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Microwave spontaneously turned on by its LED display

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Re: Microwave spontaneously turned on by its LED display

#31

Post by anitil »

r00fus wrote: post #10

I migrated our house to a "commercial" variant of the microwave oven [1] as I was tired of all the over-engineering and annoying patterns in modern microwaves. This microwave has exactly UI element other than the door - a digital dial that goes from 10s-6m. No start/cancel, no power level, no defrost, no program mode. I don't "cook" using the oven, only reheat or very rarely heat/boil small quantities of water. The m…

I have this experience with so much equipment in the kitchen. The retail variant has features and knobs etc but is otherwise somehow flimsy, but the commercial variant is rock solid and only does one job.

An example is the atrocious slow cooker that I somehow ended up with that has so many settings on its terrible display I can never remember how to run it. Oh and it maxes out at 6 hours, when my work day is typically 8+ hrs. The old one had two settings with a physical switch - high (for saute) and low (for slow cooking). Perfection.

Re: Microwave spontaneously turned on by its LED display

#32

Post by solid_fuel »

Retr0id wrote: post #27

I have a Samsung microwave with a really weird bug. If the door is just a few millimetres ajar, it turns on by itself. It's not just mine either, a lot of reviewers point out the same. It seems to be a design flaw. It's not a huge issue, since I'm not exactly in the habit of positioning the door in a half-open state. My guess is that they have some broken/inverted logic related to the "turn off if the door is open" f…

I remember this flaw in a Samsung microwave from ~2007-2008. It freaked me out when I triggered it while trying to quietly close the door.

Re: Microwave spontaneously turned on by its LED display

#33

Post by liminalsunset »

goda90 wrote: post #15
r00fus wrote: post #10

I migrated our house to a "commercial" variant of the microwave oven [1] as I was tired of all the over-engineering and annoying patterns in modern microwaves. This microwave has exactly UI element other than the door - a digital dial that goes from 10s-6m. No start/cancel, no power level, no defrost, no program mode. I don't "cook" using the oven, only reheat or very rarely heat/boil small quantities of water. The m…

The thing is, the superior way to reheat something would usually be a lower power level. But not the standard "turn on - turn off" cycle that most microwaves do. Actual lower intensity microwaves. You need an inverter for that. The food would heat more evenly, which is especially useful for things like butter that are prone to splattering.

Interestingly enough, this particular question has been tested by Rtings [1] They found that during their tests, inverters which continuously varied the power did not necessarily lead to more even heating, but they do note that small quantities of food (like the butter you mentioned) that need to be heated for very short periods show some differences between inverter and non-inverter models.

Overall, they found that the improvement was much smaller than I'd originally anticipated.

[1] https://www.rtings.com/microwave/learn/research/microwave-in...

Re: Microwave spontaneously turned on by its LED display

#34

Post by MarkusWandel »

MisterTea wrote: post #5

Notice that door switch middle is a crowbar[1] which is there to prevent the magnetron from powering on when all else fails (and there is a lot of interlocking). My friends parents had a microwave that kept dying so I opened it up and realized one of the three switches was a crowbar and it blew the fuse. I changed the fuse and it powered on again and ran for a few more days until it blew again. They decided it was un…

Ironically the switches are cheap (from Ali Express anyway) and easy to replace and TMK virtually all microwaves use the same type. But yes, when you open the door, they do the following, in order:

- open to send a "stop microwaving" signal to the controller

- open to physically open the power circuit to the magnetron transformer

- close to short out the power after the above relay (the crowbar part)

The bottom two relays (in the list, not necessarily physical order) are independent of what the control board does. If due to mechanical slop, the bottom one switches before the middle one, boom goes the fuse. Even if you're just opening the door of an idle microwave. That's why, at least in mine, it says on a label inside, if the fuse is blown, replace the door switches along with the fuse.

The sequencing is very tight. You have to push the button veeerrry slooowly to actually observe the switches clicking in sequence.

