How to Install an LCD Display Driver Board for For iMac 21.5” 4K (2015–2019)

What You’ll Need:

• Your old iMac 21.5” 4K (2015–2019)
  
• LCD controller board kit (compatible with your iMac)

Buy LCD Display Driver Board for For iMac 21.5” 2K (2012–2017)

Buy LCD Display Driver Board for For iMac 21.5” 4K (2015–2019)

Tools Included:

• Display port to USB-C Cable (included)
• Display Adhesive Cutter (included)
  
• Replacement Display Adhesives for re-assembly (included)

Tools Not Included:

• Screwdrivers Kit

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• Double Sided tape

Installation Services Available

We offer installation services for all our display driver boards. Let our technicians ensure a flawless setup.

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Step-by-Step Guide:

This guide focuses on the 21.5” 4K (2015–2019), which all feature beautiful high-resolution retina displays. We'll walk you through how to disassemble the unit, remove unnecessary components, and install a compatible LCD controller board.

Step 1: Disassemble the iMac

Start by placing the iMac screen-down on a soft surface like a towel or foam pad to protect the glass.

1. Using a cutting wheel or opening tool, slice through the adhesive tape around the perimeter of the glass. Apple used adhesive to secure the front display in these models.
   
2. Gently lift the display — don’t pull it too far yet, as it’s still connected by two cables.
3. Disconnect the display data cable (usually an eDP connector) and the backlight power cable.

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Once disconnected, carefully set the display panel aside — this is the part you’ll keep and reuse as your new monitor.

Step 2: Remove Internal Components

To create space and avoid interference, remove the internal hardware that’s no longer needed. This includes:

• Hard drive and its bracket
• Power supply unit
• Cooling fans
• Logic board (motherboard)
• Speaker (optional)
  

Use the correct Torx screwdrivers (usually T8 and T10) and keep track of your screws. Take your time and remove cables gently to avoid damaging the frame.

The speakers can be left in place if they don’t interfere with mounting, but most users remove them to give more airflow and space for the controller board.

Step 3: Prepare and Mount the LCD Controller Boar

Before we start with installation of the display driver board, let's understand the important components on the board and which ports we will be using

Now it’s time to install your LCD display driver board.

Step 4: Check the Driver Board connections.

Step 5: Disconnect the built-in eDP cable from the iMac display panel.

Step6: Connect the new eDP cable from the kit to the driver board and to the display.

Step 7: Attach the backlight power cable to both the board and the display.

Step8: Connect the red controller board, and plug in DisplayPort and power cables.

Step9: Power on and wait for the green light — verify all connections.

Here is the all steps :

Step 10: Unscrew the power port connection from the inside of the device. Use the this slot at the back to route essential cables.

 

Step 11: Stick the controller board

You can use double-sided tape to secure the display driver board inside the iMac housing. and stick the controller board at back of your iMac for easier access(as show below).

Step 12: Test the Display

Before finalizing the setup, run a test:

1. Connect the controller board to your computer using Display port to USB-C Cable.
2. Plug in the power supply and turn the display on.
3. Use the OSD buttons to select the correct input if needed.

If everything is connected correctly, the iMac panel should power up and show your computer’s display.

If the screen stays black, double-check:

• That the eDP connector is fully seated.
• That the backlight cable is connected securely.
• That the controller board is receiving power.

Step 13: Clean Up and Reassemble 

Once you've confirmed everything works:

• Route the wires neatly inside the chassis. You can use small cable clippers where necessary.

• Tape or secure the controller board and buttons using the double-sided tape.
• Reattach the glass panel using new supplied adhesive strips.

Congratulations — your iMac is now a fully functional, high-quality external monitor.

This is how the final setup will look like:

       

Please Note: For obvious reasons, the USB-C cable and power adapter will stay outside the iMac.

In case the menu appears in a non-English language, please use the following steps to change it to English:

Refer to the photo below showing the menu instructions from the cable connection.

and heres a photo of the menu where language settings are located:

Use the following key combination to navigate to the language settings:

Change the language to English using this sequence:

Menu → Down (6 times) → Menu (3 times)

After completing this, the menu language should be set to English.

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