Ask Mr. Microwave
answers to your questions about microwave ovens
updated May 1, 2013

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NEW! Microwave oven disassembly video

happy to help!
William E. Miller, AS-EET

prototech@usa.net
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Q. What safety issues are there with microwave ovens?

A. The voltages used and produced inside a microwave oven can be instantly lethal and the metal edges inside the oven can be very sharp. You must disconnect the oven from the power line before taking it apart or even before removing or replacing bulbs! Please understand that you alone assume all liability for any consequences arising from your decision to take apart & reassemble your microwave oven. That said, here are some critical safety warnings.

Safe Microwave Cooking Tips from the USDA


Q. How does a microwave work?

A. See this short video.


Q. I have Panasonic microwave that's about 5 years old. The plastic around the door has changed from white to yellow also on the front of the door the plastic screen has bent in. I was wondering if the discoloration could mean a radiation leak. Do I need a new microwave?

A. As long as the door seal is okay and the wire mesh inside the door are okay, it should be okay.
The door seal is where the back / inner surface of the door meets the front edge surrounding the opening of the microwave cooking cavity.

All of that should be clean and smooth. That's one area that keeps the microwave energy from leaking.

Also, when you look through the door glass, you'll notice a wire mesh in between the layers of the glass.
That also blocks any microwave energy from coming out.

If any leakage were occurring, there would be signs of arcing / burning.

Even if there were leakage, the danger is of a skin burn or a fire, not "ionizing radiation" in the sense of changes to one's DNA.

Microwaves do not cause cancer or radiation sickness. They just make water boil.

Q. How come if u put metal in a microwave an turn it on it blows up, however the inside of the microwave is made of metal?

A. Actually it's not true to say that a microwave will blow up if you put metal in it.

I regularly leave a spoon in a bowl of food, etc., when using a microwave, and there are manufacturer cookbooks that even show you how to use foil in a microwave.

It all depends on HOW the metal is placed in the microwave.

If one piece of metal gets close to another one (such as a metal rack or the wall of the oven), a small gap can be created which will allow the microwave energy to arc as it jumps from one piece of metal to the next.

That's what causes arcing and sometimes flames.

Also, low quality paper towels that have impurities in them can cause arcing and flame as well.


Q. (In the past) you would see signs about pace makers and other warnings next to microwave ovens. Are they still required?

No. From the FDA Web site at: http://www.fda.gov/cdrh/consumer/microwave.html

"Ovens and Pacemakers"

"At one time there was concern that leakage from microwave ovens could interfere with certain electronic cardiac pacemakers. Similar concerns were raised about pacemaker interference from electric shavers, auto ignition systems, and other electronic products. FDA does not specifically require microwave ovens to carry warnings for people with pacemakers. The problem has been largely resolved because pacemakers are now designed to be shielded against such electrical interference. However, patients with pacemakers may wish to consult their physicians if they have concerns."


Q. Is it normal to be able to slip a piece of paper between the microwave door  and the side of the microwave, when the door is closed? If it's not a tight seal, can't the microwaves escape? Is this dangerous?

That's normal.

If you look through the door glass - focusing on the glass - you'll notice a metal screen / mesh.

The holes in that screen are sized to prevent the microwave energy from escaping.

If you have a hole or gap bigger than that, there will be leakage.

VIDEO - SAFE & EASY DISASSEMBLY

Pardon the poor lighting, but we wanted to get this online for you! Please note that videos which appear in the selector bar after ours has played are not associated with us. Some also contain erroneous information, especially the one titled "How to Fix a Microwave". Please do not rely on that video for your information.

I found a humorous post, "Microwave Etiquette", which discusses the dos and don'ts of using a community microwave oven at work. Hope you like it.


Q. Dr. Mehmet Oz wrote in Esquire that we all have plastic in our bodies from eating food that was in plastic containers or wrapped in plastic wrap when it was zapped. This, I believe he wrote, is not known to be healthy. Comments, please?

A. Maybe some in very small amounts, and while some plastics may be harmful, many are not at all. I don't think it's a real issue.

Here is a link to a very good article from Harvard Health Publications which covers this issue well and also has links to some myth busting sites:

http://www.gather.com/viewArticle.jsp?articleId=281474977349561&grpId=3659174697246155&nav=Groupspace

The essential take-home message from that article is this:

"The FDA, recognizing the potential for small amounts of plasticizers to migrate, closely regulates plastic containers and materials that come into contact with food. Before approving a container, the FDA conducts tests to make sure that it doesn't leak unsafe amounts of any substance into food."

Honestly, I think most of this alarm over microwaving (and other health & environmental issues de jour) is pure bunk.


Q. Why does my microwave owner's manual say not to cook popcorn in the microwave unless it;'s labeled for microwave use or if I use a special popcorn cooking accessory?

A. Popcorn is a food that has a very low moisture content, and microwave ovens rely on moisture content (water molecules) in order to cook.

If there is not enough moisture to absorb the microwave energy, much of the the energy is reflected back to the magnetron and damage it.

This is also what damages a microwave when it is run empty.

A simple solution is to add about 1/2 to 1 cup of water in a microwave-safe container in the back corner of the oven and cook your popcorn a little longer.

You'll have to experiment a few times to get the combination right for your particular model.

But allow our microwave about 15 minutes or so for the magnetron to cool down between popcorn cooking sessions as you experiment.

Also, I would suggest putting a paper plate upside-down on the turntable tray, then putting the popcorn container on top of that.

This does two things: It keeps the extremely hot popcorn off the tray, reducing the chances it will crack. Plus it raises the popcorn up so it will heat more efficiently.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.


