Computer does not turn on DIY repair

In this section, we will look at how to repair your computer yourself. First of all, let's come to an agreement that computer repair actually consists of two independent procedures: identifying the cause of its inoperability (diagnostics) and, in fact, the stage of elimination of the breakdown (renovation).

How do you fix your computer? A person often asks himself such a question when his faithful iron “friend” unexpectedly refuses to turn on or starts “freezing”, spontaneously rebooting or detecting any other defects in work.

Remember? First things first: Doing your own computer repair starts with diagnosing the problem. From a visual examination of the “patient” 🙂 With time and experience in this matter, there is a strange feeling that can be conditionally compared with intuition. Are you starting to “feel” the computer hardware or what? 🙂

You must also understand that computer repair is (quite often) a banal replacement of one or more of its inoperative components. This is, in fact, a large-scale reassembly of it. It also happens that you need to sit over it with a soldering iron, but more on that later 🙂

Naturally, in order to successfully repair a computer, we need spare parts. Moreover, the more of them, the better. Sometimes it happens (especially for old technology) that one replaced part works fine on one computer, but does not work on another, or vice versa. In my case, there are no problems with this: there are enough different hardware in the working warehouse, choose any, but what to do at home?

I can give advice: it's trivial to collect everything that comes into your field of vision (the processor that remained after the motherboard burned out is "unnecessary" due to the upgrade, a RAM module, an outdated video card that does not "pull" a new game etc ). I think you understand me? I can assure you that over time, with this approach, you will have a sufficient collection of various spare parts and components in your home that can be used to repair your computer.

Over time, you can absolutely easily assemble yourself from such parts, for example, a second computer (especially for tests), organize your own local mini-network at home, and in general - get the necessary basic experience of “fiddling” with computer hardware. For example, I now have three fully assembled computers at home, connected into a small network and there is always the opportunity to collect several more from what is stored on special shelves.

Where am I heading in this introductory article? Besides, the question of how to repair a computer cannot be effectively resolved without an adequate supply of spare parts. This is a very important point! Have you ever visited the assembly and repair department of any small computer company? I assure you that there you will see a very wide variety of components that often help the guys there to successfully diagnose computer malfunctions.

At the end of our introductory material, I want to note that before repairing a computer, we (no matter how trite it sounds) will need to rid our “patient” of the dust accumulated in him. I must say that sometimes it happens that this procedure itself replaces the entire repair 🙂 For this purpose, an old (Soviet) vacuum cleaner, which is switched to a mode not for blowing in, but for blowing out air from itself, is very suitable for us.Simply unscrew the "trunk" of the vacuum cleaner from the front and screw it on from the back.

I wanted to supplement the article with some practical material, otherwise it turned out to be a lot of letters and little specificity. I would like to acquaint (those who do not yet know) you with such a wonderful program as "Cpu-Z" (you can download its version for 32 and 64-bit systems from the link).

Do not think that the program will not tell you how to repair your computer, but it will significantly facilitate some moments and practically allow you to “look” into the system unit without opening it. Well, here I exaggerated a little, but - just a little 🙂

What is so great about the "Cpu-Z" program? First of all, it doesn't need to be installed. It runs immediately in RAM. Its main advantage is that it will show us complete and detailed information about the main elements of our computer:

1. processor, type of its socket (socket);
2. motherboard (separately with information about the "northern" and "southern" of its microcircuits);
3. we will be able (without opening the case) to determine how many RAM slots are installed on the motherboard, which of them are occupied and what is installed in them;
4. data on the graphics adapter (video card) is displayed separately;

As you can see, there is a whole basket of pluses. And all this happiness fits into 2 megabytes! Let's take a closer look at a program that will be very useful to us, even if not in the process of repairing a computer itself, but at the stage of collecting data about it.

After launch, we see the following window:

This is the first tab titled "CPU". Let's take a closer look at it:

• The "name" field is the model of our processor;
• "Code name" "Max TDP" - the code name of its core and the maximum power consumption in watts;
• "Package" - the name of the processor socket (slot or socket);
• "Technology" and "Core Voltage" - with the use of which technological process (45 nanometers) is the voltage on the core made;
• "Specification" - the full name of the product and its clock frequency (2.80 GigaHertz)
• The bottom part of the screenshot shows the system bus clock speed and cache characteristics of the first and second levels;

Consider the "Mainboard" tab - motherboard.

• The "Manufacturer" field tells us the manufacturer (Asus);
• "Model" - full name of the board model;
• "Chipset" - chip manufacturer (Intel) and its model (G41). This - "north bridge " chipset;
• "Southbridge" - data on "south bridge“;
• Section "BIOS" - provides data on the motherboard microcircuit of the same name;

Moving on. "Memory" tab - memory.

• The "Type" line indicates to us the type of RAM (DDR2) and the mode of use (dual-channel);
• The “Size” field displays its full volume installed in the system;
• The "Timing" section shows the frequency at which it operates (Frequency) and its various delays (timings);

And let's analyze one more screenshot - a very useful tab “SPD”(Serial Presence Detect) or -“ Serial Presence Detect ”.

