A1466 / 820-3437-B / only starts on the 3rd attempt

[GfilipeZ]

Hi,

I'm trying to detect a strange anomaly that keeps repeating itself in the same way.
If i press the power button, the fan spins 1/4 and stops. I press the button again, and the fan spins normaly, but there is no boot. Then i force it to shutdown, and press the button for the 3r time, and the machine boots normaly.

If i let the macbook turned off for about 20/30 min, the anomaly comes again, and i have to do all again to make it boots.

I already tried an SMC from a donor logic board and dump a clean firmware to the EFI ic, but the problem always remains the same.

Has anyone experienced a similar problem?

Best regards.

[GfilipeZ]

Re: A1466 / 820-3437-B / only starts on the 3rd attempt

Hi,

I'm trying to detect a strange anomaly that keeps repeating itself in the same way.
If i press the power button, the fan spins 1/4 and stops. I press the button again, and the fan spins normaly, but there is no boot. Then i force it to shutdown, and press the button for the 3r time, and the machine boots normaly.

If i let the macbook turned off for about 20/30 min, the anomaly comes again, and i have to do all again to make it boots.

I already tried an SMC from a donor logic board and dump a clean firmware to the EFI ic, but the problem always remains the same.

Has anyone experienced a similar problem?

Best regards.

Hi,

Any idea?

[reformatt]

Re: A1466 / 820-3437-B / only starts on the 3rd attempt

Check for presence of PP3V3_S5_AVREF_SMC. If it's missing, usually a shorted cap next to the SMC. If this is missing, board will only start in SMC Bypass mode which sounds like what you are doing.

[GfilipeZ]

Re: A1466 / 820-3437-B / only starts on the 3rd attempt

Hi,

I'm trying to detect a strange anomaly that keeps repeating itself in the same way.
If i press the power button, the fan spins 1/4 and stops. I press the button again, and the fan spins normaly, but there is no boot. Then i force it to shutdown, and press the button for the 3r time, and the machine boots normaly.

If i let the macbook turned off for about 20/30 min, the anomaly comes again, and i have to do all again to make it boots.

I already tried an SMC from a donor logic board and dump a clean firmware to the EFI ic, but the problem always remains the same.

Has anyone experienced a similar problem?

Best regards.

I dumped another file with clean firmware to the EFI ic, and restored the Mac OS. Don't ask me how, but, solved my problem.

Thanks guys.