new 27" imac 2018 has been having random intermittent shutdowns for 3+ months (my iMac shuts down for no reason and won't restart unless unplug with full hard reset - any technical thoughts on how to resolve?

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new 27" imac 2018 has been having random intermittent shutdowns for 3+ months (my iMac shuts down for no reason and won't restart unless unplug with full hard reset - any technical thoughts on how to resolve?

All my new 27" imac 2018 has been having random intermittent shutdowns for 3+ months (my iMac shuts down for no reason and won't restart unless unplug with full hard reset) - any technical thoughts on how to resolve? I have been working with Apple Support (online and via Genius bar) for 3+ months and have not been able to resolve the problem. As a result my new 2018 IMAC (which cost me US$3500 this year) is not being working and I am typing this on my old 2012 mac book (which has always worked with no problems)

Please note this is a request for technical support ideas from the Apple community (it is not a poll or a petition) - my previous post "iMac 2018 - emergency shutdown / restart issues (due hardware failure or software or data issues)" was removed by Apple support as I asked if anyone else was having problems with their IMAC shutting down due to hardware software issues and Apple Support said they did not want this information posted for reasons set out below. I have resubmitted this so hopefully it works as I need help as I have been unable to resolve issue with apple in last 3+ months so looking for community thoughts

Here is a summary of the iMac Hardware / Software Problem and steps taken to resolve:

- In Aug / Sep 2018 my iMac started doing emergency shut downs for no known reason - the screen goes black / iMac turns off with no response to keyboard commands - the power switch at back does not work (even if hold for 30s several times) - to restart iMac I need to do a hard reset (physical unplug of computer power for 30s before computer can be restarted by pushing / holding power button at back ) - some times i needed to do 3 * hard resets before computer would restart.

- I have had this problems for last 3-4 months and have been working with Apple support and Apple Genius bar trying to resolve this screen / power / shutdown issue

- it is an intermittent problems that can occur 10 * in one day or iMac can run for 2-3 weeks with zero problems. To restart my 2018 iMac after a shutdown I need to do a full hard reset (physical unplug of computer power for 30s before computer can be restarted by pushing / holding power button at back - some times i needed to do the unplug 3 * before computer will restart)

- to date the Apple online support (software) team have reset my system, wiped my data, restored iMac to original system software, restored iMac to latest software, wiped all my data again (multiple times), reset system again (multiple times) and so on and so on - so far nothing seems to fix and problems restart after 2 weeks then slowly get worse - after Apple support online team have tried all of their remote tricks they then refer me to Apple genius Bar (hardware division)

- I have also taken my IMAC to the Apple HK genius bar (several times) and they inspect imac / run tests then normally say “test show nothing wrong” and/or “ we are unable to replicate the error” but after they kept and tested my iMac they agreed that it was shutting down unknown reason. So far Genius Bar have replace logic boards / removed ram / run hundreds of tests to show it is fine (while not resolving problem)

- it has now got to the point where Apple HK Genius Bar says “hardware ok must be a software / data issue” and Apple support software team say ok lets try all the software steps again - apple support then say “I am sorry we have taken all the steps we can remotely - please take to the Apple Genius bar" (again)

Please note, Apple Support removing my previous post for following reason: "We removed your post "iMac 2018 - xxxxxxxxxxxxx emergency shutdown / restart issues (due hardware failure or software or data issues)" because it contained a poll or a petition. We understand wanting to share experiences, but these forums are meant for technical questions that can be answered by the community."

Posted on Nov 18, 2018 5:35 PM

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Answer 1

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dwb

Level 7

33,220 points

Nov 19, 2018 7:27 AM in response to MrHk

Your problem sounds similar to an issue I experienced before we moved into our house. Long story short, my new computer would randomly shut down; it happened infrequently when I first bought it (winter) and became more frequent once warm weather came and that's what finally ended my frustrations. One hot summer day I realized that when the fridge was running and the air conditioner kicked in the computer turned off. My solution was moving the computer desk to the other wall where I could plug it in to a different circuit. You might want to check your outlets with a multimeter to see if it is experiencing any drop offs.

Since your computer checks out at Apple it only makes sense to look at the environment where it is being used.

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Answer 2

MrHk Author

Level 1

70 points

Dec 15, 2018 9:15 PM in response to Lost in Asia

See above, pricing got all parts listed - power supply chesoest part to replace

if outside warranty and software fixes don’t solve pay Genius Bar inspection fee (may want to try to get waiver) and then say happy to replace power supply

if you need to replace logic board it is expensive (see above for cost) and did not fix my problem (where as power supply change did) - still no shut downs 3 weeks in

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Answer 3

MrHk Author

Level 1

70 points

Dec 7, 2018 5:27 PM in response to Lost in Asia

Hi Sorry for delayed response, Console system.log was no use to me - it sometimes showed kernel panic but otherwise nothing

If it is a 2017 iMac are you still under warranty or apple care? if so get to apple fast - if not:

Have you tried the software fixes above? If you have and it appears to be hardware related you will need to take to apple\

if under warranty apple care then hardware problems apple needs to fix - one of the only reasons I but apple care now is that I am not convinced that apples quality control is as good as it was ( my new apple hardware seems to have more and more problems where as my old hardwares 3+ year runs well)

- if your apple iMac is not under warranty then ask apple if they will check problem for free (as number of people are having this problem) - they will probably refuse in HK and you will need to pay the apple inspection fee to find out the problem - if not clear ask them to replace power supply to see if fixes

if apple inspects and your logic board or something else is gone and not under warranty it is probably not worth fixing a 2017 iMac but ask apple to fix for free and if they don't then post a summary of problems with your 2017 iMac on all the review sites so others know of problems and buy apple care or don't buy

