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I just (very carefully) disassembled and reassembled my 27 inch mid 2011 iMac and now it will not even try to do anything when I press there power button. I have double checked that everything is plugged in. I had removed the GPU and hit it with a heat gun for a few minutes as the machine would not make it past halfway on the Apple Logo no matter what. Thank you for your help!
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@dorazio - At this point I think you’ll need to replace the GPU board and you might also need to replace the power supply as it is also failed either you have created a short which after replacing the GPU might let the power supply recover or it could be damaged and also need replacing.
This series is by far one of the better built models! I still have mine and still use it alot. If you had gotten one of the i7 systems I would fix it for sure as its still plenty powerful for what most people need.
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Thank you so much for your help-- I got this machine off of a guy that I used Target Display Mode to recover all of his data so I'm not too invested in it at this point. I'm going to retest the power supply with a multimeter as last night around 2AM sparks were flying after I touched the PSU with my finger with I then dropped the logic board and and the cooler hit the PSU... If the PSU still outputs the 12v and 4v is it working? Again, thank you for your help.
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First,using a hot air station to do you rework is a bad idea. Usually real rework stations are used “Louis rossmann on YouTube” does an example of gpu not working due to a heat gun job. He replaced it with a high quality rework machine that heats the top and bottom at a specific temp and measures everything. Unfortunately it’s very expensive to buy one…
Reheating the gpu with lots of flux and reasonable temp and airflow is ok. But you said you took it off. If that’s what you meant,did you reball it? Or did you just drag solder over the pads and toss it on? You HAVE to reball it with very very similar size balls. The gpu sits on these balls. Putting it on with a heat gun is a gamble,even if you’re Louis rossmann.
First,don’t power it on again. If you attempt this yourself,you’d need a reballing stencil,premade solder balls(not paste it squishes under the stencil and makes uneven balls on large chips),and good flux. You need to flatten(probably best to wick a gpu) pads on the logic board. Then reball the gpu. Use plenty of flux and hot air it back on. You have to be sure it’s seated though.
Currently,there’s a really high chance you shorted something too,depending on the strategy you used. But Louis rossmann’s videos would help you most I think.
Also,not starting doesn’t mean it’s the gpu. There are so many possibilities for boot looping.
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@skyethespy - I think he just tried a variation of the oven trick. Just using the heat gun to heat the GPU chip alone. Hopefully masking the rest of the board with foil so the heat and air flow don't damage the other components.
@skyethespy I also do this with a hot air rework gun. I have been 70% successful with a simple reflow. Not all of us have the big bucks Rossman does. If it fails, you've lost nothing except some time. BTW, out of the approximately 3 dozen reflows I have done over the years, the ones that worked have not failed again. So it's well worth the try.
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What does the onboard diagnostics telling you?
由 Dan 完成的
When I plug it in, the first indicator light flashes briefly, then I can’t get anything else by clicking the power button or anything.
由 Danny Dorazio 完成的