Service Manual

Warning

All features, functions, specifications, and other product information provided in this document, including but not limited to the advantages, aesthetics, price, components, performance, availability and capacity of the product are subject to change without notice.

TCL will not be responsible for any damage to the product, injury or other safety issues caused by the result of repair by an unauthorized service provider, user repair or unprofessional product repair.

Any damage to the product resulted from an attempt to repair the product by any person or 3rd party other than TCL authorized service provider will not be covered by warranty.

1 Precautions

• Use only demagnetized tools specifically designed for small electronic repairs, as most electronic parts are sensitive to electromagnetic forces.
• Use only high-quality screwdrivers when repairing products. Poor-quality screwdrivers can easily damage screw heads.
• Always use genuine spare parts. Third-party parts may not function properly or may cause damage.
• Certain parts require calibration after repair for proper function. Contact a TCL authorized Repair Center for calibration of sensors (proximity, fingerprint), dual camera, touch screen panel, speaker, motherboard, and more.
• The IPXX degree of protection cannot be guaranteed if the repair is performed by the user or an unqualified person.
• If the device has suffered water/liquid damage, repair is an option, but the cost may exceed the device's value depending on the damage level.
• For detailed diagnosis, please contact a TCL authorized Repair Center.
• Do not remove, damage, heat, short circuit, or disassemble the battery. For battery, camera, screen, or motherboard replacement, visit a TCL authorized Repair Center.
• Before any repair, back up personal information and important data.
• Many semiconductor parts are sensitive to electrostatic discharge (ESD). Work in an Electrostatic Protected Area (EPA) to prevent unrecoverable damage.
• Ensure the device is turned off before repairing.
• Perform repairs in a safe/explosion-proof environment. If the device is damaged, emits smoke, or smells of burning, stop immediately, use a fire extinguisher or fire-proof box, and contact TCL.
• When removing the back cover, be careful not to damage the product, especially the battery. Recommended safety equipment includes glasses, gloves, and masks.
• Before assembly, ensure no screws or foreign objects are near the battery.
• Before assembly, check for any abnormalities before reattaching the back cover.

2 General Product Information

3 Maintenance Preparation

• Ensure the handset has at least 50% battery charge.
• Supported accessories include Micro SD card, SIM card, 5V1A Charger, and Micro USB Cable.
• PC requirements for software update via PC tool: CPU equivalent to Pentium 1.6 GHz or above, 4GB RAM or above, 10GB Hard Disk or above, Operation System: Win7/Win8/Win10, USB port, and internet connection with minimum speed of 8Mb/s.
• Backup user data before repairing using one of the following methods:
  • Method 1 (Google Account Backup): Go to "Settings" -> "System" -> "Backup". Touch "Turn on" and then "Back up now". This backs up app data, SMS, device settings, call history, and contacts.
  • Method 2 (Switch Phone App): Back up data to another phone using the "Switch Phone" app.

4 Factory Reset

A factory reset restores the phone to its original settings, deleting all data, files, and downloaded apps. Back up user data before proceeding.

4.1 Remove Google Account Before Factory Reset

To avoid being locked out after a reset, remove your Google account first. Navigate to "Settings" -> "Accounts", select your Google account, and tap "REMOVE ACCOUNT".

4.2 Factory Reset

With the phone powered on, go to "Settings" -> "System" -> "Reset" -> "Erase all data (factory reset)". Confirm by touching "Erase all data" twice.

4.3 Recovery Mode

How to use: In power-off mode, long-press the "Power" key and "Volume up" key simultaneously until the screen lights up to enter recovery mode.

When to use: When the handset cannot start, experiences issues during startup, or cannot charge.

Data Format: Consumer data, memory, and settings will be reset to factory defaults.

Recovery Mode Steps (Visual Description):

• Step 1: Power off the device. Long-press "Power" + "Volume Up" keys until the screen lights up.
• Step 2: Use the Volume keys to navigate to "Wipe data/factory reset" and press the Power key to confirm.
• Step 3: Select "Factory data reset" and press the Power key to confirm.
• Step 4: Select "Reboot system now" and press the Power key to confirm.

