How to disassemble the Xiaomi Mijia electric screwdriver

The popularity of compact home craftsman tools is growing every year, and Xiaomi Mijia Electric Screwdriver is at the forefront here due to its stylish design and affordable price. However, like any electronics, this device can require attention: replacing a worn-out battery, cleaning contacts or lubricating the mechanism are tasks that often arise for owners after a year or two of active operation. Disassembly seems difficult due to the lack of visible screws, but with a minimum set of tools and understanding the design, the process becomes quite accessible even for beginners.

Before you start dismantling, it is important to understand that you are violating the factory sealing of the case, which can affect warranty obligations if the expiration date has not expired. The main difficulty lies in the hidden fixation of elements that requires accuracy and consistency. In this article, we will take a detailed look at the dismantling stages, typical internal layout problems and methods of solving them so that you can return the tool to factory performance.

It is worth noting that inside the device is a lithium-ion battery that requires careful handling when extracted. Negligent battery handling or damage to the control board can cause the tool to fail, so all manipulations should be carried out with the power turned off and with precautions. Xiaomi designed the device monolithic to protect the electronics from dust, but this does not mean that maintenance is impossible.

Tools and workplace preparation required

For high-quality and safe disassembly Xiaomi Mijia Electric Screwdriver you need a specific set of tools, as standard cross screwdrivers will not work here. the body of the device is fastened screws with Torx and Tri-wing screws, which are rarely found in household sets, but are required to work with modern electronics. The lack of a suitable bit can lead to the slicing of the screw faces, which will turn a simple disassembly into a complex operation to drill mounts.

Prepare a workspace with good lighting and a clean surface so that small parts and screws do not get lost or damaged. It is recommended to use a magnetic mat or organizer with cells where you will fold the fastener in order of its extraction, which will greatly simplify the process of reverse assembly. Also remember to completely discharge the battery before work to minimize the risk of short circuit in case of accidental contact with metal tools.

Below is a list of tools that are guaranteed to be needed to complete the task:

• 🔧 A set of precision screwdrivers with bits T5, T6 (Torx and Y0 (Tri-wing/Y-figurative).
• 🧤 Plastic blades (spudger) or mediator for opening latches without damaging the housing.
• 🧲 Tweezers with curved ends for extracting small plumes and screws from the depths of the body.
• 🧼 Isopropyl alcohol and soft rags to clean contacts and remove old lubricant.

⚠️ Warning: Never use metal objects to tweak the halves of the case, as this can damage the plastic or, worse, break through the battery insulation, causing it to ignite.

Algorithm of dismantling the case and removing plugs

The disassembly process begins with a visual inspection of the case, where you immediately notice the absence of obvious screws on the outer surface. The secret lies in the decorative stub located at the bottom of the handle, which hides the main fastening screw. Carefully tuck this plug with a thin plastic blade or needle, trying not to scratch the glossy surface of the plastic, and remove the hidden screw that holds the structure.

Once the bottom screw is removed, you need to find and unscrew a few more hidden attachments that may be under the stickers or in the recesses near the bit cartridge. In some versions of the Xiaomi Mijia, the screws are located under rubber inserts that need to be carefully bent without breaking them. Only after completely removing the entire fastener, you can start separating the halves of the body using a plastic card or a blade to pass along the perimeter of the seam.

Act slowly and evenly, starting at the bottom of the handle and moving up to the tool head so as not to break the internal plastic guides. If the halves of the case do not diverge, check if all the screws are removed, as often one forgotten screw blocks the entire opening process. When done correctly, the body should disperse with a slight click, opening access to the internal layout.

Internal device: control board and motor

Once the case is removed, you will see a compact internal assembly, with a cylindrical lithium-ion battery and control board (BMS) central to the car, which is fixed to the battery contacts and connected to the motor via connectors or soldering, depending on the device's revision, and the main element is a charge and protection controller that monitors current, voltage and temperature, preventing overheating and overcharging.

The gear motor is usually mounted at the top and connected to the cartridge through a system of gears that require periodic lubrication. Visual inspection reveals the status of the contacts: if they show oxidized plaque or traces of corrosion, they must be carefully cleaned with a blower or cotton swab dipped in alcohol. Electronics in these devices are quite reliable, but dust and moisture can cause unstable operation or spontaneous shutdown.