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Answer 4

MrHk Author

Level 1

70 points

Jan 18, 2019 3:53 PM in response to MrHk

Jan 2019 update: shutdown issues have started again (sigh) - another hardware iMac failure? will track log and start the painful apple hardware / software support process all over again

ps if you are having shutdown issues and need to track the history frequency you run a report in terminal - link below has details but basically open "terminal" app from search and type "

"last reboot" or "last shutdown" and press enter

Step 3: Finding Your Mac's Reboot/Shutdown History (via Terminal)

https://mac-how-to.gadgethacks.com/how-to/mac-troubleshooting-find-your-restart-shutdown-uptime-history-0168754/

...."Open up Terminal again, if it's not already, and use the last reboot or last shutdown command. Just type them out one by one, then press return on your keyboard. The former logs every time your Mac was rebooted, obviously, and the latter when exactly it was shutdown. These logs have a history from when OS X was first installed on your Mac, which is the date the logs were first created; just check out the "wtmp begins" date at the bottom of the logs."....

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Answer 5

MrHk Author

Level 1

70 points

Nov 26, 2018 6:11 AM in response to dwb

Thank you for this - sorry for delay in responding I was waiting for my iMac to come back from apple to see what they said (another logic board replacement and power supply replacement apparently) that said my repair looks identical to last repair email (and given Apple HK staff literally had no idea what was done when I picked up (honestly not sure what was done)

thank you for comments on environment - yes old house so I guess power fluctuation possible - that said the wall socket is also used for my MacBook and 2012 iMac (without problems) and also have circuit protector for all 3 so not sure if this is definitive given only 2018 iMac seems to have problems - I tried in another room / plug and same issue (but again old house so not definitive I guess)

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Answer 6

MrHk Author

Level 1

70 points

Nov 30, 2018 8:57 PM in response to MrHk

All, quick update re my problem - since apple replaced the power supply last Sunday the shutown issue has not reoccured (6 days and counting) - I did a search on this forum and some other apple forums and found that power supply replacement seems to be a common issue / fix this type of shutdown issue so may be a known error

if you are having shutdown or restart problems and the normal apple support software fixes don't work (see below) then try getting your power supply replaced - this is one of the cheaper parts to replace at apple (US$73) - my warranty plus apple care covered all costs but the support receive showed following costs:

- Power Supply Unit 300W iMac 27" was HK$572 (US$73)

- Hardware Repair Labor. HK$339 (US$43)

- Logic board 4.2 GHZ ELXTA 8GB HK$4,352 (US$558)

As you can see the expensive bit to replace is the logic board (not the power supply) and logic board has now been replaced twice by apple support (apparently)

apple support - software system resets to check shutdown / restart issues

- restart the Mac to see if problem reoccurs

- try these steps if your Mac wont turn on or you need to do a hard reset (unplug) to get it going

If your Mac won't turn on - Apple Support

- restart the Mac in safe mode to see if this resolves the problem

Use safe mode to isolate issues with your Mac - Apple Support

If above does not resolve problem then before you do anything else:

BACK UP YOUR DATA / SYSTEM

(using apple time machine or another backup tool

Then try these steps:

- do a NVRAM PRAM Reset (if needed for your model):

Reset NVRAM or PRAM on your Mac - Apple Support

- do a System Management Controller (SMC) Reset:

How to reset the System Management Controller (SMC) on your Mac - Apple Support

Then take to Apple Genius Bar

Worse case you can check if the error is software or hardware related by using Mac OS Recovery to do a full system wipe and install of latest OS software (from internet) with no Back Up data restored - You then have to run computer to see if shutdown problem still occurs. If problem reoccurs with a fresh install and no data ** then it proves error is not software related (as it is a clean install) but it is a real pain and I had to do this 5 times over last 3 months :<

Here is a support article for system wipe and restore:

About macOS Recovery - Apple Support

Here is an article with steps but basically similar to above with few extra steps

https://www.macworld.com/article/2018853/when-good-macs-go-bad-steps-to-take-whe n-your-mac-wont-start-up.html

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Answer 7

Nov 30, 2018 10:44 PM in response to MrHk

MrHk, any tips for running diagnostics on your system for this? I’ve started having a similar issue today with my 2017 iMac - six sudden shut-downs and counting - but I can’t find anything in the Console system.log that indicates why the system is crashing.

To turn the computer back on, I need to turn the power bar off and then on again.

So far I’ve tried changing the specific plug, but same wall outlet; no difference. I’ve just tried changing the power bar - who knows, mabye that’ll help. (EDIT: Nope. The computer suddenly powered off yet again. Argh!)

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Answer 8

Dec 15, 2018 4:36 AM in response to MrHk

Thanks MrHK - sorry I didn't reply earlier; I don't think I got a notification about your post.

I'm dealing with this in Taiwan, not Hong Kong, although the costs (and public transit issues!) will probably be similar.

For what it's worth, how much did you have to pay for the power supply replacement? Or was that covered by warranty?

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Answer 9

MrHk Author

Level 1

70 points

Feb 16, 2019 9:58 PM in response to MrHk

Feb 2019 - still having erratic shutdown issues - followed steps above ie full clean restore software wipe and problems reoccur woth no apparent pattern - will start the Apple repair process again at end of Feb

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Answer 10

Dec 15, 2018 9:54 PM in response to MrHk

Oops! Thanks, I should have seen the prices listed there.

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