Re: Microwave spontaneously turned on by its LED display

#35

Post by MarkusWandel »

ToucanLoucan wrote: post #14
sonofhans wrote: post #11

Partially off-topic, but I’ve seen complaints in the thread about microwaves in general. Here’s the trick — buy a commercial microwave. They’re reliable, powerful, and have only a few features. They come in all sizes. You’ll put less duty on one in a month than a commercial kitchen does in one day, so it will last forever. Time is money in a kitchen so they’re powerful and fast. They tend to have very simple, direct…

Can confirm. We got a commercial-grade Panasonic microwave I believe, that survived near daily use for almost 9 years before the magnetron finally gave out. We replaced it with an identical model, and it must be a pretty good one since a cursory comparison inside between the old and new revealed virtually no changes since our old one was made. If it ain't broke...

Can confirm because at my work, they initially put ordinary consumer microwaves in at the coffee/lunch stations. They failed quickly. The commercial ones last. However the latest ones have a very flimsy feeling control wheel, I somehow imagine a 25 cent rotary encoder behind that which, if it fails, may still cause the otherwise solid machine to be discarded.

Re: Microwave spontaneously turned on by its LED display

#36

Post by djmips »

ctrlGsysop wrote: post #28

Fascinating in that our GE microwave (still actively sold) has an undisclosed feature that if you lift the door, when fully closed, by no more than a few mm, the microwave will start. I noticed this when cleaning the enclosure with a rag and my hand ever so slightly lifted up the door from the bottom. I can see how a consumer could wedge a kitchen utensil or plate accidentally under the microwave causing it to start…

They mention that in the article but assure that the magneton does not run.

Re: Microwave spontaneously turned on by its LED display

#37

Post by djmips »

Retr0id wrote: post #27

I have a Samsung microwave with a really weird bug. If the door is just a few millimetres ajar, it turns on by itself. It's not just mine either, a lot of reviewers point out the same. It seems to be a design flaw. It's not a huge issue, since I'm not exactly in the habit of positioning the door in a half-open state. My guess is that they have some broken/inverted logic related to the "turn off if the door is open" f…

The article describes such an issue but the assures that the oven magnetron doesn't run. Maybe it's a similar problem where the turntable and light come on in that situation.

Re: Microwave spontaneously turned on by its LED display

#39

Post by neilv »

lozenge wrote: post #13
arghandugh wrote: post #6

We recently got rid of a four year old microwave where the magnetron turned on spontaneously and silently when the door was closed, runaway heating the box. Control panel, lights, turntable, fan, everything is idle. Manufacturer didn't consider this an interesting defect and refused to swap out-of-warranty. The lack of give-a-shit in appliances is becoming apparent.

The CPSC would be interested.

Maybe not. I recently did the lengthy CPSC form, to report a defective new name-brand microwave oven unit, which was manufactured with a 1/8" mis-seating of parts, where I measured with a professional meter to be leaking much more than anywhere else.

A week later, I heard back:

> [...] The product or particular concern that you describe does not fall within CPSC’s jurisdiction. You may wish to contact the agencies listed below, which we believe can best handle your concern.

> U.S. Food and Drug Administration Center for Devices and Radiological Health Document Control Center – WO66-G609 10903 New Hampshire Avenue Silver Spring, MD 20993-0002

> https://www.fda.gov/radiation-emitting-products/getting-radi... [...]

(BTW, I suspect the process apparently not forwarding a report between two agencies will result in some problems falling through the cracks. And it did, in this case, since I stopped holding the defective unit (I'd asked in my report that they let me know if they wanted to examine it), returned it to the store, and never looked into starting over the reporting process with a different agency.)

Re: Microwave spontaneously turned on by its LED display

#40

Post by hammock »

apricot wrote: post #16
goda90 wrote: post #15

Earlier quoted context omitted.

The thing is, the superior way to reheat something would usually be a lower power level. But not the standard "turn on - turn off" cycle that most microwaves do. Actual lower intensity microwaves. You need an inverter for that. The food would heat more evenly, which is especially useful for things like butter that are prone to splattering.

The commercial microwaves we have at work have both a large dial to set the time, and four large buttons under it for 25%, 50%, 75% and 100% power. No other controls. They are great.

If the power level buttons were an old school radio button that would be so cool
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