Introduction

The 24-inch 2007 and 2008 iMac's have four diagnostic LEDs on the logic board that can help troubleshoot the computer. A little disassembly is required to locate and observe the LED's. This guide is based on information sourced from the applicable Apple service manual.

**LED interpretation is also applicable to the iMac Intel 20" EMC 2133 and 2210**

Image 1/1: This screw is captive in the access door.
  • Loosen the single Phillips screw in the center of the access door.

  • This screw is captive in the access door.

  • Remove the access door from your iMac.

PH2 head necessary to remove screw.

airshack - Reply

  • The glass panel is fixed onto the front bezel with fourteen magnets around its perimeter.

  • Stick two suction cups to opposing corners of the glass panel.

  • To attach the suction cups we sell, first position the suction cup with the movable handle parallel to the face of the glass panel. While lightly holding the suction cup against the glass, raise the movable handle until it is parallel with the other handle.

  • If your suction cups refuse to stick, try cleaning both the glass panel and the suction cup with a mild solvent such as Windex.

Save $15 dollars and use a plunger. Works perfectly.

Michael Ybarra - Reply

Even better and more elegant: go to a household shop and buy two transparent plastic bathroom baskets with two suction cups each. I found them in Xenos in the Netherlands (maybe also in Germany).

freed - Reply

Perhaps not so elegant but equally effective without any adverse effects to either... try a vacuum cleaner.

Andrew Dobson - Reply

Image 1/1: The glass panel has several positioning pins around its perimeter. To avoid shearing these pins off the glass panel, be sure to only pull straight up during removal.
  • Gently pull the glass panel straight up off the iMac.

  • The glass panel has several positioning pins around its perimeter. To avoid shearing these pins off the glass panel, be sure to only pull straight up during removal.

  • Be meticulous about cleaning the LCD and the inside face of the glass panel before reinstallation, as any fingerprints or dust trapped inside will be annoyingly visible when the display is on.

The glass panel is somewhat thin and should come away quite easily without much force so be gentle.

adamngordon - Reply

Just an FYI - my glass panel did not line up perfectly when reinstalled. Off by just 1mm. May take another attempt at it later, but does not interfere with the iSight camera. Only someone with an eagle-eye (like me) will notice it's not perfect.

ajpfl - Reply

To reinstall the glass, I lined up the bottom edge first, then pivoted the top in. The magnets pulled it quickly into place.

Magnus Dalen - Reply

I didn't want to use such small suction cups.. so I got suction bathroom handles from Home Depot. Very sturdy and to me, safer choice.

Gail - Reply

Image 1/1: Eight 13 mm T8 Torx screws
  • Remove the following 12 screws securing the front bezel to the rear case:

    • Eight 13 mm T8 Torx screws

      • Alternatively, you might have six 13 mm and two 25 mm T8 Torx screws

    • Four 25 mm T8 Torx screws

      • Alternatively, you might have two 25 mm (outer) and two 35 mm (inner) T8 Torx screws

I only had two 25 mm T8 Torx on my model. (The two inner orange circles as shown in the diagram.)

stevejansen - Reply

I don't know if this is different but i am in the process of disassembling a 24' imac emc: 2134. i have only: (2) 25 mm T8 screws the inner two on the bottom of the screen. I have (4) 13 mm t8 screws the outer most holes on the bottom and the 2 holes on the right side of the monitor above the drive entrance and the remaining holes are (6) 11 mm t8 screws

ccarter314 - Reply

I have the same screws as ccarter on a 2211 except on the bottom row there are only 4 screws total, the longer ones go in the middle two.

maccentric -

The Torx set I bought from ifixIt is well worth the money. My screw heads in this step were T9 not T8. THe T8 bit was too sloppy in the screwhead and there was a risk of rounding the slots. Having the option to go a size-up was perfect.

Troy - Reply

My 2211 has a different screw configuration.

2 - 32mm long screws towards the middle of the bottom edge

4 - 18mm long screws (2 at the corners of the bottom edge and 2 along the right edge)

6 - 13mm screws along top and left edges

christian - Reply

I have the same screws as Christian. The key is to make sure all screws are flush to the surface, so that the glass can be held up by the magnets.

Kelvin Lau - Reply

On mine, for the red circles, I had the six 13mm Torx plus two 25mm Torx. It's not indicated in the picture here, but the 25mm Torx went on either side of the optical drive.

JD Fox Micro - Reply

I marked next to each hole with a pencil "S, M or L" to indicate which length screw goes where. No guess work on reassembly.

Magnus Dalen - Reply

Image 1/2: Gently lift the front bezel from its top edge off the rear case. It helps to use your thumbs to push down very gently on the corners of the display. Image 2/2: Once the top edge of the front bezel has cleared the rear case, rotate the front bezel toward the stand and lift it off the rear case.
  • The front bezel is still attached to the iMac by the microphone cable.

