How to disassemble charging from a Xiaomi laptop: a guide

Owners of Xiaomi Mi Notebook and RedmiBook notebooks often face the need to diagnose the power supply, especially when the device stops charging or emits extraneous sounds. Disassembling the charger is a complex technical process that requires not only special tools, but also a deep understanding of the principles of operation of pulse converters. Unlike smartphones, laptop power units work with high currents and voltages, which makes the opening procedure potentially dangerous for the inexperienced user.

The main reason why the question of how to disassemble the charge from a Xiaomi laptop is the design of the case. The company's engineers use ultrasonic plastic welding to ensure the monolithic and safety of the product. This means that standard screws are absent here, and the case itself is not designed to be reopened in service centers. However, with the right skill and equipment, access to the insides is still possible for deep repairs.

Before you start taking action, you need to understand the risks. Inside the power supply are capacitors that can retain charge even after you've been disconnected from the grid. Wrong manipulation of the components can lead to short circuits or electric shocks. If you don't have high voltage electronics skills, you'd better limit yourself to replacing the cable or buying a new adapter.

Tools and workplace preparation required

To successfully and safely disassemble the Xiaomi power supply, you will need a specific set of tools. A conventional cross screwdriver will not be enough here, since the main task will be to separate the welded halves of the body without damaging them.

First of all, get a thin metal scalpel or a special knife to open the case. Plastic cards or mediators can break on a tight seam, so the metal is preferable, but requires caution. A hair dryer is also necessary to heat the glue or plastic if the manufacturer used a heat-resistant sealant in addition to welding.

• 🔧 Thin metal scalpel or sharp stationery knife.
• 🔥 Temperature-adjusted building dryer or powerful heat gun.
• 🔌 Multimeter to check voltage and circuit integrity.
• 🧤 Dielectric gloves and antistatic mat.

It is important to prepare lighting. Working with small components on the board requires good visibility. Use a cold-light desk lamp to avoid heating parts during inspection. Make sure the power supply is completely off the grid for at least 24 hours before work begins so that the residual current in the capacitors can dissipate.

Design analysis and search for hidden fasteners

Xiaomi's laptop power supplies, such as the 65W or 135W models, have complex internal architectures. Visual inspection of the case often fails, as screws can be hidden under decorative stickers or rubber legs. Careful examination of the outer shell is the first step to successful disassembly.

Put your fingers around the perimeter of the device, and sometimes you can find small indentations in the corners or under the logo that indicate screws, and if you don't have screws, you've got ultrasonic welding technology, which is the standard technology for modern electronics, and you're going to be able to disassemble at the seam.

⚠️ Note: In some Xiaomi charging models, screws can be sealed. Integrity breach of seals automatically removes the device from warranty. Proceed only if the warranty period has already expired.

Pay special attention to the exit of the cable. Often this is where the crack of the case begins due to constant bending. If your goal is to replace the cable, you may need to carefully expand the hole without damaging the insulation of the internal wires. Carefully apply the plug, if any, to assess the state of the entry point.

Use a magnifier or macro image on your phone to take detailed photos of the outside before you start the intervention, which will help you to understand when you build it back, which elements are where you were, and remember the location of the indicators if they are placed on the end of the case.

The process of opening the case: technologies and methods

The most common method of opening the welded body is to use a thin blade and a neat pressure. Put the scalpel blade in the joint of the two halves of the body. The movements must be progressive, without sharp jerks, so as not to break the plastic. Move along the perimeter, gradually delving.

If the plastic is too dense and too mechanical, you can apply heat. The hair dryer is set to a temperature of about 100-120 degrees Celsius. Heat the seam evenly, driving the nozzle along the junction line. This will soften the plastic and allow the blade to go deeper. Do not overheat the body, so as not to melt the internal components.

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Use a thin line or string to cut through the seam. Wrap the ends around your fingers and saw the seam back and forth like a thread. This is safer than a knife, because there is less risk of damaging the board inside.

Once the blade has entered the entire perimeter, use plastic spudgers to finally separate the halves. Metal tools are already dangerous here - you can accidentally close contacts on the board or damage the tracks. Act slowly, feeling resistance.

Inside, you'll see a main board attached to screws or latches. Often the board is glued to one of the halves of the case in double-sided tape. Carefully tuck the edges of the board, trying not to damage the cable connectors. Disconnect the plumes if they are present, although Xiaomi charges are more likely to use direct soldering.

Diagnostics of internal components and boards

Once the board is successfully retrieved, the diagnostic phase begins, and visual inspection can reveal obvious defects, such as swollen capacitors, blackened resistors, or traces of burns on the textolite. However, most malfunctions in Xiaomi's power supplies are hidden and require instrumental verification.

First, check the inlet filter and the fuse, and often the problem is the fuse that's burned, which protects the circuit from surges, but you can't just replace it, you have to find out why it burned, and if you replace the fuse without eliminating the cause, it will burn again instantly.

Pay special attention to power transistors and diode assembly. They work in heavy temperature conditions and often fail. Check them for breakdown. If the multimeter shows a short circuit in both directions, the element is defective. Also check the PWM controller bandage.

Replacement of cable and restoration of contacts

The most common problem faced by users is a cable fracture at the base of the plug or at the entrance to the block. In Xiaomi power units, the cable is often mounted in the case and soldered directly to the board, and you will have to completely dismantle the old wire to replace it.

Carefully solder out the old cable by remembering the color marking of the wires. Usually red or yellow is a plus, black is a minus. In modern charging with PD (Power Delivery) fast charging protocols, there may be additional wires for data transfer that cannot be confused.

When soldering a new cable, use a quality solder and flux. It is important not to overheat the board, as the tracks may detach. Use a heat-adjusted soldering iron. After soldering, be sure to check the reliability of the connection by slightly pulling the wire. The exit of the cable from the case should be strengthened with shrinkage or glue.

⚠️ Warning: Incorrect soldering of wires can cause a change in the resistance of the circuit.This can knock the calibration of the power controller, and the laptop will not receive the declared power while operating in power saving mode.

If the cable changes to a longer or different thickness, make sure that the wire cross section corresponds to the load current. Charging 65W and above requires a wire cross section of at least 0.75 mm2, preferably 1.0 mm2. Thin wires will warm and create a voltage drop.

Assembly, testing and safety measures

The final step is to assemble the device, if you cut the case, you have to glue it together, use a special plastic glue or an epoxy resin, apply a thin layer of glue around the perimeter, avoid getting inside the board, squeeze the halves of the case hard and lock them with rubber bands until they dry out.

Before connecting to your laptop, do a primary test. Connect the power supply to the network through a multimeter in voltage measurement mode. The output should be stable voltage (usually 19V or 20V for Xiaomi). If the voltage floats or is absent, the assembly is incorrect or components are damaged.

Only after a successful idling test can you plug in your laptop.