# Microwave Sparks



## m_ridzon (Sep 29, 2017)

I have a GE Profile Advantium 120 microwave in my home. It's well taken care of, so I wouldn't expect our newest problem to be a result of neglect or abuse. However, it started sparking recently while in use. It's intermittent. Someone will probably say, "you had metal in there." Nope. The item I heated last night was a plastic bottle full of water, and I had done this a thousand times in the past, same bottle, with no issues. What are some tips folks can share about what might be causing the issue?

Thanks in advance!
M Ridzon


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## jmon (Nov 5, 2012)

I found a video that may help. As your user name implies, lincensed pro engineer, I'm sure you can figure something out. If it's not under warantee, I would just buy a new microwave - but that's me. Just my thoughts. Hope you can get it fixed.


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## m_ridzon (Sep 29, 2017)

jmon said:


> I found a video that may help.


Thanks! That was helpful. I saw something else on Google talking about a faulty wave guide cover. So I'm going to check that, for sure.



jmon said:


> As your user name implies, lincensed pro engineer, I'm sure you can figure something out.


Yup, I'll figure something out, but coming to forums always helps, since I'm not omniscient.:wink2:



jmon said:


> If it's not under warantee, I would just buy a new microwave - but that's me.


Tossing it out is not my first option. This is a pretty fancy microwave with advanced "oven-type" features, and it is part of a stove/micro set. So I'm going to try and salvage it, within reason of course. 

Thanks again!


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## rooster4321 (Feb 25, 2018)

the video tells you about a piece you can buy for $5 or usually more than that but if you take it out you can clean it maybe with some very fine sandpaper I have done it and it works

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## BayouRunner (Feb 5, 2016)

Jmon nailed it on the wave guide. Although good luck with buying a part from ge for $5. It’s a pretty common occurrence


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## Dave Sal (Dec 20, 2012)

I had the same problem last year and simply removing the waveguide, cleaning it on both sides, solved the problem. I found a replacement on RepairClinic.com but didn't need to order it as cleaning it worked.


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## m_ridzon (Sep 29, 2017)

Can someone explain the purpose of the wave guide cover? It looks like nothing more than a flimsy piece of cardboard. And how can it cause a lightning storm in the microwave, merely from splattered food upon it?


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## adamz (May 13, 2018)

If you read the link below, the cover's job protects the electronics inside the microwave. Please be careful and I would avoid using it until it's fixed.


https://www.hunker.com/13407957/can-i-operate-a-microwave-oven-without-the-waveguide-cover


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## m_ridzon (Sep 29, 2017)

adamz said:


> If you read the link below, the cover's job protects the electronics inside the microwave. Please be careful and I would avoid using it until it's fixed.
> 
> 
> https://www.hunker.com/13407957/can-i-operate-a-microwave-oven-without-the-waveguide-cover


Thank you, I too had previously found and read that article. I'm no microwave expert, so maybe my ignorance is bliss, but it doesn't really say how or why a flimsy cardboard cover is an integral part of the machine, other than to cover internals. Nor does it say how food splatter on it leads to poor performance.


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## Nealtw (Jun 22, 2017)

m_ridzon said:


> Thank you, I too had previously found and read that article. I'm no microwave expert, so maybe my ignorance is bliss, but it doesn't really say how or why a flimsy cardboard cover is an integral part of the machine, other than to cover internals. Nor does it say how food splatter on it leads to poor performance.


