How to fix the power supply of the Xiaomi phone: disassembling 90% of breakdowns with photos and schemes

Xiaomi’s power supply is one of the most vulnerable parts of the brand’s gadget ecosystem. According to service centers, up to 40% of charging problems are not related to the smartphone battery, but to the malfunction of the original or third-party charger. 8 out of 10 breakdowns can be repaired independently with a soldering iron, multimeter and basic electronics knowledge at hand. In this article, we will analyze the unique “diseases” of Xiaomi power supplies that are not found in other brands, from the characteristic “rustle” when connected to a sudden disconnection of charging by 80%.

It's important to understand that repairing a power supply requires care and safety, and we're not going to talk about trivial things like "check the power outlet" or "change the cable" -- we're going to focus on deep diagnostics and repairing the internal components. All instructions are suitable for popular models: Redmi Note 10/11/12, POCO X3/X4/X5, Mi 11/12/13, and also for fast charging 33W/67W/120W. If your power supply has a non-standard connector (for example, Xiaomi HyperCharge), pay attention to the special section at the end of the article.

1. Diagnosis of malfunction: how to determine that the power supply is broken

The first step is to eliminate problems on the phone and cable, connect the charger to another gadget (e.g., power bank or second smartphone), if charging is not on any device, the problem is precisely in the power supply.

• 🔌 Charging is interrupted through 5-10 seconds after connection (characteristic of malfunctioning) IC-controller).
• ⚡ Sparks or cracks when connected to a socket (a problem with capacitors or a diode bridge).
• 🔥 The power supply is heated to 60°C+ in standby mode (short circuit or transistor breakdown).
• 📉 Charging is only in a certain position of the cable (poor contact on soldering). USB-port).
• 🛑 Charging indicator flashes red (voltage mismatch or protection has worked).

For accurate diagnosis, take a multimeter and measure the voltage at the output of the power supply (on contacts). USB-Normal values for different charging standards Xiaomi:

If the voltage is absent or is very different from the norm (for example, 3.7V instead 5V), If the voltage is normal but it's not charging, check the integrity of the lines in the unit. USB-cable (often damaged by D)+ D-).

⚠️ Warning: Do not connect the power supply to the mains if you see bloated capacitors or burnt tracks on the board on visual inspection.

Disassembly of the power supply: tools and safety

You'll need to take this apart.

• 🔧 Flat screwdriver (for smearing the body).
• 🔥 A soldering iron 30-60W slender-stinged SMD-component).
• 🧲 Tweezers and a sucker for SMD (microchip-breaking).
• 📏 loope USB-microscope (to examine small details).
• 🔌 Isolated clips "crocodile" (for fixing wires during soldering).

Most Xiaomi power supplies are assembled on latches, but some models (e.g. Mi) 120W GaN) have adhesive around the perimeter to disassemble such a block:

1. Disconnect the block from the network and let it cool down. 10-15 minute

2. Screw the seam between the halves of the body (start with USB-port)

3. If the body does not lend itself - warm up with a hair dryer around the perimeter (temperature). 60-80°C)

4. Carefully disconnect the board from the case, do not pull the wires

5. Take a picture of the location of the parts before dismantling-->

Pay special attention to warranty seals. On the original Xiaomi blocks often have stickers with the QR-code (e.g. on models) MDY-12-ED Their damage will void the warranty - if your block is still warranty, it is better to contact the service center.

After disassembly, check the fee for the subject:

• 🔥 Blackened or bloated capacitors (especially near the transformer).
• 🕳️ Microcracks on the tracks (often near the USB-plug).
• 💥 Burned resistors (usually labeling begins with R).
• 🧲 Oxidized contacts (green coating on the legs of components).

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If the board has a white coating (oxidation from moisture), clean it with an alcohol solution of isopropyl alcohol (90%+) Don't use acetone, it destroys the marking of parts!

3.Typical breakdowns of Xiaomi power supplies and repair methods

Let’s look at the 5 most common faults and how to fix them, and for each fault, we’ll show the error codes that you can see on your smartphone screen (if the power supply supports Quick Charge).

