Xiaomi’s modern chargers are renowned for their reliability and compactness, but even they are not immune to breakdowns. Most often, users experience a cable break at the base, contact oxidation or internal capacitors failure after a voltage surge, in which there is an urgent need for repairs that are impossible without opening the case.
But the accessories are designed to prevent unauthorized access. The manufacturer uses ultrasonic plastic welding to make the case monolithic and strip it of visible screws or latches. That's why the question of how to carefully disassemble the power adapter Xiaomi remains one of the most popular among amateur masters and enthusiasts of electronics repair.
Before you start active action, you need to be aware of the risks. There is a high voltage inside the power supply that can remain on the capacitors even after disconnection from the mains. Unprofessional intervention can lead not only to final failure of the device, but also to electric shock. This article describes the technical process of disassembly for informational purposes only.
Tools and workplace preparation required
The success of the operation depends on the quality of preparation and the availability of a specialized tool, and a regular screwdriver is not necessary, because we have to work with a sealed seam and miniature components, you need a thin and durable blade that will not break under pressure.
Organize a well-lit workplace. It is advisable to use an antistatic mat to protect the board from static electricity, although this is less critical for simple power supplies than for smartphones. Prepare a container for collecting small parts, as when you open the springs or cogs can fly apart.
The core set of tools includes:
- 🔪 Thin stationery knife or scalpel with sharp blade.
- 🔧 A set of thin screwdrivers (cross and flat).
- 🧤 Dielectric gloves to protect against residual current.
- 🔨 Plastic blade or mediator for plastic deflection.
- 🧪 Isopropyl alcohol for cleaning contacts.
⚠️ Note: Use of metal tools inside a device that is switched on or recently disconnected is strictly prohibited.Always give capacitors time to discharge or force them to discharge through a resistor before touching the board.
Pay special attention to the choice of knife. The blade should be new to cut plastic, not crumple it. A dumb tool will increase the risk of slipping and injuring your fingers. If you have the opportunity, use a special knife to open the electronics cases with a cut depth lock.
Design analysis and search for hidden fasteners
Most Mi Power Adapters have a classic two-part design, two halves of the body connected around the perimeter, and at first glance, the seam seems to be perfectly smooth, but when you look closely under the magnifying glass, you can see a subtle junction line. In some revisions, the manufacturer hides one screw under a technical information sticker.
So if you find a sticker, warm it up with a hair dryer and remove it, and you can have a screw with a thread underneath it that holds one of the halves of the body, and if you don't have a screw, you have classic ultrasonic welding, and you have to disassemble it by cutting the seam.
The main types of connections in Xiaomi adapters:
- 🔩 Screw joint (rarely seen, usually 1 screw under the label).
- 🔥 Ultrasonic welding (main method, requires the destruction of the seam).
- 🧩 Plastic latches (used in combined assembly variants).
It's important to understand that when you disassemble the welded joint, it's almost impossible to maintain the integrity of the body, so you either have to cut a thin layer of plastic around the perimeter or you have to carefully unpack the seam, leaving the serrated ones. After repair, you have to glue the body back together again, so make a quality plastic glue or an epoxy resin in advance.
If you are planning frequent repairs, it makes sense to purchase a special milling machine to open the seams, but for a one-time operation, a sharp knife and patience are enough. The main thing is not to damage the internal board when passing the cutting edge through the outer layer of plastic.
Technology of opening of the welded body
The process of splitting the halves of the body is the most time-consuming step. There are two main methods: mechanical incision and heating. The mechanical method is safer for electronics, but requires a firm hand. A dryer can soften the plastic, but there is a risk of overheating the internal components or melting the insulation.
In the mechanical method, take a sharp knife and start driving it along the seam with a little pressure. Your goal is to cut through the plastic comb that formed during welding. The movements must be progressive, without jerking. The depth of the blade should not exceed 1-2 mm so as not to touch the board.
☑️ Checklist for safe autopsy
If you've chosen a heating method, use a building dryer at a minimum temperature. Warm the perimeter evenly for 2-3 minutes. Plastic will become softer, and it will be easier to separate the halves. However, remember that the shrinkage inside can shrink and the components can shift.
Once you've been through the perimeter, insert a thin plastic blade or mediator into the gap, gently loosen the body as you move along the seam, don't put too much effort, if the body doesn't lend itself, you haven't fully cut through the weld in the place, and the knife procedure needs to be repeated.
Diagnostics of internal components of the board
Once you've done a successful opening, you'll see a compact circuit board with a densely packed circuitry. Xiaomi adapters typically use a pulsed circuitry to convert the voltage. First, visually inspect the board for traces of burns, capacitor bloating, or disconnected contacts.
Frequent causes of malfunctions that can be eliminated:
- 💥 Bloating of electrolytic capacitors (requires replacement).
- 🔌 Breaking the wire from the payment at the soldering site (requires soldering).
- 🌫 Oxidation of contacts USB-port (requires cleaning with alcohol).
- 🔥 Breakage of the fuse or varistor (requires replacement).
Pay special attention to the input capacitor. Even if it's visually intact, check it with a multimeter. Often, it's the loss of capacity that causes the charger to malfunction or the appearance of a high-frequency squeak. Use components with similar or larger voltage and capacity parameters to replace it.