EPSON PHOTO 830U printer power circuit

EPSON PHOTO 830U printer power circuit

Shown is the power circuit of the EPS ON PHOT0 830U printer , which is a switching regulated power supply.     During normal operation, the power supply input socket supplies 2,20V AC power to the circuit board. After the 220V AC power is fed in, it is first filtered by the fuse and mutual inductance filter. After being filtered, the 220V AC power is sent to a bridge rectifier circuit composed of four rectifier diodes, which rectifies the 220V AC power into a DC voltage of about 300 V, and then sends it to both ends of the electrolytic capacitor CI1. The withstand voltage of this electrolytic capacitor is 400 V, and it is mainly used to filter the DC voltage of 300 V. After filtering, the 300 V Leopard DC voltage is sent to the switching transformer Tl, and the other end of the switching transformer Tl is connected to the drain of the switching transistor VT1. The 300 V DC voltage provides the starting voltage to the gate of the switching field effect transistor after passing through the starting resistor R18 . After this voltage is added to the gate of the switching field effect transistor, current begins to flow, so there will be current in the primary winding of the switching transformer. In the switching transformer, there is a group of positive feedback windings, which generate an induction signal as soon as there is current , causing the switching field effect transistor to enter an oscillation state. After oscillation , a high-frequency oscillating current will be generated in the primary winding of the switching transformer. , an induced current of corresponding frequency will also be generated in the secondary. After the output voltage of the secondary side of the switching transformer is rectified and filtered, two DC voltages are output from the output leads and sent to the main circuit board.