(1) Circuit Maintenance and Precautions When the household microwave oven fails, the first thing to do is to check it, mainly to see if there are any burn marks on the inside of the oven door and the walls of the oven cavity. If yes, the high-voltage component is damaged. Remove the steam baffle at the coupling in the cavity, and check whether the magnetron outlet is polluted by oil and whether the metal seal is loose; Open the cover, and check whether the connector of the control part is loose and the magnetron magnet steel is broken.
When checking the control part, for the sake of safety, try to avoid power-on, because the high-voltage winding of the microwave oven high-voltage transformer has several thousand volts, and the high-voltage capacitor still has high voltage after power failure. Therefore, after the power is cut off, it is necessary to discharge the high-voltage capacitor and disconnect the magnetron from the circuit to prevent the microwave from harming the human body.
(2) Familiar with common troubleshooting actions.
① The fuse is blown.
A. the fuse is blown when the power supply is connected. This is caused by a short circuit between the interlock switch or the power cord and the wire. When overhauling the interlock switch, unplug the power plug, remove the cover and discharge the capacitor. Do not bend or break the mounting plate during operation, so as not to affect the position of the switch, and replace the interlock switch if necessary.
B. The fuse blew when the oven door was opened. Check and adjust the interlock switch, and pay attention to check whether the fixed lever and operating lever are reset.
C. After the timer is adjusted, the fuse is blown for a short time. This is mostly caused by short circuit of capacitor. After discharging, remove the capacitor and measure it with a multimeter. If the multimeter indicates that the resistance is zero, it means that the capacitor has been short-circuited and should be replaced according to the original model and specification.
D when the timer is adjusted, the fuse will be blown immediately. This is mostly caused by short circuit of power transformer winding. When overhauling, cut off the power supply, remove the cover, take out the transformer after the capacitor is discharged, and measure the resistance value of the high-voltage winding with a multimeter. If the measured resistance is extremely low, the winding is short-circuited, and a new power transformer should be rewound or replaced.