Omron PLC switch power supply drawings and maintenance methods

Omron is the most important brand of Japanese PLC, and its PLC products occupy the top share in Chinese Mainland. It is of universal industrial control significance to study the maintenance of Omron PLC. The following takes the maintenance of switching power supply as an example to analyze the maintenance process of Omron PLC.

If an Omron PLC does not display after being powered on, it is often due to a faulty switch power supply. Don’t think it’s too difficult to repair, so it’s a pity to reimburse this PLC. The switch power supply of Omron PLC is often very simple, and the actual circuit surveyed is as follows:

The circuit is simply too streamlined. Except for one power module, it seems that no other components can be seen. I have repaired several recently. There is a common problem with this type of power supply: there are only three faulty components, F11 fuse; IC11 power module; This third component is least noticed, which is the C12 electrolytic capacitor. In fact, it is also the culprit of the entire power supply damage. But it’s a bit unfair to say it’s the culprit, listen to me.
C12 is installed next to the heat sink of the power module, and after a long time, its internal electrolyte is heated and evaporated, gradually drying up. And C12 shows no abnormalities on the surface, and there is no short circuit during online measurement. If removed, its capacity is measured to be only a few micrometers, which is one tenth of the original capacity. The power module used to use steady current, but after the capacitor lost capacity, the circuit current started to surge. The power module can’t bear it now, so it’s natural for it to break through and short circuit. F11, of course, also follows your orders and plays together. The loss of capacity phenomenon of C12 exposes the unreasonable structural layout of the power supply – the electrolytic capacitor cannot be installed close to the heat sink. This is certainly the designer’s negligence. Therefore, for Omron PLCs that have been in use for several years or more, when there is a phenomenon of no power on despite being powered on, most of it is due to the loss of capacity of C12, and the IC11 module and F11 have already passed away.
The damage to IC11 and F11 can be easily detected by measuring the probe, while C12 is sometimes overlooked. After replacing the good part, it may still work without load when powered on, but with load, you can hear a “snap” sound, and the good part you replaced is broken again. Don’t complain that the supplier is providing you with defective products, but rather that your maintenance skills are not up to par.
Be sure to check C12!!
The circuit is simple, but you still want to understand the background of the IC11 MIP0223SC power module – how the circuit works. If you can’t figure this out, the circuit is really too simple. Let’s take a look at the schematic data table of IC11 :

It’s not a big deal. It is not necessary to guess all the parameters, nor is it necessary to understand all the unit circuits in the schematic diagram. For the block diagram, knowing the functions of each pin of the component and what is connected inside the pins is generally sufficient. At least in terms of measurement, you know how to get started. If you can detect a short circuit or open circuit, you’ll be hit. For the data table, only three to five key parameters are enough. The power supply voltage, oscillation frequency, working current, power capacity, signal driving current, and voltage of the module are also sufficient. I can’t understand, but I can guess seven or eight!
Alright, the circuit principle should be carefully studied when you have nothing to do. Providing circuit diagrams and module information is not enough for maintenance purposes.