iMac Intel 21.5" EMC 2428 CPU Replacement

Unplug your iMac's AC cord along with any peripheral devices.

Lay your iMac face-down on a soft, clean surface as shown.

Loosen the three Phillips screws securing the access door to the bottom edge of your iMac.

Remove the access door.

Gently slide the black plastic RAM pull tab out from the RAM slot.

Pull the black plastic tab away from the bottom edge of the iMac to eject the module(s) on that side of the RAM bay.

Slide the old RAM module(s) out of their slots in the RAM bay and set them aside.

Repeat the process in the previous steps to remove the RAM module(s) from the other side of the RAM bay.

Be sure the small notch cut into each RAM module (shown in the first picture) mates with the protrusion in each RAM slot (shown in the second picture).

Stick a suction cup near each of the two top corners of the glass panel.

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

Gently lift the glass panel perpendicular to the face of the LCD enough to clear the steel mounting pins attached along the underside of the top edge of the glass panel.

Pull the glass panel away from the lower edge of the iMac and carefully set it aside.

Remove the eight 8 mm T10 Torx screws securing the display to the outer case.

Slightly lift the top edge of the display out of the outer case.

Pull the vertical sync cable connector out of its socket on the LED driver board near the top left corner of your iMac.

Rotate the display out of the outer case enough to disconnect the LED backlight power cable from the LED driver board.

Grab the plastic pull tab secured to the display data cable lock and rotate it towards upwards.

Pull the display data cable straight out of its socket on the logic board.

Disconnect the LCD thermal sensor cable connector from its socket on the logic board.

Carefully pull the display toward the top edge of your iMac and lift it out of the outer case, minding any cables that may get caught.

Remove the following four screws:

One 9.3 mm T10 Torx screw with a large head

Three 9.3 mm T10 Torx screws with a normal sized head

Pull the optical drive thermal sensor connector straight up from its socket on the logic board. Pull parallel to the board.

Lift the inner edge of the optical drive and maneuver its connector past the GPU frame attached to the logic board.

Carefully pull the optical drive off its mounting pins on the right side of the outer case to gain clearance for disconnecting the optical drive cable.

Allow the optical drive to hang down as you de-route the optical drive thermal sensor connector from behind the GPU heat sink.

Disconnect the optical drive cable by pulling its connector away from the optical drive.

Remove the optical drive from the iMac.

Remove the single 13 mm T10 Torx screw securing the optical drive fan to the outer case.

Pull the optical drive fan off the pins attached to the outer case.

Pull the optical drive fan connector away from its socket on the logic board.

Remove the optical drive fan from the iMac.

In the proceeding steps, you will disconnect the following cables:

SD Board

Left/Right Speaker and Microphone

Audio Port

Wi-Fi Antenna

Right Temperature Sensor, Bluetooth/Ambient Light Sensor/Camera/Left Temperature, and Hard Drive Fan

CPU Fan/Ambient Temperature and Power Button

IR Sensor

Pull the SD board cable out of its socket on the logic board.

Disconnect the microphone, left speaker, and right speaker cables by pulling their connectors toward the right side of the iMac.

Use the flat end of a spudger to pry all three AirPort antenna connectors up from their sockets on the AirPort board.

Pull the hard drive fan connector toward the top edge of the iMac to disconnect it from its socket on the logic board.

Use your thumbnails on both sides of the Bluetooth/ambient light sensor/camera/left temperature connector to push it toward the top edge of the iMac and out of its socket on the logic board.

Use your thumbnails to push the right temperature sensor connector toward the top edge of the iMac and out of its socket.

Pull the CPU fan/ambient temperature sensor connector toward the bottom left edge of the iMac and out of its socket on the logic board.

Pull the power button connector toward the bottom left corner of the iMac to disconnect it from its socket on the logic board.

Use your thumbs to push the IR sensor connector toward the top edge of the iMac and out of its socket on the logic board.

Pull the IR sensor board up from behind the front face of the outer case.

Remove the IR sensor and set it aside.

Pull the audio port cable connector toward the left side of the iMac to disconnect it from the logic board.

Peel the audio port cable off the front face of the logic board and let it hang down as shown in the second picture.

Remove the following seven screws:

Two 7 mm T10 torx screws

One 30 mm T10 Torx screw

Two 25 mm T10 Torx screws

Two 21 mm T10 Torx screws

Remove the following four screws:

One 9.3 mm T10 coarse-threaded screw

One 25 mm T10 coarse-threaded screw

Two 22 mm fine-threaded screws

Pull the upper right and lower left corners of the power supply away from the rear case to dislodge the mounting posts attached to the power supply's corners.

Carefully lift the power supply out of the outer case and rotate it to expose the cable lock as shown, minding the DC-out and AC-in cables still attaching it to the iMac.

Disconnect the DC-out cable by depressing the locking mechanism on the connector while you pull the connector away from its socket on the power supply.

Once the locking mechanism has cleared the socket, pull the DC-in connector away from the power supply.

Disconnect the AC-In cable by depressing the locking mechanism while pulling the connector away from its socket.

Remove the power supply from the outer case.

Remove the plastic wall that is installed directly to the right of the LED driver board.

Slightly pull the logic board away from the back of the outer case, then lift it upward to clear the lower front face of the outer case.

Disconnect the LCD temperature cable by pulling its connector up and out of its socket on the logic board.

Depress the locking mechanism and carefully pull the DC-In cable out of its socket on the back of the logic board.

Being careful not to damage the socket on the logic board, gently pull the hard drive SATA data cable straight out of its socket on the logic board.

Pull the hard drive power cable connector out of its socket on the logic board.

Remove the logic board from the outer case, minding any cables that may get caught.

Peel the piece of tape covering the heat sink thermal sensor cable up off the logic board.

Lift the heat sink thermal sensor connector straight up out of its socket on the logic board.

If present, remove the "Warranty void if removed" sticker covering one hidden screw on the heat sink.

Remove the following five screws securing the heat sink to the logic board:

Four 6.4 mm T8 Torx screws

One 4.3 mm T10 Torx screw

Carefully lift the logic board off the heat sink.

Carefully pull the CPU retaining bar away from the CPU socket.

Rotate the bar away from the logic board.

Carefully lift the CPU straight up off its socket.