5 Software Update

Upgrading to the latest software version is recommended for optimal performance. Ensure your data is backed up and the phone is fully charged before updating.

5.1 Software Update by FOTA

Firmware-Over-The-Air (FOTA) allows wireless firmware updates. The process runs in the background. Access this via "Settings" -> "System" -> "Updates" or "System Update".

5.2 Software Update by using Mobile Upgrade Tool

1. Download the tool: Mobile_Upgrade_S_Gotu2_v1.3.2.
2. Run the downloaded Setup.exe file, choose the language, and install the tool.
3. After installation, click "Finish" and restart your computer.
4. Open the tool, select the language and model "T431". Click "Start" -> "Next" -> "Yes". Power off your phone and connect it to the computer via USB cable. Wait for the software package to load.
5. When prompted "Please disconnect your device from the USB cable to proceed", click "OK" and disconnect the phone.
6. Click "Upgrade device" and reconnect your powered-off phone to the computer to begin the upgrade.
7. The upgrade process will show progress. Upon successful completion, a confirmation message will appear.

6 Function Test with Support Centre

1. Ensure the Nano SD card is inserted correctly.
2. Power on the product to start the auto test.
3. If the product displays "input NCK code", the software is network or SIM locked. Use a compatible SIM card or enter the NCK code if available.
4. Open the "Support Centre" app. Click "AGREE", then navigate to "Hardware diagnosis" -> "START TESTING". Grant necessary permissions (Camera, Microphone, Location, Phone) by touching "OK" or "ALLOW" when prompted. Follow the on-screen instructions to test components like Communication, Network, Battery temperature, Charger, Vibration, Touch panel, Speaker, and Earpiece. The test results will indicate if components are "Pass" or "Not test".

7 Troubleshooting

7.1 What should I do if my device reboots by itself?

• If occasional, it might be a file anomaly; continue normal use.
• Check if it happens during charging; try the official charger and data cable.
• If using a third-party app, ensure compatibility with your device and Android version; try uninstalling it.
• If using a built-in app, try resetting or updating the device.

7.2 What should I do if my device system lags or freezes?

• Restart the device.
• Charge the device to at least 20% battery.
• Close background apps and clear system cache via the Menu key -> "Clear all" to close tasks.
• Uninstall unused apps periodically to free up storage.
• For third-party app issues, uninstall the problematic apps.
• If lagging during media consumption or gaming, check network connection. Enable Airplane mode for a few minutes, then disable it, or move to an area with better signal.
• Try resetting or updating the device.

7.3 What should I do if my device cannot charge or charges slowly?

• Inspect the USB cable, charger, and device charging port for damage. If damaged, back up data and contact a repair center with proof of purchase.
• Charge the device with a TCL official charger for at least 30 minutes.
• Uninstall any third-party power management apps.
• Avoid prolonged use while charging.
• Try resetting or updating the device.

7.4 What should I do if my device's battery drains under normal use?

• Avoid use in extreme high or low temperatures.
• Deactivate Bluetooth, Wi-Fi, or GPS when not in use.
• Note that battery drain is normal during intensive tasks like gaming or video streaming.
• Close background apps and clear system cache via the Menu key -> "Clear all".
• Try resetting or updating the device.

7.5 What should I do if my device auto powers off?

• Charge the device with a TCL official charger for at least 30 minutes, then try to power it on.
• If the issue occurs with a third-party app, ensure compatibility and try uninstalling it.
• Try resetting or updating the device.

7.6 What can I do if my device heats up?

Heat sensation is normal due to CPU activity handling data. It is not harmful. To reduce temperature:

• Avoid prolonged exposure to direct sunlight.
• Close power-intensive applications (music, chat, GPS, gaming, video streaming).
• Reduce screen brightness.
• Avoid using the device while charging.
• Remove the protective case if it hinders heat dissipation.

