Beijing LG Microwave After-sales Service Phone, September 23, 2011 Technical Summary. LG microwave oven buzzer does not sound.
**Fault Phenomenon**: The buzzer does not sound, but everything else works normally.
**Fault Cause**: The buzzer is damaged.
**Analysis and Maintenance**: When a button is pressed or cooking is completed, the CPU (HD6433642RA68P) outputs pulses from pins 44 and 45, which are amplified by Q50 and Q51, driving the BZ1 buzzer to sound, indicating that the operation is effective or that the cooking process has ended. Using a 500-type multimeter set to the R1Ω range, intermittently contact the two ends of the buzzer with the red and black probes. If no sound is heard (normally there should be a slight "click" sound), it indicates that the buzzer is damaged. After replacing the buzzer, the fault is resolved.