Q: 27 iMac (2012) crashes and requires smc reset to turn on

ohmyggg wrote:

 

FWIW, I went ahead and ordered a new power supply on Ebay for $55 and did the replacement myself. Computer has been running without random shutdowns for 2 months now. Previously, I was getting anywhere from a few days to a week before the computer would crap itself.

 

I'm not a trained technician, but I've hacked into things like this before so I was confident in my abilities (plus I was desperate since my $3500 computer was a useless pile of junk due to the shutdowns). YMMV on confidence/abilities.

 

Note, hacking into the iMac will void your warranty but if you're considering this, that probably means you're off AppleCare anyway. If not, go through the process and have Apple to do it.

@ohmyggg -

you guys all seem confident the power supply is the long standing issue?  I asked here before for an official Apple link indicating the issue, but no one's replied.  Is there some documented of Apple admitting a problem?

I'm not trying to cause grief, but suggestions, as I've been through this issue twice, with my first one being replaced, and the second one basically being gutted with all new parts.  One issue was there was an actual recall for a certain video card which my second qualified for.  But in all - my power supply for both my iMacs were never replaced.

As for doing repairs yourself - the real pain in the but is the awkwardness of working with the all-in-one iMac, and then keeping the inside of your display, and the inside of the glass cover clean and clear of any particles.  My second Mac had it's parts replaced with an on-site repair.  I was fortunate because I was able to watch over the tech, and secondly; he was a part time photographer and graphic artist so he, himself was picky how the screen looked.

I digress:  Seeing how you're convinced this is a power supply issue - you've probably already purchased your power supply?  It didn't sound like you were afraid of hacking into the iMac, but I would encourage you to still try with Apple.  I use to work with Apple CR.  Get through to Customer Relations and straight up... ask for a warranty exception (for whatever you want to try) - especially and primarily if you already have repair history, or documented discussions with Apple (cases) 

Have them look again, or have them do the repair - if they will.  It's also still possible to find AASP's (Apple authorized Service Providers)  They all have their hourly rate, and sometimes have jobs already marked hourly of how long it will take. Sure... it may cost $100 - $200 to repair (I think that's on the high side) but... if something gets screwed up - THEY'RE on the hook for the cost.  If there's dust under the screen, or something not working right afterwards - they, again are on the hook.  Just depends on how much you think your time, and possible future issues are worth to you.

just my 2¢

I still am curious to know of any documentation point to the power supply being the issue?

I have been suffering with the same issue since Nov 2015. After 4 repairs and 4 failed attempts by Apple to replicate the issue, they have FINALLY make a breakthrough and replicated it.

They informed me they replicated the shutdown during an "extended memory test" of the RAM chips. My original build was supplied with 8GB RAM and I added another 16GB myself. The store switched in and out new and old chips but the issue still occurred. The average genius in an apple store won't know how to remedy this.

A referral to Apple Engineering ensued and they recommended "switch the logic board".

My advantage here was that I already had the logic board switched about a month ago - and the issue remained.

By this point I had the apple store manager involved and on my side.

The recommendation from him (and his Genius team) was that switching the logic board wouldn't resolve, so he would authorise a replacement machine.

So my advice to you is persist - replace the hardware they recommend, and if that fails - the manager of the store can authorise a replace but the whole process has lasted about a year. I sat in the store today and listed off all the things I had tried:

• New 3TB Fusion Drive x 2
• New Logic Board
• Old / New RAM
• El Capitan (from restore)
• El Capitan (from new)
• HDD wipe and reinstall original OS X (Mountain Lion)

What also really helped was videos I took which captured the behaviours of the random shutdowns. This gives you evidence when apple technical support tell you they can't replicate the issue.

Hope this helps.

I started one of the very first strings SIX years ago on all these issues  (27-inch / 27" iMac Random Shut down) which included a possible issue with RAM, heat, SMC, a weird video interruption screen, random shut downs and restarts, random shut downs with black screen but power remained on.

I experienced ALL of the issues on my first iMac, and none of the "supposed" fixes corrected my iMac including SMC reset.  One of the most popular, but unconfirmed suspicions was RAM - even six years ago, but I was convinced it was not.  People mentioned the issue at 8gigs, some mentioned at 16gigs, and I had both, switched them in and out with brand size, and it didn't matter. 

I agree with @C4MEL - go for having Apple to replace components.  Apple, however won't start talking replacement until the a 3rd repair is done, and you're looking at your 4th.  FURTHERMORE - I strongly suggest NOT doing more than one component per repair.  Apple almost screwed me over by replacing 2 -3 components in one repair, which would normally have been done in separate repairs.  They nearly considered the repair only as ONE, and even though I had been going through issues for more than 1 ½ years.

