iMac startup sound or display

Question

iMac startup sound or display

I have a mid 2011 21.5inch iMac (Model A1311). I was upgrading from Mac OS 10.12 to 10.13. During the install I was in another room and heard a long tone. When I looked at the iMac the screen was blank. Pressing a key on the keyboard didn't activate the display. I left it for about an hour then I forced it to shut down by holding the power button.

On pressing the power button the computer powers up - I can hear a faint whir of the hard drive or fan. But there is no startup sound and the display remains blank. I can switch it off by holding the power button for a few seconds.

I've tried resetting the SMC but holding down command option shift and the power button. Still blank screen and no startup sound.

I've tried disconnecting the mains cable for 15 seconds.

I've tried disconnecting the keyboard. It's the only thing connected.

I've tried removing the ram to see if I get the ram missing tone - I didn't.

Any ideas?

iMac, macOS High Sierra (10.13.6), null

Posted on Jul 29, 2018 1:35 PM

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Answer 1

Old Toad

Level 10

215,676 points

Jul 29, 2018 2:20 PM in response to Darren Pullman

Try the following: Reset NVRAM or PRAM on your Mac - Apple Support.

If that fails see if you can boot into the Recovery volume (boot with the Command + R keys held down). If so run Disk Utility, repair the drive and try to reboot normally.

If you can run Disk Utility but still can't boot normally reboot in to the Recovery volume and reinstall the system.

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Answer 2

Old Toad

Level 10

215,676 points

Jul 29, 2018 2:37 PM in response to Darren Pullman

It might be time to make an appointment at the nearest Apple Genius Bar for a free diagnostic check. However, since Apple considers that aged iMac to be Vintage (everywhere except California and Turkey) they won't be able to make repairs on it. You'll need an Apple Authorized Service Provider for that. That age of a Mac is prone to breakdown. My 2011 iMac died of a broken GPU several weeks ago. We had a nice memorial service for it. 🙂

Re the Firmware password. That would have been nice to now at the start. See the last paragraph of this article: http://osxdaily.com/2014/11/22/fix-macbook-pro-booting-black-screen/

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Answer 3

Tesserax

Level 10

158,094 points

Jul 29, 2018 1:49 PM in response to Darren Pullman

Sounds (no pun intended) as your iMac may have a problem with either the power supply or system board.

Regardless, I suggest that you start here: (although Kappy may be right about it might just be time for a new Mac)

If your Mac won't turn on - Apple Support

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Answer 4

Kappy

Level 10

362,007 points

Jul 29, 2018 1:56 PM in response to Darren Pullman

If the display has gone you are looking at a nearly $500 component. The GPU is in the $300 range if I remember correctly. This does not include parts and labor - assuming you can find the parts. Apple no longer will fix it for you. You may need some repair tools which you can buy at OWC and also find a disassembly tutorial.

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Answer 5

Kappy

Level 10

362,007 points

Jul 29, 2018 1:43 PM in response to Darren Pullman

I'd say it's time for a new iMac.

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Answer 6

Jul 29, 2018 1:50 PM in response to Kappy

It was working perfectly ok before I ran the update to High Sierra. In my experience software updates don't break hardware. I'm reluctant to throw it away unless I know for sure that it's beyond economic repair.

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Answer 7

Jul 29, 2018 2:02 PM in response to Tesserax

Thanks for the link. I followed the troubleshooting. There is power getting through as I can hear a whir. I tried swapping the mains cable just in case.

The long tone I heard initially sounded like a firmware update. I wonder whether there is a firmware problem.

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Answer 8

Jul 29, 2018 3:35 PM in response to Old Toad

I gave that go but no luck. I noticed that the light on the caps lock key didn't come on when I pressed it so I suspect that the keyboard isn't talking to the Mac. I tried another keyboard just to be sure.

It looks like a call to a service provider tomorrow.

Thank you all for your help.

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Answer 9

Jul 29, 2018 2:03 PM in response to Kappy

If the display has failed then I don't see why this would prevent the startup sound.

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Answer 10

Jul 29, 2018 2:26 PM in response to Old Toad

I tried resetting the PRAM. I held the keys for at least a minute. Still no startup sound or display.

I tried holding Command R, that didn't work either.

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Answer 11

Jul 29, 2018 2:28 PM in response to Darren Pullman

I should add that this Mac is protected with a firmware password. As I get nothing on the display I can't see whether it's waiting for me to enter the password.

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iMac startup sound or display

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