Q. Is there anything inside of microwaves that would be hazardous for disposal purposes, i.e., circuit boards with metals, capacitors with oil?

A. The capacitors in a microwave that's less than 30 years old (appx.) will not contain PCBs or oil. The circuit boards up until very recent ones do indeed contain lead, which of course is a hazardous material.

We are always interested in buying some brands and models of control panel assemblies for refurbishment. If you're disposing of one, feel free to let me know the brand, model, and symptom and we may buy it: prototech@usa.net


Q. How can I can I tell how many cubic feet my microwave is?

A. Measure the cavity width, depth and height in inches, and enter the values here. This will calculate the volume of your cavity in cubic feet.


Q. A baked potato was cooking in my microwave when I noticed from the other room that there was a fire inside! I put the fire out, but my oven and house smell awful! I want to sue! What do I do?!

A. Manufacturers will note that they warn in their owner manuals to never leave a microwave running unattended, so they won't help you any further, I'm sure.

Most modern microwaves have a flame sensor inside that will shut the microwave down completely in case flames get too high. Then the cooling fan and power will shut off, and the fire will almost certainly be smothered pretty quickly due to a lack of air inside the oven.

Also, the inside is metal, thus the only fuel for the fire would have been the potato, which would not have lasted long. So as scary and disturbing as this event was, I would say the real danger of a fire outside of the oven was miniscule.

The fire probably occurred due to a dry or irregular spot in the skin of the potato. Once it's dry, it will of course burn much easier.

So now to the smell...

You should do a Google search on "odor microwave" or "microwave smell" where you can find tips on boiling water & baking soda, then vinegar and water in the microwave to neutralize the smell.

If your microwave does not work, then it may have blown the flame sensor (thermal fuse) and that would have to be replaced.


Q. I have a GE Spacemaker built-in microwave, only about 2 years old.  It seems to be melting plastic wrap and other plastic items a lot more lately.  In addition, the glass turntable gets hot when we reheat food, after only 2 or 3 minutes. Knowing that microwaves are supposed to pass through plastic and glass without heating them, does this mean that there is a problem with our microwave?  The power level is on high by default, but it always has been and it just seems that the melting and hot plates are happening a lot more now.

A. One quick test would be to put one cup of tap water in a glass container (like a Pyrex measuring cup) and heat it for 2 minutes, 30 seconds on high. Assuming your oven is a 1000W model, it should start to boil in about 2 minutes.

If it boils much more quickly than that, you may have a magnetron that is dying. Sometimes - like a star - they can burn hotter right before they die.

Another test is to run the microwave empty for about 20 seconds and see if you hear or see any arcing. It may be that your stirrer (above the ceiling panel) is not turning. If so, that will create some hot spots and eventually cause arcing, which will damage the stirrer.

Another problem is when food is placed in the center of the turntable, it will heat unevenly, as opposed to placing it sightly off-center, which is the preferred placement. This will also protect your turntable from repeatedly heating in the same spot, which can cause it to crack or split.

Standard Microwave Oven Heating Test / Microwave Heating Power Test

The following test will provide a suitably accurate measurement of the output power of any microwave oven. Variations or errors in performing this test will produce uncertain results. If the line voltage (from the electrical outlet) is low, the magnetron output will be correspondingly low.

Equipment needed:

  • Microwave safe container with 1000 mL (1 Liter) gradation.
  • Fahrenheit or centigrade thermometer

Procedure:

Pour exactly 1000 mL (1 Liter) of cool tap water into the container. Using the thermometer, stir the water, then measure and record the temperature. For accurate results the water should be about 60 degrees F (20 degrees C).

Place the container on the center of the oven cooking shelf (do not leave the thermometer in the container and remove any metal racks), and heat the water (at full power) for 63 seconds. Use the second hand of a watch, not the oven timer.

After the heating time is completed, immediately remove the container, stir the water, re-measure and record the temperature of the heated water.

Subtract the starting water temperature (step 2) from the ending water temperature (step 3) to obtain the temperature rise.

To determine the output power in watts, multiply the total temperature rise by a factor of 38.75 if you're using a Fahrenheit thermometer or 70 if you're using a centigrade thermometer.


Q. What makes certain kinds of china/ceramics unsafe for use in the microwave? What happens if 'unsafe' china is used? Are there any ways of telling whether a particular piece is safe or not, without trying it?

A. A substance is deemed microwave safe if microwave energy passes through it without being absorbed to a degree causing the material to heat up.

If an item is not marked as microwave safe, the next way to tell is to put it in the microwave empty, with nothing else inside, for about a minute on high power. Then carefully feel the item to see if it is getting hot.

Using an item that is not microwave safe will cause it to heat and reheat every time it is used, and it can eventually burn you. It can also explode with enough force to damage the finish or crack the glass.


Bad Microwave Display? Hood Lamps Not Working?

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Q. Where can I order parts and accessories for my microwave oven?

A. The best place to order parts for Sharp, Panasonic, L.G. Goldstar, is Encompass (formerly Tritronics). Or you can call them toll-free at 866-779-5835.

You can find wiring diagrams and parts lists and order parts for most other brands from the Pros here.

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Q. Where can I order parts and accessories for my Litton microwave oven?

A. Litton was taken over by Maytag. You can still find and buy parts for many Litton models here.

If you need an owner's manual, check here for a free one, then here to see if it's available for purchase.

NOTE: When searching, try entering your full model number with and without any dots or dashes it may have.



Q. Which uses more energy - heating a cup of water in the microwave or on the stovetop? I realize there are many variables, but are there any general guidelines about the relative energy efficiency of using the microwave versus using a conventional stove?

