Testing the mobile phone charger transformer circuit diagram

　　The method of testing a mobile phone charger is very simple. Just remove the transformer on the charger, connect the transformer on the standby side, and measure whether the output voltage of the charger is qualified. It is usually 4.5, 4.6 or 5.0. There are two major problems with the 5.1 test method. One is that other components of the charger are often burned out. The other is that there is not much difference between the genuine and defective products. Some of them differ by only 0.1 negative. The most vulnerable ones are 4148, small triodes, and voltage regulators. If it is a transformer that can be directly connected to AC power, just connect the transformer directly to AC power, and then measure the AC voltage of the transformer secondary. For safety, a 1:1 isolation transformer can be used to isolate the mains. The characteristic of this method is that the transformer is directly measured, and other components of the charger will not be damaged due to an unqualified transformer.

　　Circuit principle: The charger circuit is mainly composed of oscillation circuit, charging circuit, voltage stabilization protection circuit, etc. Its input voltage is AC220V, 50/60Hz, 40mA, output voltage is DC4.2V, and output current is 150mA-180mA. Before charging, connect the battery to be charged and check whether the test indicator on the charger panel is on. If it is on, it means the polarity is correct and you can connect the power supply to charge; otherwise, it means the polarity of the battery and the polarity of the charger output voltage are opposite. At this time, you need to press the polarity conversion switch AN1 (test key).