TCL 4042S T312D1 User Repair Manual

Important Information

A. Read the entire manual before starting a repair. Do not proceed if you are unsure about performing the repairs as described.

B. Features, functions, specifications, and other product information in this document, including price, components, performance, availability, and capacity, are subject to change without prior notice.

C. This repair manual is intended for repairs outside the warranty period. If the product is still under warranty, contact customer service before attempting self-repair or ordering parts. Modifications or alterations to the software or hardware by unauthorized persons will void the warranty.

D. The information and instructions in this document are for individuals with the necessary knowledge and experience to repair electronic devices. TCL is not liable for product damage, injury, or other product safety issues resulting from repair attempts that do not follow the instructions or are caused by misunderstandings or improper handling of tools or installations. TCL is not liable for product damage, injury, or other product safety issues resulting from repair attempts with tools or installations not supplied or approved by TCL.

Table of Contents

1. Precautions
2. Instructive Symbols and Notes
3. Safety Regarding ESD (Electrostatic Discharge)
4. Glass Breakage Safety
5. Battery Safety
6. Reset to Factory Settings
7. Software Update
8. Basic Troubleshooting
9. Contacting the TCL Hotline and Service Centers
10. Disassembly and Reassembly

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. Low-quality screwdrivers can easily damage screw heads.
• Always use original spare parts. Third-party parts may not function correctly or could cause damage or accidents.
• Certain parts may require calibration after disassembly or repair to function properly. For professional repairs, contact a TCL-authorized service center. These parts include sensors (proximity, fingerprint), rear camera, touchscreen module, speaker, and motherboard.
• Water and dust resistance cannot be guaranteed if the device is repaired by the user or an unqualified person.
• If the device has suffered water/liquid damage, the repair costs may exceed the device's value.
• Do not damage the battery by heating, puncturing, short-circuiting, or disassembling it. Contact a TCL-authorized service center if the battery is damaged or requires professional attention.
• Back up personal information and important data before any repair.
• It is recommended to set up and work in an Electrostatic Protected Area (EPA) to avoid electrostatic discharge, which can cause irreparable damage to the device and its parts.
• Ensure the device is fully discharged and powered off before repair.
• Use appropriate safety equipment and ensure the work area is free of flammable materials, foreign objects, and sharp materials. Have fire extinguishers and safety equipment available.
• Be careful not to damage product parts or the battery when removing the back cover.
• Before reassembly, ensure there are no screws or foreign objects around the battery.
• Before reassembly, check for any anomalies before reattaching the back cover.
• When purchasing the product, refer to the user manual and quick start guide included in the packaging. For more information, visit www.tcl.com.

2 Instructive Symbols and Notes

Failure to follow instructive notes may lead to fire, injury, data loss, or damage to the device, parts, or other property.

Warning - Highlights instructions to reduce the risk of safety problems or injuries. Failure to comply may lead to fires or other safety issues, potentially resulting in injury or death. Always prioritize safety over cost savings. If unsure, contact TCL support or a professional repair shop.

Caution - Highlights instructions to reduce the risk of data loss or damage to the device or other equipment.

Please note – Other instructions, tips, and notes for successful procedure completion.

3 Safety Regarding ESD (Electrostatic Discharge)

What is ESD?

ESD (Electrostatic Discharge) is the rapid, spontaneous transfer of electricity (static charge) caused by a strong electrostatic field, which can damage electronic components. ESD damage can result in latent defects that may not be immediately apparent but can lead to premature device failure.

How to prevent electrostatic discharge?

All conductors in the vicinity, including personnel, must be grounded or electrically connected to a known or artificial ground. Using ESD protective equipment (antistatic wrist strap and gloves), antistatic tools, and an ESD protective mat can mitigate the risk of ESD events during repair.

4 Glass Breakage Safety

The device's display is made of glass and can break due to:

• Falls onto hard surfaces
• Crushing, bending, or deformation
• Other types of hard impacts

Warning - Avoid touching broken glass or sharp glass shards without appropriate protective equipment (e.g., cut-resistant gloves and safety glasses), as sharp edges pose a safety risk.

