs to discharge the logic board. The. Plugging in the MagSafe will spontaneously restart. Of course in a failing condition that only goes so far, and besides you could create a bigger problem in this state.

To get into diagnostics, press the D key just as the system starts up. Let us know what the error is.

Reference Mac startup key combinations

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@danj Thanks. The diagnostic only says “battery missing”, which is true because I removed it.

There’s no further notice about possible errors.

I must add that I can start the machine simply by disconnecting power, holding the power button pressed for 15 secs, then smc reset combination for another 15 secs, and reconnecting the magsafe it fires up. Still very annoying. And I suppose that this won’t work if I get a battery installed

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@mafomo - Well… that explains it!

Laptops don’t always run properly without a battery. The Process load can exceed what the charger can supply for power and the connection isn’t always 100% as in the case of moving the system or charger.

Here we also have SMC getting in the way as it should! Latching the system as it doesn’t see the battery.

Let’s get the battery connected and try diags again

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@danj - the problem was there also when the battery was installed. I have another A1502, with battery, so tomorrow I’ll swap the logic boards and report the result.

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@mafomo - Once you install the battery, install this gem of an App CoconutBattery

Moving the logic board doesn’t test the systems battery.

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