PCB Tech - PCB process Industrial control circuit board repair method

PCB process Industrial control circuit board repair method

Circuit board repairs are divided into repairs with pictures and repairs without pictures.
The repair method with pictures is to refer to the schematic diagram, analyze the circuit principle and signal trend, and then test the signal at the key points. In this case, it is easy to repair the circuit, but many industrial control board circuit boards do not have schematic diagrams. The circuit board manufacturers treat them as confidential. Not to general users.
Professional repair companies, repair circuit boards are almost always repaired without pictures. I myself will exchange the experience of repairing circuit boards without pictures in the past few years.

A circuit board is composed of circuit boards, components, and software. I personally feel that the ability of the maintenance personnel and the inspection and other maintenance tools are very important when repairing the circuit board. It is difficult to repair modern circuit boards if they only rely on one person's experience and lack the necessary tools, and it is also difficult to do so by advocating testing equipment such as online testers without paying attention to the quality of personnel.
When repairing, the board you face is different and the treatment method is different. But the most basic idea is to find out the bad components and replace and repair them. So, can we just replace all the components that can be replaced on the board? I have tried to replace them, but some components need to be debugged, and pay attention to the overall effect.

Use online tester and other tools like mine-sweeping, check each component with a mark, and compare the VI curve. In this way, some faults can be found, but the board may not be completely repaired, "because the chip passed by the online tester is not necessarily damaged; the chip that passes the test is not necessarily undamaged." And not every component can be in the component library. Found in the machine tool circuit board is constantly updated and upgraded, so your inspection tools must also be constantly updated.

The quality of the maintenance personnel directly affects the success or failure of the maintenance. When there is no schematic diagram, a relatively unfamiliar circuit board needs to be repaired. In addition to a solid foundation in hardware, a maintenance engineer who has a good understanding of the circuit principle and structure is required. For unfamiliar circuit boards, you should carefully observe the hardware structure to determine the role of this board, and ask the customer what kind of warning signal the board is installed on at the time.

When judging the function of a circuit board, it is necessary to construct a block diagram of the secondary circuit board in mind. From the alarm information analysis, which link is faulty, which may be the components, and then test after replacement. If you want to ask if the maintenance personnel are so good at designing, they are still repairing? In fact, design and maintenance are all profitable. We treat maintenance personnel no less than design, and maintenance is more challenging. You do it every day. Faced with different things, I still like the feeling of finding problems and fixing them.

When repairing, the method of the staff is also very important. Repairing the circuit board is a very delicate job. There are many components and circuit boards and are easily damaged. Therefore, the operation must be very careful and requires the necessary fixtures and other auxiliary tools. You must be proficient in disassembly, welding, etc. Before you start, you must think through the operation process to avoid unnecessary damage. For chips with programs, try to back up those that can be backed up, and don't move those that are not allowed to be backed up. If it is found that the chip with the program is damaged, and no spare or replacement chip is found, the circuit board cannot be repaired.

The inspection of circuit boards and components requires professional inspection tools, such as whether there is a broken wire inside the multilayer circuit board, and whether there is a false solder on the component.
In addition to finding the broken things and repairing them, the most difficult thing is to check whether you have repaired them and debug them on the machine. No matter how you repair them, they must be installed on the machine tool for use, and the circuit board delivered to the customer must be used. Yes, it must be tested on the machine before it is sent. Our company purchases a large number of maintenance experiment test benches, and simulates production tests based on the customer's board to ensure that the circuit boards sent to the customer can be used normally without delay. Production.

We sell and repair some imported precision measuring instruments, such as electronic online testers, logic analyzers, and ICT. If you are interested in repairing circuit boards, then repair tools and instruments are indispensable. You must be familiar with the hardware and read more. New components currently launched and their applications. Because every circuit board upgrade is based on hardware replacement. More hands-on repair of complex circuit boards can continuously improve your repair ability.