 It is not regular cardboard.
*What should I do ?*If there are any issues with your waveguide cover it should be replaced. When new the mica sheet is rigid and firm. Over a period of time it absorbs moisture and gets food splatters on it. It then becomes soft and flexible. The cover can be replaced either with a suitable replacement made by the manufacturer of the microwave or if the old cover is in good enough shape to be used as a template, blank sheets of mica can be purchased and cut to fit.

waveguide cover material - mica sheets

We often replace waveguide covers in our workshop. We are also asked to supply them directly. They are available mail order via our website ready made for some of the leading manufacturers or as blank sheets to make your own.


https://microwaveexpert.wordpress.com/2010/11/09/microwave-waveguide-cover/


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## m_ridzon (Sep 29, 2017)

Nealtw said:


> It is not regular cardboard.
> *What should I do ?*If there are any issues with your waveguide cover it should be replaced. When new the mica sheet is rigid and firm. Over a period of time it absorbs moisture and gets food splatters on it. It then becomes soft and flexible. The cover can be replaced either with a suitable replacement made by the manufacturer of the microwave or if the old cover is in good enough shape to be used as a template, blank sheets of mica can be purchased and cut to fit.
> 
> waveguide cover material - mica sheets
> ...


So what does the cover do, other than protecting against splatter, because I could get a piece of cardboard to do that. But it seems "mica" is the required material, for some unknown reason.


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## Nealtw (Jun 22, 2017)

m_ridzon said:


> So what does the cover do, other than protecting against splatter, because I could get a piece of cardboard to do that. But it seems "mica" is the required material, for some unknown reason.


I likely spreads the pattern out so you don't have one hot spot.


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## m_ridzon (Sep 29, 2017)

Nealtw said:


> I likely spreads the pattern out so you don't have one hot spot.


Okay, so now this thread is getting more insightful about what is actually going on. Thanks for this information.


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## m_ridzon (Sep 29, 2017)

Update & looking for more insight:

I cleaned the wave guide cover with a wet wash rag (first image below). 

Sparks continue though. My wife observed it this morning for 90 seconds while microwaving food. She said the sparking occurs at the top (blue circled area in the second image below). That area is part of the advanced "oven" feature available in this appliance. To my knowledge, it does nothing while operating as a traditional microwave, so I'm not sure why sparks might exist there. There is food grime behind the mesh though, on the oven coils. Does anybody know if that might be part of the problem? Any insight?


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## BayouRunner (Feb 5, 2016)

Replace your waveguide. It’s bad. Don’t use your microwave until you do. You can ruin your magnetron 


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## m_ridzon (Sep 29, 2017)

BayouRunner said:


> Replace your waveguide. It’s bad. Don’t use your microwave until you do. You can ruin your magnetron


I'm not an appliance expert, so I'm still new to the jargon. When you save "waveguide," are you referring to the mica cover that I wiped off with a dish rag? (I understood that piece of mica as the waveguide _*cover*_, so that's where my confusion lies)


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## BayouRunner (Feb 5, 2016)

Yes


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## adamz (May 13, 2018)

Is the "paint" wearing off anywhere in there? This can cause sparks too.


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## u3b3rg33k (Jul 17, 2018)

m_ridzon said:


> I have a GE Profile Advantium 120 microwave in my home. It's well taken care of, so I wouldn't expect our newest problem to be a result of neglect or abuse. However, it started sparking recently while in use. It's intermittent. Someone will probably say, *"you had metal in there." * Nope. The item I heated last night was a plastic bottle full of water, and I had done this a thousand times in the past, same bottle, with no issues. What are some tips folks can share about what might be causing the issue?
> 
> Thanks in advance!
> M Ridzon


I put metal dishes in mine all the time. never had a problem.


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## m_ridzon (Sep 29, 2017)

adamz said:


> Is the "paint" wearing off anywhere in there? This can cause sparks too.


Hopefully you noticed my pictures earlier in the thread showing a complete stainless steel interior; i.e., no paint. Otherwise, yes I would be looking for chipped paint.

