Step-by-step disassembly of Xiaomi Mi 9C: from the back cover to the motherboard

Xiaomi Mi 9C

detailing

Mi 9C

Many people are afraid to disassemble Xiaomi smartphones because of the fragile plumes and glue joints. Indeed, improper disassembly can lead to damage to the display or connectors. However, with the right tools and patience, the process becomes quite manageable. 9C not as repairable as the flagship models, and requires special care.

If you’ve never taken a smartphone apart before, we recommend that you practice on an old device or watch video guides first, and in this article we’ll take a step-by-step approach to the critical areas where errors are most common.

Preparation for disassembly: tools and security measures

Before you get started, make sure you have everything you need. - Xiaomi Mi 9C It has a glue back cover and brittle plumes, so a regular screwdriver wouldn't be enough:

• 🔧 Plastic mediators (2-3 (a) - for separation of the back cover without scratches.
• 🔨 The screwdriver. PH00 — motherboard screw.
• 🧲 Suction - helps to lift the cover after heating.
• 🔥 Dryer or thermo-air station - for softening the glue (temperature 60-80)°C).
• 📦 Logs for screws - so as not to lose small details.
• 🧴 Isopropyl alcohol (90%+) — glue-cleaner.

Also, prepare the workspace: it should be well lit, without dust and static electricity, and put a soft substrate on the table (for example, a silicone mat) so that the case of the smartphone does not scratch.

⚠️ Warning: Do not use metal tools to separate the lid! even a slight pressure can damage antenna lines or leave scratches on the aluminum frame.

If you are planning to replace the battery, order the original battery with adhesive base in advance (article: MB-J18). Cheap analogues may not match the thickness and cause assembly problems.

Removal of the back cover: heating and neat separation

Mi back cover 9C It's glued around the perimeter, and removing it is the most critical step.°C, you can damage the glue under the battery or deform plastic cells. Optimum temperature is 70-80°C.

Algorithm of action:

1. Turn off your smartphone and remove it. SIM-map.
2. Heat the hair dryer back cover around the perimeter for 2-3 minutes, keeping it at a distance of 5-7 cm.
3. Apply the suction cup to the bottom of the lid (where the Type-C connector is located) and pull up slightly.
4. In the resulting gap, insert a plastic mediator and carefully conduct them along the edge, separating the glue.

If the lid doesn't respond, repeat the heat again. Don't make too much effort, it can cause the plume of the fingerprint scanner to rupture, which runs under the lid at the top left corner.

After removing the cover, you will see:

• 🔋 Battery with glue strips.
• 📱 Motherboard closed with metal screen.
• 🎤 Dynamic and vibrator at the bottom.
• 📷 Main chamber (module) S5KGM1).

⚠️ Attention: Don't touch the motherboard with your bare hands! Static electricity can damage the chips. Use an antistatic bracelet or periodically touch a grounded object.

Disconnection of the battery and work with plumes

Before you continue disassembling, be sure to turn off the battery.

1. Carefully put a plastic mediator black connector battery (located motherboard).
2. Unplug the plume by pulling the tongue up.

If the connector is boiling, you can slightly tuck it on the side with a non-metallic tool. Do not use a screwdriver under any circumstances, this can damage the contacts.

Next, it is necessary to disconnect all plumes that prevent the removal of the motherboard:

• 📱 Display plume (the widest, at the top of the board).
• 🔊 Front camera and sensor plume (thin, under the display module).
• 👆 Fingerprint scanner plume (fragile, easily torn!).

For convenience, take a picture of the plumes before you shut down, which will help with the reverse assembly.

💡

If the plume doesn't detach, check if there's a latch on it. 9C Some connectors have plastic locks that must be lifted before being removed.

Withdrawal of motherboard and access to components

Once all the plumes are turned off, you can start removing the motherboard, which is mounted on 12 screws of different lengths, so remember which screw is twisted from where, and we recommend you to arrange them in the tray in order or take pictures of the location.

Demolishment algorithm:

1. Unscrew all the screws (start with the corners of the board).
2. Carefully tuck the board with a plastic mediator from either side.
3. Raise the charge at a 30-45 angle° Check if the remaining sleeves are disturbing.

