iMac Intel 27" EMC 2546 Logic Board Replacement

Starting on the left of the display, near the power button, insert the iMac Opening Tool into the gap between the glass panel and the rear case.

Use the tool like a pizza cutter—roll it along through the gap, and it will cut the foam adhesive through the center.

Run the tool up along the left side of the display.

Continue wheeling the tool up around the top left corner.

Cut the adhesive along the top left of the display.

Continue along the top of the display.

Push the tool around the top right corner of the display.

Wheel the tool down along the right side of the display.

Finish pushing the opening tool to the bottom of the right side of the display.

Set the iMac face-up on a table.

Starting from the top right corner of the iMac, insert a plastic card between the display and frame.

• Be careful not to insert it more than 3/8" (9.5 mm), or you may damage internal components.

Gently twist the plastic card to open the space between the display and frame, and cut any remaining adhesive near the corner.

• Using too much force will crack the glass. Work carefully, and don't try to create a gap any larger than about 1/4" (6 mm).

Slide the card toward the center of the display, to cut any remaining adhesive.

Put the card into the corner again and let it stay there to keep the adhesive from resettling.

Insert a second card into the gap between the display and frame in the top left corner.

Gently twist the card, slightly increasing the space between the display and frame.

Slide the plastic card toward the center, again stopping just before the iSight camera.

Insert the card back into the top left corner.

With the cards inserted as shown near the corners, gently twist the cards to increase the gap between display and case.

If there are any sections that seem to stick and won't separate, stop twisting and use one of the cards to cut the adhesive in the problem area.

Begin to lift the top of the display up from the frame.

While holding the display up with one hand, use the other to unplug the display power cable.

• Lift the display up enough to have easy access to the connections, but not so much that you stretch the cables and stress their connections (about 8").

Flip up the metal retaining bracket on the display data cable.

Disconnect the display data cable.

• This is a delicate connection that can easily be broken. Be sure to pull the display data cable connector straight out of its socket, toward the top of the iMac.

Lift the display up to a near-vertical position.

Remove as much of the adhesive as possible by grabbing it at the outer edges, and then pulling or rolling it towards the middle.

If necessary, a plastic card can be used to cut any remaining sections of the bottom adhesive strip.

Lift the display up from the frame and remove it from the iMac. Lay the display face down on a flat, soft surface.

It may be necessary to slowly lift from one side, to peel against the remaining adhesive.

With the hinge free to move, the iMac will be unbalanced and hard to work on. Repairs can be completed with the iMac laying down, but are faster and easier with an iMac service wedge.

Remove two 10.0 mm T10 screws.

Unplug the left speaker cable from its socket on the logic board. Be sure to pull straight up out of the socket.

De-route the cable from the gap between the hard drive and logic board.

Use a spudger to disconnect the power button connector from its socket on the logic board.

Lift the left speaker straight up, until the power button cable is exposed (about 0.5").

Gently de-route the power button cable from its groove in the left speaker.

Lift the left speaker straight up and remove it from the iMac.

Pull straight up on the SATA data/power cable to disconnect it from the drive.

Remove two 7.3 mm T10 screws securing the left hard drive bracket to the rear case.

Grab the hard drive and left hard drive bracket together.

Tilt the left side up away from the rear case, and slide the assembly to the left.

Remove the hard drive and left hard drive bracket from the iMac.

Remove the left hard drive bracket.

Disconnect the power supply control cable from the power supply.

Remove the following four screws securing the power supply to the rear case (size T8 or T10 depending on the exact model):

• Two 23.7 mm Torx screws
• Two 7.3 mm Torx screws

Move the power supply board towards the left edge of the case and up to free it from the notch in the logic board.

Depress the tab on the DC power cable connector, then pull it straight out of its socket on the back of the logic board.

Flip the top of the power supply towards you, like opening a mailbox, to reveal the AC inlet cable connector.

Disconnect the AC inlet cable connector.

Remove two 10.0 mm T10 screws.

Gently rock the right speaker slightly to the right, to allow access to its cable's connection on the logic board.

Use a spudger to loosen the right speaker cable's connector from its socket on the logic board.

Pull the connector to the right to remove it from its socket.

Lift the speaker straight up and remove it from the iMac.

Use the tip of a spudger to disconnect the fan cable's connector from its socket on the logic board.

Peel the black tape connecting the fan to the exhaust duct back slightly.

Leave the tape in place on the exhaust duct, you only need to expose the joint to free the fan.

Remove three 12.4 mm T10 screws securing the fan to the rear case.

Remove the fan from the iMac.

Use the flat end of a spudger to disconnect each of the four antenna connectors from the AirPort/Bluetooth card.

Flip up the metal retaining bracket on the iSight camera cable.

Pull the camera cable connector straight out of its socket, toward the top of the iMac.

Use the flat end of a spudger to disconnect the headphone jack cable connector from its socket on the logic board.

Gently push the cable out of the way.

Remove the following screws from the front of the logic board:

• Two 23.7 mm T10 screws
• Four 7.4 mm T10 screws
• One 20.8 mm T25 spacer screw
• One captive T10 screw

  • This screw is beneath a hole in the logic board. You'll need a fixed screwdriver or the 60 mm extension from an iFixit driver kit to reach it.

Pull the cable and connector through the right hard drive bracket. Move the cable to the right side of the iMac, out of the way of the exhaust port.

Remove two 5.7 mm T10 screws from the top of the heat sink exhaust duct.

Tilt the logic board slightly forward.

Lift the logic board straight up and out of the iMac. Be careful not to snag on any of the screw posts attached to the inside of the rear case.

When reassembling your iMac, be very careful to align the exterior I/O ports correctly. The logic board can sit crooked even when secured with all its screws.

You can use a USB flashdrive or ethernet cable to ensure the logic board is seated correctly while you screw it in.

Pull up on the SATA power cable connector to disconnect it.

Unplug the SATA data cable connector by lifting it up.

Remove the SATA cable from the logic board assembly to get it out of the way and prevent it from being damaged.

Remove the four 7.5 mm T8 screws from behind the GPU on the logic board.

Remove the bracket from behind the GPU heat sink.

Remove four black stickers from the back of the CPU heat sink.

Remove four 12.3 mm T10 screws from the back of the CPU heat sink.

Remove the spring plate from behind the CPU heat sink.

Lift and remove the backing plate from behind the CPU heat sink. The backing plate has two posts that fit into alignment holes in the logic board.

Lift the heat sink up from the logic board.

Use your thumbs or index fingers to unlock the tray by pushing the tabs outward, away from the RAM.

Pull the tabs out and up, swinging the RAM tray up to a near-vertical position.

Remove a stick of RAM by grabbing it with two hands and pulling straight out of the RAM tray.

Remove any remaining sticks of RAM.

Remove two 3.7 mm T5 screws from the back of the logic board.

Lift the end of the AirPort/Bluetooth Card up slightly and pull it straight out of its socket on the logic board.

Remove the single 5.3 mm T8 screw securing the SSD to the logic board.

Lift the end of the SSD up slightly and pull it straight out of its socket on the logic board.

Remove the power supply cable from its connector by pulling it parallel to the logic board.