iMac Won't Boot After Power Failure

[sle39lvr]

I have a 2009 27" i5 iMac.

For few months now, there was a significant delay after I press the power button to machine to power up.

Few weeks ago, I had a power outage and aftwards it woud not turn on. Things I tried:

- Resetting SMC
- Leaving it unplugged from the wall
- Leaving it unplugged from back of the machine
- Holding down the Power button while plugged in
- Holding down the Power button while unpugged
- Leaving it unplugged with RAM out

About an hour after, it mysteriously powered up.

Yesterday, I had another power outage. This time I tried the same things, but did not power up for about 6 hours.

Today, I had to unplug it after shutting down to switch power outlets and now it won't boot again. So I have to wait for it to mysteriously do it's own thing.

Every time after it powers up, it works without any issues.

What can cause this? Could it be a bad PRAM battery?

 

[old-wiz]

well..first I would suggest you get a UPS.

do you have "restart after power failure" checked? I think it's best if it is off.

If you don't have a UPS/surge protector when the power comes back on it sometimes comes on as a surge, and can damage your machine.

 

[sle39lvr]

do you have "restart after power failure" checked?

I had it on.

Can anyone tell me if this could be the PRAM battery?

 

[sle39lvr]

Machine haven't booted for the day. It has been over 12 hours now and this is the 3rd time that this happened.

 

[sle39lvr]

Took it to Apple store. I am getting charged $105 for power supply replacement. It could be more if logic boards need replacements afterwards.

 

[bp1000]

It would seem logical to suggest the PSU went but surprised it blew, the surge must have been significant. I wouldn't recommend a surge projection extension socket.

It likely did its job of protecting the other components. Hope it gets fixed soon.