The fuse has burned out (most common failure)

Symptoms: power supply does not show signs of life, multimeter shows 0V exit.

Reason: a power surge in the network or a short circuit in the phone.

Repair:

1. Find a safety lock on the board (usually this one) SMD-labelling F1 or FUSE, plug-in 220V).
2. Call him multimeter in "couple mode." Resistance must be 0 ohms.
3. If the fuse is burned - replace it with a similar one (the nominal value is indicated on the case, for example, 5A 250V).

The filter capacitors are up.

Symptoms: the power supply is warming, charging is jerking, high-frequency squeak is heard.

The reason: electrolyte drying in capacitors due to overheating or old age.

Repair:

• 🔍 Find the capacitors (their upper part is convex or leaky).
• 🔥 Drink them with a soldering iron, clean the contact areas.
• 🛠️ Install new capacitors with the same nominal value and operating voltage (for example, 1000µF 16V).

Diode bridge malfunctioned

Symptoms: the power supply is not turned on, when connecting to the network, a crack is heard.

Cause: breakdown of one or more diodes in the rectifier.

Repair:

• Find a diode bridge (usually an assembly of 4 diodes in a square case or 4 separate diodes). 1N4007).
• Call each diode with a multimeter in diode mode. The correct diode passes current in one direction (shows) 0.5-0.7V), reversed, infinity.
• Replace the faulty diodes. Xiaomi blocks will do 1N4007 (1A) or BY229 (3A).

The transformer winding is damaged.

Symptoms: the power supply is heated, but does not give out voltage at the output.

Cause: interturn circuit or break in the transformer.

Repair:

The transformer is the hardest part to repair, and if it's burned, it's easier to buy a new power supply, but 30 percent of the time, the contact mixing solves the problem.

• Check the integrity of rations on the legs of the transformer (they often crack from overheating).
• If the winding is intact but the unit is not working, the key transistor may have burned (usually) MOSFET near-transformer).

Charging controller burned down (IC)

Symptoms: the power supply gives a voltage, but the phone does not see it or shows Slow charging.

Cause: failure of the controller chip (e.g, CY7724 or SC8989 in Quick Charge blocks).

Repair:

Replacing the controller requires soldering experience BGA-If you're new, you'd better take the unit to the service:

1. Find the datasheet on the chip (by marking on the case).
2. Order a similar one on AliExpress or in the radio store.
3. Remove the old chip using a thermo-air station or soldering iron with a nozzle.
4. Install a new one, observing polarity (the label on the case must match the original).

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90% of Xiaomi power supply failures are related to a fuse, capacitors or diode bridge, and if the unit fails to work after replacing them, the transformer or controller is a problem, and repair becomes economically inefficient (it is cheaper to buy a new unit).

4. Features of repair of power supplies with fast charging (33W/67W/120W)

Xiaomi’s fast-charging power supplies have additional protection and phone communication schemes, which are complicated by the presence of:

• 🔌 Additional Protocol Controller (e.g, CYPD2104 Quick Charge 4 for the first time+).
• 📡 Data lines in USB-cable (D)+ and D-, responsible for the "agreement" of voltage).
• 🛡️ Two-stage protection against overheating (thermistor) + program-limit).

If your power supply is supported 67W or 120W (model MDY-12-ED, AD65), Keep in mind when repairing:

For blocks with GaN transistors (e.g., Mi) 120W GaN) critically maintain thermal conditions after repair:

1. Apply a new heat paste on a radiator (such as Arctic) MX-4).
2. Check the integrity of the gaskets between the transistors and the housing.
3. Do not load the unit at full capacity for the first 24 hours (let the paste "curl up").

⚠️ Attention: Power supply units Xiaomi HyperCharge (120W) If the phone shows "Non-Original Charger" after repair, you'll need to run the controller through the phone. USB-UART Adapter (this is a separate theme for advanced users).

5. USB-Port: Re-establishing contact

One of the most common problems is poor contact with USB-The power supply port:

• 🔌 Charging is only possible if you keep the cable at a certain angle.
• 📱 The phone is constantly connected/disconnected.
• ⚡ Sparks inside the connector when connected.

