No power to internal HDD on 2011 27 inch iMac

Hi Dan, many thanks for getting back to me.

So this wouldn’t be a bad logic board then?

I was under the assumption that the logic board sends power to the HDD from the PSU board as far as I can tell the HDD SATA power cable is connected to the logic board itself.

The power supply offers multiple 5 volt taps that feed different parts of the logic board. The drives use a different set of lines from the power supply. So that is why I would start with the most logical failure. Power supplies tend to get the worse of it between power surges and lightning hits. which is why I would focus their first.

Is it the power supply and/or the logic board without getting deep in probing the board to validate the connection pathway its a hard to say. It's even possible both got damaged.

Makes sense Dan. I assumed that might be the case. I think I will start at the power supply and hope that fixes it.

Do you know if this a common problem with the iMac?

@timgr - No its not a common issue the SATA power feed would die. It's not uncommon for the power supply to fail though!

The rest of the iMac operates just fine so let’s just hope it is that particular rail of the PSU has gone bad which a replacement will solve. Many thanks for the replies!