  • Gently lift the front bezel from its top edge off the rear case. It helps to use your thumbs to push down very gently on the corners of the display.

  • Once the top edge of the front bezel has cleared the rear case, rotate the front bezel toward the stand and lift it off the rear case.

  • When reinstalling the front bezel, start at the lower edge and make sure it is flush with the rear case before lowering the top edge onto the iMac.

The microphone cable must be disconnected BEFORE rotating the bezel towards the stand.

Also, the bezel covers the sides of the case, not just the front. This isn't obvious from the pictures.

wallace - Reply

Looking at the meaning of the LEDS

i've got 3 LEDS on but i don't get a chime or the screen.

i am going to check the inverter voltages but can only find info for the 20" macs iMac Intel 20" EMC 2210 Power Supply Output Voltage Test

does anyone know where i can get info for the 24"

samraby - Reply

i have the same thing, 3 LEDs on but no chime and no screen.

what is the fix? and problem?

Bill -

I'm in the same position. 3 LED's, No chime, no life in the screen, Optical drive starts up but no other signs of life i.e.:fans also don't start up.....

Any guidance would be greatly appreciated!!

Dominik - Reply

Image 1/1: For the front bezel to sit properly, be sure to tuck the microphone cable and connector into the void next to the camera board.
  • Disconnect the microphone cable connector, removing tape as necessary.

  • For the front bezel to sit properly, be sure to tuck the microphone cable and connector into the void next to the camera board.

I didn't disconect the cable. I was working on a large table that allowed me to carefully flip the bezel upside down and rest it that way with the cable connected through the entire process.

fulker - Reply

I also skipped disconnecting the microphone cable. I have a large table and I stacked some books next to the iMac. There was plenty of cable for the bezel to fold nicely over the top of the iMac.

mikkorongas - Reply

I needed to move the bezel away, so disconnected the cable. On reassembly found that the pins had pulled out of the plastic housing. Need to know orientation of the 3 wires in the housing.

prreitz - Reply

I used the floor instead of a table and left the cable connected.

Frank Carrano - Reply

Image 1/1: Locate the Diagnostic LED's between the RAM slots and the SATA connector.
  • To observe the LED's you need to apply power to the iMac with the front bezel off. Please ensure you don't touch any part of the iMac or the exposed circuit boards while you have power connected.

  • Locate the Diagnostic LED's between the RAM slots and the SATA connector.

  • The LED's are numbered 1-4 from left to right. You may need to move the SATA cable to get a clear view of the LED's.

  • If you are using this guide for iMac Intel 20" EMC 2210 and 2133 the LED's are located above the SATA connector and not as visible.

  • 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.

I have LED 1,2 and 3 lighting up, LED 4 is off. Does that indicate a videocard issue?

nbeijer - Reply

3 leds appear to be the correct status - LED power supply and logic board tests

Gwyn Evans -

LED 1 lights when I plug in the power. As soon as I touch the power button, LED 1 goes off, and nothing else. All LEDs are off. Unplug and replug and LED 1 lights. This indicates there's no problem with the power supply.

I'm fixing the oft-defective NVIDIA GeForce 8800 GS GPU. I reflowed the GPU and am in the process of seeing if the reflow worked. Before disassembly, the machine could turn on. Now nothing. During the process, I cracked the connector on the power inverter cable that goes from the power supply to the back of of the display.

In my interest to get my iMac together, I placed the single dangling wire on its pin, then placed the two intact sides of the inverter connector on either side. (Gluing the connector together just didn't work.) I plan to order a replacement cable as soon as I can.

Could this wonky cable connection cause the whole system to not function? I think it could, but thought I'd ask. Any other thoughts or gotchas from people who've done this type of work?

walkingwired - Reply

Ok, display is black, I have led #1 lit when power is connected, led #2 comes on and stays on when power button is pressed, the fans come on, it checks the optical drive, I hear faint hard drive noise, but led #3 & led #4 do not come on. And I do not get a startup sound. What would this indicate?

ferglesharky69 - Reply

2008 24" iMac EMC 2211 Model 8,1 no power. I removed bezel and looked for Led lights. Non lit up. I'm thinking power supply? Thoughts. Video card? Thanks in advance.

harley24052000 - Reply

Conclusion

To reassemble your device, follow these instructions in reverse order.

32 other people completed this guide.

Richdave

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3 Comments

Hello,

I have iMac 2008 24" When I turn on the computer no startup sound but DVD / Motherboard / CPU Fan is still on. also two green LED is static on, anyone help me....

Raza

Syed Irfan Raza Abidi - Reply

Does anybody know where I can buy the thermopads for the 4 chips on the video card. The ones it already had were all melted and can't reuse them. I appreciate your time and help. Thank you.

Jesus Juarez - Reply

Does anybody know where I can buy the thermal pads to put on the 4 chips on the video card? Any help is very appreciated. Thank you.

Jesus Juarez - Reply

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