What is the circuit diagram of a TV power supply and how to repair it?

Many people must want to know about the TV power supply circuit diagram , because TV series are something we all have at home, and we often watch TV together with our families and change channels. So how much do you know about its power supply circuit diagram ? Let’s work together Learn about.

The switching power supply of LCD color TV is mainly composed of AC anti-interference circuit, rectifier filter circuit, power factor correction circuit (most models have this circuit), starting circuit, switching power supply control circuit, voltage stabilizing circuit, protection circuit and other parts.

TV power supply circuit diagram

The A3 movement power supply first appeared on Sanyo's la7680 movement, hence the name. It is now widely used by various manufacturers because of its simple circuit, high efficiency, easy expansion, and easy maintenance. R520, R521, and R522 are the starting resistors, the (1) and (2) windings of R519, C514, R524, V513, and T501 form a positive feedback loop, and C514 is the oscillation capacitor. V553 and peripheral components, VD515, V511, and V512 form a voltage stabilizing control circuit. R552 is the sampling resistor, and VD561 provides the reference voltage for the emitter of V553. When the power output voltage is too high, the conduction degree of V553, VD515, V511, and V512 increases, causing the base of the switch tube V513 to be shunted, and the output voltage increases accordingly. decrease; conversely, if the power supply output voltage decreases, the conduction degree of V553, VD515, V511, and V512 will decrease, which will reduce the base shunt of the switch tube V513, and the output voltage will increase accordingly. VD518, VD519 and R523 form an overvoltage protection circuit. In addition, VD563 also provides overvoltage protection.

Repair process:

Plug in the LCD TV power cord and observe whether the power indicator light is on. If it doesn't light up, the power supply is probably broken. Open the back cover and measure whether there is a DC voltage of 300~320V at both ends of the filter capacitor after the power supply is rectified. All of this is a problem with the subsequent circuit; if there is no such voltage, it is the power cord, fuse, rectifier bridge and various filter devices . failure. If there is a voltage of more than 300 volts at both ends of the large filter capacitor, you should unplug the power cord at this time, disconnect each group of power supplies from the secondary output to the motherboard, and measure whether the rectifier diode of the rear output has broken down and whether the filter capacitor is in good condition (note Is there any bulge? If there is no problem with these, connect each group of power supplies at the downstream stage and measure the resistance value of each group's positive power supply to the ground. If a short circuit is found, repair the subsequent short circuit fault; if the resistance value is basically normal, the fault is Power supply oscillation module , module peripheral components and optocoupler voltage stabilization, feedback circuit. Some power supply failures are not completely damaged. When measuring, it can be found that there is power, but the voltage is insufficient. For example, when measuring the filter capacitor behind the rectifier bridge, it is less than 300V. Pay attention to whether the filter capacitor capacity is sufficient, whether there is any leakage of components, etc. Another situation is that the power light is on but the power is not turned on, which means there is a standby power supply. This does not mean that the power supply is necessarily good. Check whether the output voltage of each group is normal. Input the simulated startup voltage and measure the output voltage value at the same time. If the voltage of a certain group is incorrect, the machine cannot be started. Check whether the components of the group have any problems such as numerical changes or weak soldering. If there is no voltage at both ends of the 300V filter capacitor, check again. When the fuse is blown, do not rush to install the fuse and start the machine. The cause of the fuse burning should be checked in detail to avoid causing a larger failure. During the maintenance process, it is sometimes necessary to turn on the AC power for measurement, so pay special attention to safety.

The editor has told you the TV power supply circuit diagram and how to repair it. If your TV is broken and you really don’t know how to repair it, you can contact the owner who sells the TV to check it for you.