Foods that are low in density or low in moisture (such as bacon and popcorn, respectively) can cause the magnetron to overheat.
That's because there is not enough of either mass or moisture to absorb enough of the microwave energy put out by the oven.
The excess energy then reflects back to the magnetron and causes a standing wave (like a poorly tuned transmitter antenna) and causes the magnetron to overload and overheat.
When the mag gets too hot, it trips the magnetron thermostat, a protective device. In the bets of cases, your model has a thermostat, which rests when it cools. The worst cases is a thermal fuse, which is a one time device which must be replaced when it trips.
If this overheating is a persistent problem, a stopgap is to put about 1/3 to 1/2 a cup of water in a microwave-safe container (a Pyrex measuring cup is ideal) in a REAR CORNER of the microwave whenever you cook such items.
And of course I always suggest that food items be placed off-center in the microwave, NOT in the center of the turntable, otherwise the food is not exposed evenly enough to the microwave energy and will not heat as efficiently as it could.
(Placing it in the center is sort of like stirring paint by twirling a stick in the center instead of pulling it around in a circle in the paint can).
Such inefficient heating wastes the energy at best, and at worst it puts a strain on the magnetron.
If a magnetron is repeatedly subjected to such stress, it will prematurely fail. It will also draw excessive current, which can strain the high-voltage transformer.
That in turn will often lead to the oven's drawing excessive current, resulting in a hot cord and plug, and the fuse will blow - hopefully before the transformer or magnetron does! See my user name if you need more help. |