It is remarkable in that it gives us the opportunity, by opening the list under the “Memory Slot Selection” inscription, to “see” how many RAM slots are installed on the motherboard (in this case, two: slot # 1 and slot # 2). This greatly simplifies the situation when, for example, you need to quickly determine whether it is possible to add a module to the computer and whether it has free slots for this to grow it? We do not need to open it for this.

Below you will find detailed information on each slot separately. It can be seen which chips are used, which manufacturer, the serial number of the product (I used to use this number to clarify additional characteristics of the proprietary module "Corsair" on the manufacturer's website). Again - the frequency of work, operating voltage (Voltage).

Once again - I highly recommend this program "Cpu-Z", download it yourself and use it.

And now - let's move on to practice and find out how to repair a computer if it breaks down?

One of the important components of a modern personal computer is a power supply unit (PSU). The computer will not work if there is no power.

On the other hand, if the power supply generates a voltage that goes beyond the permissible limits, then this can cause the failure of important and expensive components.

In such a unit, with the help of an inverter, the rectified mains voltage is converted into an alternating high frequency, from which low voltage flows necessary for the operation of the computer are formed.

The ATX circuit of the power supply consists of 2 nodes - a mains voltage rectifier and a voltage converter for a computer.

Mains rectifier is a bridge circuit with a capacitive filter. At the output of the device, a constant voltage of 260 to 340 V is generated.

The main elements in the composition voltage converter are:

• an inverter that converts direct voltage to alternating voltage;
• high frequency transformer operating at 60 kHz;
• low-voltage rectifiers with filters;
• control device.

In addition, the converter includes a standby voltage power supply, amplifiers of a control signal for key transistors, protection and stabilization circuits, and other elements.

The reasons for faults in the power supply can be:

• power surges and fluctuations;
• poor quality product manufacturing;
• overheating associated with poor fan operation.

Malfunctions usually lead to the fact that the system unit of the computer stops starting or, after a short time, turns off. In other cases, despite the operation of other units, the motherboard will not start.

Before starting the repair, you must finally make sure that it is the power supply that is faulty. In this case, you must first check the functionality of the mains cable and the mains switch... After making sure they are in good working order, you can disconnect the cables and remove the power supply from the case of the system unit.

Before re-enabling the power supply unit autonomously, it is necessary to connect the load to it. To do this, you need resistors that are connected to the corresponding terminals.

First you need to check motherboard effect... To do this, you need to close two contacts on the power supply connector. On a 20-pin connector, this would be pin 14 (the wire that the Power On signal goes through) and pin 15 (the wire that matches the GND pin - Ground). For a 24-pin connector, this would be pins 16 and 17, respectively.

After removing the cover from the power supply, you must immediately use a vacuum cleaner to clean out all the dust from it. It is because of the dust that radio parts often fail, since dust, covering the part with a thick layer, causes overheating of such parts.

The next step in identifying faults is a thorough inspection of all elements. Particular attention must be paid to electrolytic capacitors. The reason for their breakdown may be a severe temperature regime. Defective capacitors usually swell and leak electrolyte.

Such parts must be replaced with new ones with the same ratings and operating voltages. Sometimes the appearance of a capacitor does not indicate a malfunction. If, by indirect indications, there is a suspicion of poor performance, then you can check the capacitor with a multimeter. But for this it needs to be removed from the circuit.

A faulty power supply can also be associated with faulty low voltage diodes. To check, you need to measure the resistance of the forward and reverse transitions of elements with a multimeter. To replace faulty diodes, you must use the same Schottky diodes.

The next malfunction that can be determined visually is the formation of ring cracks that break the contacts. To find such defects, you need to look very carefully on the printed circuit board. To eliminate such defects, it is necessary to use careful soldering of the cracks (for this you need to know how to properly solder with a soldering iron).

Resistors, fuses, inductors, transformers are inspected in the same way.

In the event that a fuse is blown, it can be replaced with another one or repaired.The power supply uses a special element with soldering leads. To repair a faulty fuse, it is soldered from the circuit. Then the metal cups are heated and removed from the glass tube. Then a wire of the required diameter is selected.

The wire diameter required for a given current can be found in the tables. For the 5A fuse used in the ATX power supply circuit, the diameter of the copper wire will be 0.175 mm. Then the wire is inserted into the holes of the fuse cups and fixed by soldering. The repaired fuse can be soldered into the circuit.

The above considered the most simple malfunctions of a computer power supply.

1. One of the most important elements of a PC is the power supply, if it fails, the computer stops working.
2. The computer power supply is a rather complex device, but in some cases it can be repaired by hand.

Despite its apparent power, the personal computer is fragile. To disable any part, just careless handling of it is enough. For example, do not clean the system unit and its components. As a result, a lot of dust forms on the parts, which negatively affects the operation of the device as a whole.

