I had this exact same problem with my Late 2012 iMac 27" i7. Must be something particularly sensitive with the PSU on these models.
Anyhow, I replaced the PSU with a new one ordered from Amazon and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
-
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was UNGROUNDED. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done.
+
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was '''UNGROUNDED'''. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done.
-
Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!
+
'''Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!'''
=== Update (05/07/2018) ===
I still contend that the random shut downs are due to faulty power supply unit inside iMac.
'''Once these get tweaked by sags or surges in current from your electrical or ungrounded outlet the damage has been done!'''
I HAVE had a faulty logic board on a previous machine but it was exhibiting different behavior.
In my experience, when the logic board fails you see strange colors and picture on screen. When the machine just shuts off, I believe that is not a logic board issue and rather a PSU problem.
Apple is no help in getting this resolved.
Thanks to the iFixit guides and a little online shopping I fixed the issue 100% myself (and I’m no hardware guru, I’ve only opened up my iMac once).
Check out these attached pics of a failing logic board and you will see that that is a separate issue. If your Mac is randomly going black, shutting down and the only way to hopefully power it back on is after you leave it unplugged for a few minutes.. You, my friend have a faulty power supply!
I had this exact same problem with my Late 2012 iMac 27" i7. Must be something particularly sensitive with the PSU on these models.
-
Anyhow, I replaced the PSU with a new one ordered from Amazon ([http://a.co/hXgDH0S|http://a.co/hXgDH0S]) and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
+
Anyhow, I replaced the PSU with a new one ordered from Amazon and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was UNGROUNDED. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done.
Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!
=== Update (05/07/2018) ===
I still contend that the random shut downs are due to faulty power supply unit inside iMac.
'''Once these get tweaked by sags or surges in current from your electrical or ungrounded outlet the damage has been done!'''
I HAVE had a faulty logic board on a previous machine but it was exhibiting different behavior.
In my experience, when the logic board fails you see strange colors and picture on screen. When the machine just shuts off, I believe that is not a logic board issue and rather a PSU problem.
Apple is no help in getting this resolved.
Thanks to the iFixit guides and a little online shopping I fixed the issue 100% myself (and I’m no hardware guru, I’ve only opened up my iMac once).
Check out these attached pics of a failing logic board and you will see that that is a separate issue. If your Mac is randomly going black, shutting down and the only way to hopefully power it back on is after you leave it unplugged for a few minutes.. You, my friend have a faulty power supply!
I had this exact same problem with my Late 2012 iMac 27" i7. Must be something particularly sensitive with the PSU on these models. Anyhow, I replaced the PSU with a new one ordered from Amazon ([http://a.co/hXgDH0S|http://a.co/hXgDH0S]) and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
+
I had this exact same problem with my Late 2012 iMac 27" i7. Must be something particularly sensitive with the PSU on these models.
-
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was UNGROUNDED. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done. Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!
+
Anyhow, I replaced the PSU with a new one ordered from Amazon ([http://a.co/hXgDH0S|http://a.co/hXgDH0S]) and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
+
+
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was UNGROUNDED. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done.
+
+
Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!
=== Update (05/07/2018) ===
-
I still contend that the random shut downs are due to faulty power supply unit inside iMac.
'''Once these get tweaked by sags or surges in current from your electrical or ungrounded outlet the damage has been done!'''
I HAVE had a faulty logic board on a previous machine but it was exhibiting different behavior.
In my experience, when the logic board fails you see strange colors and picture on screen. When the machine just shuts off, I believe that is not a logic board issue and rather a PSU problem.
Apple is no help in getting this resolved.
Thanks to the iFixit guides and a little online shopping I fixed the issue 100% myself (and I’m no hardware guru, I’ve only opened up my iMac once).
Check out these attached pics of a failing logic board and you will see that that is a separate issue. If your Mac is randomly going black, shutting down and the only way to hopefully power it back on is after you leave it unplugged for a few minutes.. You, my friend have a faulty power supply!
I had this exact same problem with my Late 2012 iMac 27" i7. Must be something particularly sensitive with the PSU on these models. Anyhow, I replaced the PSU with a new one ordered from Amazon ([http://a.co/hXgDH0S|http://a.co/hXgDH0S]) and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was UNGROUNDED. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done. Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!
+
+
=== Update (05/07/2018) ===
+
+
I still contend that the random shut downs are due to faulty power supply unit inside iMac.
+
+
'''Once these get tweaked by sags or surges in current from your electrical or ungrounded outlet the damage has been done!'''
+
+
I HAVE had a faulty logic board on a previous machine but it was exhibiting different behavior.
+
+
In my experience, when the logic board fails you see strange colors and picture on screen. When the machine just shuts off, I believe that is not a logic board issue and rather a PSU problem.
+
+
Apple is no help in getting this resolved.
+
+
Thanks to the iFixit guides and a little online shopping I fixed the issue 100% myself (and I’m no hardware guru, I’ve only opened up my iMac once).
+
+
Check out these attached pics of a failing logic board and you will see that that is a separate issue. If your Mac is randomly going black, shutting down and the only way to hopefully power it back on is after you leave it unplugged for a few minutes.. You, my friend have a faulty power supply!
I had this exact same problem with my Late 2012 iMac 27" i7. Must be something particularly sensitive with the PSU on these models. Anyhow, I replaced the PSU with a new one ordered from Amazon ([http://a.co/hXgDH0S|http://a.co/hXgDH0S]) and so far so good! Upgraded the HDD to a 1TB SSD while I was in there!
So what causes these faulty PSUs on the iMac? I had no problems with this iMac until I started taking the unit home from work and plugging it into an outlet that was UNGROUNDED. I suspect that the fluctuations in current, be it sags or spikes, created this problem. I only did this under 10 times, but the damage was done. Word of caution to anyone who has a failing PSU on their iMac.... check to make sure that you are strictly using a grounded outlet (even better if you equip it with a UPS with AVR) once you get your faulty PSU replaced!