Strange power issue with my 2013 iMac 27”

[heya]

Experiencing a very strange problem with my iMac.

When I shut down the Mac, I can’t turn it back on immediately. To start/turn on again, I’ll have to unplug the power cable from the wall then wait for 30-60 seconds before connecting the power cable back into the (wall) power then it will turn on. Sometimes it doesn’t start after a restart and I have to do the same thing with power.

Looks like it needs some kind of power “reset”. Spoke to Apple on the phone and they asked me to try the following commands which I did but the issue still exists.

1. Option 1: Shift+Ctrl+Option+Power for 10 seconds
2. Option 2: CMD+Option+P+R until the second startup noise

Any idea? Hope it’s nothing serious as in something to do with main circuit or motherboard.

Please suggest any solution if you have come across this issue before.

 

[Fishrrman]

What follows will not "solve" your problem.
It may make things a little easier coping with it.

1. Get a power strip with an on/off switch.
2. Plug the iMac into the power strip.
3. Normally, leave the power strip OFF (until you use the iMac, of course)
4. If you shut down the iMac and it won't respond to the power-on button, reach down and turn the power strip OFF. Then turn it back ON.
5. Press the power-on button again. Any different...?

I would not send the iMac in for a [potentially expensive] repair, if doing something like I have described above "works around" the problem...

 

[heya]

Thanks mate. Do you know what may be causing this and when you say potentially expensive repair, what would you say may need repairing?

What follows will not "solve" your problem.
It may make things a little easier coping with it.

1. Get a power strip with an on/off switch.
2. Plug the iMac into the power strip.
3. Normally, leave the power strip OFF (until you use the iMac, of course)
4. If you shut down the iMac and it won't respond to the power-on button, reach down and turn the power strip OFF. Then turn it back ON.
5. Press the power-on button again. Any different...?

I would not send the iMac in for a [potentially expensive] repair, if doing something like I have described above "works around" the problem...

 

[mikeboss]

it's most probably the power supply on it's way out... I've seen this behavior many times on 2012/2013 iMacs.

 

[heya]

Thanks Mike. I hope that's what it is and nothing major/more serious. How much would it cost me to replace the PSU?

it's most probably the power supply on it's way out... I've seen this behavior many times on 2012/2013 iMacs.

 

[mikeboss]

I usually find them for less than 100 EUR/USD on e*ay. I prefer to get brand new ones instead of used power suplies.

 

[Fishrrman]

OP:

Try "the workaround" I gave above before you go spending money on a power supply.
It just might work.