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Model A1225 / Early 2009 / 2.66, 2.93, or 3.06 GHz Core 2 Duo processor

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Is my power supply bad?

I have an A1225 24" iMac that is not booting consistently.


  • Often black screen with no chime, although I can hear hard drive/optical drive or fans spin up briefly.
  • Once I got a half chime and screen worked until chime quit
  • Twice it started to the OS X recovery screen - I tried to install the OS, it stayed alive enough to download and then half install.

What I tried:

  • PRAM reset - could not tell if anything happened

Current LED light status:

  • 1st LED lit (current coming in from wall),
  • 2nd LED is a sporadic, mostly off condition, but will come on occasionally -- seems aligned with when the spin up of fan or drive happens. (makes me think power supply bad)
  • 3rd LED blinks - but only when 2nd LED is on
  • I have not observed the 4th LED going on

I see the power supply is $120 here - would that likely fix this, or is there a good chance there is something else wrong?

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Sounds like a failing power supply to me. I'd pull it and check for cold solder joints before replacing it as it does work sometimes. Here's how to try to spot them:


Here's what Apple says:

LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

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If unit is completely powering off during these installs, then power supply. If LEDs, fans, etc.. are still running, you may be experiencing a bad display. Connecting an external display to the computer during these trials will shed more clarity as to what is functioning and what is not... All depends on activity of LEDs.

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I would agree if #2 LED stayed on, but it does not.


Yes, but with LED 1 lit, voltage available, suggest issues other than power supply. Look at video card. remove video card and see if you boots properly..


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