A. I've been meaning to address this. Here are some sources:

From http://www.energyquest.ca.gov/saving_energy/index.html

"If you need to warm up or defrost small amounts of food, use a microwave instead of the stove to save energy. Microwave ovens use around 50 percent less energy than conventional ovens do. For large meals, however, the stove is usually more efficient. In the summer, using a microwave causes less heat in the kitchen, which saves money on air conditioning."

From http://oee.nrcan.gc.ca/residential/personal/new-home-improvement/home-energy-saving-tips.cfm?attr=4
(paragraphs 2 & 3 make very important points!)

"You can save up to 50 percent of your cooking energy costs by using a microwave oven instead of a conventional oven.

"Microwave ovens cook food faster than conventional ovens because the energy goes directly into heating the food, not the oven or utensils.

"Food cooks faster when placed at the edge of the rotary tray, as more microwaves can interact with the food there than at the centre.

"Cooking in a microwave oven does not add unwanted heat to your kitchen."

Here's some more interesting thoughts on the subject:
http://www.grist.org/advice/ask/2007/02/26/boiling/

All this and more was found with the following Google search:

energy efficiency microwave vs. stove

The search URL is http://www.google.com/search?hl=en&q=energy+efficiency+microwave+vs.+stove

Hope that helps!


Q. Would you recommend putting an Xbox 360 console inside a microwave to re-heat bad solder connections within the unit, in order to bring it back to life? I ask because I recently ran into a problem with my Xbox 360 and, because it's out of warranty, I started looking into DIY solutions, one of them being the microwave trick.

A. No way! You need even, controlled heat like that from a gas or electric oven, not a microwave, which heats via radio waves and which will destroy your Xbox.

I think about how an IC (chip, CPU, microprocessor etc., as they are called) is constructed.

It has a plastic case (usually black) whose functions are essentially to protect the innards, make it large enough to handle, and allow for the attachment of solderable leads. The microwaves will pass right through this plastic shell.

At the heart of the chip is a tiny silicon wafer. Running from the wafer to the legs are ultra-thin gold wires (whiskers, really) that must be soldered by machine or by microscope or both, depending.

I think those little gold whiskers would be very quickly vaporized by the microwaves, even though the forums talk about putting it in for a minute or less, that's a long time in microwave time!

Ever see a small piece of foil put in the microwave? Look how quick that starts to arc - about 3 seconds!

See a video here: http://youtube.com/watch?v=U9bz995uvAA

If you're still curious, there's a video on YouTube where a guy puts a PS2 in a microwave. He doesn't say how long he put it in, but judging from the dial position, I would guess 2-3 minutes. It smoked and even flamed!

Here's that video: http://youtube.com/watch?v=4X-YzQLqbnQ

If it has bad connections, they need to be manually resoldered. If heat is an issue, it may need to have the heat sink pad removed and replaced with high-quality heat sink compound. Dig a little deeper in your online searches for these types of fixes instead.


Q. I use mild detergent with water to keep a previously used microwave clean, however, recently the paint on the roof interior is chipping off. This happen to another microwave (every old model) two years ago. What makes this happen? Is it necessary to replace a working microwave to avoid paint chip getting into digestible food? Please advise.

A. This is usually due to the accumulation of moisture in the microwave.

Normally the moist air is blown out by the cooling fan, but some conditions allow the moisture to remain in the air and on inside surfaces of the microwave - even if you can hardly see it.

This can be prevented by either leaving the door open a while after cooking or wiping it dry before you close the door.

To fix the paint job, use steel wool or sandpaper to remove all the loose paint, clean the sanded area squeaky clean with alcohol, and then paint the area with appliance touch up spray paint.

You can get this high temperature paint at stores like Wal-Mart, Lowe's, Home Depot, or other department stores and home improvement stores. Or you can order it online from the Pros here - just search under "By Part Description" for the word paint.

The key is to you catch and correct the chipping before the metal starts to rust badly!


Grape Microwave Plasma Video
This is just a fun little diversion to watch,
but I'm NOT gonna suggest trying it!


Q. I was cooking popcorn in my microwave and the glass turntable broke. Why?

A. Microwave popcorn gets VERY hot while cooking.

Even though the turntable is made of tempered glass, intense heat applied in the same spot over and over can weaken the molecular structure of the glass. After so many expansions and contractions, it will crack.

This is yet another reason I recommend to my customers that they place the food off-center on the tray - not in the center. The oven also heats better when the food is off-center.

Also, it's a good idea to place a paper plate or two upside-down on the tray under the bag.


Q. Can water suddenly explode in a microwave?

A. Yes. It's rare, but can cause serious injury! For more info, read this interesting article.


Q. We go to Florida in the winter, and my husband insists on turning the heat down to 45 for the three months we're gone, which I think is too low. I worry about damage to my computers, particularly the monitors, at this low of a temperature. And I don't want to have something happen to my new microwave display. Can you advise?

A. I looked at few different owner's manuals and didn't find that issue addressed at all. Storage companies just seem to say make sure they're dry.

I do always recommend against storage in an unheated garage, shed or storage area, because that can cause rust and also lead to mineral deposits on the circuit board which are very destructive.

I think the real problem is a big temperature fluctuation, especially in more humid environments. Say you have a warm, humid day, then night falls, and it gets cool. You will have dew forming. If it forms on or in your appliance or electronics, you will have problems.

45 *seems* kind of low to me, but I can't back that up with facts. It's just sort of my gut reaction.

