Amoi 8250 DVD player power supply principle and maintenance - Power Circuit - Circuit Diagram

05L0380R, so that the switching power supply circuit has the advantages of simple periphery, wide input voltage adaptation range, high efficiency, less radiation, stable output voltage and so on. Such integrated circuits are used more in brand machines such as Amoi and BBK. At present, there are few articles detailing the working principle and maintenance method of this kind of power supply circuit. I actually painted the power supply of the Amoi 8250 DVD player during the maintenance process and drew its circuit diagram (as shown in Figure 1). At the same time, also consult the relevant information, combined with my maintenance experience, write this article for the reference of the majority of maintenance peers. When testing various types of optocouplers, it is necessary to use R × 1Ok block detection, it is best to use the substitution method to avoid more detours.
Example 2: The image is normal during playback, but each channel is silent. Analysis and overhaul: According to the analysis of fault phenomena, the parts causing the fault of the machine may have audio digital/analog conversion circuit, audio analog amplification circuit and power supply circuit. Based on the principle of easy and difficult to open, the voltage of the F2+12V and -12V terminals was directly measured after opening the cover. It was found that the output voltage of -12V was only -3.6V. The voltage at the input terminal of the uP06 (7912) is normal, indicating that the UP06 is damaged and the fault is removed after the UP06 is replaced. Example 3: Boot all at all.
Analytical maintenance: This is a machine damaged by lightning strikes. Open the cover and visually find that the AC fuse FP01 (1.6A250V) is blown and black, indicating that the machine has a serious short circuit fault. Using a multimeter to detect, it is found that the UP012 foot is damaged to the ground, UP02 (3, 4 feet have also been short-circuit damaged. The above damaged components are replaced one by one and then energized, and the measured output voltages are normal (the power supply has been disconnected), After the plug is connected to the motherboard, the test machine is troubleshooting.