Common problems of AC / DC power module

The external power supply of AC / DC series power module products is generally 220V mains power supply, because it will be affected by external unstable voltage a little more than that of DC / DC series. In addition, commercial power is generally affected by unknown voltages such as lightning, so AC / DC series module power supplies may often encounter some failures during use. The following classification briefly analyzes the causes.

1. When customers use our AC / DC products, how can the output voltage be much lower than the normal value? What's going on?

1) Output overcurrent: if the power of the load at the output end exceeds the rated power of the product, the output voltage may be lower than the normal value, and other normal output characteristics may not be guaranteed;

2) The capacitive load of the output belt is too large.

2. Why did our wide voltage products burn out as soon as they were connected? What's going on?

1) The input voltage is too high and far exceeds the allowable voltage input range.

3. Why is there no voltage output after the customer uses our AC / DC products?

1) . the load power at the output end is too large;

2) . the output filter capacitance is too large;

3) . the input power is too small;

4) Input is connected incorrectly, and connect n or l to FG;

5) Module damage caused by too high input voltage.

4. When the customer uses our AC / DC dual output products, he finds that the secondary output voltage is unstable. What's the matter?

1) The load power of the output + / - voltage is unbalanced, the load of + voltage is large, and the load of - voltage is small.

5. When customers use one of our AC / DC products, they feel that the ripple noise is very large, which has some impact on the back circuit. What is the reason?

1) There are high-frequency products near the test, which will cause interference;

2) The test method is incorrect. The power supply needs to use a 20MHz oscilloscope, and the probe should be removed for testing. Refer to the test method shown in Figure 1 below for details.

6. When a customer uses one of our AC / DC products, he finds that a small number of them are damaged and other products have good performance. What is the matter?

1) Excessive load power: if the load power at the output end is too large, it may cause a small number of modules to be easily damaged, because there is a certain margin in the design of our products, but it is impossible that the power margin of each product is the same, some are more and some are less, which is also related to the process. Therefore, modules with small margin may be overloaded and damaged due to excessive load;

2) The output filter capacitance is too large: it is easy to cause overcurrent damage when the module is frequently started.

3) There is high-voltage surge to the input end: due to the difference of devices, some bear high surge points and some bear low surge points. Therefore, modules that bear low surge points may be damaged due to input high-voltage surge.