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shanomurphy

macrumors newbie
Original poster
Jan 29, 2016
2
0
Model: Late 2009 iMac 27" A1312 2309 (Core 2 Duo)

Need some help please. I woke up one morning recently to find my iMac was dead to any input. It was working fine the night before, I didn't shut down and just let it go to sleep on it's own. There is zero response when the power button is pressed, no boot chime, no screen response, no fans/hard drives spin… nothing.

What I've tried so far:
  • Different power sockets, different power lead
  • Reset SMC
  • Replaced PRAM battery
  • Replaced iMac power supply
  • Removed graphics card
There is only one diagnostic led lit on the logic board (labelled LED601) when the iMac is plugged in:

24ll8br.jpg


There are 4 LEDs in total and it's the led furthest from the board edge that lights up. Strangely the service manual for this model seems to list the LEDS in an opposite order to my board:

23w9n5y.jpg


I assume the LED that is lit up must be LED 1? ( indicating that trickle voltage from the power supply has been detected by the logic board).

Does this mean that it's most likely a logic board fail? why would the logic board suddenly fail overnight when iMac was sleeping?
 
Last edited:

Samuelsan2001

macrumors 604
Oct 24, 2013
7,729
2,153
Model: Late 2009 iMac 27" A1312 2309 (Core 2 Duo)

Need some help please! I woke up one morning recently to find my iMac was dead to any input. It was working fine the night before, I didn't shut down and just let it go to sleep on it's own. There is zero response when the power button is pressed, no boot chime, no screen response, no fans/hard drives spin… nothing.

What I've tried so far:
  • Different power sockets, different power lead
  • Reset SMC
  • Replaced PRAM battery
  • Replaced iMac power supply
  • Removed graphics card
There is only one diagnostic led lit on the logic board (labelled LED601) when the iMac is plugged in:

24ll8br.jpg


There are 4 LEDs in total and it's the led furthest from the board edge that lights up. Strangely the service manual for this model seems to list the LEDS in an opposite order to my board:

23w9n5y.jpg


I assume the LED that is lit up must be LED 1? ( indicating that trickle voltage from the power supply has been detected by the logic board).

Does this mean that it's most likely a logic board fail? why would the logic board suddenly fail overnight when iMac was sleeping?

It's 7 years old and electronics fail with more frequency over time, eventually every piece of electronic equipment will just fail, that's just the nature of the beast. There is a reason most companies won't give more than 3 years warranty and never more than 5 years, and this is it.
 

shanomurphy

macrumors newbie
Original poster
Jan 29, 2016
2
0
It's 7 years old and electronics fail with more frequency over time, eventually every piece of electronic equipment will just fail, that's just the nature of the beast. There is a reason most companies won't give more than 3 years warranty and never more than 5 years, and this is it.
Yeah I understand that… I'm not complaining, I'm just trying to diagnose what component has failed.

I'm thinking it must be the logic board unless anyone else can offer some suggestions? I've actually sourced a used logic board from a 2009 core i5 iMac complete with CPU so I'm going to see if I can resurrect it with that. If it works it should also be a nice performance boost too compared to the Core 2 Duo it currently has. Heck if it works I could even potentially stick a 2011 model i7 cpu in there to really extend it's life some more! It is already a bit of a frankenstein as it has a 2011 GPU (6770M) and SSD :)
 
Last edited:
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