Power adapter details

　　With the increasing power consumption of notebook computers, ordinary power adapters may no longer meet the requirements of the next generation of notebook computers. Let us learn about the power adapter of notebook computers today!

　　The power adapter is the source of power for the notebook computer. It is a high-quality switching power supply. Its working principle is the same as the switching power supply in home appliances such as color TVs. between). The power adapters of notebook computers are all sealed and small in size, and their power consumption is generally up to 35W90W, so the internal temperature is high, especially in the hot summer, touching the power adapter during work will feel hot. Because of this, the failure rate of the power adapter is relatively high compared to other parts of the notebook. After the power adapter is damaged, it will cost hundreds of yuan to buy a brand new one, and hundreds of yuan to buy it in the second-hand market. In fact, many power adapters are not severely damaged. Users who have a little knowledge of circuits can try to repair them. This article will take IBM’s "meat bone" power adapter (16V, 4.5A) as an example to introduce its disassembly and easy maintenance. For reference.

　　Disassembly of laptop charger

　　The upper and lower covers of the notebook computer power adapter are injection-molded or glued with super glue, without any screws, so generally it can only be cracked with violence. However, as long as the method is right, the disassembled power adapter can be restored to its original state, and there are almost no traces of disassembly without careful observation.

　　Disassembly tools: electrician's knife, hammer, screwdriver, electric soldering iron, utility knife, etc.

　　Place the power adapter on the white paper and cut it along the gap between the upper and lower covers of the power adapter with the blade of an electrician's knife, and then hit the back of the electrician's knife with a hammer to cut the electrician's knife between the upper and lower covers of the adapter. At different positions of the gap between the upper and lower covers of the adapter, use the tip of an electrician's knife to move along the gap. When a certain part of the upper and lower covers is first cracked, the tip of the knife is deepened, and then the upper and lower covers of the adapter are slowly separated.

　　In order to open the power adapter of the shell, you can see that there is a copper shielding layer outside the adapter circuit. Use a utility knife to cut the tape on the shielding layer, and then use an electric soldering iron to weld the two solders connecting the shielding layer to the internal circuit board. Click to remove the shielding layer.

　　There is a thick hard plastic film between the shielding layer and the circuit board. After cutting it with a utility knife, you can see the real face of the circuit board.

　　Power adapter structure analysis

　　Next, let’s take a look at the internal structure of the power adapter. The main components of the circuit have been marked with circles, and the names and functions of the components are as follows:

　　1. Varistor, its function is that when the external voltage is too high, the resistance of the varistor will quickly become very small, and the fuse in series with the varistor will be blown, thereby protecting other circuits from being burned out.

　　2. The fuse, the specification is 2.5A/250V, when the current in the circuit is too large, the fuse will blow to protect other components.

　　3. Inductance coil (also known as choke), the main function is to reduce electromagnetic interference.

　　4. Rectifier bridge, the specification is D3SB, the function is to change 220V alternating current into direct current.

　　5. The filter capacitor, with a specification of 180μF/400V, is used to filter out the AC ripple in the DC power and make the circuit work more reliable.

　　6. Operational amplifier IC (integrated circuit), an important part of protection circuit and voltage regulation.

　　7.The temperature probe is used to detect the internal temperature of the power adapter. When the temperature is higher than a certain set value (different brands of power adapters, the set temperature thresholds are slightly different), the protection circuit will cut off the voltage of the adapter Output, thereby protecting the adapter from damage.

　　8. The high-power switching tube is one of the core components in the switching power supply. The switching power supply can work "one on and one off", and the switching tube is indispensable.

　　9. Switching transformer, one of the core components in switching power supply.

　　10. The secondary rectifier tube, the function is to change the low-voltage alternating current into low-voltage direct current. In IBM's power adapter, the rectifier tube is often operated in parallel by two high powers to obtain a larger current output.

　　11. Secondary filter capacitor, the specification is 820μF/25V, there are two in total, which can filter out ripples in low-voltage direct current. In addition to the above components, there are adjustable potentiometers and other RC components on the circuit board.

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