The screen glass cannot be separated from the screen module. If the glass is broken, the entire screen module must be replaced.

5 Battery Safety

Warning This device contains a non-removable Lithium-Ion battery with hard battery cells. Battery safety is paramount when repairing a device.

Improper handling of the battery can lead to overheating, swelling, gassing, leakage, or a battery-related thermal event, which can cause fires, injuries, death, data loss, or damage to the device, its parts, and surrounding property.

5.1 Best Practices for Handling Batteries

Warning Adhere to safety guidelines and maintain a safety-oriented workspace to prevent hazardous incidents when handling batteries.

Safety in the Workspace:

• Ensure the workspace is free of flammable materials, foreign objects, and sharp materials.
• Equip the area with necessary safety equipment, such as fire extinguishers and protective gear.

Avoid Physical Damage:

• Use caution when using sharp tools near the battery. Do not throw, drop, puncture, crush, or damage battery cells to avoid triggering a battery-related thermal event or the release of harmful fumes.

Prevent Short Circuits:

• Do not use conductive tools and ensure the battery terminals do not come into contact with metal objects or conductive surfaces while handling the battery.

Temperature Control:

• Maintain the ambient temperature within the battery's operating range.
• Ensure adequate ventilation to prevent overheating.

Precautions During Assembly:

• Do not leave anomalous objects (e.g., debris, loose screws) inside the device before reassembly.

Proper Disposal:

• Dispose of or recycle used batteries in accordance with local environmental laws and regulations.

5.2 How to Handle a Battery-Related Thermal Event?

Warning A battery-related thermal event is a sudden chemical reaction within a Lithium-Ion battery that rapidly releases stored energy, potentially causing gassing and fire. This can be caused by physical damage, improper handling, incorrect replacement, or temperatures outside the safe operating range.

Act immediately upon noticing signs of a battery-related thermal event to ensure the safety of people and the environment.

Signs of a Battery-Related Thermal Event:

1. Smoke, sparks, or soot emanating from the battery or device.
2. The battery casing swells rapidly or bulges.
3. Hissing or popping sounds from the battery or device.

Immediate Actions:

1. Extinguish the fire: Quickly cover the battery or device with plenty of clean, dry sand to contain the reaction.
2. Contact authorities: Call the local fire department for assistance.
3. Evacuate and ventilate: Leave the area for 30 minutes to allow smoke to dissipate and ensure the environment is safe.
4. Proceed with caution: After 30 minutes, wear heat-resistant gloves and safety glasses before removing the device from the sand.
5. Clean the area: Wipe the affected area with water first, then use an ESD-safe cleaning solution to ensure safety.
6. Proper Disposal: Dispose of the damaged battery or device and any residues according to local environmental laws and regulations.

6 Reset to Factory Settings

Caution: Resetting to factory settings will format the device, returning it to its original factory settings. This will erase all user data, including files and downloaded apps. Back up all important data before resetting. TCL is not responsible for any data loss.

6.1 Reset to Factory Settings

You can perform the following steps to reset the phone to factory settings if it can be powered on:

Go to Main Menu -> Settings -> Phone Settings -> Reset to Factory Settings -> Enter password "1234" and tap "OK" -> Tap "OK" in the opened window.

7 Software Update

It is recommended to update the phone's software to the latest version to improve performance. Remember to back up your data and fully charge the phone before upgrading.

7.1 Software Update via FOTA

Firmware-Over-The-Air (FOTA) is a method by which a mobile device's firmware is updated wirelessly by the manufacturer. The firmware runs in the background without user intervention to ensure the device's hardware functions correctly. Start the "Settings" app on the device, select "System" -> "Check for updates" -> "OK".

8 Basic Troubleshooting

Refer to the official TCL website for troubleshooting common issues:

1. Visit https://www.tcl.com/mobile-support
2. Scroll down to the "Troubleshooting" section and click "View More".
3. Select the product type and follow the step-by-step questions and options.

Please note: If the above options do not help, contact the TCL hotline or a service center for professional technical support.