7.7 What should I do if my device cannot power on?

• Charge the device with a TCL official charger for at least 30 minutes, then try to power on.
• Press and hold the power key for 10-15 seconds for a forced reboot.
• Try resetting or updating the device.

If issues persist, contact TCL's hotline or repair center for assistance via the TCL website or the "Support center" app.

8 Contact of TCL hotline and service centers

For official professional repair, visit HOTLINE & SERVICE CENTERS (tcl.com) and search for your country/region.

9 Disassembly and Reassembly

9.1 Disassembly Tools

Tools required for disassembly and reassembly include:

• Plastic Plectrum
• Anti ESD Tweezers
• Plastic Spudger
• Screwdriver

9.2 Disassembly Process

Follow these steps for disassembly. Note that specific component replacement may allow skipping certain steps, but the general method must be followed carefully.

Step 1: Power off the device and remove the back cover, SIM card, and SD card.

• Step 1.1: Power off the device. Cover the screen with an electrostatic protective film.
• Step 1.2: Use a Plastic Plectrum to carefully pry open the back cover.
• Step 1.3: Remove the SIM card and SD card.

Step 2: Remove the Battery, 21 Screws, and Furnished Frame.

• Step 2.1: Remove the Li-ion Battery. ⚠️Warning: Improper battery handling can cause fire or burns. Follow disassembly guidance strictly and avoid using sharp tools to pry the battery. Keep a fire extinguisher nearby.
• Step 2.2: Remove the 21 screws from the furnished frame using a screwdriver. Note the screw torque: 0.7±0.05kgf.cm.

Step 2.3: Remove the Furnished Frame (2 SIM).

Use a Plastic Plectrum to remove the furnished frame.

Step 3: Disconnect connectors and remove Main Camera, screws, and Front Camera.

• Step 3.1: Disconnect the LCD and TP FPC connectors.
• Remove the Main Camera and its screw. Disconnect the Front Camera connector.

Step 4: Remove Main PCBA and other components.

• Step 4.1: Remove the Main PCBA using a plastic flake.
• Step 4.2: Remove the Front Camera and Speaker.
• Step 4.3: Remove the Side Key Furnished FPC and MIC Rubber.
• Step 4.4: Remove the Coin Vibrator.

9.3 Reassembly Process and Tools

Reassembly is the reverse of disassembly. Follow these precautions:

1. Replace double-sided sponge tape, battery packing, and all adhesives on the battery cover with new ones. Conductive cloth, high-temperature adhesive, and double-sided adhesive tape may also need replacement depending on condition.
2. Ensure TP FPC conductive foam secures the TP FPC to the Furnished Front Casing.
3. Before assembling the Main PCBA onto the Furnished Front Casing, ensure the Side Key Furnished FPC, Front Camera, and MIC Rubber are properly attached.
4. Assemble the Audiojack rubber and USB Rubber onto the Main PCBA.
5. Pay attention to the correct orientation of the Speaker.
6. The T431D features an 8MP main camera.
7. Ensure screws are reinserted correctly (Screw Torque: 0.7±0.05kgf.cm) into the Main PCBA.
8. Connect the TP FPC and LCD FPC connectors after assembling the Main PCBA.

10 Exploded View

The exploded view diagram shows the internal components of the TCL 403. Key components include:

• TP&LCD (1)
• Furnished Front Casing (2)
• Speaker Furnished FPC (3)
• Coin Vibrator (4)
• Speaker (5)
• Audio jack rubber (6)
• Front Camera (7)
• MIC Rubber (8)
• USB Rubber (9)
• Rear Camera (10)
• Furnished PCBA (11)
• Rubber (12)
• Furnished frame (13)
• Screw (14)
• Battery Cover (15)
• TPU Protective Shell (16)
• LI-Polymer Battery (17)
• Screw (18)
• Side-key Furnished FPC (20)
• Camera (5M) (21)
• Camera (8M) (22)

11 Split View

The split view diagram illustrates the arrangement of various internal components, including PCBs, connectors, and structural elements, numbered for identification.

Part List