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Dustin
Dustin, Mac Support Specialist
Category: Mac
Satisfied Customers: 12697
Experience:  Over a decade putting the missing byte back into Apple. Also worked in The US Army as A Network Switching Systems Operator/Controller
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When pressing the power button on my mid 2011 27" imac I can

Customer Question

When pressing the power button on my mid 2011 27" imac I can hear the fan run for about 3 or 4 second then stops and starts again 3 to 4 seconds over and over and never get a chime.
Submitted: 17 days ago.
Category: Mac
Expert:  Dustin replied 16 days ago.

Welcome to Justanswer.com, my name is Dustin.
I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.

Expert:  Dustin replied 16 days ago.

Did you still need help with this issue?

If so, lets start by removing any USB sticks, SD cards, remove anything connected to the USB ports on your imac except your Keyboard , and mouse, and monitor.

Disconnect EVERYTHING besides the keyboard mouse and monitor.

T hen, shut down the machine, unplug it from power.. Then hold the power button for 20 seconds.

Then, plug it back in and try this repair first

Shut down your Mac.
Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
Turn on your Mac.
Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
Hold these keys until the computer restarts and you hear the startup sound for a second time.
Release the keys.

Then, see if the mac starts.. If it does, let me know as we have further repairs to do.

If it wont start, let me know if it shows any screens or errors and get back to me so we can carry out further steps as needed.

Thank you,

I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.

Dustin S.

Senior Technician and Network Switching Systems Operator / Maintainer.

Customer: replied 16 days ago.
Nothing of this worked , I had already done all of this.The fan tries to work and does for a few seconds over and over but does not and I get no chime or anything.
Customer: replied 16 days ago.
no
Expert:  Dustin replied 16 days ago.

Lets try this instead..

  1. Shut down the Mac.
  2. Plug in the MagSafe or USB-C power adapter to a power source and to your Mac.
  3. Using the built-in keyboard, press Shift-Control-Option on the left side of the keyboard, then press the power button at the same time.
  4. Release all keys, then press the power button again to turn on your Mac

Any change afterwords?

Customer: replied 16 days ago.
what is a Magsafe ?
Expert:  Dustin replied 16 days ago.

Just follow the steps with the power cord plugged in..

  1. Shut down the Mac.
  2. Using the built-in keyboard, press Shift-Control-Option on the left side of the keyboard, then press the power button at the same time.
  3. Release all keys, then press the power button again to turn on your Mac
Customer: replied 16 days ago.
Still does the same thing.
Expert:  Dustin replied 16 days ago.

Lets try this.

Lets remove, and then reinsert the ram.. This video will show you how

https://www.youtube.com/watch?v=k8Sj10wYXAI

If it wont work with both sticks.. Try one stick at a time.

If it still wont work or even do anything different.. Then next, we need to consider replacing the Pram battery

Its not the easiest task, but whats clear is that you are having a hardware fault.. Sometimes the steps above will cure it, it just depends on which module / hardware specifically is faulting.. But the steps above are a solid place to start trying to fix the issue.

Let me know if you get stuck or run into any issues,

Dustin S

Customer: replied 15 days ago.
Where can I get a diagnostic pin diagram to check voltage on the PSU and logic board on my mid 2011 27" imac mod. #A1312 ?
Expert:  Dustin replied 15 days ago.

At the moment, cant find a pinout. However, starting on page 35 and going through the deep dive steps of this guide, may help n arrow down the issue.

http://tim.id.au/laptops/apple/imac/imac_27_mid10.pdf

Customer: replied 12 days ago.
I replaced the power supply with new. Still got the same problem. When I plug the power cable into the back of the computer the fan tries to start without pressing the on/off button. But I can barely hear it and then it stops and then it tries to start again without pressing the on/off button and it does it over and over if I hold the on/off button down it will quit. If I press the on/off button again I can barely hear the fan try to start over and over . Any suggestions ? PLEASE
Customer: replied 12 days ago.
Still got the same problem. The troubleshooting guide says to replace the logic board. What do you think ?
Expert:  Dustin replied 12 days ago.

Did you follow it closely, starting with page 35 / deep dive..

Did the LED lights you seen match every step of the way for the end result of replacing the logic board?

If so, whats the exact model number of your Mac?

Customer: replied 12 days ago.
The only LED to light up was #1 and it lights up as soon as I plug in to 120 volts. I never do get a chime and I followed ever step and it lead me to replace logic board. I have one on the way should get it in a couple of days. I will let you know if that cure's the problem. Thanks
Expert:  Dustin replied 12 days ago.

Allright, it sounds like you were thorough, and if thats the only led you see..

A new logic board should do the trick.. When it arrives, Ill be here if you need anything,

Dustin S

Customer: replied 12 days ago.
I will let you know. Thanks again.
Expert:  Dustin replied 12 days ago.

Not a problem, and Im not trying to spam message you.. Its company policy that I always send the last reply of each conversation.

Dustin S