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Many folks have experienced the failure of a microwave which blows fuses when the door is opened. People change the switches and fuses, but the problem often remains.
So what’s wrong with door that causes the fuse to blow? The door switch is designed to do two things: First is to signal the control circuit to turn off the power supply if it’s on. Second, the backup safety function, is to apply a near dead short across the output of the power supply. This dead short blows the fuse if the power supply hasn’t been shut off.
The origin of the problem is either the power shut-off function of the door switch, or there is leakage through the supply sufficient to blow the fuse
So what’s wrong with door that causes the fuse to blow? The door switch is designed to do two things: First is to signal the control circuit to turn off the power supply if it’s on. Second, the backup safety function, is to apply a near dead short across the output of the power supply. This dead short blows the fuse if the power supply hasn’t been shut off.
The origin of the problem is either the power shut-off function of the door switch, or there is leakage through the supply sufficient to blow the fuse
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