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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**

  1. Loosen the single Phillips screw in the center of 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 - Yanıt

    • 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 - Yanıt

    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 - Yanıt

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

    Andrew Dobson - Yanıt

    The same kind of suction cups are available from Harbor Freight Tools (Item # 62715) for $2.99 each or $5.98/pair (plus sales tax).

    Bob Atkinson - Yanıt

  2. Gently pull the glass panel straight up off the iMac.
    • 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 - Yanıt

    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 - Yanıt

    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 - Yanıt

    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 - Yanıt

  3. Remove the following 12 screws securing the front bezel to the rear case:
    • 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 - Yanıt

    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 - Yanıt

    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 - Yanıt

    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 - Yanıt

    Mine is the same — two very long, four medium, and six short. Also my T9 worked better than my T8 which was a bit loose.

    johann beda -

    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 - Yanıt

    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 - Yanıt

    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 - Yanıt

    I dropped my screwdriver on the lcd and nicked it. :(

    hewsey - Yanıt

  4. 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.
    • 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 - Yanıt

    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 - Yanıt

    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 - Yanıt

  5. Disconnect the microphone cable connector, removing tape as necessary.
    • 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 - Yanıt

    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 - Yanıt

    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 - Yanıt

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

    Frank Carrano - Yanıt

  6. 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.
    • 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 - Yanıt

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

    Gwyn Evans -

    Hi friend, Your model is 24” a1225 emc2211? I have exactly the same problem...

    According to the led test it is a problem of the connection of the display or the video card, but I am almost sure that it is power supply, Did you find any solution?

    Victor -

    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 - Yanıt

    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 - Yanıt

    Any update on this? I seem to be having the same problem.

    Hieu Nguyen -

    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 - Yanıt

    it’s possible, I have the same issue. The #1 light is on when plugged in but soon as I press the power button it is gone….then no lights at all. Let it sit for 10 minutes plug it back in …no lights …nothing. I think maybe the power supply. I don’t think you can tell if it’s anything else like the logic board unless you have a known working power supply.

    QuickTech -

    I removed my screen to put in a hdd but after i put lcd back the forth light didnt come on, no display or start up tone.. cant work it out!?

    airbrushkits - Yanıt

    Hi, I have a similar problem? Did you solve it?

    Daniele Sforza -

    On A1224 iMac i have LED 1 On. When I press power switch, led 2 turns on, but nothing more happens. I have not power on sound and fans do not turn on. What do you think is the issue? Videocard issue?

    Jorge Yerbito - Yanıt

    I have light one come on stays on as long as the power cords plugged in light to stays on as soon as it boots or whatever and it makes a sound like 3 stays on but light for does not come on and I have nose thing on my screen but the screen works great prior to me upgrading the paste on my GPU and CP

    Clark Heisler - Yanıt

    I get all four lcd lights on but nothing shows up on the lcd panel. Is there a way to test if it the panel or the inverter ?

    Kyle - Yanıt

    Chances are you have a bad Lcd. They have fluorescent tubes that make the screen light up. Try a very high powered flash light to check for an image. If you see an I make chances are you need a new Lcd panel.

    mamashannon4u -

    I had this issue with an old iMac that stood for ages and the onboard battery ran flat. Replaced it and the machine powered on but no beeps or display. 4th LED was off. Only once I had it apart I tried various RAM combinations and got the bong with that. Re-connected everything and all good, including the 4th LED and display. Check the ram with known good RAM and try a few times.

    Alistair Wallis - Yanıt


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

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8 Yorum


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....


Syed Irfan Raza Abidi - Yanıt

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 - Yanıt

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 - Yanıt

Imac would not boot up (LED #1 lit only) about 9 months ago so I replaced PSU at that time. iMac was working fine until recently when it would not boot up again. Only LED #1 lit so I replaced the PSU again thinking this would solve problem……it did not. Only #1 stays lit and SuperDrive starts to spin yet no fans or chime or screen.

Question: Any other checks before logic board needs to be looked at or replaced. Is it worth replacing logic board on 10 year old iMac? How long and any special tricks?

Thanks from Florida.

Andreas - Yanıt

Imac 24 2008 3.06ghz when turn on hear the chime screen on trying to boot up the bar under Apple logo starts moves about quarter way and stops

and would not move any further ,tried holding down all suggested sorts of key combinations no success .I also tried replacing new HDD ,after replacing and switch on screen comes on and display ? at this stage I loaded the Mac OS X Snow Leopard disc in the optical drive ,it starts spinning

the Apple Logo appears and below the logo a buffering circle starts spinning and carries on and on ,nothing else happens ,tried tuning computer on and off no success ,any suggestions what could be the fault.


Basheshar S Legha - Yanıt

I am also having some problem with led indications …. When i power plug plug into socket 1 led is constatnly lights, 2nd and 3rd leds on and off on and off… 4th led continuesly off.. any one gave suggestions for this problem.. i replace new power suply board also with ifixit support… but here is the problem… 2nd and 3rd on and off on and off…. What does it means any one explain.. please…

Ravi Komar - Yanıt

Hi all,

my iMac A1224 has the following Situation:

- LED 1: always on

- LED 2 and 3: Flashing every 6 Seconds

- LED 4: always off

Do i need a new Power Supply?

SebastianM - Yanıt

Hi all,

i replaced the power supply and it didnt fix my issue. The mag still does not switch on and boot. The LED behavior is still the same. Then i unplugged the power chord, pressed and hold the power button and plugged it on again. After a release and push again of the power button, the fans run up to full speed. LED 1-3 were constantly on. LED 4 is constantly off and there is no chime… The mac Still does not boot what could this be…?

SebastianM - Yanıt

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