Notice the condition of the wires going to the trigger button and the LED light: they should not be rubbed or have traces of melting. Often the problem with the broken button lies in the break of a thin conductor inside the insulation or the oxidation of contacts under the button itself. For diagnostics, you can use a multimeter in vertebrae mode, checking the integrity of the circuit when you pull the trigger.

Battery replacement and battery maintenance

The most common reason for resorting to disassembly is a decrease in battery life when the tool stops holding a charge or quickly discharges under load. Xiaomi Mijia uses a standard battery form factor, often similar to the 18650, but with its own mounting system and contact group. To replace, you need to carefully solder or disconnect the old battery connector, observing polarity, and install a new cell with similar voltage and capacity characteristics.

When choosing a new battery, it is critical to pay attention to the presence of a built-in protection board (BMS), which prevents deep discharge and short circuit. Using cells without protection or with other parameters can lead to failure of the charge controller of the screwdriver itself or even fire. Safety is the number one priority here, so saving on battery quality is strongly discouraged.

The process of installing a new element requires care when soldering: use a soldering iron with a thermostat and quickly make connections so as not to overheat the battery. After installation, be sure to check the voltage on the contacts and make sure that the connection is correct before the final assembly of the case. If you are not sure of your soldering skills, it is better to consult a specialist or use ready-made modules with connectors.

⚠️ Warning: Do not attempt to charge a faulty or bloated battery, nor do you mechanically impact it when installed.

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Keep the original nickel plate with contacts from the old battery – it is ideal for welding or soldering to the new element, providing reliable contact.

Lubrication of the gearbox and mechanical part

The mechanical part of the screwdriver, which includes the gearbox and the cartridge, also requires attention, especially if you notice increased noise, creaking or difficulty rotating. Inside the gearbox are plastic gears that eventually lose their factory lubrication or, conversely, overgrown with a thick layer of dust and an old consistency mixture. To maintain, you need to remove the gearshaft, clean the gears from contaminants and apply a new specialized lubricant.

Use conventional machine oil or WD-40 is strictly impossible, as they are too liquid and quickly leak, without providing the necessary protection of rubbing vapors. The optimal choice is lithium lubricant or special formulations for plastic gears (for example, based on silicone or Teflon), which are not aggressive to plastic and retain viscosity over a wide range of temperatures. Apply the lubricant with a thin uniform layer, avoiding excess that can get into electronics.

Once you lubricate, assemble the gearbox and check the ease of rotation of the shaft with your hand: it should move smoothly, without jerking or jamming. If the mechanical assembly has been heavily contaminated, it makes sense to blow it with compressed air before applying a new lubricant to remove the smallest abrasive particles. Regular maintenance of the mechanics prolongs the life of the motor, reducing the load on it when working.

• 🛠️ Carefully remove the remnants of the old lubricant with Kalosha gasoline or isopropyl alcohol.
• 🛠️ Apply the new lubricant with a toothpick or a thin brush directly to the gear teeth.
• 🛠️ Check the integrity of plastic teeth gears – chips require replacement of the node.

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High-quality lubrication reduces the noise of the work and increases the torque at the output, making the tool more efficient.

Device assembly and final inspection

The final stage, assembly, requires a reverse sequence of actions, but with increased attention to the stacking of wires and positioning of components. Make sure that all plumes and wires are laid in their channels and will not be clamped with the body when the screws are tightened, as this can lead to damage to the insulation and short circuit. Carefully combine the halves of the body, making sure that all guides have entered the slots without distortion, and only then start twisting the screws.

Turn the screws cross-cross, gradually tightening them to ensure that the halves of the body fit evenly and avoid the appearance of gaps. After the complete assembly, check the tool: turn it on, check the rotation in both directions, the lighting and the charging process. If all functions are working properly, you can consider the repair or maintenance successfully completed.

If the device doesn't turn on or doesn't work properly after assembly, don't panic, but re-disassemble it and check all the connections. Often the problem lies in a poorly inserted battery connector or a forgotten screw that blocks the contact. Xiaomi Mijia is a reliable tool, and if handled carefully, it will last for many years after maintenance.