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Thick1992

macrumors newbie
Original poster
Feb 24, 2021
3
0
Hey, I’m not sure if this is the right place to post this question but today my 27” 2017 iMac encountered a problem, there was a iPhone charger plugged into the USB port and the computer powered on but in sleep mode and my fiancé went to grab the cable and it flung around and the tip that plugs into the phone hit a metal prong on our heaters power cable that was sticking halfway out the power supply.(if that makes any sense). Basically now the iMac won’t turn on at all, I’ve tried holding the power button for 5 secs etc, I’m just curious what would be the first parts to “fry” in an event like that, I was thinking the logic board or maybe the power supply, I do see a small arc burn on the power supply prong where you’d plug the power cord into the Mac, So Basically my questions are what would break in a situation like I explained above? , should I start with replacing the power supply since I see a small arc burn? ,and is there anything I could look for with the computer apart that would help diagnose the broken/fried parts? I’d really appreciate any help,I’ll attach photos to the post, thanks
 

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DeltaMac

macrumors G5
Jul 30, 2003
13,578
4,481
Delaware
Don't forget the simple things. Make sure that the outlet or power strip that your iMac is using is actually supplying power. Plug in something like a lamp or some other device, just as a quick check, or bypass the power strip by trying the iMac plugged directly into a wall power outlet.
Unplug everything from the back of your iMac. Let it sit for 10 or 15 seconds. Plug in power cord, and try the power button.

Pretty sure there are a set of LEDs on the logic board that (I think) can be viewed from the bottom of the iMac. One LED should light up whenever the power cord is plugged in. Tells you that you have power available, and that the power supply "trickle voltage" is available. That tells you something about the health of the power supply, Press and release the power button should turn on a second LED. Third comes on when the display gets a video signal.
If you don't get any LED, even one, then likely the power supply would be your first step. (Again, be sure to verify the power cord)
 
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KaliYoni

macrumors 68000
Feb 19, 2016
1,744
3,855
OMG that was one crazy accident!

That placemat or table cloth threw me for a second. At first I couldn't figure out why you would want to add a charred cable to your burger (a Corded Power With Cheese?)...
 
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TwoH

macrumors 6502
May 19, 2019
451
270
How the actual hell does an accident like that happen lol, it’s the first I’ve ever heard of something like this.
worryingly because the surge of power would be travelled through the logic board, I’m to guess there would be an issue with the logic board itself.

might be worth taking the machine apart and looking for any burnt components on the board though.
 
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Nguyen Duc Hieu

macrumors 68030
Jul 5, 2020
2,926
966
Ho Chi Minh City, Vietnam
The tip of the USB-C cable is actually connected to the ground (mass) of the whole logicboard.
You guys have accidentally connected it with the hot wire of an AC outlet.
Considering that, I would say your logiboard was toasted.
If you are lucky enough, your data stored in the HDD may still intact, but the SSD might have gone already.
The LCD may survive, too, but chances are slim.
 
Last edited:

Thick1992

macrumors newbie
Original poster
Feb 24, 2021
3
0
How the actual hell does an accident like that happen lol, it’s the first I’ve ever heard of something like this.
worryingly because the surge of power would be travelled through the logic board, I’m to guess there would be an issue with the logic board itself.

might be worth taking the machine apart and looking for any burnt components on the board though.
i have no idea how she managed to do it lol but I’ll be taking it apart this weekend to see the damage
 
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