So I’m having a big party, and I needed to do the broccoli & cheese in the microwave. So I go to turn it on and nothing happens. I open the door and IT STARTS RUNNING. I put my hand in it briefly, but it didn’t feel hot or anything. So now I have to get a new microwave. And it’s only three or four years old. Damnit.
Do you think microwaves are coming out of it when it’s open?
Probably not. Microwave ovens have three door interlock switch, and every one of them would have to fail for that to happen. Chances are only one of the switches has failed, and just the fan and light runs when the door is opened. I repaired a unit with similar symptoms ome time ago, and replacing one of the interlock switches fixed it.
I am sure that it is reparable. Most things are. The cost of a new one vs. reparing the old one is high compared the the repair. Take it to the shop and you will be happy.
To amplify Q.E.D.'s answer…
One of those interlock switches creates a dead short across the high-voltage power supply while the door is open. If you try to run the microwave without depressing that switch you will blow the ceramic fuse. This renders the microwave dead until someone pulls the cover off and sorts everything out.
In order for the microwave to run with the door open, you would need all three switches to fail simultaneously. Short of deliberate tampering, I don’t think this is likely.
(Even in the case of deliberate tampering, the nitwit in question would have to know enough to disable all three switches on his first attempt.)
Thanks for your responses. I only paid around $75 for the microwave, so we pitched it last night and bought a new one. It’s bigger, it’s GE, and now, it’s mine.
Who knew about the triple interlock switches? I suppose if it was one of those fancy-schmancy ones that’s built into the range, I may have made more of an effort to fix it. But maybe some handy guy will snag it off the side of the road, huh?
What if it had been working? How much damage would an average mircrowave oven do to a hand left in the beam for a few (lets say 5) seconds? Would you feel pain or heat and be able to pull away before serious injury occurs?
I’ve obviously never tried it, but I’m thinking you would probably feel enough heat that you could pull your hand away before any serious damage occurred. Once you feel pain though you are pretty much screwed. RF burns tend to be deep tissue burns just becaue of the nature of microwaves (this is how it cooks your food too) so be expecting a rather nasty painful injury.
We have the same issue with our microwave. It’s a built in unit though. Is it a “big deal” to take it out and into a shop for repair? Any one want to suggest an estimate range of what it might be for such a repair. I’m in Texas, if that helps much.
Call Sears. They repair most brands of appliances on site, even if you didn’t buy from them. Their rates were fairly reasonable the last time I bothered to check.
Well, I figure five seconds doesn’t even melt butter, so even if you did feel heat, I don’t think it would have done any damage.
I must admit, my decision to become a home experiment for the microwave industry was fueled by a few glasses of wine. I would probably have put some cheese or something in there otherwise.
I would think the “built in” type would be more worth it than the shitty little counter-top model I had. My sister-in-law said most places will charge $70 or so just to look at it. Totally not worth it to me.
I believe that with the door open, the resonant frequency would drop significantly.
I heard ghosts like carrots.
Chop up some raw carrots to a size of about a quarter of an inch. Space them on a plate about an eight of an inch apart. Place the plate in the microwave and cook them for about 15 to 20 seconds.
The resulting show of arcs and sparks between the carrots is amazing and makes a great party trick. If you have a radio near by listen to it while the arcs are going on. The interference is like that of a lightning storm.
I am in ah of the power available inside of a microwave. I’ve done this trick several times in my microwave with no problems.
The resonant frequency of what? The oven chamber?
Yes, one of the chamber’s resonant frequencies would change. But so what? It’s not like the magnetron is pumping broadband noise into chamber. The magnetron’s frequency is fixed at 2.45 GHz, IIRC. Opening the door while it’s running won’t change this.
I’ve played around a little with microwave cavities and a network analyser.
The cavity had a lid. If the lid was removed, the peak would move at a lower frequency and the power would drop significantly. The power (and Q-point) drops because there is a lot of energy lost through the opening. The frequency drops because the cavity volume has increased.
The network analyser was set to do a “frequency sweep”. I don’t know how it works, but I assume that the network analyser delivers full power (a few micro or milli watts) at each frequency. So in that respect, it is similar to the oven magnetron. I believe that although the magnetron continues to emmit waves at the same frequency, the heating effect of the oven will be significantly diminished when the door is open.
Also, what do you mean by “one of the chamber’s resonant frequencies would change”? In my experiment I was only interested in the first mode, but I believe that all modes of resonance were affected by more-or-less the same amount of frequency drop.
Dog8:
A microwave oven doesn’t perform a frequency sweep. The magnetron is (more-or-less) fixed at 2.45 GHz. No passive component (which includes a cavity) is going to change this. (This isn’t strictly true, but we can assume so for this discussion.) Now if you’re asking, “Will removing the door change the average power level inside the chamber?” The answer is, “Probably.” But this is primarily due to energy escaping via the door.
A chamber has lots of resonate frequencies, depending upon the orientation of the E-field. And in any orientation, there will be many modes.
But why did you say that only one of them will change? Won’t all of them drop by the same amount?
One of my few claims to yame (that I’ve posted on here before) is that I have microwaved my arm. As a freshman in college, one of the microwaves in the cafeteria of my dorm didn’t turn off when you opened the door.
I pulled something out of the microwave once without turning it off. It was warm, but it didn’t cause any injury.
[sub]I don’t count the third arm I grew as an injury per se…[/sub]