One way to check is to look at various appliances when you go back and see if there is any rust or even fine surface oxidation on any unpainted / unchromed / bare metal surfaces of your appliances. You may have to look underneath, etc. to find such areas.

If you see any rust or surface oxidation, then you should keep it warmer. If not, you're probably okay.


Q. My microwave seems to be running okay, but it won't heat.

A. If you are a do-it-yourselfer with the right equipment and care, you can do quite a bit of troubleshooting, but once you get near the high voltage section, it is time to be VERY sure of your actions.

DANGER: Microwaves produce lethal voltages. They can kill.

Before you go any further, you should read the safety warnings here: http://www.microwavedisplay.com/safety.txt

If you find line voltage (100-125 VAC) on the primary of the high-voltage transformer while the oven is running, the problem is indeed in the high voltage section.

If that line voltage is not present, then the problem is not in the high voltage section. Door switches would be one suspect, as well as a control panel problem. To check door switches, see this file. If you have or suspect control panel problems, see details of the repair service here.

There are a few prime suspects to be aware of in the high-voltage section, mainly the high-voltage rectifier diode, the magnetron, and the high-voltage transformer.

DIODE: Did the oven pop during the cooking cycle? If so, that's pretty good evidence that the diode has gone bad, not that's not the only way it can fail. High-voltage rectifier ID & diagnosis can be found here: http://www.microtechfactoryservice.com/microtech/diode.html

MAGNETRON: Sometimes everything looks and seems okay, but the magnetron is simply not producing heat. At other times, it may be arcing inside, and producing a noise that sounds something like someone growling into a coffee mug. It's also possible that the mag may have a cracked magnet. Check for that, too.

More likely, it may be that the magnetron filament connectors have loosened (they should be snug) and, due to resistive heat, the terminal connections have deteriorated and burned loose to some degree. A photo showing that area can be found here: http://031d26d.namesecurehost.com/mwd/magterm.jpg .

Here are some tips if you have loose connections:

  • If the connectors feel loose, and any burning or melting seems minor, you should be able to carefully tighten the connectors with a pair of pliers, then sand or file the rusty-looking terminals of the magnetron until they are clean and shiny.

  • If the burning is more serious, the connectors may need to be replaced. They can be obtained from home improvement centers and auto parts stores. They are 1/4" connectors and can be squeezed in place onto stripped wire with proper crimpers or a pair of pliers. Another option is to cut the connectors off the wires and solder the wires directly to the magnetron terminals. If this is done, do not apply heat to the terminals any longer than necessary.

  • If the burning is really bad, the plastic surrounding the magnetron terminals is charred or melted, the magnetron may need to be replaced.

HIGH-VOLTAGE TRANSFORMER: When the voltage transformer fails, it will often emit heat and smoke, but with the fan running, you might not smell it. With the cover off, it may be easier to smell. Also, you can look at the windings and see if they look discolored due to heat. If a high-voltage transformer is shorting, it can blow the fuse a few seconds after pressing the start button to start a cooking cycle. High-voltage transformer ID & diagnosis can be found here: http://www.microtechfactoryservice.com/microtech/xformer.html

HIGH-VOLTAGE CAPACITOR: The high-voltage capacitor will usually fail by shorting. When it does, the fuse will be blown right after you press the start button to begin a cooking cycle. If the capacitor is old and dries out, then it can fail by just not allowing the high-voltage to be doubled. I don't remember having ever seen this condition. High-voltage capacitor ID & diagnosis can be found here: http://www.microtechfactoryservice.com/microtech/cap_test.html

More information on the high-voltage circuit can be found here: http://www.microtechfactoryservice.com/microtech/doubler.html

Again, be safe!


Q. If you accidentally put something containing metal in the microwave, and it sparks, are the fumes toxic?

A. While something that's toxic is not always lethal, it would be safest to assume so, mainly due to the paint used. Acrid smells like that are pretty scary!

If the microwave's still arcing, it may need to be sanded until the bad spot is gone, either to clean paint or bare metal, as needed.

Then you can repaint with high-temperature appliance spray or bottle paint you can get at paint stores, appliance parts stores, home centers, and places like Wal-Mart.

If the waveguide is burned, you may also need to replace it.

Let me know if you still have questions. Thanks!


Q. My microwave oven is "dead". I have no display, no lights when I open the door, and no beeps when I press the keypad. What do I do?

A. First, read these safety notes.

A microwave can be dead for many reasons.

If it goes dead for a while during or after cooking then comes back on, the magnetron is probably overheating and causing the magnetron thermostat to open. Then when it cools, it closes the circuit and allows power through again.

If it's intermittent or random, it may be a bad connection, usually on the control board or a loose fuse holder, or even an intermittent fuse!

You should do a continuity test the fuse while it's in the holder (with the microwave unplugged, of course) then turn the fuse by hand or take it out and put it back in, then test it again.

If you remove the fuse, then press the meter leads against the ends, it can allow internal contact to be made and make a bad fuse appear to be good.

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

If it goes dead or blows the breaker when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

If the fuse is good, it may be an open thermal fuse, thermal cutout or thermostat. (see photos below) One is usually located mounted on or above the magnetron, and others can be on the top or side of the cooking cavity. These should read "closed" during a continutiy check.

On over the range models, there is usually one located on the floor of the oven chassis, and it should read "open". If you replace the wrong one, your exhaust hood fan wiull run all the time.

thermostats and thermal cutouts


Q. My Sharp microwave's control panel is not working, but the inside light comes on when I open the door. What now?

A. It may have been hit by lightning or a line surge. Is there a burned looking device like the varistor shown here?

In any case, we are usually able to repair control panels for Sharp and other microwave ovens.