9 Contacting the TCL Hotline and Service Centers

For official professional repairs from TCL, please visit the HOTLINE and SERVICE CENTERS pages on the TCL website to find a contact person in your country/region.

10 Disassembly and Reassembly

10.1 Basic Tools

Warning: Wear appropriate protective equipment for your safety when repairing devices. Additional tools may be required for disassembly and assembly steps. Refer to individual steps for details.

10.2 Disassembly for Replacement

Before Disassembly:

1. Back up your device data.
2. Fully discharge the battery.
3. Turn off the device.
4. Disconnect all cables.
5. Remove all covers and housings.
6. Clear and clean your workspace.
7. Put on an ESD wrist strap and connect it to a properly grounded ESD mat.
8. Product specifications may vary by country, region, or provider.

In cases of broken glass:

Please read "4 Glass Breakage Safety" first. Apply an acrylic protective cover to prevent glass shards from reaching the screen. The screen glass cannot be separated from the screen module. If the glass is broken, the entire screen module must be replaced. If you experience difficulties during repair, take the device to a professional or a TCL-authorized service center for assistance.

Removing the Back Cover:

Insert your fingertip into the recess on the back of the housing and open the battery compartment.

[Image of back cover removal]

The back cover is removed.

[Image of removed back cover]

Battery:

Remove the following parts before starting:

• Back Cover Removal

Warning: Please read Section 5 Battery Safety before proceeding. If you encounter difficulties during repair, take the device to a professional or a TCL-authorized service center for assistance.

Carefully remove the battery using your fingertip from the battery removal slot shown in the illustration.

[Image of battery removal]

Warning: Be careful not to press or crush the battery with force. If you encounter difficulties during repair, take your device to a professional or TCL-authorized repair center for assistance.

The battery is now removed.

Battery Part Number: 601GH0100110

[Image of battery removed]

Display Assembly (LCD):

Remove the following parts before starting:

• Back Cover Removal
• Battery

Removing the Middle Frame:

Warning: Please read Section 5 Battery Safety before proceeding. If you encounter difficulties during repair, take the device to a professional or a TCL-authorized service center for assistance.

Remove the eight Phillips head screws on the lower frame.

[Image of screws being removed]

Quantity: 8, Torque: 1 kgf.cm

Insert the opening tool and slide it along the left edge, starting to release the frame according to the arrow direction shown below, until the frame is completely detached.

[Image of frame being pried open]

The disassembly of the frame is now complete.

Pull off the acetate fabric.

[Image of acetate fabric removal]

Disconnecting Components:

1. Disconnect the LCD FPC connector.
2. Remove two battery clips.

[Image of FPC connector and battery clips]

Removing the Main Board:

Loosen the main board and place it on the front housing.

Caution: Do not completely remove the main board at first to avoid damaging the light cable and receiver cable.

Remove the LED light from the front housing.

[Image of LED light removal]

Disconnecting Receiver Cable:

Disconnect the receiver cable.

[Image of receiver cable disconnection]

Removing the Receiver and Main Board:

Remove the receiver with a plastic tweezer and then remove the main board from the housing.

[Image of receiver and main board removal]

Removing the LCD Display:

Carefully remove the LCD display.

[Image of LCD display removal]

10.3 Reassembly Procedure

Follow the disassembly instructions above in reverse order to reassemble the device.

Here are some important tips for individual steps:

1. Double-sided foam tape and all types of adhesive on the housing lens must be replaced with new ones once removed. Conductive tapes and copper tapes are selectively replaced upon breakage or according to their adhesiveness.
2. Before mounting the main board to the front housing, tilt the LED light slightly downwards and insert it diagonally into the LED light slot on the front housing. Route the cables as shown in the following illustration.

[Image illustrating cable routing]

3. Follow these steps to mount the battery clip:
• Prepare the rechargeable battery clips and silicone.
• Attach the silicone to the battery clips.
• Mount the battery clips to the front housing.

[Image sequence for battery clip mounting]

4. Do not leave foreign objects (e.g., debris, loose screws) in the device and check this before reassembling it.