For repairs:

1. Take it down carefully. USB-port with board (it is usually soldered) 4-5 contact).
2. Clean the port legs and contact pads from oxidation (use an eraser to clean the contacts or alcohol).
3. Seed the port back, making sure that all legs are evenly warmed up.
4. Check the integrity of the resistors near the port (R22 and R23 most-schematic).

If the legs of the port are removed together with the contact areas, you can:

• 🔗 Solder wires directly to the board tracks (use a thin mounting wire).
• 🔄 Transplant the port from the donor board (any USB-Type-A with leg increments is suitable). 2.54mm).

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For rationing USB-Use flux gel port (e.g. Amtech) NC-559) — it prevents the formation of "sellows" solder and improves grip on contact areas.

6.A post-repair check: how to make sure the power supply is safe

After the repair, be sure to perform the following checks:

1. Visual inspection: are there any forgotten fallen parts or bare wires

Insulation check: multimeter in "megaommeter" mode (resistance between 220V and USB must have >10Mo)

3. No load test: connect the unit to the network for 1 minute (no burning or cod smell)

Voltage check: multimeter measure the output voltage (should meet the standard)

5.Luth test: plug your phone in and check charging stability for 10 minutes-->

If the power supply is stable, but the phone shows "Slow Charging", the problem may be:

• 📱 Porte phone charging (clean it of dust with a toothpick).
• 🔌 Cable (try another, original Xiaomi).
• ⚙️ Phone Settings (enable Quick Charging in Settings) → Battery).

For final check, use the Ampere app (available on Google Play) to show the actual charging current:

• 🔋 100-500mA — The power supply is working, but in "emergency" mode.
• 🔋 500-1500mA — standard (5W).
• 🔋 2000mA+ — The block gives full power (Quick Charge works).

⚠️ Warning: If the power supply is heated above 60 after repair°C at normal load, immediately turn it off. This is a sign of a turn-to-turn circuit in the transformer or a malfunction of the key transistor!

7 When repair is not advisable: signs of malfunctions that are not repaired

Not all Xiaomi power supply breakdowns are repairable.Take the unit to scrap or buy a new one if:

• 🔥 The transformer burned (blackened, melted, smelled of burns) and the cost of a new transformer often exceeds the price of a block.
• 💥 An electrolytic capacitor exploded (the body ruptured, the electrolyte fluid leaked) and it damaged other components.
• 🧲 Logs on board in several locations are cut off (recovery requires professional equipment).
• 🔌 Damaged. USB-port with a break of internal contacts (in the block a non-standard connector is used).
• 📡 The fast charging protocol controller (e.g.) has burned, CYPD2104). His replacement requires BGA-rations.

The average cost of the new original power supply Xiaomi:

If you are buying a new block, pay attention to:

• 🔍 Marking on the case - it must match the original (for example, MDY-08-EZ).
• 🔌 Type of connector – some Xiaomi models use non-standard USB-C (For example, HyperCharge).
• 📄 Certificates (the package must have signs) CE, RoHS).

8.Prevention: How to prolong the life of Xiaomi power supply

Compliance with simple rules will increase the life of the power supply unit in 2-3 once:

• 🔌 Do not leave the block in the socket without load - this reduces the resource of the capacitors.
• 🌡️ Avoid overheating – do not cover the unit while working (especially important for GaN models).
• ⚡ Use network filters – they protect against voltage surges.
• 📱 Do not rot the cable at the base – it damages the internal wires and port of the block.
• 💧 Store the block in a dry place - moisture leads to oxidation of contacts.

For fast-charging units (33W+):

• 🔋 Clean once every 3 months USB-dust port of the block (use compressed air or soft brush).
• 📉 Do not use the unit at maximum power all the time – this reduces the resource of GaN transistors.
• 🔄 If the block began to warm stronger than usual, check it with a multimeter - the capacitors may have failed.

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Xiaomi’s original power supply units are designed for 500-800 When used intensively (daily charging), their resource is 2-3 Third-party units serve in 1.5-2 less.

FAQ: Frequent questions about repairing Xiaomi power supplies