Disassembling the Xiaomi MDY-10-EF power supply is often a necessity when the original charger stops supplying current or starts to work unstable.This model, known for its Quick Charge 3.0 fast charging technology, has a dense internal layout, making the process of opening the case a non-trivial task for the untrained user.
Before you start physical intervention, it is important to realize that you will violate the factory sealing and deprive yourself of the warranty if it was still in effect. However, if the device fails and you do not want to buy a new original, careful dismantling can prolong the life of the power supply. In this article, we will examine in detail the stages of dismantling, the necessary tools and technical nuances of Xiaomi internal circuitry.
It's worth noting that inside the unit are high voltage elements even after disconnection from the mains. Capacitors can retain charge, so the first rule of repair is safety. Next, we'll go to the description of the required toolkit and the immediate process of opening the case.
⚠️ Warning: Before starting work, make sure the power supply is completely disconnected from the power supply for at least 15 minutes.Residual voltage on the capacitors can cause an unpleasant shock or damage the multimeter during diagnosis.
Tools and workplace preparation required
For high-quality disassembly of the power supply of a conventional set of screwdrivers will not be enough. the plastic case Xiaomi MDY-10-EF is fastened by ultrasonic welding, which requires the use of specific methods of opening without damaging the external walls. You will need a thin metal blade, a medical scalpel or a special tool for opening the electronics casings.
In addition to cutting tools, a soldering iron with a thin sting is needed, since many elements inside can be soldered to the board in hard-to-reach places, and a multimeter is also necessary to check the integrity of chains and the presence of short circuits. It is convenient to use a magnetic mat or a organizer with cells to fix small parts.
☑️ Preparation for repairs
The organization of the workspace is critical. Light must fall on top and side to see the small seams on the body. If you're planning to replace the capacitors, pre-select analogues with identical capacitance and voltage parameters. Incorrectly selected components can cause the device to break down again or even burn up.
The process of opening the case and dismantling the board
The most difficult step is to separate the two halves of the body, and the seam runs around the perimeter of the device, and it needs to be carefully dissected, insert the blade of the scalpel into the joint, and, with a slight twist of the tool, lead it along the entire length of the face. Don't try to open the block from one corner, the plastic can crack.
After passing the blade around the perimeter, use a thin plastic card or mediator to unclutch the halves. Inside, you will see the main board, which usually sits tightly in the slots. In the Xiaomi MDY-10-EF model, the board is often additionally fixed with glue or sealant in the corners.
To retrieve the board, you may need to unfurl the mains wire if it goes directly to the contacts without an intermediate connector. Be careful with the tracks: copper on such boards is thin and easily peels off when overheated. Use solder paste to improve contact and reduce the melting point of solder.
Ultrasonic welding technology
Diagnostics of the main components of the scheme
Once you've successfully removed the PCB, you'll see a complex structure with many elements. Primary diagnostics begin with a visual inspection. Look for blackening, capacitor bloating, or a crack in the textolite. Often the cause of a breakdown is an output capacitor or a transistor breakdown.
Special attention should be paid to the fuse, which is located at the entrance of the network cable, if it is blackened or the thread inside is broken, this indicates a short circuit in the circuit. You can't just replace the fuse, you need to find the cause of the surge in current, otherwise the new element will burn instantly.
To check the elements, use the multimeter in diode vertebrae or resistance measurement mode. Transistors and diodes should ring one way and not ring the other. If the device shows a short circuit in both directions, the element is faulty and needs to be replaced.
| Component | Function | Frequent malfunction | Method of verification |
|---|---|---|---|
| Safety lock | Protection from the KZ | Chain break | A vertebra |
| Condensers | Smoothing out pulsations | Bloating, capacity loss | Visually + ESR-meter |
| Transistors. | Nutrition keys | Breakdown (CZ) | Multimeter (diodes) |
| Shim controller | Frequency management | Burnout of conclusions | Replacement/Observation |
It's important to check not only the power elements, but also the control controller bandage. The Quick Charge chip can fail due to a power surge. If it has chips or burnouts visually, repairing the unit will require a deep knowledge of electronics and a soldering station.
Replacement of capacitors and soldering of elements
The most common cause of unstable power supply is electrolyte drying in the capacitors, as measured by the bloated top cover or changing container parameters, replacing the old element with polarity and installing a new one.
When soldering, it is important not to overheat the board. Prolonged exposure to high temperature can lead to detachment of tracks or damage to adjacent components. Use a soldering iron with a power of no more than 40 watts and use flux for better spreading of the solder. Contact time of the sting with contact should not exceed 3-5 seconds.
If you're changing a capacitor, make sure it's at least the same voltage as the original one, for example, if you were standing at 25V, you can't put it at 16V, and you can put it at 35V or 50V, you can and you even need it to be safe. The capacity should be as close to par as possible.
⚠️ Note: When installing a new capacitor, strictly observe polarity. The negative output (usually marked with a strip on the case) must match the marking on the board.
After the components are replaced, it is advisable to wash the board with isopropyl alcohol or a special contact cleaner, which will remove the residue of the flux, which over time can become a conductor of current and cause corrosion, and allow the board to dry completely before assembly.
Assembly of the device and check of performance
The assembly begins with the board being put back into the case. Make sure all wires are laid neatly and not clamped with plastic walls. In the Xiaomi MDY-10-EF model, it is important to correctly combine the USB connector with the hole in the case, otherwise the cable plug will not enter the end.
To fix the halves of the body after disassembly, the usual glue will not work due to heat. Better use epoxy glue or a special heat-resistant sealant. Apply the composition with a thin layer along the seam so that it does not leak in and damage the components.
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Use rubber harnesses or stationery gums to tighten the body during the drying of the glue, which will ensure tightness and no gaps.
The first switch on after repair is better done through the safety chain, for example, through an incandescent lamp with a power of 40-60 watts, switched on in series with the mains. If the lamp flashes and goes out when you turn on, there is probably no short circuit. If it burns in full heat, there is somewhere left KZ.
Check the output voltage with a multimeter. It should be USB (5V) or activate the fast charging mode when you connect a compatible device. If all parameters are normal, you can consider the repair a success.
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High-quality assembly and use of heat-resistant materials during the gluing of the body will prolong the service life of the repaired power supply unit and ensure the safety of operation.
Typical repair errors and safety measures
One of the biggest mistakes newcomers make is ignoring insulation. The inside of Xiaomi's power supply is very tight, and uninsulated contacts can lock onto each other. Always check if the legs of the radio parts are touching metal parts of the case or each other.
It is also common to use inappropriate analogues of components, where Chinese manufacturers may use non-standard resistor denominations or specific transistors, and replacing them with "similar" ones without calculating parameters can disrupt the PWM controller.
Remember the temperature. The power supply warms up when you're working, and if you pour in the insides with regular glue, it can leak and short the contacts. Use only dielectrics designed for high temperatures.
- 🔌 Isolation: Always check for no circuits between items before being included in the network.
- 🌡️ Heat resistance: Use materials that withstand heating until 80-100 degrees Celsius.
- ⚡ Nominations: Do not replace components with counterparts with worse voltage and current characteristics.