I too ordered a power supply from E**y for $65, and I am having it installed tomorrow.  The funny thing is, like others have stated, if I unplug the computer overnight, or at least 2-3 days at a time, I don't experience any shutdowns.  But if I leave the computer on for about a week, then I have the shutdowns.  It's strange how by just unplugging it overnight puts the shutdowns at bay, why?  I don't understand it honestly, but like I said, I am having the power supply changed tomorrow and I will keep you posted.  The only thing is so many other people have had the power supply changed and the shutdowns came back eventually.  I tell you, I just don't understand it.  I also read online that people have been suffering with these random shutdowns for years with previous macs as well, not just 2012 and up.  At any rate, this is my last attempt at paying to have something changed in this mac, if this doesn't work, I will result to the unplugging thing for a while, and eventually by a new computer down the line.  But I am really tired of dealing with this issue as the rest of you are as well I'm sure. Stay tuned......Ugh!!!!!

Hmm, is there a way to PM on this forum?

Mods edited out a lot of the information I included in my post about the power supply repair.

To address some of the other questions, I had included a link to the specific power supply replacement that I purchased but the mods removed it.

It's a 300W power supply and the Model # is A1419. It also goes by Apple Part #: 661-7170

I also included links to the other things you'll need (guitar pick, spudger, adhesive strip kit, and torx screwdriver) but that information was also removed by mods.

Anyway, with a little digging around, you should be able to figure out what you need and where them. Total cost was about $85 and the repair takes an hour.

And someone asked about dust particles getting lodged between the glass and LCD. This will NOT happen on the late-2012 iMacs because the glass and LCD are bonded together. When you do the repair, you're removing that entire front assembly (glass and LCD) so there is no risk of dust getting in between there.

in the last days, I've tried to unplug imac in the night.

and in the day after no shutdown occours, with simple use: word, safari....

I've to try with long video rendering now... because in the last months this ever shutdown my imac.

Stay tuned.

(if it occours, i'll buy new power supply on ebay. I now that it will not be a solution for ever. but 60$ for some year for me is a good solution. My imac was 3750€!!! (2012))

i'm watching that there is two or more version of PSU.

the common liteon one:

http://www.ebay.it/itm/Apple-27-iMac-A1419-MD095-MD096-300W-Power-Supply-Board-6 61-7170-PA-1311-2A-/171549612912

http://thmb.inkfrog.com/thumbn/sjinmin/15131_6.jpg=550

and another one (this one have more efficient and additional heatsink...):

http://www.ifixmaccomputers.com/661-7170-apple-power-supply-imac-27inch-late-201 2-a1419

http://www.ifixmaccomputers.com/image/cache/data/661-7170-500x500watermark.jpg

the secondone has a different layout too...

i don't know if it is a wrong picture or if it is really a different one.

But i am sure that i read of two different factory that produce PSU for our late 2012 and up imac.

is it possible that shutdown occours only with liteone one?

All was good for a few days, then last night, it shut down again.  This time I noticed that the temperature of the CPU (per Hardware Monitor) was about 125F.  It seems to run ok below this temp.  Has anyone else observed this?

Thanks,

Hank

I suspect this is a "total power draw" problem, that the power used for the processor, the internal hard drive, Bluetooth, and external devices, is exceeding the amount the power supply can provide.

I suggest if you post, list Bluetooth status, wireless/wired, and speed, along with all external devices, whether the are powered by a brick or hub, hard drive type, and processor.

MIne for example, Mid 2011 iMac, Bluetooth off, wireless N 5 GHz, internal WD Black 2 TB, two FireWire external drives, both on power bricks, 2.5 GHz 2400S processor....

Note that their appears to be two motherboards, one supporting 65 watt processors, and one supporting 95 watt....

And another thing I'm noticing.  It seems to be a temperature issue as well.  I just added Macs Fan Control, and suddenly, in the evenings for some reason, the temp will rise to about 130f on the CPU A (hardware monitor) and the power draw will increase, then it's shut down time.

Is the temp rising due to the power supply or what?

Comments, please.

Thanks,

Hank

ElBartolomeo wrote:

 

the secondone has a different layout too...

i don't know if it is a wrong picture or if it is really a different one.

 

But i am sure that i read of two different factory that produce PSU for our late 2012 and up imac.

is it possible that shutdown occours only with liteone one?

Hi Elbartolomeo,

I think I have found out there are 2 brands of the power supply Liteon and Delta:

Liteone : PA-1311-2A

Delta: ADP-300AF T

I am still asking some of seller in Aliexpress to explain what is the difference between these two. However, apparently the ifixmaccomputers are the Delta one.

Glasguy,

today I added an SSD into the blade slot of my iMac 27 2012 and now I run 8TB HD with 1TB SSD without shutdowns today.

During the installation I checked my PSU - its from Delta (Model: ADP-300AF T).

During the last weeks (I was running my system on a single SSD) I had no shutdowns as well.

What did I change?

- 1TB HDD to 256GB SSD (until today, now I run on 2 drives - see above)

- started to switch off the iMac over night (I never did this before)

- skipped my Superdrive DVD from being attached always

- OSX 10.11.6 installed from scratch

Until now I dont have any shutdowns over the last 4 weeks. I will drop a line if a they come back.

Just wanted to let you know!

Cheers,

Nick

Hi Nick,

Would you be able to let me know what is the model of the SSD blade. As think I am going to upgrade in once when I swap out the bad PSU.

Cheers,

Lune