UPDATE: A couple weeks ago, I ran to the local appliance parts store and bought a new piece of mica. I trimmed it to size and installed it. It seems to have made a positive impact, but oddly enough, I don't think the issue is completely resolved. The occurrences of sparking has dropped dramatically. However, since the repair a couple weeks ago, my wife and I have "heard" the sparking from afar a couple times. We quickly run over to the microwave, only to find that it won't act up again. Most folks don't stand and stare into their microwave glass while it operates, so we've not been fortunate to "see" the sparking since the mica repair. About once a week, she heats one particular dish with pieces of baking chocolate to melt. This particular scenario does seem more prone to "hearing" sparks. The dish is completely ceramic though and was perfectly fine up until a month ago, when this all started. I don't know if there's something special about this dish or the chocolate that might aggravate this issue though. Maybe its shape is exacerbating the underlying root issue; I don't know though. So I asked her to try using a different dish next time. And a couple times, I've heated 4oz water in a small plastic cup that I've "heard" sparks from while standing somewhere nearby; again this has been done hundreds of times in the past, problem free. It all seems bizarre to me. I'm clueless. Anybody else have thoughts about it?


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## BayouRunner (Feb 5, 2016)

Theoretically you shouldn’t have any. We get them in ours when we heat up vegetables for our bird. I don’t add water which is why I believe it does it. She adds water and no issues. You shouldn’t have any sparks with a glass of water. You may have to disconnect the power. Look at magnetron and see if there is any food or burnt items on it or near it. Make sure there is no area inside the cabinet that it could arc too. Like if it has a shelf but some food has been spilled and gotten behind clips. Other then changing the board and cleaning it well that’s all I can offer. I don’t know offhand what brand yours is but if it has a stirrer make sure it’s working. That would require cabinet removal to check it. Some have them, some don’t. You could look at an exploded view to check and see if you have one without taking it apart


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## m_ridzon (Sep 29, 2017)

BayouRunner said:


> Look at magnetron and see if there is any food or burnt items on it or near it.


Where is the magnetron? Isn't that behind the mica wave guide cover? If so, I imagine it would be clean since it's covered. Is that correct? I think I recall looking at it when I replaced the wave guide cover, and don't recall seeing any debris on it.



BayouRunner said:


> Make sure there is no area inside the cabinet that it could arc too.


I think I'm going to take it apart and do a deep clean on it. There is food grime behind some of the vent perforations inside. Maybe that is part of the problem.


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## BayouRunner (Feb 5, 2016)

Yes it’s right behind the plate. If you see food debris you need to get rid of it. That’s probably what it’s arcing to


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## m_ridzon (Sep 29, 2017)

UPDATE: Today, my wife heated the chocolate again. This time, she used a different bowl. Lo and behold, no sparks (or sounds of them). So I told her to revert back to the original bowl next time. I'll see what happens then.

The other ironic aspect about the original bowl, is that it's often used to heat many other things. It never seems to give issues though, except when she's trying to heat the chocolate. Very weird.


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## u3b3rg33k (Jul 17, 2018)

m_ridzon said:


> UPDATE: Today, my wife heated the chocolate again. This time, she used a different bowl. Lo and behold, no sparks (or sounds of them). So I told her to revert back to the original bowl next time. I'll see what happens then.
> 
> The other ironic aspect about the original bowl, is that it's often used to heat many other things. It never seems to give issues though, except when she's trying to heat the chocolate. Very weird.


if the bowl has small metallic objects in it or in the glaze (e.g. iron filings, metallic paint), they can act as tiny antennas and cause strange behavior.


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## m_ridzon (Sep 29, 2017)

Well, I give up. Week and a half ago, I dismantled most of the microwave to deep clean it, and remove the grime from the vent holes in the heating cavity. I then reassembled. Everything works great 99% of the time. On a couple rare occasions, I "hear" the spark from the other side of the kitchen while heating a small plastic bottle with water in it (this bottle is heated daily as part of my morning routine). Because it's only momentary, I can't race back to the microwave quick enough to view the activity through the viewing window.:sad:

So I think I've done all I can do and I'm going to chalk this up to some weird happenstance and just ride it out, hoping for the best. It's very intermittent, so maybe it'll continue operating for a long time. Who knows?!


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## steves7839 (Aug 18, 2019)

The common factor is your use of a cut-to-fit piece of material for a waveguide cover. YMMV until you spring for the OEM cover. 

Microwave energy will find the path of least resistance.


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