microwave power fluctuates

Old 06-03-05, 12:23 PM
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microwave power fluctuates

We own an older home, late 50s.
I changed some electrical wires a few months ago, I upgraded some outlets to three prongs. I started noticing that in the kitchen, the microwave seems to slow down, then gain speed again when we use it. It is like if there is a power loss.
Not sure what the cause could be. I disconnected one of the outlets I had connected to the same braker as the one the microwave is on.
It is getting anoying and am affraid to ruin the microwave oven.

Any ideas of what could cause that?

Old 06-03-05, 12:31 PM
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It kinda sounds like the microwave is being utilized at less than 100% power. By that, I mean than when it is set to, say 50% power, it cycles on and off to achieve that. The turntable may appear to slow down and the light dims a little while power is on (and the voltage drops to the unit) and then the light brightens and the turntable speeds up (or appears to) when power goes off. Are you sure it set for full power?

Try an electric hair dryer on the same receptacle (don't try to run the microwave simultaneously). See if the sound the hairdryer makes cycles in a similar manner.
Old 06-03-05, 01:22 PM
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Wild card guess. If you are in defrosting mode it will cycle the power to keep from cooking the food while you are defrosting.
Old 06-03-05, 02:35 PM
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The change in sounds that you are noticing are _normal_ if there is any voltage drop in the line feeding the microwave oven. As the microwave power cycles on and off, the electrical load on the line will change, and the voltage drop will change. Other loads in the oven (things like the light, the fan, the turntable) will respond to this change in available voltage. The fan gets slower, the light gets a bit dim, etc.

Because wires have resistance, there will _always_ be some of this 'voltage drop' effect.

However if you have noticed an _increase_ in the magnitude of this drop, then that indicates a loose connection or damaged wire somewhere. Since you describe this problem as occurring after you did some work, this suggests that one of the connections in the circuit is loose.

Old 06-03-05, 03:17 PM
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Thumbs up microwave power fluctuates

Thanks for the answers,
I will check the connections and also look at the power settings on the microwave. It is a new GE microwave/Grill oven.

Old 06-06-05, 08:33 AM
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I also have a GE brand microwave, and that cycling is normal operation.
Old 06-06-05, 05:08 PM
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Red face microwave power fluctuates

I tried the previous suggestions first with no change.
I looked at the manual and sure enough they say it is normal operation.

Thanks to all for responding.

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