6 Tips for Printed Circuit Board Maintenance

Since most modern printed circuit boards do not have official schematic diagrams and more and more chip applications come with programs, engineers will face challenges in all aspects. With a lot of practice, there are ways to avoid these challenges. Below we will share 6 PCB maintenance methods.

Look, ask, smell, cut. Observe whether there is a burnt place on the circuit board and whether there is any damage on the copper-clad part. Smell whether the circuit board has a peculiar smell, whether there is any bad soldering, whether the interface and gold fingers are moldy and black. It is also necessary to ask the customer about the fault phenomenon and fault process, and the focus of the fault can be concentrated on certain parts. Through the above processing, we can often find some problems.

Conduct a test on all components and replace defective components to achieve the purpose of repair. If you encounter a component that cannot be detected by the instrument, you should use a replacement method. It means that no matter whether the components are damaged or not, they should be replaced with new ones. In order to ensure that all components on the board are in good condition and achieve the purpose of maintenance.

The method is simple and effective, and the technical level of engineers is not high. But operation requires a high degree of care and responsibility. Otherwise, some devices will not remember the location when removed. And the wrong installation will lead to maintenance failure. In addition, this method cannot solve the problems such as unusable holes, broken copper plating, and poorly adjusted potentiometers. This method cannot be used for chips with programs and data.

The comparison method is one of the most commonly used methods for circuit board maintenance without drawings. The practice has proved that the effect is very good. By comparing the state of the good board, the purpose of finding the fault is achieved. And find abnormalities by comparing the curves of each node of the two boards. However, many times we don't have a good board to compare with.

But that doesn't mean we can't use this method. For example, we can find circuits with the same properties in a circuit board. There are three identical interfaces on one board, and the circuits of the three interfaces are the same. We can use the curves of the three identical interfaces to compare each other to judge the problem.

The status method is to check the normal working status of each component. If the working state of a component does not match the normal state, there is a problem with the equipment or the affected part. For example, when we check the CPU, we will check whether the crystal oscillator is working normally, whether the reset signal is normal, etc., and judge whether the device is normal by whether the input and output logic of the gate is correct. When using this method, the input is usually a forced stimulus signal.

For example, a signal generator is used to send a signal to the input of an operational amplifier, and an oscilloscope is used to measure the amplitude and distortion of the output signal to determine operation and discharge problems. The input level of the logic gate circuit is forced to be pulled high or low.

The state method is the most accurate of all repair methods. The difficulty of its operation is beyond the grasp of ordinary engineers. It requires a wealth of theoretical knowledge and practical experience. To meet national requirements, engineers must try to test circuits better than curve sweeps. Whether it is the peripheral circuit or the peripheral circuit of the IC, you can find it.

Grounding a circuit is the way to build a circuit. After installing the missing integrated circuit, the circuit can work normally to verify the quality of the tested integrated circuit. For example, in order to judge whether a 555 integrated circuit is good or bad, we can use the 555 circuit to build a time base oscillation circuit. The integrated circuit under test is then placed into the circuit. If the circuit works fine, then the 555 is fine, and vice versa.

This method can achieve 100% accuracy, but there are many types of ICs to be tested and the packaging is complicated, so it is difficult to integrate all integrated circuits into a set of circuits.

This method is to analyze the working principle of a board. For engineers, some boards, such as switching power supplies, can know the working principle and details without drawing pictures. It is very simple to know the parts of the schematic diagram and know the maintenance. However, for some relatively complex and scarce equipment, there is no ready-made schematic diagram reference. We can draw the schematic diagram through manual reverse engineering, and then use the schematic diagram to repair it, which can be said to be a great success.

This method requires great patience and a caring attitude of the engineer to complete. Effort once, benefits for life. However, whether this approach is actually adopted depends on the value and volume of maintenance and the difficulty of the work.

The method of maintaining the PCB board in 6 has been introduced in detail above, if you want to order a new PCB board, please contact us.

Singo is a professional custom PCB board manufacturer. Our products involve home appliances, digital products, industrial control, and medical equipment. After years of hard work, we have established long-term cooperative relationships with some well-known international companies. With many years of experience, we have won a good reputation from customers in the field of electronic production with reasonable prices, abundant resources, and punctual delivery.