⚠️️ Before disassembling, do not forget to turn your phone off.
Disassembly/Repair of the mobile device Xiaomi 12T (Xiaomi 12T 22071212AG) with each step description and the required set of tools.
Step 2. Remove the tray
Use the ejection tool (aka Needle) or Paperclip. Push the tip all the way into the hole until the tray ejects, and then pull the tray of SIM card out.
⚠️️ Pay attention! The tool must be inserted into a hole on the edge of the phone's housing. Do not press too hard. It may break the tray eject mechanism.
Step 3. Open the back cover
We need to heat the surface of the back cover to a temperature of about 65-70 ° C or 160 ° F, for this we use a heating mat you can use a hair dryer.
And after 6-8 minutes we can move on to disassembly.
To detach the back cover, we use a plastic film, this is the protective film from the new display. We insert it into the hole between the middle cover and the back cover. Choose a corner where we can slip the film under the back cover. Push it through and run it lengthwise.
We can additionally use isopropyl alcohol to dry the adhesive base. We need to be careful in the area of the cameras and not to put the tool too deep so as not to damage the lenses.
Step 4. Unscrew the screws
We move on to unscrewing the ten screws, we use a 1.5mm Phillips screwdriver or #000. The screws may be different and so we recommend placing them on a special surface in an easy to remember order for reassembly.
Step 5. Open the cover
After unscrewing the screws, we need to remove the cover that hides the battery connectors. The cover has a recess on the edge, which we can pry to detach it.
There are antenna lines on the cover.
Step 6. Disconnect the battery connector
We can disconnect the two battery connectors. It's best to use a non-metal tool. In our case, it's tweezers with ceramic tips.
ℹ️️ The Xiaomi 12T 22071212AG model has a battery BM5J with a capacity of 5000 mAh (also known as a rechargeable battery).
Step 10. Remove the inter-board cable
We disconnect the connectors on the sub-board and motherboard and remove the inter-board cable.
⚠️️ Be careful when removing the cables from the connectors, the cables are pretty thin, and it is easy enough to break them or damage the contact tracks inside.
⚠️️ This model doesn't have any arrows on the FFC cable (flexible flat cable) to indicate its correct position.
Step 11. Disconnect the connectors
We disconnect connectors of the display cable, and the fingerprint sensor cable.
Step 12. Remove the daughterboard
Remove the sub-board. It may be glued to the frame or attached with attachments like latches or hooks, so be careful.
ℹ️️ The sub-board contains a charging port (Micro USB), microphone, sim cards holder, spring contacts for the speaker, vibration motor, and an antenna unit.
⚠️️ It is not necessary to insert the tool underneath when removing the sub-board. Internal components could be damaged.
Step 13. Remove the small board
Then we disconnect the coaxial cable connector on the small board and remove the board itself. This board is most likely responsible for the 5G antenna.
Step 14. Remove the cameras
Then we can detach the front camera. The camera is traditionally taped to the shield on the motherboard with a heat dissipating foil. All cameras on this phone are taped to the display frame or motherboard, so we need to be careful.
We can detach the rear cameras too. The large camera is located in a small box with copper plating on the bottom, we can take it out as well. If there is a heat dissipating foil on the cameras, it is better to keep it undamaged for reassembly. The small cameras are glued to the motherboard.
Step 15. Disconnect the connector
Move on to disconnecting the coaxial cable on the motherboard and release the cable from its securing fasteners.
Step 16. Remove the motherboard
Carefully remove the printed circuit board. There is no need to use a lever or try to reach the circuit board by force. Make sure that nothing is getting in the way or holding the circuit board.
The motherboard, also, may be attached with attachments like latches or hooks, be careful.
⚠️️ Do not bend the circuit board when removing it or push tools under it. Unbeknownst to yourself, you can damage components or cables from the inside.
Step 17. Remove the battery
And we move on to removing the battery. We need to read on the brown tabs A and B for which one we need to pull, but we must unwrap all of them so that they do not prevent us from detaching the battery and do not hold it.
And as it becomes clear from the description, we have to pull the wide tab A. With one hand we hold the display frame, and with the other hand we carefully pull up the tab with the letter A, detaching the battery. As we can see, the battery is also held on the transparent protective coating that protects the display frame.
Step 18. In the display frame remained
ℹ️️ In the display frame remained: the earpiece speaker, coaxial cable, and vibration motor.
Detailed disassembly instructions of Xiaomi 12T in the video, made by our mobile repair & service center:
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