I hope I gave enough so that it helps you understand it some. There's more I could write, but that's enough of this lesson. However, the ohmmeter may STILL not adequately reveal that there's a problem since an ohmmeter can't LOAD the switch with current flow like actual circuit operation does. So, you could be thinking there continuity when there is actually more resistance than the switch should have. I personally DON'T use that feature since, depending on the meter, some meters will BEEP when resistance is as much as 20 ohms or less. Some meters have that BEEP feature to indicate continuity. NOW.I don't know what kind of meter you're using and what your definition of CONTINUITY is. By design, if the interlock's sequencing has failed at ANY point and no matter HOW briefly, the fuse is there to blow and shut everything down. They prevent ANY possibility of the oven still "microwaving" when the door is opened. Those three switches (as an assembly) are called the " door interlock" and are a MAJOR safety aspect of the microwave. secondary, monitor) don't open or close in proper sequence, a direct short occurs. A given failing switch may remain stuck CLOSED j-u-s-t long enough to disrupt the sequence designed between the operation of the three switches in there. However, the switch's internal spring tension can overcome that if the welded areas are minute. The "sticking" begins to occur when the switch contacts get hot enough to weld together. Insufficient CLEAN contact surface area (of the switch contacts) relative to current flow demands will ALSO cause heat In either case:Ĭurrent flow through electrical resistance causes heat Additionally, what carbon build that there is (due to arcing) m-i-g-h-t conduct current flow, but with some resistance. So, as switch contacts become pitted, they'll have less CLEAN usable contact area. To give some idea of that power, it's about the same as if you had SIXTEEN 60 watt light bulbs running from the same electrical outlet.
How much that is varies with your oven's wattage rating. The HV transformer's power requirements are significant. In your microwave, the door switches carry ALL current flow demands to energize the high voltage transformer (along with everything else). Over-the-Range Microwave-Stainless Steel with 1000 Watts, Two Speed Fan/300 CFM Hood, 9 Power Levels, SpaceWise Rack and. It's a normal occurrence in ANY mechanical switching device. Pitting occurs over time and is caused by the arcing which occurs each time switch contacts make or break during their closing or opening to energize/de-energize a circuit. In the case of microwave ovens, those switches will STICK due to pitted contacts.
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