How to see the quality of the power supply, teach you how to check the power supply.

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The transparency of information in the Internet era allows us to obtain the latest news anytime, anywhere. The difference lies in whether you have such a heart to learn. In the DIY field, a specific manifestation is the difficulty of customs clearance of the installed copy. These days, it’s easy for you to make an inadequate power supply, shrink it and make big news. But in all fairness, do you dare to court death? I believe that many brands that sell power supplies have their answers.

We are delighted to see that although the power supply cannot be measured by performance and cannot escape the law of homogeneity, the overall quality of the power supply has made significant progress compared to before. For example, grabbing a lot of 80 Plus certified power supplies was unimaginable back. But after all, careful sailing is a ten-thousand-year-old ship, and paralyzing our minds will always lead us to commit muddled behaviors. Therefore, reviewing the shrinking power supply with the reverse angle is necessary.

So, what kind of power supply is called shrinkage?

1. Main capacitor

The reason why we put the main capacitor in the first place is that it is easy to be manipulated in the factory process. Still, unless you are knowledgeable about capacitors, you are very easy to be tricked.

Why do you say that? For example, three power supplies: a 350W power supply uses a Taiwanese Fengbin main capacitor of 270μF, a 350W power supply uses a domestic main capacitor of 270μF, and a 400W power supply uses a domestic main capacitor. The one with 270µF. Let me ask you a question, which one has shrunk the most? Suppose you know the mathematical proportional relationship in middle school. In that case, you will definitely feel that the third model has shrunk more severely, while the first and second models will not shrink.

270uF 400V capacitor, the maximum rated power should not exceed 450W

In fact, the quotations of these three power supplies on the market are actually similar. This is the hidden profit. The current status quo is that people generally prefer to shrink the main capacitor. In fact, it is not called “shrinking”, but just meets the power upper limit achieved by the main capacitor specification. From the table below is the selection of main capacitors with a relative margin, and you can learn the power relationship corresponding to the size of the capacitor.

Capacitor Size Estimated Power

180uF 400V250-300W

220uF 400V300-350W

270uF 400V350-400W

330uF 400V400-550W

390uF 400V450-600W

470uF 400V500-700W

560uF 400V600W or more

The material can be considered if you add 50W to the upper limit part of the above table. If it is significantly higher than the power range in the above table, it is suspected of shrinking. Everyone must pay attention to this when evaluating the power supply evaluation and purchasing the power supply to see the parameters.



2. Main components

Large electrolytic capacitors, Schottky diodes, triodes, etc. The selection of these components directly affects the life of the power supply. Some manufacturers use old materials to reduce costs, but it is impossible for manufacturers to know how long the old devices still have a lifespan. In addition, capacitors have high requirements to withstand voltage values. Large-capacity capacitors can withstand high voltages and have good filtering performance. Of course, the cost is also high. If the application does not meet the requirements, when the voltage is too large, the electric solute in the capacitor will be left, which may cause an explosion and cause great harm.



3. Main transformer

We know that the transformer of the PC power supply is to convert the 220V voltage into the output voltage of each component, such as +5V, +12V and so on. In fact, main transformers of different specifications will determine the matching of rated power.

Using the main transformer of E35 specification, the power can reach more than 400W, but it is best not to exceed 500W

The commonly used core shapes of transformers are generally E-type and C-type cores. The PC power supply is generally an E-type iron core, and the E-type is a Japanese-shaped iron core. According to the length of the steel sheet, it is divided into E35, E39, E43 and other specifications, and the corresponding rated power can reach 400W, 500W, 600W. So, if you come across a 500W rated power supply that uses an E35 core main transformer, then this power supply has shrunk.



4. EMI circuit mode

EMI circuits, composed of several special capacitors and inductors, can greatly reduce the impact of external interference signals, especially common-mode interference signals on the computer. Purify the working environment of the power supply and improve the stability of the computer work. Because the mains power is not very constant 220V, the input voltage may exceed the predetermined range, the load will also have overcurrent, short circuit, and when the voltage itself has problems, the protection circuit can stop the output of the circuit to prevent unsafe voltage from damaging the computer equipment. Without this protector, the consequences can be imagined.

This part of the circuit does not affect the normal operation of the power supply, but it is of great help for stability. Now the brand power supply basically has EMI, but the cottage and inferior power supply will omit it, but the shielding of the power supply will be greatly reduced.



5. PFC

The PFC circuit in the power supply can be said to be a very important part of the entire power supply, which can greatly improve the power utilization efficiency of the power supply. PFC is usually divided into the passive type and activity type. The active type has a higher power factor than the passive type, which can reach 0.97~0.99, and is small in size and light in weight. The power supply can be used in a wide input voltage range (such as 90~264VAC) and Works in a wide frequency band, but the cost is higher. Some small workshop technologies cannot be achieved, so they just make up for it. In reality, it cannot be realized at all, and some are simply omitted. This module is mandatory after the 3C certification is confirmed. If there is no PFC circuit in the circuit, it must be a fake 3C. Generally, this situation only occurs in cottages or inferior power supplies.

Generally, there are two main types of PFC circuits: one is passive PFC (also called passive PFC), and the other is active PFC (also called active PFC). Now mainstream power supplies basically use active PFC planning, and active PFC can save more energy than passive PFC. Development to today, the use of active PFC power supply is king, generally only low-cost low-power entry power supply will use passive PFC. If you see a 500W power supply still using passive PFC, it must be unreasonable.

6. Wire

Some power output lines have inconsistent diameters, the cross-sectional area is not enough, the power supply workload is slightly larger, and the power output lines will heat up and become soft, which is a serious concern. For modular power supplies, if the material of the wired interface is not good, line loss will also occur, which will affect the normal use of the computer. In addition, the positive deviation of the input and output plug and socket tolerance is large, and the graphics card and hard disk will be difficult to connect to the power supply or even work abnormally.



The quality of power supply materials affects the regular work of the whole machine and the health and safety of users, and we cannot ignore it. Before buying, it is best to choose high-quality and honest suppliers.

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