Chosen Solution
I have a iMac that I have been working on - I replaced the power supply about two days ago because I wasn’t getting any signs of life from it. The iMac hasn’t been displaying anything. No Apple logo bootup screen. No startup chime when I click the power button. I came to iFixit to check for anything and while hunting for some sort of answer I rubbed my arm agains the iMac and my Macbook Pro and got this bad electrical shock from it and I’m unsure what could have caused that. I thought that someone on here might be able to help. The “other problems” that I’ve experenced with this iMac are - No power to keyboard / mouseNo hard drive sounds (hard drive was replaced from what I’m told)No fan soundsDisplay isn’t giving any signs of life The specs of the iMac are - 2 TB hard drive disk by Toshiba4x 2gb RAM sticksMid-2011 iMac 21.5 inchNew power-supply in iMac I hope that I’m able to get some help with this because it has just been bugging me and I wanna get this computer fixed for my friend.
Lets start at the wall outlet as you appear to have a hot ground! Thats why you got a shock. Go the to the local hardware store to get a simple AC outlet tester like this one: 3-Wire Receptacle Tester. Test the outlets your system’s and the peripherals are plugged into make sure they are good. You’ll also need to check the breaker panel ground connection to the buildings ground point which is either a metal water pipe or one or more grounding rods. Make sure there is no corrosion buildup on the connections. You may want to get an electrician in to fix your outlets and check the breaker panel internally to make sure there is not issues within it. You’ll also want to get a DVM to test the voltages between your two systems cases (like how you shocked your self before) carefully measure the voltage. At this point you’ll need to check the AC power cord to your iMac and the one going to the MacBook Pro’s MagSafe charger. Do they have any physical damage? With the cord fully disconnected put your DVM in to continuity mode clip one lead to the ground pin and then touch your other probe to it as well the meter should beep and show the connection is shorted which of course it is. Now take the free probe touch each of the plug blades the meter should not beep (no short to ground). Now do the other line cord in the same way. One issue you might have here is if you bought a replacement MagSafe charger for your MacBook Pro, it might be bad as many non-apple units are poorly wired and have known to have issues with hot grounding. To test that you shouldn’t see a voltage from your system case to the the outlets ground point or continuity when you have the system under charge. OEM MagSafe Chargers vs Cheap Imposters: Teardown for Truth Let’s start there tell us what you find, did you discover any issues with the power? Until we are sure your AC services are good fixing your iMac won’t go to well as you could just burnout the replacement parts like it sounds you’ve done here.