Visit www.microwavedisplay.com Please include your brand, model number and exact symptoms if you e-mail for help.

For microwave display and other control panel repair, see microwavedisplay.com .


Q. My control panel is not the LCD type. It's an older VFD type and it's dim or not showing anything. Can you help me?

A. You may have a dim display or a fading display, or the circuit board may need to be repaired. We do these regularly for $39.95 nationwide.

On some models, the VFD display tube can be replaced. Please contact me right away with your model number for an estimate or advice. If I can't help you directly, I'll try to give you the best advice or opinion possible.

For microwave display and other control panel repair, see microwavedisplay.com .


Q. I have a GE Microwave model JES1351WB003, made in 2002. The magnetron went bad and GE sent me a free replacement under warranty. I put it in, and here's the weird thing: it works fine with the outer cover removed, but when I put the cover back on, the microwave will work for a few seconds then shut down totally. It's not the thermal override switch: I shorted the circuit around it and it still shuts off with the cover in place. Any thoughts?

A. The first part of my answer below is probably the most likely in many cases, but please read the whole answer to be sure you are as fully informed as possible.

As I suspected, it has been confirmed (to customers on-site, but not officially) by GE-authorized servicers that the magnetrons are the culprit. Whether you need a complete kit (with magnetron, stirrer and diode) can be answered if you have one of the oven models mentioned in this bulletin. Below is a photo of the kit:


WB27X10489 kit

Maybe you inadvertently left off the mesh RF gasket that goes around the antenna. (see a photo at http://www.microtechfactoryservice.com/microtech/images/magnetron.gif ). Also you can look under "Replacement Considerations" at this page: http://www.microtechfactoryservice.com/microtech/mag_test.html.

Years ago I left off a gasket and the oven acted like it was possessed! What happens is that RF interference from the magnetron - at a very high level - leaks out from the seal and gets into the circuits of the control panel. This extreme interference is like scrambling its brains, so to speak. Another possibility is that somehow a high voltage wire is passing too close to the case or to a signal wire, etc. But I doubt it. I bet it's the gasket.


Q. My microwave just beeps and makes no sense. It seems to be fried.

A. We can handle that in most cases for only $39.95 in most cases. See http://www.microwavedisplay.com for details.

Good luck, and observe safety rules such as those at http://www.microwavedisplay.com/safety.txt!


Q. What if I can't do it myself?

A. If you're not a do-it-yourselfer we will be happy to do the repairs for your local appliance repair or service shop or electronics service shop to get your board fixed.

They can come to your home or office to remove your board, and send it to us for full service.

We will need them or you to prepay via check or money order or PayPal also & include our repair form.

You can print our card & take it to your local service shop.


Q. I can't set the clock on my microwave oven! Help!

A. The child lock may be set. Press CUSTOM HELP button at the top right and then follow the instructions to turn off the child lock. To set the clock on a Sharp-made microwave, you generally do one of two things:

a. Press the TIMER / CLOCK button below the 9 button. Press the numbers corresponding to the time of day. Press the TIMER / CLOCK button again.
- OR -
b. Press the TIMER / CLOCK button below the 9 button. Press the number 2 to set the time of day. Press the numbers corresponding to the time of day. Press the TIMER / CLOCK button again.

If this does not work, you may have some moisture in the works. This is usually caused by spraying cleaner on the keypad (a big no-no!) instead of on the cleaning cloth. Or you may have a defective keypad.

Once you look into this, if you still have trouble, please let us know. Just contact me.

If you have a recent Panasonic / Quasar model, this diagram should help:


Recent LG / Goldstar Microwave Oven Clock Settings
click on either photo for full-sized view

CLICK FOR FULL-SIZED CLICK FOR FULL-SIZED


Q. My display says "LOCK" or "CHILD LOCK!" & I can't do anything!

A. Press the "Custom Help" pad and follow the on-screen instructions to unlock the oven.

Some other brands & models have a sliding lock switch located on the bottom edge of the control panel frame. Or you may be able to hold the CLEAR or OFF or STOP button for three to five seconds to get it to unlock.

If you still have trouble, call Sharp Customer Service at 1-800-BE-SHARP & have your model number handy. If yours is another brand, see my tips page for phone numbers to call or contact me with your brand and model.


Q. I have a Sharp microwave that's very old and cannot find what is comparable to it. The model # is R-3A54 (R3A54). Can you suggest anything?

A. I don't have the specs on it, but it appears to be an 800W model. Are you looking to replace it in a built-in application, etc.?

Sharp *should* be able to tell you what model(s) replaced it. You can call them at 1-800-237-4277 (1-800-BE-SHARP).

Contact me if you still have questions.


Q. I need a "Wave Guide Cover" but it's no longer available from the manufacturer or they just don't seem to supply it. What can I do?

A. You can use the old cover as a template to cut a new one out of universal waveguide cover material.

You can find that at Encompass (formerly Tritronics). Or you can call them toll-free at 866-779-5835.

Part # 40QBP1012 UNIVERSAL WAVEGUIDE MATERIAL 10" X 12" (Cut To Fit)

If you don't have the old one, you can use a sheet of paper to trace the area where it goes, then transfer that pattern to the waveguide material, which can be cut with a razor, utility knife, or scissors.


Q. My Goldstar Multiwave model MA1172M microwave is locked. I lost my manual. Any help appreciated.

A. If it has a "HELP" pad, press that to see if you find an option to turn off the child lock.

Otherwise, you'll have to press and hold a certain pad for 5 seconds.

On some models, it's the "0" pad, on others it's the "START" pad.

