Mac Repair Central

Removing the Logic Board

Note: Some of these photos are taken from the original iMac G5 logic board take apart since the procedure is very similar.

1. At the top of the logic board, near the fan, disconnect the two fan cables and the two hard drive connectors.

2. Remove the two video cable screws and disconnect the video cable.

3. Disconnect the hard drive thermal sensor (near the memory slots) from the logic board. Leave the other end of the thermal sensor attached to the hard drive.

4. Using a T-8 screwdriver, disconnect the two fan duct screws and lift the duct off the logic board. Note: These two screws are longer than the other silver screws securing the logic board to the midplane chassis.

5. Disconnect the lower fan cable.

6. Disconnect the two connectors (microphone and speakers). Note: Pull on the connector, not the cables.

7. Disconnect the power supply cable and the ambient light sensor.

8. Using a T-10 screwdriver, remove six silver logic board screws and with a Phillips #2 screwdriver, remove the three brass screws on the logic board. Note: The numbers are for replacement order, disregard for take-apart.

1. Carefully lift the logic board out of the midplane chassis.
2. Look on the back side of the logic board for the light pipe. Remove the light pipe and place it on the replacement logic board.
3. Look on the back side of the logic board for the light pipe. Remove the light pipe and place it on the replacement logic board.

11. If you don't see the light pipe on the back of the logic board, it may be stuck in the chassis (shown below). Use a needlenose pliers to remove the light pipe.

12. Return the logic board to Apple in the packaging provided.

Replacing the Logic Board

1. Locate the cleaning wipe and syringe in the replacement logic board box.

Replacing the Logic Board

1. Locate the cleaning wipe and syringe in the replacement logic board box.

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2. Clean the copper heatpad (circled). Use the alcohol wipe to clean the copper heatpad.

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2. Clean the copper heatpad (circled). Use the alcohol wipe to clean the copper heatpad.

3. Whenever you remove the logic board clean the U3 chip (circled) and reapply thermal grease.

4. Add 1 1/2 to 2 syringes of thermal grease to the U3 chip to ensure sufficient cooling. Spread the paste evenly across the surface of the chip.

Locate the light pipe gasket on the replacement board. Peel the adhesive backing off of the gasket.

7. Before placing the logic board into the midplane chassis, move or tape the cables (shown below) out of the way.

1. Lower the logic board into the chassis. Caution: Do not twist, bend or flex the board as you lower it into the chassis. Flexing the board may jeopardize the thermal interface between the heartsink and the processor. Make sure the light pipe seats properly into the bottom left corner and that the cables are not caught under the board.
2. Lower the logic board into the chassis. Caution: Do not twist, bend or flex the board as you lower it into the chassis. Flexing the board may jeopardize the thermal interface between the heartsink and the processor. Make sure the light pipe seats properly into the bottom left corner and that the cables are not caught under the board.

9. Connect the microphone and speaker cables to the logic board.

10. Using a T-10 screwdriver, replace the six silver torx logic board screws. Use a Phillips #2 to replace the three brass screws. Note: Make sure the hard drive cables are not obstructing the screw hole at the top of the logic board.

11. Connect the power supply cable and the ambient light sensor.

13. Connect the hard drive thermal sensor (near the memory slots) to the logic board.

14. Using a T-8 screwdriver, connect the two fan duct screws. Note: These two screws are longer than the other silver screws securing the logic board to the midplane chassis.

15. Connect the video cable to the logic board and replace the two screws.

16. Reconnect the hard drive and fan cables to the logic board.

1. Replace the memory.
2. Replace the inverter.
3. Replace the optical drive.
4. Replace the AirPort and Bluetooth card and connect the antennas.
5. Replace the modem.
6. Replace the fan cover.
7. Replace the back cover.

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