This machine is a computer-controlled microwave. Open the shell, first check the fuse inside the machine, in good condition. According to the circuit diagram and maintenance experience, determine the initial failure in the power supply control circuit, which some components are: fuse, thermal cut, safety interlock switches and secondary primary switch, monitor switch, transformer primary, primary and relay contacts RYZ between the connector elements. These components are connected in series to the power supply circuit in which, as long as a component is damaged, constitute the power circuit, high voltage current transformer without the high voltage output can not be led without heating does not work, and the screen is not displayed. Check these components, found the main contact RY2 power relay circuit board is not closed, resulting in lack of a current transformer, and then measuring RYZ no 12V relay coil voltage, and the relay coil pathway intact. When the case then check the power input circuit board, the power supply input line and then plug off, and then connect the power on, the screen display, the heating is also normal.nYhservice manual download site