On this model, I don't know. I would suggest trying them each for 5 seconds until one works.

If that doesn't work, do a Google search for "LG support".


Q. My microwave's turntable / carousel is not turning. What's NCPL-B002MRF0 couplerwrong?

A. I would first suspect that you have a broken turntable coupler. You can check this by taking out the glass turntable, and gently trying to wiggle the little square-headed device (see photo)  that drives the turntable support.
 
If the coupler feels loose, it's probably broken.

If it feels tight, grip it very firmly with your fingers and try to turn a little it as if you were imitating the motor. If it turns the motor, you'll hear the whining sound made by the motor gears. That would mean your coupling is probably okay. It takes a little force to turn it.

If it doesn't turn, you may not be turning enough, or the coupler may be bad. You will probably need to remove the motor to check the coupling.

(video: how a turntable motor should sound)



Q. My turntable thumps and jerks while cooking. What's wrong?

A. Look first at the three-legged part is the turntable support. At its middle is its center hub, like a bike wheel. In some cases, the legs of the support get too hot and bend downward in relation to the hub. When this happens, the support does not fully engage the turntable motor coupler / shaft below it.

I have solved this problem in the past by heating the area where the legs meet the hub, using a gas stove flame or a torch. Then I place it on a flat surface, weighted down so as to hold the legs so they will cool in the correct position. If you have to do it more than once, the support should be replaced.

In other cases, the problem is a failing turntable motor.

One way to do a quick mechanical check is to remove the glass turntable / tray, but leave the turntable support inside. Grab the support and slowly but firmly try to use the turntable support to make the motor move. Not too fast, just steady pressure. The motor should whine with a pitch that increases as you go a little faster. You can turn it in either direction. If it grinds, clicks, or slips, you have a motor going bad. (see video in question above for a demonstration)

(video: a "clunking" turntable)


Q. The keypad on my LG LMVM1935Sb is not responding. It seems to be on but none of the keys get a response. The light comes on when you open the door.

A. This model does have a child lock. If it's on, the display will say "LOCKED". It is turned on and off by holding down the "0" key for 4-5 seconds.

You may also have a bad keypad, which in many cases can be replaced. A bad keypad may be worn out due to age, damaged, or it may have gotten wet or otherwise contaminated.

Moisture and contamination can be caused by spraying of cleaners, by storing the microwave in an unheated garage or shed, or infestation.

I warn my customers to never spray cleaner directly onto the microwave keypad, since the liquid can get inside and "lock up" or even ruin the keypad or controller.

Apply an alcohol-based cleaner (such as the purple kind) to a cloth (paper towels can scratch) and gently wipe it off.

I suggest to my customers that they NEVER use any ammonia-based cleaner (like the blue stuff) on a microwave, since the ammonia will crack and distort polycarbonate plastics.


Q. My hood lamps / cooktop lights don't work!

A. We fix that problem, too, for only $39.95 postpaid nationwide. The lights over your rangetop are controlled by the circuit board.

We repair brands such as Sharp, Amana, Dacor, GE G.E. General Electric, Panasonic, and Quasar.

Please note that it is recommended that you always unplug the power to your microwave before you change bulbs. Just a word to the wise.

For details about our service, e-mail prototech@usa.net or visit www.microwavedisplay.com.

Sharp Models include but are not limited to R1380 R1381 R1382 R1480 R1481 R1482 R1490 R1491 R1492 R1600 R1601 R1602 R1610 R1750 R1751 R1752 R1754 and many many more.


Q. I have a Kenmore Microwave that mounts over the stove. Inside the unit it sparks. Inside on the top there is a plastic cover. When removed it houses a metal part that looks like it should spin. When the microwave is used this metal part sparks. I removed the part. It just sits in that cover. The microwave still works. What is this part for and why does it spark?

A. The metal part is the stirrer. It actually stirs the microwaves to ensure even cooking.

If it doesn't turn, it can arc due to the waves hitting the same spot over and over and they can reflect back and eventually damage the magnetron.

Some stirrers are run by a motor from above, and others are run by air flow. If yours is the latter, then the waveguide cover (stirrer cover) is designed not only to keep grease and food off the stirrer, but also to channel the air flow. So without the cover, the air flow is not concentrated enough to turn the stirrer, and it arcs.


Q. My turntable / carousel is not turning. What's wrong?

A. I would first suspect that you have a broken turntable coupler. You can check this by taking out the glass turntable, and gently trying to wiggle the little square-headed device (see photo below) that drives the turntable.

If the coupler feels loose, it's probably broken.

If it feels tight, grip it very firmly with your fingers and try to turn a little it as if you were imitating the motor. If it turns the motor, you'll hear the whining sound made by the motor gears. That would mean your coupling is probably okay. It takes a little force to turn it.

If it doesn't turn, you may not be turning enough, or the coupler may be bad. You will probably need to remove the motor to check the coupling.

You can find links to helpful exploded view diagrams and part ordering help here.


Q. My turntable is missing or unavailable. What can I do?

A. This sort of arrangement can be a good temporary fix until a suitable replacement tray can be found, or even a permanent solution.

Place a microwave-safe saucer upside-down over your roller ring / turntable support assembly. Then place a microwave-safe plate right side-up atop the saucer.

Be sure both are centered, checking them frequently to be sure shifting does not occur. Otherwise, a spill of hot material could result. Safety first!

Another option is to check Wal-Mart and other stores to see if they have a Rubbermaid or Nordic Ware wind-up turntable such as the Micro-Go-Round.

You can find links to helpful exploded view diagrams and part ordering help here.