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

The most critical situation is when the computer does not respond to the power button... This means that important points were missed that could indicate an imminent breakdown. For example, an unnatural sound during operation, a long turn-on of the computer, an independent shutdown, etc. Or, perhaps, such malfunctions were noticed, but it was decided not to resort to repairs.

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

• The occurrence of various errors when turning on the PC.
• Sudden computer restarts.
• Increasing the volume of coolers (small fans).
• Various errors when the PC is turned on.
• Stopping the hard drive or some coolers.
• Loud beeping from the system unit (indicates overheating).
• Electric shock when touching the cabinet.

Such signs indicate the need for an early repair, which can be done by hand. However, there are also more serious problemsclearly indicating a serious malfunction. For instance:

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

Most people, when such problems arise, turn to a repairman for a repair. Typically, a computer technician advises purchasing a new power supply and then replacing the old one. Nevertheless, with the help of repairs, you can "reanimate" an inoperative device with your own hands.

To completely solve the problem, you need to understand why it could appear. Most often, the computer's power supply fails for three reasons:

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

In most cases, such malfunctions lead to the fact that the power supply does not turn on or stops working after a short time. In addition, the above problems can negatively affect the motherboard. If this happened, then do-it-yourself repairs will not be enough here - it will be necessary to change the part to a new one.

Less often, malfunctions in the computer's power supply occur due to the following reasons:

• Poor software (poor OS optimization has a bad effect on the operation of all components).
• Lack of cleaning of components (a large amount of dust makes the coolers run faster).
• A lot of unnecessary 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 this component should not be ignored. Otherwise, repairs are inevitable.

The power supply in the computer is responsible for distributing and converting electrical current. The fact is that each element in a PC needs its own voltage level. In addition, AC power is used in electrical circuits, and computer components operate on DC. Therefore, the device of the power supply is quite specific and you need to know it for do-it-yourself repairs.

In each power supply unit there are 9 important components:

Without at least an approximate idea of ​​the structure of the power supply, it is impossible to fully carry out an independent repair.

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

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

• Work only with the power supply off. Despite the banality of the 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 turned off, and only then start repairs.
• To preserve the components and also 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, then the network has shorted somewhere. If it lights up and immediately goes out, then everything is in order.
• Power capacitors are energized especially for a long time. Therefore, even after disconnecting the power supply from the network, you should not immediately get down to work.
• It is better to check the operation of the device away from flammable substances, since there is a risk of short circuit and "fireworks" sparks.

To make repairing a power supply unit simple but effective, each home craftsman will need certain tools to work. All these products can be easily found at home, asked from neighbors / friends, or purchased in a store. Fortunately, they are inexpensive.

So, for renovation you will need the following tools:

• Soldering station with built-in power regulation 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 hold the wires together).
• 100 watt light bulb.
• Tweezers (for removing small components).
• Alcohol or refined gasoline.
• An oscilloscope may be required (if the cause of the problem is not determined).

First you need disassemble the power supply... To do this, you only need a screwdriver and accuracy. When unscrewing the bolts, you do not need to shake the PSU in order to quickly fix the problem. Careless handling of it can lead to the fact that do-it-yourself repairs will be simply useless.

For the correct formulation of the "diagnosis", it is necessary to conduct an initial diagnosis, as well as a visual inspection of the device. Therefore, first of all, you need to pay attention to the fan of the power supply. If the cooler cannot spin freely and gets stuck in a certain place, then this is clearly the problem.

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

Also, some products fail. due to voltage surges... Therefore, it is necessary to carry out a visual inspection for burnt parts.This sign is easy to identify by swollen capacitors, darkening of the textolite, carbonized insulation or broken wires.

Finally, it is worth moving on to the most important point - do-it-yourself BP repair. For convenience, the entire process will be presented in the form of a list. Therefore, it is recommended not to "jump" from one point to another, but act in a specific order:

It so happens that outwardly everything is in order: the components are not melted, there are no cracks or contact violations. What is the problem then? It is best to carefully examine all the details again. It is possible that a malfunction was missed due to carelessness. If no problems were detected during the secondary inspection, then in 90% of cases the malfunction lies in standby power supply or in the PWM controllerusing wide pulse modulation.

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

At system startup, the motherboard checks the voltage for all elements. If everything is in order, it is formed feedback signal "Power good" and the system starts up. If there is a lack or excess of voltage, the system start 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, the absence of voltage or its deviation from the nominal value is usually revealed. If the problem is PS_ON, the problem is in the PWM controller. If there is a malfunction with contact + 5VSB, then the problem lies in the electric current conversion device.

It is also useful to check the PWM itself. True, for this you need an oscilloscope. To check, you need to unsolder the PWM and use an oscilloscope to check the contacts by ringing (OPP, VCC, V12, V5, V3.3). For better ringing, the check must be carried out relative to the ground. If the resistance between ground and any of the contacts (on the order of several tens of ohms), then the PWM must be replaced.

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