iMac (24-inch, M1, 2021, Four ports) Logic Board

Before You Begin

Remove the following parts before you begin:

Tools

2.5 mm hex nut driver
Antenna tool
Nylon probe (black stick)
Support wedges
Torx T3 screwdriver

Caution

This procedure requires System Configuration. After you’ve completed all removal and reassembly steps, learn how to initiate the System Configuration process.

Removal

Use the T3 screwdriver to remove the five T3 screws (923-05559) from the low-speed flex cable cowling on the adapter board.
Remove the low-speed flex cable cowling and save it for reassembly.
Use the flat end of the black stick to lift both ends of the low-speed flex cable off the connectors on the adapter board.
Peel off the foam pad from the speaker cable connector. Save the foam pad for reassembly.
Use the flat end of the black stick to lift the end of the speaker cable off the connector.
Peel off the polyester film tape from the display backlight cable connector. Save it for reassembly.
Pinch the sides of the end of the display backlight flex cable and slide it out of the connector.
Use the flat end of the black stick to press and hold the “PUSH” button on the zero-insertion force (ZIF) microphone flex cable connector. Then, slide the end of the microphone flex cable out of the connector.
Use the flat end of the black stick to press and hold the “PUSH” button on the ZIF audio board and power button cable connector. Then slide the end of the audio board and power button cable out of the connector.
Use the black stick to support the battery board cable. Then gently lift the end of the battery board cable off the connector.
Pull the tab to flip up the locking bar on the high-speed flex cable.
Slide the end of the high-speed flex cable out of the connector.
Pull the tab to flip up the locking bar on the camera and eDP flex cable.
Slide the end of the camera and eDP flex cable out of the connector.
Use the T3 screwdriver to remove the five T3 screws from the antenna grounding clips.
- (923-05174) (1)
- (923-05173) (2)
Use the antenna tool to lift the ends of the three antenna coaxial cables off the connectors.
Use the 2.5 mm hex nut driver to remove the two 2.5 mm hex nut screws (923-05573) near each of the fan cables.
Position the housing with the back facedown and the top closest to you.
Use ESD-safe tweezers to peel back the polyester film tab on the fan cable connector.
Use the flat end of the black stick to flip up the locking lever on the fan cable connector.
Spread the tips of the ESD-safe tweezers and insert one tip under the fan cable. Carefully slide the ESD-safe tweezers toward the fan to loosen the adhesive between the fan cable and logic board.
- Important
  - Don’t touch any of the small components on the logic board.
  - Keep the tweezers parallel with the logic board surface to prevent damage.
Gently slide the end of the fan cable out of the connector.
- Caution: Don’t bend or twist the fan cable.
Repeat steps 19 through 22 to remove the other fan cable.
Rotate the housing and position it with the logic board closest to you.
Use the 2.5 mm hex nut driver to remove the seven 2.5 mm hex nut screws from the logic board.
- 923-05573 (1–3)
- 923-05556 (4–7)
Move the flex cables out of the way as you tilt up the logic board. Then lift the logic board and low-speed flex cable out of the housing.
- Note: The low-speed flex cable is attached to the back of the logic board.

Reassembly

Move cables out of the way. Then position the logic board and low-speed flex cable in the housing.
- Caution: Don’t trap any loose cables under the logic board.
Use the 2.5 mm hex nut driver to reinstall the nine 2.5 mm hex nut screws into the logic board.
- 923-05573 (1–5)
- 923-05556 (6–9)
Route the shorter antenna coaxial cable (2) under the longer antenna coaxial cable (3). Use the blunt end of the antenna tool to press the ends of the three antenna coaxial cables to the connectors.
Use the blunt end of the antenna tool to press the ends of the three antenna coaxial cables to the connectors.
Use the T3 screwdriver to reinstall the five T3 screws into the antenna grounding clips.
- (923-05174) (1)
- (923-05173) (2)
Press the end of the speaker cable to the connector. Then reinstall the foam pad over the connector.
Slide the end of the display backlight cable into the connector. Then press the polyester film tape back to the display backlight cable connector.
Slide the end of the microphone flex cable into the connector.
Slide the end of the audio board flex cable into the connector.
Press the end of the battery board cable to the connector.
Slide the end of the high-speed flex cable into the connector. Then flip down the locking bar on the high-speed flex cable.
Slide the end of the camera and eDP flex cable into the connector. Then flip down the locking bar on the camera and eDP flex cable.
Slide the end of the right fan cable into the connector.
Press the polyester film tab to the right fan cable connector.
Slide the end of the left fan cable into the connector. Then flip down the locking lever on the left fan cable connector.
Press the polyester film tab to the left fan cable connector.
Press the ends of the low-speed flex cable to the connectors on the adapter board.
- Note: Ensure that the low-speed flex cable connectors are fully connected.
- Caution: Don’t bend the connectors.
Position the low-speed flex cable cowling over the connectors.
Use the T3 screwdriver to reinstall the five T3 screws (923-05559) into the low-speed flex cable cowling.