Q. My microwave seems to heat large items better than small items or it's inconsistent.

A. While this could indicate a problem with your oven, I always recommend that you place food off-center on the turntable, not in the center.

If the food is off-center, it gets better exposure to the microwave energy than items placed in the center.

The turntable's purpose is to move the food through the microwaves, which is a stirring action. To put it anothe rwya, when you stir something, do you keep the spoon in the middle?


Q. I was wondering if you could steer me in the right direction. I have a Sharp R-1490 over the stove microwave oven. I came home today and the door is wide open and the light is on. It seems that the spring that holds the two door catches down is not working. Is this something that can be repaired at home or must it be serviced by an authorized repair center?

A. It would require disassembly of the door but not door removal.

There is a part inside the door called the latch head, and its "hooks" extend from the door to hold it to the latch hooks (door switch holders) inside the microwave. (The part names are a bit contradictory!)

On the latch head, there is a spot where a spring attaches to it. That little piece of plastic has broken. The spring is still inside the door.

You can drill a tiny hole near that spot and reinsert the spring. Or you can use epoxy (not super glue) to reattach the spring.

Otherwise, you can order a new latch head part # LSTPPB030MRF0 from Encompass (formerly Tritronics). Or you can call them toll-free at 866-779-5835.

(If your model is not the same, please look up the correct latch head at  Encompass (formerly Tritronics). Or you can call them toll-free at 866-779-5835.

We have a couple of service manuals on our site which are similar to your model. They use the same type of part, so they can be useful to you:

http://031d26d.namesecurehost.com/mwd/r1610_sm.pdf
http://031d26d.namesecurehost.com/mwd/r1380_sm.pdf

You can find links to helpful exploded view diagrams and part ordering help here.

AppliancePartsPros.com, Inc.


Q. Why all ordinary microwave ovens open only one direction - the door opens from right to left when you face it? For examples, in my kitchen (the particular spot where my microwave is placed) due to ergonomic reasons it would be much more convenient to have the control panel on the left side and the door swirling from left to right. What is the exact reason that all manufactures of microwave ovens build them with this strict "rule"? I am aware of vertically opening ovens but never seen those I would like to have in my kitchen.

A. This is not really an uncommon question. Quite a few folks have asked about left-handed microwaves elsewhere online.

I think it's market forces, ultimately. Most people are right-handed, and once a trend starts, it's hard to stop.

Just look at the old VCR format wars: Beta had much higher video quality, yet VHS easily became dominant due mostly to marketing.

Also, safety interlock switches are required in the door system, so having a convertible option would introduce too much risk of improper alignment and leakage. Making it convertible would also be pretty expensive.


Q. I purchased an Emerson 1000w microwave for my Mother yesterday, and it has a stainless steel covering on the outside. She called me this morning and said the covering gets hot when she runs the microwave. I don't know what she means by "hot" but it could be just getting warm. Is this normal during operation, or could it be defective?

A. There are two or more thermostats / thermal cutouts inside which will kill all power to the microwave if internal temperatures gets beyond a certain level.

That level is well beyond the boiling point of water - far hotter than you could stand to touch.

So chances are it's not a problem unless the cover is too hot to touch, say 100 degrees or so.

She should hear the fan running, but if she has hearing trouble, she could instead feel for air flow from the cooling fan.

While it's running, she can feel across either the front vent if it has one, or the area right behind the back right corner.

If for some reason the cooling fan should happen to be not running, the thermostat will eventually shut the oven down, but not necessarily before damage occurs to the oven.

If you still have questions, please write back.


Q. I have a built-in convection/microwave oven. The kids put microwave popcorn in it and it started shooting flames out of one of the holes where the rack is held by these little hooks.

I tried to clean it best I can, but it won't come completely clean. Could this be causing the problem? And, why can't you cook microwave popcorn in it?

A. Thanks for writing. The water content of the food being cooked determines how much of a "load" the food comprises.

Popcorn is a very dry food, so there's not much to absorb the microwave energy.

So it's much more likely for the little food and grease deposits in the rack support crevices to arc & spark.

Normally the only reliable fix is to remove the rack supports, clean the holes thoroughly, then install new rack supports.

It's better to replace them all for a fresh start, plus often the manufacturers will substitute improved parts without mentioning it!

You can find links to helpful exploded view diagrams and part ordering help here.

If you can let me know what brand and model you have I can probably offer more specific advice.

Also, a good digital photo of the area might be useful.


Q. What if I have other problems?

A. We repair circuit boards to component level. We don't replace circuit boards unless we have to.

If while cooking, your microwave stops after 59 seconds or one minute, you may have a bad damper switch, damper motor or damper. See the helpful photo here http://031d26d.namesecurehost.com/mwd/damper.jpg.

The best place to order parts for Sharp, Panasonic, L.G. Goldstar, is Encompass (formerly Tritronics). Or you can call them toll-free at 866-779-5835.

You can find wiring diagrams and parts lists and order parts for most other brands from the Pros here.

If the hood lamps / under range lamps / hood lights / work lights/ on your Amana, Dacor, GE G.E. General Electric. Panasonic, Quasar, Samsung, Sharp or other microwave oven are not working, we repair these, too.

If your fan or inside light comes on by itself, see my file on the diagnosis & replacement of door switches here: http://031d26d.namesecurehost.com/mwd/doorsw.txt.

Need do-it-yourself tips on diagnosis & repair? Some problems (not display problems or component-level troubleshooting) can be repaired by a do-it-yourselfer with proper information & careful work. Ask Mr. Microwave.

Please let us know your exact brand & model number if you inquire via e-mail.

