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

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

Thanks for the update Nick,

I can confirm that the PSU that is replaced was also the Delta (Model: ADP-300AF T).

All going well with my iMac since replacing the PSU.

Best

Thank you too for your update.

Which PSU you are running now? A new Delta or the liteon?

Cheers,

Nick

Thanks for the great information.

I have 128G fusion drive already as a fusion, look like the people using dual connections to boost the speed up to 900Mbs. I may consider that in the future.

I just bought the Samsung 850 Evo 1Tb SSD. I am planning to install this SSD when I swap out the PSU.

Also, The PSU I have bought is a Liteon, and I am still waiting for its arrival.

The reason I bought the Liteon, because most of the iMac PSU are found as Delta. I suspect Delta has more issues than Delta, I just give it a try.

I will do some stress test once I installed the Liteon PSU. see how does it go?

Regards,

Lune