iMac 27" late 2012 won't power on

Discussion in 'iMac' started by patmac7, Feb 2, 2014.

  1. patmac7 macrumors newbie

    Feb 19, 2013
    My Imac late 2012 fusion drive failed to power on last night. It came after a power failure. I changed power cable to no avail. I struggled the whole night.
    This morning It just power on.
    Has anyone experienced this? what could be the cause/cure?
  2. Lucianrider macrumors member

    Jan 1, 2012
    St. Lucia, West Indies
    It sounds like you did an SMC reset without knowing it.

    To do an SMC reset you pull the power cord out then hold the power button for about 5 seconds then release the power button. Reconnect the cable and power the iMac up normally.

    Basically that kills all power in the power supply by discharging the capacitors, something in the hardware is reset and allows the computer to power up.

    Leaving the computer unplugged for 30 minutes or so would basically achieve the same thing.

    If you don't have any further problems then I would not worry about it. If your iMac is not on a UPS, I highly recommend that you get one. They are very cheap insurance...
  3. patmac7 thread starter macrumors newbie

    Feb 19, 2013
    Thank you very much for the SMC stuff. I did press the power button for around 15s but with the power cord plugged in. May be leaving it overnight has cured it.
    yes I'm not on UPS now. What UPS capacity for an iMac 27"?
  4. patmac7 thread starter macrumors newbie

    Feb 19, 2013
    Brought my mac to Apple representatives here...they said they did a diagnostic on Apple Server and found nothing abnormal.
    Took my Mac back home and everything is normal up to now.
    I really do not believe that they did nothing as they said.
    i'm just happy it's fixed...but I dont know if there is some issues known to Apple that they won't tell us....coz so many people has had these sudden black screens.
  5. patmac7 thread starter macrumors newbie

    Feb 19, 2013
    Dear friends troubles continue. They wanted to change the power supply...finally they changed only the CMOS it back to me telling that all is normal. since then unit fails everyday.
    They told me to wait another two weeks until Apple send a Main Logic board for replacement. still waiting......
    I'm really desperate
  6. Beebi macrumors newbie

    Sep 26, 2014
    much later...

    Did you ever resolve this issue? We are having a similar problem.
  7. patmac7 thread starter macrumors newbie

    Feb 19, 2013
    Problem solved

    They changed the Main Logic board...problem solved since then.
    But now I'm having a lesser problem........Sometimes I heard a "chick" sound ....I mean sound like a small chick and then. Not continuous.
    Apart from this all is good

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6 February 2, 2014