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Current version by: Benjamin Luman ,

Title:

iMac doesn't boot. Only left LED on Logic Board is lit

Text:

My Mid 2011 27" iMac EMC 2429 will not boot. The display doesn't come on, out of the 4 LED's on the Logic Board, only the 1st LED lights up, the other three are not.

My question is, I know it's not the PSU because the Logic board recognizes that it's getting power. Could it potentially be  a failed Logic Board? and what does it cost to get it replaced?

Upon further inspection:

Removal of LCD screen. When powering on, there is some noise of noise activity from the PSU. No other activity seen or heard from other components. Upon holding the power button for 5 seconds, sequencing a hard shut down of the system; the noise level of the PSU drops from a 5 to a subtle 2. Upon further inspection of the PSU, there is an white-ish discoloration around the border of the unit (shown in pictures).The middle of the unit, excluding the border has a glossy, almost oily presentation.

Upon testing voltage of Pin 11, we have a 12.01V reading on the voltmeter.

No voltage reading from Pin 4.

Coin battery voltage measures at 3.0V.

[image|852460]

[image|852462]

[image|852459]

[image|852456]

Device:

iMac Intel 27" EMC 2429

Status:

open

Accepted Answer:

316139

Edit by: oldturkey03 (vote details) ,

Title:

iMac doesn't boot. Only left LED on Logic Board is lit

Text:

My Mid 2011 27" iMac EMC 2429 will not boot. The display doesn't come on, out of the 4 LED's on the Logic Board, only the 1st LED lights up, the other three are not.
 
My question is, I know it's not the PSU because the Logic board recognizes that it's getting power. Could it potentially be a failed Logic Board? and what does it cost to get it replaced?
 
Upon further inspection:
 
Removal of LCD screen. When powering on, there is some noise of noise activity from the PSU. No other activity seen or heard from other components. Upon holding the power button for 5 seconds, sequencing a hard shut down of the system; the noise level of the PSU drops from a 5 to a subtle 2. Upon further inspection of the PSU, there is an white-ish discoloration around the border of the unit (shown in pictures).The middle of the unit, excluding the border has a glossy, almost oily presentation.
Removal of LCD screen. When powering on, there is some noise of noise activity from the PSU. No other activity seen or heard from other components. Upon holding the power button for 5 seconds, sequencing a hard shut down of the system; the noise level of the PSU drops from a 5 to a subtle 2. Upon further inspection of the PSU, there is an white-ish discoloration around the border of the unit (shown in pictures).The middle of the unit, excluding the border has a glossy, almost oily presentation.
 
Upon testing voltage of Pin 11, we have a 12.01V reading on the voltmeter.
No


No
voltage reading from Pin 4.
Upon testing voltage of Pin 11, we have a 12.01V reading on the voltmeter.
No


No
voltage reading from Pin 4.
 
Coin battery voltage measures at 3.0V.
 
[image|852460][image|852462][image|852459][image|852456image|852460]

[image|852462]

[image|852459]

[image|852456
]
[image|852460][image|852462][image|852459][image|852456image|852460]

[image|852462]

[image|852459]

[image|852456
]

Device:

iMac Intel 27" EMC 2429

Status:

open

Accepted Answer:

316139

Edit by: Benjamin Luman ,

Title:

iMac doesn't boot. Only left LED on Logic Board is lit

Text:

My Mid 2011 27" iMac EMC 2429 will not boot. The display doesn't come on, out of the 4 LED's on the Logic Board, only the 1st LED lights up, the other three are not.
 
My question is, I know it's not the PSU because the Logic board recognizes that it's getting power. Could it potentially be a failed Logic Board? and what does it cost to get it replaced?
 
ThanksUpon further inspection:

Removal of LCD screen. When powering on, there is some noise of noise activity from the PSU. No other activity seen or heard from other components. Upon holding the power button for 5 seconds, sequencing a hard shut down of the system; the noise level of the PSU drops from a 5 to a subtle 2. Upon further inspection of the PSU, there is an white-ish discoloration around the border of the unit (shown
in advance.pictures).The middle of the unit, excluding the border has a glossy, almost oily presentation.

Upon testing voltage of Pin 11, we have a 12.01V reading on the voltmeter.
No voltage reading from Pin 4.

Coin battery voltage measures at 3.0V.

[image|852460][image|852462][image|852459][image|852456]
ThanksUpon further inspection:

Removal of LCD screen. When powering on, there is some noise of noise activity from the PSU. No other activity seen or heard from other components. Upon holding the power button for 5 seconds, sequencing a hard shut down of the system; the noise level of the PSU drops from a 5 to a subtle 2. Upon further inspection of the PSU, there is an white-ish discoloration around the border of the unit (shown
in advance.pictures).The middle of the unit, excluding the border has a glossy, almost oily presentation.

Upon testing voltage of Pin 11, we have a 12.01V reading on the voltmeter.
No voltage reading from Pin 4.

Coin battery voltage measures at 3.0V.

[image|852460][image|852462][image|852459][image|852456]

Device:

iMac Intel 27" EMC 2429

Status:

open

Original post by: Benjamin Luman ,

Title:

iMac doesn't boot. Only left LED on Logic Board is lit

Text:

My Mid 2011 27" iMac EMC 2429 will not boot. The display doesn't come on, out of the 4 LED's on the Logic Board, only the 1st LED lights up, the other three are not.

My question is, I know it's not the PSU because the Logic board recognizes that it's getting power. Could it potentially be  a failed Logic Board? and what does it cost to get it replaced?

Thanks in advance.

Device:

iMac Intel 27" EMC 2429

Status:

open