DIY power supply repairDespite the apparent power, a personal computer is a fragile thing. To disable any part, simply careless handling of it. For example, do not clean the system unit and its components. As a result, a lot of dust is generated on the details, which negatively affects the operation of the device as a whole.

One of the most important components of a PC is a power supply. It is he who distributes electricity to the system unit and controls the voltage level. Therefore, the failure of this device can be attributed to one of the most unpleasant. Nevertheless, to do repair and fix the problem with their own hands under the power of each.


  • 1 Signs of a disabled power supply
  • 2 Main causes of faults
  • 3 Computer Power Supply Device
  • 4 Precautionary measures
  • 5 Required Tools
  • 6 Inspection and diagnosis
  • 7 Repair Instructions
  • 8 No problems, but BP does not work.
  • 9 In conclusion

Signs of a disabled power supply

The most critical situation is when the computer does not respond to the power button

. This means that important points were missed, which could indicate a quick breakdown. For example, unnatural sound during operation, long turn on the computer, self-shutdown, etc. Or maybe similar faults were noticed, but it was decided not to resort to repair.

In addition to the most critical moments, there are several signs that help identify problems in the operation of a computer power supply:

  • What to do when the power supply is not workingThe emergence of various errors when turning on the PC.
  • Sudden computer restart.
  • Increase the volume of the coolers (small fans).
  • Various errors when the PC is turned on.
  • Termination of the hard drive or some coolers.
  • Loud squeaking from the system unit (talking about overheating).
  • Electric shock when touching the case.

Such signs indicate the need for quick repairs, which can be done with your own hands. However, there are more serious problems, clearly indicating a serious malfunction. For example:

  • "Screen of death" (blue screen when turning on or operating the device).
  • The appearance of smoke.
  • No reaction to the inclusion.

Most people in the event of such problems turn to the master for repair. As a rule, a computer specialist advises to purchase a new power supply, and then install it instead of the old one. Nevertheless, with the help of repair, it is possible to "reanimate" an idle device with your own hands.

Main causes of faults

To completely solve a problem, it is necessary to understand why it could appear. More often computer power supplyfails for three reasons:

  • Voltage drops.
  • Low quality of the product itself.
  • Inefficient operation of the ventilation system, leading to overheating.

In most cases, such faults lead to the fact that the power supply does not turn on or stops working after a short operation. In addition, the above problems may adversely affect the motherboard. If this happens, then repairing it yourself is not enough - it will be necessary to change the part to a new one.

Less commonly, malfunctions in a computer's power supply are caused by the following reasons:

  • Poor software (poor OS optimization has a bad effect on the operation of all components).
  • Lack of cleaning components (a large amount of dust makes coolers work faster).
  • A lot of extra files and "garbage" in the system itself.

As mentioned above, the power supply is a rather fragile thing. Nevertheless, it is very important for the computer as a whole, so you should not deprive this component of attention. Otherwise, repair is inevitable.

Computer Power Supply Device

How does the power supplyThe power supply in the computer is responsible for the distribution and conversion of electrical current. The fact is that each element in the PC needs its own voltage level. In addition, the electrical network uses a variable current, and computer components operate on a constant. Therefore, the power supply device is rather specific and you need to know it to do it yourself.

In each BP There are 9 important components:

  • The main board (large and flat component) - many details are attached here (by analogy with the motherboard).
  • An input filter (a device mounted on large wires) or power capacitors (products in the form of a cylinder) are needed to “smooth” the voltage.
  • Voltage vector (coil made of large copper wire mounted on one of the walls) or diode bridge (plastic device, shaped like a sim card with 4 metal diodes) - is responsible for converting power.
  • Voltage monitoring circuit (motherboard installed vertically next to the inverter) - controls the current level.
  • A transformer (small plastic device with numbers and letters) - creates the necessary voltage in the power supply.
  • Pulse transformer (similar to the previous component, but larger) - receives a high voltage from the injector to change it to a low voltage.
  • A radiator (usually a gray grille) is required for cooling.
  • The board with connectors for wires (not present in all models of power supplies) is used to disconnect unused wires.
  • Power Drosser (usually a copper coil with colored wires) - is engaged in voltage stabilization of the group.
  • The cooler speed controller (a small plastic device, sometimes installed not on the main, but on the daughter board) is responsible for adjusting the operation of the fan in the power supply.

Without having at least an approximate idea of ​​the device power supply, it is impossible to fully carry out self-repair.

Precautionary measures

Before you start solving the problem in the computer with your own hands, you need to think about your own safety. Repairing such a device is a dangerous task. Therefore, first of all, you need to work thoughtfully and without haste.

For greater security, there are several important rules to keep in mind:

  • DIY power supply repairWork only with the power supply turned off. Despite the banality of advice, this is a very important point. No one is immune from the "fool's syndrome", so it is better to check once again that everything is off, and only then take up repair.
  • To save components and to avoid “fireworks”, it is recommended to install a 100 watt light bulb instead of a fuse. If the light remains on when the power supply is turned on, the network is somewhere closed. If it lights up and immediately goes out, then everything is in order.
  • Especially long under power are the power capacitors. Therefore, even after disconnecting the power supply from the network, you should not immediately get to work.
  • It is better to check the operation of the device far from flammable substances, since there is a risk of short circuit and sparks “fireworks”.

