How to check the power supply of the computer at home
There are quite a few reasons why a computer might malfunction or not turn on at all. For example, it may be a malfunction of the RAM modules, incorrect settings of the system BIOS, overheating of components, or “floating” of the parameters of the power supply unit. By checking and logical calculation, they identify the culprit and in one way or another restore their working capacity. In the following list, the most difficult issue is how to check the power supply of the computer. Of course, you can take the "sistemnik" in the service center, but their services cost money. In addition, it often happens that the true reason is so banal that it is even a shame to give up your "honestly earned." Self diagnosis is a good idea. At least at the initial stage.
Safe testing conditions
All modern computer power supplies are created in full compliance with the ATX standard.Their AT predecessors for the mass market are no longer being released, so we are not considered. If it is nevertheless necessary to figure out how to check the performance of the power supply unit of the outdated standard, then the information given in this paper cannot be used. We note in particular that some ready-made computer systems (for example, Dell) work with units of their own design, so it is important to make sure that the power source is ATX.
The next important point is the observance of the rules for working with electronic components. Since there is always a certain electrical potential on the surface of the human body, when working without a grounding bracelet, in some cases a static discharge occurs that can damage sensitive components. The conclusion is simple: it is not enough just to know how to check the power supply of a computer. Be sure to take care of safety (your own and electronics), since the correct measurements can be performed only with a working system in which there are life-threatening voltage and current.
The above-mentioned ATX standard currently has two modifications - versions 1.xx and 2.xx.To figure out how to check the power supply of the computer, you must understand what the differences are. The first version has two rows of contacts on the plug: 1-10 and 11-20. The beginning is easily identified by a special form of contact - it is square, the so-called “key”. In the second version, four more pins appeared - two in each row. For compatibility, these additional pins are often made with a separate plug. In total, 1-12 and 13-24 are obtained. The “key” is also defined according to the form. Since measurements are performed on a running computer, it is recommended to remove the plug from the connector on the previously de-energized system and carefully study the numbering. This is very important, since subsequently this knowledge will help not to “get lost”, where is the contact, when the whole structure is assembled.
People interested in how to check the computer's power supply will need to purchase a multimeter. Best of all, if it is a model with a digital display, rather than an arrow deflecting system. The cost of such devices starts from 250 rubles. If there is a question “how to check the health of the power supply,” then the capabilities of such a budget model will be quite enough.If the probes are not thin enough, then you can use the following "focus": tightly wound a needle or pins tightly to the metal.
How to check the parameters
The power supply must provide for each pin (except the "ground") a certain voltage value. Moreover, during load the drawdown must be within acceptable limits. Otherwise, the computer will at least fail. So, how to check the power supply with a multimeter? Budget models do not have an auto-tuning function for voltage, so you must first select the VDC measurement mode with a value of 20 using a switch. This is enough with a margin. After that, on a working system, one of the probes should be carefully touched to contact No. 3 (any version of ATX), and the other to No. 5. This is VSB voltage, which should be 5 V (+ -5%). The greater the deviation from the standard, the worse the condition of the power supply. It is also useful to check the value at pin no. 8. It should be between 3 and 5 V, but not lower than 2.5 V. At pin no. 1 it should be about 3.3 V (including sinking and error). It is important to number 10, which should be 12 V.
Sometimes you have to figure out how to check the power supply of a laptop.With a multimeter, this can be made even easier. In VDC 20 mode, it is enough to touch the probes to the two poles of the plug of the power supply unit. If the label indicates 19 V (mass models), then the display should be around 19.7 V.
Despite the fact that the power source of the ATH standard produces quite a lot of voltages, the most important are +5 and +12 V. So, -5 V was required for ISA cards; -12 V for serial interface; a +3.3 B is obtained by lowering from the base +5 V. That is why several independent +12 V lines are often present in the newer power supply units, which makes it possible to evenly distribute the load, thereby reducing the natural incidence. Note that in some powerful models, even +5 V is obtained from the reference +12 V.
We give the values of the voltages at which the computer remains operable:
- for + 12 V, normal modes are limits from 11.4 V to 12.6 V;
- for 5 V, respectively, from 4.75 V to 5.25 V;
- for 3.3 V from 3.14 V to 3.30 V.
If even under load (running game) values are within the specified limits, then the unit is fine.
Preliminary check of internal chains
In addition to measuring voltages, you can check the state of resistance. To do this, turn off the power supply and remove the plug from the connector on the board.After that, it remains only to switch the multimeter to the omega mode of 200 ohms and, with one of its probes, touch the grounding plug of the power plug, and the other to all the colored wires of the connector alternately. Values must not be lower than 50 ohms.