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Microwave spontaneously turned on by its LED display

blog.stuffedcow.net

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Re: Microwave spontaneously turned on by its LED display

#21

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.

If your country has decent consumer rights there's probably another way to follow-up!

Re: Microwave spontaneously turned on by its LED display

#22
post #8

Earlier quoted context omitted.

What was the model? I recently encountered something similar with a GE over-the-counter microwave. One day it stayed on after opening the door. I replaced the control module and the board in it looks exactly like the one in the OP photo (Midea with all of the same components), which leads me to think the fault is the same as the one described in the post.

Yep, the GE over-the-range model PNM9196SF3SS. GE is just a Haier badge since 2016. I'm not surprised by a Chinese company not giving a shit, but for a microwave magnetron to fire on its own feels like a sign of deep engineering rot. The only fix was to unplug it then swap the logic board. Once it happened again with the new board we threw it out.

I had non-stop issues with GE OTR microwaves for 2 years. I started with a PVM2188SLJC that I ended up getting replaced three times by GE over a year for separate issues (buzzing turntable, cracked casing). I ended spamming the executive team and got an upgraded model with convect for free.

Fast forward two years later, and the fuse tripped inside the microwave after I forget a bottle sterilizer overnight, on Christmas Day.

I said fuck this, and went and got a Panasonic NN-SG158. The twist was that it looked like it was a different version of the first GE microwave we had from the same OEM, but a little reworked.

Re: Microwave spontaneously turned on by its LED display

#23
post #8

Earlier quoted context omitted.

What was the model? I recently encountered something similar with a GE over-the-counter microwave. One day it stayed on after opening the door. I replaced the control module and the board in it looks exactly like the one in the OP photo (Midea with all of the same components), which leads me to think the fault is the same as the one described in the post.

Yep, the GE over-the-range model PNM9196SF3SS. GE is just a Haier badge since 2016. I'm not surprised by a Chinese company not giving a shit, but for a microwave magnetron to fire on its own feels like a sign of deep engineering rot. The only fix was to unplug it then swap the logic board. Once it happened again with the new board we threw it out.

Mine was a PEM31DF2WW. The control panel layout looks slightly different but the segment display looks identical to yours.

The board that I replaced is a Midea MD1001LSE EMLAA5G-S3-K VER17. Not an exact match to the OP but in the same family.

Re: Microwave spontaneously turned on by its LED display

#24
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…

It's so limited without a power level feature. It needs to be able to cycle power to heat food evenly.

Re: Microwave spontaneously turned on by its LED display

#25
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…

It's so limited without a power level feature. It needs to be able to cycle power to heat food evenly.

It does heat food as evenly (possibly more evenly) than my other microwaves.

Re: Microwave spontaneously turned on by its LED display

#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" feature.

Re: Microwave spontaneously turned on by its LED display

#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 and continue to run. Zero logic protection.

Re: Microwave spontaneously turned on by its LED display

#29
One of the comments linked to an article about keyboard problems caused by a LED, which was previously discussed here:

https://news.ycombinator.com/item?id=36581204 - Repair adventure: A single white LED causing stuck keys on a RN988 keyboard (2023-07-05)

I wasn't thinking about the color of the LED at the time, but after reading this article, I wonder if we should prefer products with green LEDs in general, like green LEDs are just more reliable than blue/white LEDs for some reason?

Also, I can't seem to find microwave ovens with red LEDs.

Re: Microwave spontaneously turned on by its LED display

#30
The title is a bit clickbaity, since the actual "oven" part (the magnetron) stayed off. As it should, since the safeties for it are much more robust than the other parts:

I’m quite impressed by how many independent mechanisms there are to prevent the magnetron from accidentally turning on. Not only are there three door switches to ensure the door is closed, there’s also a mechanism to guard against a faulty microcontroller or software.

Personally, I think the ones with mechnical controls, no microcontroller, are the most reliable and also easiest to repair.

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