Microwave Oven Failure: Spontaneously turned on by its LED display (2024)

3 hours ago

Microwave oven malfunctioned by randomly powering on lamp, fan, and turntable due to a failing LED display.
The control board incorrectly sensed the door as open due to reverse-biased leakage in the LED display, causing the microwave to behave as if the door were open.
The issue was traced to shared microcontroller GPIO pins between the LED display and door switch sensing, a cost-saving measure that led to the malfunction.
Repair involved adding a diode to prevent LED display leakage from affecting door switch sensing, though the display itself continued to degrade.
A replacement LED display module was designed and installed when the original display became unusable due to further degradation affecting keypad functionality.
Analysis of similar microwave models showed that those with blue LED displays had significantly higher failure rates compared to those with green displays.
The design vulnerability highlights the risks of sharing GPIO pins between LEDs and critical functions without tolerating reverse leakage current.
Safety mechanisms in the microwave include multiple independent checks to prevent the magnetron from turning on accidentally, showcasing robust failsafe design.

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