Which contacts to close to start the power supply. How to turn on the power supply without a computer

Hi all. I hope that you all know very well that in the system unit of a computer there is such an interesting and useful thing as a power supply. And for us, folk craftsmen, power supplies are of particular value. Surely many people have them lying around idle. This happens - bought new computer, and spare parts from the old one are collecting dust in the closet. Let's try to find a use for them.

The ATX standard power supply produces the following voltages: 5 V, 12 V and 3.3 V. In addition, they have good power (250, 300, 350 W and so on). But here's the problem. How to run it without motherboard? This is what we will look at in today’s material.

Old AT standard power supplies were launched directly. The ATX standard power supply cannot be started this way. But it's still not a problem. To turn on the power supply, we only need to have one small wire, with the help of which we close 2 contacts on the plug.

But first I want to warn you - disconnect all wires from the motherboard, screws and drives, in case you are smart enough to run the power supply directly in the system unit.

So let's get started. First, we remove our block from the system unit.

One more warning. No need to idle your unit. In this way you shorten his life. You definitely need to give it a workout. For this purpose, you can connect a fan or an old hard drive to the power supply.

As a matter of fact, to start the power supply, you need to close the PS_ON contact to zero. In most cases these are the green and black contacts on the plug, but sometimes among cunning Chinese There are colorblind people who get confused with color markings. Therefore, I recommend studying the pinout first. It is presented in the following image. On the left is a plug of the new standard with 24 contacts, and on the right is an older standard with 20 contacts.

In my case the older standard (20 pins) will be shown. My color coding is intact.

To start it, I made this jumper.

This is how we close our contacts.

If you plan to use the power supply constantly, then for convenience you can make a button like this.

If you want to check the functionality of the power supply, but you do not have a computer, then there is one way to do this. All you need is a couple of wires and a single-pole switch that stays on or off when changing positions. Below we will tell you how to do this.

Standard blocks ATX power supply are not intended to be turned on idle unless they are properly connected to the motherboard. This ensures that they cannot damage computer components if the connector is not fully connected or is not connected correctly.

Note: Never turn on the power supply without a load! This can lead to its complete failure. The load can be either a resistor or a connected drive, floppy drive, or hard drives.

Another problem is that if you connect the power supply to the mains, it simply does not initialize. It will wait for a startup signal from the motherboard to turn on (usually the signal is controlled by a button on the front of the computer). The article describes the direct initialization of the power supply by closing the corresponding connectors.

Prepare two long pieces of wire to connect them to the switch and the power connector (20- or 24-pin connector).

Strip the insulation from both ends of each wire, leaving enough wire to wrap around the power button (or solder). At the other end, expose a strip sufficient to make sure contact with the 20- or 24-pin connector of your power supply.

Wrap the long end of the bare wire around the switch and repeat the process with the other wire. Set the switch to the "OFF" position.

Turn off the computer's power and remove the power supply connector.

Hold the 20- or 24-pin power supply plug in one hand. Find the green wire (mother ATX board signals the command to start the power supply via “PS_ON #”, which is indicated by the green wire). This contact number 16 on the 24 pin connector and pin number 14 on the 20 pin connector. On the 20/24 pin connector you need to find the black wire (GND). It's usually next to the green one.

Note: Each row has one green wire, it doesn't matter which one you use, they both perform the same function.

Insert one end of the pre-prepared wire from the switch into contact with the green wire. Insert the other wire into contact with the black wire.

Connect the power supply to the network, and then turn the switch to the “ON” position. The power supply will turn on and you can now use it to power devices or for testing purposes.

To make sure the power supply is working properly, you can measure the output voltage using a multimeter. The drawing above shows the output voltage of each pin (+12V, +3.3V, +5V, COM). Pin 13 can be either a +3.3V supply or can be used as a power supply sensor to measure cable loss.

In this simple way, you can easily, and most importantly, safely turn on your power supply without a computer.

The skill of starting a power supply without a computer and motherboard can be useful not only system administrators, but also ordinary users. When problems arise with your PC, it is important to check the functionality of its individual parts. Any person can cope with this task. How to turn on the power supply?

How to turn on the power supply without a computer (without a motherboard)

Previously, there were power supplies (abbreviated as PSU) of the AT standard, which were launched directly. WITH modern devices ATX will not work such a trick. To do this, you will need a small wire or a regular paper clip to close the contacts on the plug.

On the left is a 24-pin plug, on the right is an older 20-pin plug

IN modern computers ATX standard is used. There are two types of connectors for it. The first, older one, has 20 contacts on the plug, the second - 24. To start the power supply, you need to know which contacts to close. Most often this is the green PS_ON pin and the black ground pin.

Pay attention! In some “Chinese” versions of the power supply, the wire colors are mixed up, so it is better to familiarize yourself with the contact diagram (pinout) before starting work.

Step by step instructions

So, when you have become familiar with the wiring diagram, you can start starting.

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

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

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

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

Mains rectifier is a bridge circuit with a capacitive filter. At the output of the device it is formed constant voltage ranging from 260 to 340 V.

