Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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Unable to boot, stuck in power cycle

Here's a video of what's happening

  • When trying to boot, machine is stuck in cycle trying to power up
  • Can hear fan and cd-rom making noise and getting power, then shutting off and cycling again in the same pattern (see video below with back panel removed)
  • Cannot boot from USB (have done this successfully in the past with this machine)
  • Nothing on screen at all during process
  • AC Charger indicator light comes (orange or green as normal)
  • Apple store gave a vague answer about power supply and wanted $475 to fix
Contestado! View the answer Yo también tengo este problema

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Solución Elegida

Seen your short video and I understand the answer you got from Apple centre..since they don't do component level repairs they'd be changing the logic board. They might be right, some power sensing issue or the likes seem to to be the right answer here but only deeper lab testing can give a clear answer.

Try to start it with battery unplugged just not to let that untried, but probably it won't make a difference.

If you want to dedicate some extra time try also starting the Mac after removing one at a time the various connectors, lvds, battery sensor, trackpad and so on, to rule out possible shorts..one can never know for sure without trying.

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Thanks for the reply. I was able to replace the all hardware and just swap out the HDD thanks to a friend having an extra machine. I will update the thread if my friend solves the issue on the original problem machine.

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Respuesta Más Útil

Mayer has some suggestions in this post My MacBook won't boot - HDD and fan spin, but no chime!

He suggests resetting the SMC, maybe try this article's procedure!

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@sam - no luck with resetting SMC or PRAM. When resetting the SMC, the charger light went from orange to green on release, the article says that is an indicator that the procedure was done correctly.

One more fact that may (or may not) be relevant. The computer only started misbehaving after an airplane flight (well protected in hard shell in carry-on luggage).

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Paul Dumoulin estará eternamente agradecido.
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