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Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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[SOLVED] Missing capacitor c5501 on iMac emc2428 logicboard?

Hi all

I have a quick question today I disassembled an iMac EMC2428 because it is not starting anymore and see something I think is wrong. I suspect that 2 capacitors are missing on the logic board. C5501 and the one next to it.

Can someone tell me if this is normal?

Please see attached picture for details.

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Thanks a lot


I received new capacitor and soldered them. All is working fine now .

Thanks to all


Answered! View the answer I have this problem too

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search for your board number somewhere on the logic board. It should read 820-xxxx. With the board number make a search on google to find the board schematic, it’s a pdf file. Once you have the schematic open the file and make a search for C5501 and C5511 (not sure of the last one). Now you’ll see the two capacitors description and if you see “NO STUFF” it’s indicate that the two components are no present. If they should be there you’ll have the capacitors values so you’ll know which capacitors you need to find to replace them.

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Thank you I just found and the C5501 is for AMBIENT temp sensor

the C5511 is for ODD Temp sensor.

0.0022UF 50v

I must find some parts to replace them or can I leave that like this ?

The base problem for the iMac was the power Button where the ring inside was lift out so no power button effect. This is repaired.

But I don’t know if I could mount the logicboard back without the capacitors.


You checked with the schematic and the capacitors should be on the board ? No "NO STUFF" mention ? Since they are "Temp sensors" they monitor temperature so I think the board would work but fans will spin max speed. Someone can confirm this ?


Hi I can confirm that the fan run at full speed without them.

I am waiting the capacitors to be delivered to replace them and test with them.



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Here’s a snapshot of the schematic

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Yes I wait for capacitors to be delivered and will be back to say if it works. I hope nothing other is damaged by this missing components...



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Hi Pierre,

do you know if anyone has opened the device before you? if not I wouldn’t worry too much about it as i have seen many boards with pads for capacitors and resistors that simply were not used. possible a different model had a feature that utilized those spots but instead of producing two entirely different boards the simply left off the un-needed parts. it would be odd for someone to remove the caps and just leave it like that. there seem to be several spaces empty on that board for resistors and caps alike. see if you can find any info on their intended function maybe try to find the board schematic to shed some light on certain parts and their role in the overall workings of the board?

I work for a small electronics repair company and while I wish it was as simple as replacing a missing part the actual solution nearly always comes from some existing pat not doing their job. follow the traces and check voltage values where you can and you will find your answers . hope this helps

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@yeswedofix - Hi Matt, Please create a business page and put your contact details there. We strive to keep self promotion to the business card. You are encouraged to point people to it from your answer.


Thanks for your answer I don't know if the mac was opened. My customer buy it refurb he use it and got startup problem. The power switch was too pressed and the ring lift out.


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Pierre Gagliardi will be eternally grateful.
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