The main elements in the composition voltage converter are:

• an inverter that converts direct voltage into alternating voltage;
• high frequency, operating at a frequency of 60 kHz;
• low-voltage rectifiers with filters;
• control device.

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

The inverter includes two power transistors operating in switching mode and controlled using signals with a frequency of 60 kHz coming from a control circuit implemented on the TL494 chip.

A pulse transformer is used as the inverter load, from which the voltages +3.3 V, +5 V, +12 V, -5 V, -12 V are removed, rectified and filtered.

Main causes of malfunctions

The causes of malfunctions in the power supply can be:

• surges and fluctuations in supply voltage;
• poor-quality manufacturing of the product;
• overheating associated with bad work fan

Malfunctions usually result in system unit The computer stops starting or turns off after a short period of operation. In other cases, despite the operation of other units, the motherboard does not start.

Before starting repairs, you need to finally make sure that it is the power supply that is faulty. In this case, first you need check functionality network cable and power switch. After making sure that they are in good condition, you can disconnect the cables and remove them from the system unit case.

Before you turn on the power supply autonomously again, you need to connect the load to it. To do this, you will need resistors that are connected to the corresponding terminals.

In this case, the value of the resistance of the load resistors must be selected so that currents flow through the circuits, the values ​​​​of which correspond to the nominal values.

The power dissipation must correspond to the rated voltages and currents.

First you need to check influence of motherboard. To do this, you need to close two contacts on the power supply connector. On a 20-pin connector, these will be pin 14 (the wire that carries the Power On signal) and pin 15 (the wire that corresponds to the GND - Ground pin). For a 24-pin connector, these will be pins 16 and 17, respectively.

The serviceability of the power supply can be assessed by the rotation of its fan. If the fan rotates, the power supply is working.

Next you need to check voltage correspondence at the unit connector their nominal values. It should be taken into account that, in accordance with the documentation for the ATX power supply, the deviation of voltage values ​​for the -12V power circuit is allowed within ± 10%, and for other power circuits ± 5%. If these conditions are not met, you must proceed to repair the power supply.

ATX computer power supply repair

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

The next step in troubleshooting is a thorough inspection of all elements. Particular attention should be paid to electrolytic capacitors. The reason for their breakdown may be severe temperature regime. Faulty 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 the capacitor does not indicate its malfunction. If according to indirect signs If there is a suspicion of poor work, then you can. But for this it needs to be removed from the circuit.

Deterioration in thermal conditions inside the unit may be due to poor performance of the cooler. To improve performance, it must be cleaned of dust and the bearings lubricated with machine oil.

A faulty power supply can also be caused by faulty low-voltage diodes. To check, you need to measure the resistance of the forward and reverse transitions of the elements using 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 annular cracks that break the contacts. To detect such defects, you need to look very carefully printed circuit board. To eliminate such defects, it is necessary to carefully solder the places where cracks form (for this you need to know).

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

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

The wire diameter required for a given current can be found in the tables. For the 5A ATX fuse used in the circuit of the ATX power supply, 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 most common faults are discussed above. computer unit nutrition.

Detecting and repairing more complex faults requires good technical training and more sophisticated measuring instruments, such as an oscilloscope.

In addition, elements that need to be replaced are often in short supply and are quite expensive. Therefore, in case of a complex malfunction, you should always compare the costs of repairs and the costs of purchasing a new power supply. It often happens that it is more profitable to purchase a new one.

Conclusions:

1. One of essential elements A PC is a power supply; if it fails, the computer stops working.
2. The computer power supply is a rather complex device, but in some cases you can repair it yourself.

If you need to check the functionality of the power supply, but you don’t have a PC at hand, there is a simple way to carry out this manipulation. You only need a piece of wire. How to turn on the power supply without a computer? Let's answer this question.

We turn on the power supply without third-party components

Now all power supplies are ATX standard. They are not intended to be turned on without other components, since they are waiting for a start signal from the motherboard, but such an operation can be carried out.

To do this you need:

• First, take a small piece of wire and strip the ends.

• Then we pay attention to the power supply connector. The essence of our manipulation is to close the PS-ON and GND pins. These are the green and black wires, the first is number 14 on the twenty-pin connector, and the second is always located nearby. You can also pay attention to color coding, but the Chinese sometimes confuse the wires, so it’s better to clarify the pinout.

• Now we close these contacts with a pre-prepared wire, connect the power supply to the network and turn it on. The power supply will start, the cooler will start working. There are systems with load regulation, then the fan will not spin without connected devices. In this case, attaching the optical drive will help ensure that the device is in working order.

Useful information

If you need longer startup times, take two pieces of wire, strip them, and solder them to a power switch you previously purchased or removed from your PSU. Connect the remaining free ends of the wires to the previously designated connector contacts. Now the power supply can be turned on by pressing a key.

What if it doesn't turn on?

If the computer refuses to work, you need to check the presence of power at the power supply input. If it is there, even when the computer is turned off there will be a voltage of +5V. This is easy to check by armed with a multimeter and checking the ninth pin (wire purple). If it is not there, then there are technical problems. There are many of them - from cable breaks to short circuit at the exit, with such a problem it is better to go to the service center.