Required Tools

To repair the power supply was simple but effective, each home wizard will need certain tools to work. All these products can be easily found at home, asked from neighbors / friends or purchased at the store. Fortunately, they are inexpensive.

So for repair The following tools are required:

  • How to use a computer power supplySoldering station with built-in power control or several soldering irons, each of which is designed for a certain power.
  • Solder and flux for soldering components.
  • To remove solder - braid or suction.
  • Several screwdrivers with different tips.
  • Multimeter
  • Side cutters (devices for cutting plastic "clamps" that fasten the wires).
  • 100 watt bulb
  • Tweezers (for removing small components).
  • Alcohol or refined gasoline.
  • You may need an oscilloscope (if the cause of the fault has not been established).

Inspection and diagnosis

It is first necessary disassemble the power supply. For this you only need a screwdriver and accuracy. When unscrewing the bolts do not need to shake the PSU to quickly fix the problem. The careless handling of it can lead to the fact that repairing it yourself will simply be useless.

For the correct statement of the "diagnosis" it is necessary to conduct a primary diagnosis, as well as a visual inspection of the device. Therefore, first of all it is necessary to pay attention to the power supply fan. If the cooler can not spin freely and is stuck in a certain place, then the problem is clearly this.

In addition to the fan products, you should also inspect the device as a whole. After a long service life, it accumulates a lot of dust, which has a negative effect and hinders the normal operation of the PSU. Therefore, it is imperative to clean the product from the accumulation of dust.

Also some products fail due to voltage drops. Therefore, it is necessary to conduct a visual inspection for burnt parts. This sign can be easily identified by swelling of capacitors, darkening of the PCB, charred insulation, or broken wires.

Repair Instructions

Finally, it is worth moving to the most important point - repairing the power supply with your own hands. For convenience, the entire process will be presented in a list. Therefore, it is recommended not to “jump” from one point to another, but act in a certain order:

  1. How to repair the power supplyInspection fuse. When traces of melting are detected, it is not necessary to immediately replace the product. This is usually due to problems with other components. Therefore, it is recommended to check the power transistors and the diode bridge.
  2. If damage to other components is not detected, and the fuse itself is swollen - it should be evaporated from the board. Then heat the metal plugs and remove them from the glass tube. Finally, you need to insert a wire of the desired diameter, solder the holes and install the fuse in place.
  3. Inspect the thermistor. Almost always, this element stops working due to power surges. Therefore, if this device turns black and cracks when touched, you need to replace the thermistor and then the fuse.
  4. Check the condition of the primary circuit elements (those installed near the thermistor and fuse).
  5. Inspect the capacitors. If no external signs of damage are found, you can drop out these elements and check with a multimeter.
  6. Take out the cooler, lubricate its bearings with engine oil and then reinstall the fan.
  7. A multimeter to measure the resistance of each diode in the bridge. If the resistance is different, the defective item needs to be replaced. Non-working components are replaced with Schottky diodes.
  8. Inspect the circuit board. With careful inspection, you can identify small annular cracks that break the connection of the contacts. If a similar malfunction has been detected, it is necessary to use soldering to close the cracks.
  9. Inspect the contacts of resistors, fuse, transformer and inductor. If problems were observed in connection with the board or ring cracks, then you need to fix the damage by soldering.

No problems, but BP does not work.

What are the reasons why the power supply does not workIt so happens that everything looks fine: the components are not melted, there are no cracks or contact disturbances. What is the problem then? It is best to once again carefully examine all the details. It is possible that due to inattention any malfunction was missed. If the secondary examination problems are not identified, then in 90% of cases the fault lies in standby power or in the PWM controllerusing wide pulse modulation.

To correct the problem with the voltage, you need to know the basics of the power supply. This component of the PC works almost always. Even when the computer itself is turned off (in not disconnected from the network), the unit operates in standby mode. This means that the PSU sends “on-demand signals” of 5 volts to the motherboard, so that when the PC is turned on, it can start the unit itself and other components.

When starting the system, the motherboard checks the voltage for all elements. If everything is in order, is formed response "Power good" and the system starts up. If there is a shortage or excess voltage, the launch of the system is canceled.

This means that first of all on the board you need to check the presence of 5 V on the PS_ON and + 5VSB pins. When checking usually revealed the absence of voltage or its deviation from the nominal. If the problem is observed in PS_ON, the reason is in the PWM controller. If the fault is with contact + 5VSB, then the problem lies in the device for converting electric current.

Also, it is useful to check the PWM itself. True, for this you need an oscilloscope. To check, you need to drop out the PWM and use the oscilloscope to test the contacts (OPP, VCC, V12, V5, V3.3). For a better sound, checking should be carried out against the ground. If the resistance is between the ground and any of the contacts (of the order of several tens of ohms), then the PWM must be replaced.

In conclusion

Self-repair of the power supply is a rather complicated process, which will require the necessary tools, basic knowledge of the work of BP, as well as accuracy and attention to detail. Nevertheless, with the right approach, each person can repair the unit, despite its complicated structure. Therefore, it should be remembered that everything is in your hands.