what causes microwave fan and other electronics to power on by their self?

[haywire]

I was at a friends house and the microwave fan came on no one pressed power button and i could not turn it off with the button. Its happened three times I was there twice and it happened at different times of day and night. This also happens with the tv turning on randomly. its not daily but often enough. she seems to have alot of issues with computers acting strange and cell phone reception is poor. I figure its interference of some kind but she said her neighbors dont have any problems. She lives in a mobile home park. Is it an emf issue? Anyone have thoughts on this?

 

[GoldDigger]

I was at a friends house and the microwave fan came on no one pressed power button and i could not turn it off with the button. Its happened three times I was there twice and it happened at different times of day and night. This also happens with the tv turning on randomly. its not daily but often enough. she seems to have alot of issues with computers acting strange and cell phone reception is poor. I figure its interference of some kind but she said her neighbors dont have any problems. She lives in a mobile home park. Is it an emf issue? Anyone have thoughts on this?

For anything with sophisticated electronics inside, particularly electronics that is taking the place of a mechanical on/off switch, it is important that the computer inside is started up cleanly. And in this context the microwave and the TV also have microprocessors inside just as computers do.
Every computer will have circuitry inside that lets it turn on, lets the voltage rise to a minimum level, and then sends a signal to reset the computer to a known condition and let it boot up.
Sometimes this startup circuit is not very conservatively designed, with the result that short power fluctuations (glitches) can lower the voltage enough that the computer malfunctions, but does not lower it enough for the power-up reset circuit to be properly activated. That can cause things of the sort you see.
There may be an intermittent or high resistance connection somewhere in the electrical feed to the trailer. If in addition to the behavior you saw, there is also light dimming or flickering, changes in the sound of refrigerators or fans, etc, then this is very likely the problem.

This should not have any direct connection with bad cell phone service, so that is probably just a coincidence.

The other possibility that would also explain the cell phone problem would be emissions from an alien spacecraft hidden under that space in the park.

 

[gar]

130526-0751 EDT

haywire:

Fundamentally poor design of the electronic circuitry.

I have two GE appliances that cause problems. A microwave and a wall oven. The microwave performs as you describe. The solution is to unplug and plug back in, then it is fine for a while. The wall oven wants to randomly beep at me when it is supposed to be off. Solution is to turn the oven breaker off and don't use the oven unless really necessary. Otherwise the oven works fine. This also saves on energy use by using a small tabletop toaster oven.

Otherwise both appliances are pretty good.

I have a freezer that is about 40 years old, Amana, and works fine and has never had to be serviced. I have furnaces with continuous pilot flame. Only necessary to replace thermocouple once in a while. I have a Maytag washer that predates electronic control, washes clothes successfully, and has no electronics. Recently it was leaking. Had this repaired. The serviceman said it should be kept going as long as possible because the new machines are junk. This is not just because he wants business. My son has a much newer furnace with electronic ignition and control. Has had to replace the electronic board twice in a few years.

I have a moderately recent AT&T phone. This is a piece of junk. I have a 50 year old AT&T phone with a touchtone key pad. It still works. Made before the government mandated breakup of the phone company when quality and longevity was the design criteria. Today design criteria is cheap.

I had equipment in auto plants starting in 1975 where I used battery backed up CMOS memory for storing setup parameters. These systems worked fine with all sorts of power interruptions and did not have data loss or corruption.

.

 

[ELA]

China,

 

[kwired]

China,

One thing to add to that is that there are things made there with specifications that came from elsewhere.

I still blame the specifications more so than the manufacturing process for a lot of todays "junk". Even good stuff often is not as good as earlier versions because of reduced specifications to cut costs.

 

[eHunter]

One thing to add to that is that there are things made there with specifications that came from elsewhere.

I still blame the specifications more so than the manufacturing process for a lot of todays "junk". Even good stuff often is not as good as earlier versions because of reduced specifications to cut costs.

:thumbsup:

 

[delectric123]

when shopping for any appliance, tool, whatever..... you usually get what you pay for. Sometimes its not a big deal if its a little on the cheap side, because what you intend to do is not so demanding, and not for everyday use. But otherwise, going with name brands that have been around a long time and have been known for long-term durability is the best option. The higher price can usually signify more thorough engineering. I am a bit involved in electronic circuit design(noncommercial) and can say it takes plenty of scrutinizing to have a glitch-free circuit, especially large complex designs. There are often hundreds of components that have to work together. And a "Made in China" label doesn't help things either.

 

[robbietan]

For anything with sophisticated electronics inside, particularly electronics that is taking the place of a mechanical on/off switch, it is important that the computer inside is started up cleanly. And in this context the microwave and the TV also have microprocessors inside just as computers do.
Every computer will have circuitry inside that lets it turn on, lets the voltage rise to a minimum level, and then sends a signal to reset the computer to a known condition and let it boot up.
Sometimes this startup circuit is not very conservatively designed, with the result that short power fluctuations (glitches) can lower the voltage enough that the computer malfunctions, but does not lower it enough for the power-up reset circuit to be properly activated. That can cause things of the sort you see.
There may be an intermittent or high resistance connection somewhere in the electrical feed to the trailer. If in addition to the behavior you saw, there is also light dimming or flickering, changes in the sound of refrigerators or fans, etc, then this is very likely the problem.

This should not have any direct connection with bad cell phone service, so that is probably just a coincidence.

The other possibility that would also explain the cell phone problem would be emissions from an alien spacecraft hidden under that space in the park.

I use an EMF meter to find spectral entities should the voltmeter fail to help me...

but I like the aliens answer better

 

[kwired]

I can't believe nobody has said there are ghosts in the house yet

 

[david luchini]

I can't believe nobody has said there are ghosts in the house yet

:thumbsup: You beat me to it!

 

[ELA]

China comment was mostly for fun and in reference to poor quality, especially ROHS solder joints. I inspect PCAs regularly with bad solder joints that result in intermittent operation.

Regulatory Standards ( driving better EMC design) are indeed very important and unfortunately the US is lagging way behind Europe in that regard. Europe's CE marking requirement drives EMC compliance.

Yet you can have a CE requirement to sell in Europe, build in China, and still have a cold solder joint ruin your day :slaphead:

 

[cowboyjwc]

Had that happening in a house, turns out it was a bad main breaker. TV would turn on when the lights were turned on, kitchen fan would turn off when lights in bathroom came on, or something to that affect.

 

[Jraef]

130526-0751 EDT

haywire:

Fundamentally poor design of the electronic circuitry.

I have two GE appliances that cause problems. A microwave and a wall oven. The microwave performs as you describe. The solution is to unplug and plug back in, then it is fine for a while. The wall oven wants to randomly beep at me when it is supposed to be off. Solution is to turn the oven breaker off and don't use the oven unless really necessary. Otherwise the oven works fine. This also saves on energy use by using a small tabletop toaster oven....

Interestingly, I too had a GE microwave and it did the same thing. Unplugging it for a few minutes helped for a while, but it progressively got worse until more things started happening, ending in the timer coming on but no magnetron. I took a look at all of the internals but didn't see anything obvious. The Wife called a "real" repairman (as she refers to those useless idiots) who did exactly the same thing I did, said the control board had failed, told me that the board was $400, then charged me $150 for the call :rant: But according to him, the control boards, made in New Jersey by the way, have a poor design on the front end power supply circuit that consistently fails in about 10 years at most, usually between 5 and 7 years.

I complained to GE customer service, they sent me a $100 certificate toward a new GE microwave. So the moral is, if you don't like their POS appliance, you deserve ANOTHER one!