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3 How to troubleshoot an iMac 27 late 2012 that wont power up?
So I decided to upgrade my iMac with a blade ssd. I followed ifixit guide carefully. Everything went fine, there were no trouble at all, so I decided to put a new thermal paste in the cpu while i'm at it. The reassembly of the cpu didn't go as smooth, but I did managed to assembled it. But as I reassembled the machine, the iMac wont boot up. There is no sound coming from the iMac. The LED #1 on the logic board is lit, but nothing on the others when I push the power button.
My initial thought is that I have toasted the cpu, as it was the only step I had trouble with. Worst case scenario is that I have toasted the logic board. Is there anyway to check which unit is the cause of the power up failure? Can I assume that the power supply is fine when there is light on the LED #1?
Symptoms before the ssd upgrade: The iMac had trouble waking up from sleep. It went on "hibernating" mode and it took a while to start up again. I tried pram and smc reset andd it didn't help. Which is one of my reason to upgrade to ssd.
Esta é uma boa pergunta?
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4 comentários
Hello,
What kind of difficulty did you encounter with the CPU reassembly? It may shed some light into whether that's the cause or not.
por Arthur Shi
The more info the better!
por Dan
After the first reassembly and the iMac won't start up, I disassemble the whole machine again to see if I missed a wired or anything alike. I disassembled the heatsink from the cpu again. But I find it very difficult to know if cpu sit aligned in the socket as the only thing that's holding it's the two very thin hatch from the cpu and the socket plastic. So I have no idea when putting the heatsink on, if its sit perfectly in place. And the spring from the heatsink (step60 on ifixit) is very hard to screw back, so I might have moved the heatsink and thereby misplacing the cpu on the socket. This uncertainty make me think that this could be in this step that I screw up.
por Thien Khanh Nguyen
Update:
I had bend some of the pins while doing the cpu thermal paste. I have since make the pins straight again and it now power up and I now have 2 LED light on the logic board, but at the same time, I get a loud error sound instead. That kind of error sound you get when you forgot to put the ram inside. And yes I had working ram inside. And I have also checked cpu, ram and psu for error on a working iMac. From that I isolated the problem to be a faulty logic board, but than again iam not a professional and can only do this much. I have spend a lot of hours assembling and disassembling the iMac that I could probably get a job in one of those assembling factory.
por Thien Khanh Nguyen