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I have a 2013 MacBook Air 13" (A1466), which all off a sudden wouldn't boot up. The charging LED on the cable was always green.

I then attempted:

  1. Holding the power button down 10 secs
  2. SMC Reset
  3. Using a charger from my Macbook Pro (which I know works)

No difference.

I then thought I would warm the Macbook Air up slightly (by placing it in front of a blow heater). This resurrected the Macbook Air as it started up after a few minutes.

However the next day, it wouldn't boot up again and this time even heating it up didn't work.

So I then ordered a replacement battery from iFixit, as it was a lot cheaper than taking it to the nearest authorised service centre for diagnostics, thinking the there was a reasonable chance that the battery was playing up (it was 7 years old, and starting to show its age anyway).

After replacing the battery, the Macbook Air still won't start. I opened everything back up, and tried to disconnect all visible cables, removed the I/O board, and put it back again, in case a cable had come loose. There was no visible damage on the I/O board either. All cables seemed to be OK.

One thing I've observed is that the charging cable LED never changes colour - it is always amber. And there is not a hint of warmth whilst connected.

I'm now suspecting that there is something wrong with the I/O board. Is there any way of diagnosing a fault with the I/O board? Any other suggestions to look into?

Prembo
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  • I also disconnected the battery, replaced the bottom cover and reconnected the charger. Still didn't boot up. But interestingly, the charging cable LED is always amber. Does this point to the I/O board or Logic board? – Prembo Mar 29 '20 at 02:52
  • The charging cable LED is usually orange. When I perform the SMC reset, and release the Shift+Ctrl+Option+Power after 10 seconds, the charging cable LED turns green momentarily, before turning amber again.

    Also, I tested the pins of the battery cable / socket. Without a schematic and not knowing the pinout, what I can measure is what seem to be 8V & 3.3V rails, with and without the charging cable plugged in. So I'm assuming that this means that the I/O board is functioning properly, and the battery is receiving the correct voltages. So looks like the logic board is dead?

     – Prembo Mar 29 '20 at 05:06
  • Also tried the power-on pads override technique to no avail (https://beetstech.com/blog/macbook-air-power-pads) – Prembo Mar 29 '20 at 05:07

1 Answers1

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Is there any way of diagnosing a fault with the I/O board? Any other suggestions to look into?

It’s possible that it’s your DC In Board as you stated, however the symptom you describe indicates it may be something worse; it may be your logic board.

The amber led means that the MacBook has sensed the charger (1 wire charging circuit) and is sending power, but the battery isn’t charging. We know this because it won’t turn on and the battery never completes a charge cycle (light never goes to green)

It’s cheap and easy to replace the DC in board, so that’s pretty much the diagnostic. If that doesn’t solve the issue, it’s your logic board (possibly your SMC, any of the power rails, the battery charging circuitry, etc.)

Allan
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