Under the motherboard, you'll find:

• 🎤 Microphone (upper part).
• 📡 Antenna modules (sides).
• 🔊 Dynamics (lower part, glued).
• 🔋 Battery with glue strips.

⚠️ Attention: In Mi 9C The board is connected to the frame through ground springs, and when you assemble it, make sure that they are in place, otherwise there may be problems with the sensor or communication.

If you need to replace the speaker or the vibrator, they can be removed now.The speaker is glued, so you'll need to heat up with a hair dryer (60)°C) and neat tampering.

Replacement of the battery: nuances and risks

Battery in Mi 9C It has a capacity of 3,000 mAh and is glued to the body in two strips:

1. Plug the adhesive strips with a plastic mediator (not metal!).
2. Carefully pull the black tongues to separate the battery.
3. Clean the installation site from glue residues with isopropyl alcohol.

The new battery is set in reverse order. Please note that the adhesive strips must be replaced with new ones (they come with the battery). If they are not, you can use double-sided tape. 3M 467.

After replacing the battery, check:

• 🔌 Correct connection of the connector (must be clicked).
• 📊 Charge level in Settings → Battery.
• 🔥 No swelling (if the battery is "bubbling", immediately turn it off!).

1. Connect the battery connector.

2. Integrity of the feed plume.

3. the presence of a short circuit (measure the voltage on the contacts with a multimeter).-->

Disassembly of the display module and screen replacement

The Mi screen. 9C — This is a prefabricated module that includes AMOLED-It's a matrix, a touch layer, a protective glass, and it needs to be very careful to replace it, because the plume is very fragile.

Procedure:

1. Heat the screen edge with a hairdryer (60)°C) and apply a plastic mediator to it.
2. Carefully separate the display from the frame, starting from the lower corner (where the connector is located).
3. Disconnect the display and sensor plume (they go separately!).

When installing a new screen:

• 🖥️ Check the compatibility of the model (original article: TDDI-OLED-FHD-6.08).
• 🔧 Make sure all the plumes are connected before fixing (it will be difficult to fix the error after gluing).
• 🧴 Use a new adhesive layer (for example, B7000 or LOCA for OLED).

⚠️ Note: If after replacing the screen, stripes or artifacts appeared, check: - Integrity of the plume (possibly damaged during installation). - Density of the display adjoining to the frame (air gaps can cause interference). - Correct connection of connectors (sometimes they are inserted "upside down").

Build a smartphone: reverse order and testing

Assembling Xiaomi Mi 9C It should be in reverse order, but with a few key points in mind:

• 🔩 Screw the screws cross-curl to avoid skewing the board.
• 🧩 Connect the plumes last so as not to damage them when installing the cover.
• 🔋 Check the battery for swelling before the final assembly.
• 📋 Stick the back cover onto a new adhesive layer (e.g. Tesa 61395).

After assembly, be sure to test:

1. Turn on your smartphone and check the work of the sensor, display, cameras.
2. Call the device to make sure the speaker and microphone are working.
3. Connect the charger and check the charge indication.
4. Test the fingerprint scanner and contactless payment (NFC).

If something doesn’t work, take your smartphone apart again and check:

- Connect all the plumes.

Integrity of contacts (possibly oxidation).

Correct installation of screws (too long screws can damage the board).

💡

If the smartphone warms up or discharges quickly after assembly, the heat paste on the processor is likely to be a problem. MX-4).

Frequent Mistakes and How to Avoid Them

Even experienced masters sometimes make mistakes when disassembling Xiaomi Mi 9C. Here are the most common ones and how to prevent them:

If you damage a plume or connector, do not try to repair it with a soldering iron - in Mi. 9C microconnectors with a pitch of 0.3 mm are used. It is better to order a new plume (for example, on AliExpress on request "Mi" 9C flex cable").

Another common problem is the non-working NFC It's more often than not connected to the assembly:

Incorrectly connected antenna plume (check the battery connector).

- damage to the antenna module (to inspect for integrity).

- No grounding (check the springs under the board).

FAQ: Answers to Frequent Questions