If an OMRON plc is not displayed after power-on, the switching power supply is often broken. Don't think how difficult it is to fix, so it is a pity to reimburse this PLC. The switching power supply of OMRON plc is often very simple. The circuit according to the physical mapping is as follows:
The circuit is simply too lean. Except for one power module, it seems that no other components are visible. I have recently repaired a few. Found that this type of power supply has a "common problem": only three bad components, F11 fuse; IC11 power module; this third component is the least attention, that is, C12 electrolytic capacitor. In fact, it is also the "culprit" of the entire power supply damage. But it is a culprit, and it is a bit embarrassing, listen to me.
C12 is installed close to the heat sink of the power module. After a long time, the internal electrolyte is evaporated by heat and gradually dried up. The C12 does not see an abnormality on the surface, and the online measurement is not short-circuited. If it is removed, the capacity is only a few microfarads, which is one tenth of the original capacity. The power module originally used a smooth current. After the capacitor was out of capacity, the loop current was somewhat turbulent. This power module can't stand it, and it is a good thing to break through the short circuit. Of course, F11 is also a stalwart, and the piece is finished. The loss of capacitance of C12 exposes the unreasonable structure of the power supply—the electrolytic capacitor cannot be mounted close to the heat sink. This is of course the negligence of the designer. Therefore, for the Omron PLC that has been used for more than a few years, when there is a sign that power is on, it seems that there is no power supply, most of them are C12 has been lost, and the C12 is out of tolerance, IC11 module and F11 have been "end to sleep".
The damage of IC11 and F11, it is known that the C12 is sometimes ignored. After replacing the good ones, it is okay to power up without a load. When you carry a message, you will hear a bang, and the good ones you replaced are broken. Don't complain that the supplier is offering you a defective product, but your maintenance is not in place.
Be sure to check C12! !
The circuit is simple and simple, you still want to find out the ins and outs of the IC11-MIP0223SC power module - how the circuit works, can't get through this, the circuit is really too boring. Let's look at the schematic data sheet of IC11 (also in English, no way, difficult to find Chinese): 
In fact, the foreign language information is not very big. It is not necessary to guess the parameters, and it is not necessary to thoroughly understand the various unit circuits in the schematic block diagram. For the block diagram, knowing the function of each pin of the component, the pin has some internal connections, which is roughly enough. At least in the measurement know how to start, short circuit or open circuit can be measured out. For the data sheet, it is enough to only look at three or five key parameters. Such as the module's supply voltage, oscillation frequency, operating current, power capacity, signal drive current and voltage, it will do. Can't read, guess and guess a big eight!
Ok, the circuit principle is still going to ponder when you are fine. Given the circuit diagram and module information, it is enough for maintenance.
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