Repair T800 & T900 Smart Watch

T800 & T900 Smart Watch Repair Guide

➠ Board Number: LJ736-MB-V2.3
➠ Serial Number: S2335017

▶  Board Install All Parts List: 
1. Motherboard
2. Wireless Power Supply Module (Magnetic Levitation)
3. Vibrator
4. Microphone
5. Mini Speaker
6. Display
7. Battery
8. Switch
9. Human Body Health Measurement Sensor and System

▶ Common ICs Used in T800/T900 Smartwatches -
➠ Power IC/CPU: JQ7011
➠ Touchscreen Controller IC: CSI8160
➠ Charging IC: 9212
➠ Charging Protection IC: 61 N UE
➠ Switching IC: UC25H016
➠ LED Control Transistor: 662K
➠ Vibrator Control Transistor: A2SHB


▶ General Guidelines for Repair:
Before delving into individual problems, let’s outline a few general principles when repairing any smartwatch, especially the T800 and T900 models.

▶ Tools Required:
➠ Heat Gun or Hair Dryer
➠ Multimeter for diagnosing electrical shorts and faults
➠ Plastic Pry Tools for safely removing components without damage
➠ Tweezers for handling small parts
➠ Anti-static brush and cleaning solvents such as isopropyl alcohol or thinner
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▶ Safety Precautions:
➠Always work in a clean and static-free environment to prevent static discharge damage to sensitive components.
➠ Avoid using metal tools directly on the PCB as it can cause scratches or short-circuiting.
➠ Be cautious with the heat application as too much heat can damage the screen, battery, or internal components.

▶ Problem 1: How to Open the T800 & T900 Smart Watch
▶ Solution: ➠ Step 1: Heating the Display: To remove the display, use a heat gun or hair dryer and set the temperature to 350°C with the airflow at level 2. Heat the edges of the screen evenly for about 30 seconds. The adhesive around the display will soften.

➠ Step 2: Prying Open the Display: Use a plastic pry tool and carefully slide it between the display and the frame. Slowly work your way around the watch, lifting the display little by little. Be cautious not to force it, as it can crack the screen.

➠ Step 3: Removing the Display: Once the adhesive is loosened, gently pull the display away from the body. Be mindful of the display cable, which is still attached to the motherboard. Disconnect it using tweezers.


▶ Problem 2: How to Clean the Dust on the Motherboard
▶ Solution: ➠ Step 1: Use the Proper Cleaning Solution: Using a small, anti-static brush, dip it lightly in thinner or isopropyl alcohol. These solvents help remove dust, dirt, and grime without leaving residue.

➠ Step 2: Brush the Motherboard Gently: Carefully scrub the dust off the board, paying attention to not damage any delicate components such as capacitors, resistors, or connectors. Ensure that the brush is soft and does not create static electricity.

➠ Step 3: Inspect and Dry: After cleaning, inspect the motherboard under a microscope if available to ensure no debris remains. Allow the solvent to evaporate before reassembling.
▶ Problem 3: Battery Backup Problem
▶ Solution: ➠ Step 1: Reset the Smartwatch: If the battery backup is poor, start by resetting the watch via the settings menu. A factory reset can sometimes resolve battery-related software issues.

➠ Step 2: Check Battery Connection: Open the watch and inspect the battery connector. Use a multimeter to check if there is a short circuit at the battery connection point. A short circuit here can lead to rapid battery drain.

➠ Step 3: Battery Replacement: If the battery connection is fine but the backup remains poor, the battery itself is likely faulty. Replace the battery with a new one of the same specification, ensuring proper polarity alignment.

▶ Problem 4: Repairing a Dead T800 & T900 Smart Watch
▶ Solution: ➠ Step 1: Initial Charge: If the watch is dead, connect it to a charger and wait for 15-20 minutes. Sometimes deeply discharged batteries take time to show charging indicators.

➠ Step 2: Check Battery Voltage: If there is no charging indicator after a while, open the watch and check the battery voltage using a multimeter. If the voltage is too low (below 3V), the battery may not hold a charge anymore.

➠ Step 3: Replace Battery: If the battery is determined to be faulty, replace it. After replacing, check if the watch powers on. If the watch still doesn’t start, the problem may lie in the motherboard or power IC (JQ7011).


▶ Problem 5: Charging Issues
▶ Solution: ➠ Step 1: Check the Charging Cable and Adapter: First, test the charging cable and adapter using a different device to ensure that they are functioning properly.

➠ Step 2: Inspect Wireless Power Supply Module: The wireless charging module in the watch may be faulty. Use a multimeter to measure the output from the charging coil to ensure proper voltage delivery.

➠ Step 3: Test and Replace Battery: If the charging module is functioning correctly but the watch still doesn’t charge, test the battery. Replace it if necessary. If the battery is fine, check the charging IC (9212) for any visible damage or failure.

▶ Problem 6: Speaker Issues
▶ Solution: ➠ Step 1: Check for Dust and Debris: Open the watch and inspect the speaker area for any dust or debris that might be clogging the speaker. Use a soft brush to clean it.

➠ Step 2: Test Speaker Continuity: Use a multimeter to check for continuity across the speaker terminals. If there’s no continuity, the speaker is likely damaged.

➠ Step 3: Replace Speaker: If the speaker is found to be faulty, replace it with a compatible mini speaker. Ensure proper connection and check for any damage to the speaker flex cable.
▶ Problem 7: Short Circuit on the Board (Dead Watch)
▶ Solution: ➠ Step 1: Diagnose the Short: Use a multimeter to check for continuity across various components. A short circuit can occur due to damaged components such as capacitors, diodes, or ICs.

➠ Step 2: Locate the Fault: Identify whether the short is full or partial. For full shorts, use a short-killer tool to safely remove the shorts from the board. If the short is partial, you’ll need to remove components one by one and test again until you identify the faulty component.

➠ Step 3: Replace Faulty Components: Once the faulty component is identified, replace it. Common areas to check include the power IC, charging IC, and any capacitors near the power supply.

▶ Problem 8: Touchscreen Issues
Solution: Inspect the touchscreen controller IC (CSI8160) and check for any broken or damaged flex cables.

▶ Problem 9: Bluetooth Connection Issues
▶ Solution: Inspect the Bluetooth antenna and related circuitry for physical damage. Check for firmware updates that may fix Bluetooth instability.

▶ Problem 10: Sensor Malfunction (Health Measurement)
▶ Solution: Test the human body health measurement sensor system for continuity. Replace the sensor if damaged.

★  Common Questions & Answer  T800 & T900 Smart Watch :

☛ Questions: How much is the T800 ultra Smart Watch battery price?
☛ Answer: Indian Rupee150 - 250, Doller is 1.79 - 2.98.

☛ Question: Why T800 Ultra Smartwatch is not working?
☛ Answer: You read this post, and you will find your answer in this post, I am also saying that either you have a battery problem or a switch problem, so your smartwatch is not turning on.


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