Magnetron keeps running after cook cycle is done.
Intermittent problem: sometimes the magnetron will keep running after the cook cycle. The interior light, fan, and turntable all turn off at end of cook cycle, but magnetron will keep going and keep cooking food hotter and hotter until we open door -- magnetron stops. Close door again, the magnetron will keep going, but still light/fan/turntable stay off like they are supposed to.
Thought it might be the power relay (that feeds the magnetron) sticking...but I reason that, since the relay is NO (normally open), it would have to be fused/welded to stay shut. And if it was welded shut, it should be a permanent problem, not intermittent. Right?
Thought about door switches too, but I've tested every possible combination of the three door switches being activated/deactivated and can't get it to repeat. I often hear of bad/dirty door switches causing light/fan/turntable to keep going after cycle...and that is something I can reproduce just by a certain combination of door switches. Magnetron alone, via door switches I can't reproduce. So, not door switches as the problem?
Any thoughts?
Schematic:
crwdns2934109:0crwdne2934109:0
crwdns2944067:03crwdne2944067:0
Relays can stick intermittently. Once they start doing that it's only a matter of time until it becomes permanently stuck either open or closed. This is usually caused by buildup of something such as carbon from the small amount of arcing produced when it opens or closes. But it CAN stick intermittently. Next time it does it, give the relay a tap with the back of a screwdriver
crwdns2934271:0crwdnd2934271:0 brandon k crwdne2934271:0
@brandon_k Well good to know -- sticking will soon become permanent...and then I'll have a house-fire on my hands. I'll be swapping out control boards then. Thanks!
crwdns2934271:0crwdnd2934271:0 Sam Elsinger crwdne2934271:0
@itbebroke yes let's not burn anything down, shall we? If the relays sticks sometimes, time to replace it.
crwdns2934271:0crwdnd2934271:0 brandon k crwdne2934271:0