If you have bad keys / keypad, poor heat or no heat, a lost / obsolete turntable tray (carousel), broken buttons, weak display, locked control panel, can't set the clock, etc., continue reading this FAQ list or feel free to contact us for advice.

NOTE: Some one-touch features such as "MINUTE PLUS" are disabled after three minutes when the oven is not used. These features are automatically enabled again when the door is opened and closed or when the STOP/CLEAR button is pressed.

OTHER TIPS: Need tips or help with other Sharp models such as those below? Please contact me. I'll try to help with whatever information I can. You may have a dim display or a fading display. On some models, the VFD display tube can be replaced. Please contact me right away for an estimate or advice. If I can't help you, I'll try to steer you the best way.

Microwave Display Terms

LCD display"LCD" means "liquid crystal display". We fix these! It has a backlight to provide light from behind, otherwise you can't see it. Sometimes when these fails, some segments may be unlit or intermittent, or the backlight may be off, making it impossible to see. For a good good definition of LCD, please see this article.

  • "LED" means "light-emitting diode". It's like the power light on the front of your PC. I don't think LEDs were ever used for microwave displays, but I could be wrong!

  • "NLA" means "no longer available". Disappointing to hear when you need parts!

VFD display"VFD" means "vacuum fluorescent display". We fix these! It is a vacuum tube that glows when powered up. Older microwaves used VFDs, like early calculators. After so many years, they grow dim, like this one. We can repair some models, but please e-mail your model number for an estimate.

 


MICROWAVE OVEN RECALLS


General Electric GE G.E. G. E.

NEWS from CPSC
U.S. Consumer Product Safety Commission
Office of Information and Public Affairs
Washington, DC 20207

FOR IMMEDIATE RELEASE
December 5, 2007
Release #08-110

GE's Recall Hotline: (888) 240-2745
Sear's Recall Hotline: (888) 679-0282
CPSC Recall Hotline: (800) 638-2772
CPSC Media Contact: (301) 504-7908
General Electric Media Contact: (888) 240-2749

General Electric Recalls Microwave Combo Wall Ovens Due to Fire Hazard

WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in
cooperation with the firm named below, today announced a voluntary
recall of the following consumer product. Consumers should stop using
recalled products immediately unless otherwise instructed.

Name of Product: Built-in Combination Wall and Microwave Ovens

Units: About 92,000

Manufacturer: GE Consumer & Industrial, of Louisville, Ky.

Hazard: The door switch in the microwave oven can overheat and ignite
plastic components in the control area, posing a fire hazard to
consumers. The lower thermal oven does not pose a hazard.

Incidents/Injuries: GE is aware of 35 incidents of minor property damage
and one incident in which a fire damaged adjacent kitchen cabinets. No
injuries have been reported.

Description: The recall includes GE combination microwave and
conventional built-in wall ovens sold under the following brand names:
GE, GE Profile(r) and Kenmore. The ovens were sold in white, black,
bisque and stainless steel. The brand name is printed on the lower left
corner on the front of the microwave door. The following model and
serial numbers can be found inside the microwave oven on the left
interior wall.

Recalled GE / GE Profile Models:

JKP85B0A3BB, JKP85B0D1BB, JKP85W0A3WW, JKP85W0D1WW,
JKP86B0F1BB, JKP86C0F1CC, JKP86S0F1SS, JKP86W0F1WW,
JT965B0F1BB, JT965C0F1CC, JT965S0F1SS, JT965W0F1WW,
JTP85B0A2BB, JTP85B0A3BB, JTP85B0A4BB, JTP85B0A5BB,
JTP85B0D1BB, JTP85W0A2WW, JTP85W0A3WW, JTP85W0A4WW,
JTP85W0A5WW, JTP85W0D1WW, JTP86B0F1BB, JTP86C0F1CC,
JTP86S0F1SS, JTP86W0F1WW, JTP95B0A2BB, JTP95B0A3BB,
JTP95B0A4BB, JTP95B0A5BB, JTP95B0D1BB, JTP95W0A2WW,
JTP95W0A3WW, JTP95W0A4WW, JTP95W0A5WW, JTP95W0D1WW

Serial number begins with:

AZ, DZ, FZ, GZ, HZ,
LZ, MZ, RZ, SZ, TZ,
VZ, ZZ, AA, DA, FA,
GA, HA, LA, MA, RA,
SA, TA, VA, ZA, AD,
DD, FD, GD, HD, LD,
MD, RD, SD, TD, VD,
ZD, AF, DF, FF, GF,
HF, LF, MF, RF, SF,
TF, VF, ZF

Recalled Kenmore Models: (All model numbers start with 911)

41485991, 41485992, 41485993, 41485994, 41489991, 41489992,
41489993, 41489994, 49485992, 49489992, 47692100, 47699100,
47862100, 47869100, 47812200, 47813200, 47814200, 47819200,
47792200, 47793200, 47794200, 47799200

Serial number begins with:

0, 1, 2, 3

Sold at: Department and appliance stores from January 2000 to December
2003 for between $1,500 and $2,000.

Manufactured in: United States

Remedy: Consumers should stop using the microwave oven immediately.
Consumers should contact GE regarding their GE/GE Profile micro-oven
combo or Sears for their Kenmore unit. GE is offering a free repair or
rebate on a new product, a $300 rebate toward the purchase of a new GE
brand unit, or a $600 rebate toward the purchase of a new GE Profile
brand unit. Sears is offering a free repair or $300 rebate toward the
purchase of a new Kenmore brand unit. Consumers can continue using the
lower thermal oven.

Consumer Contact: For additional information on GE /Profile units,
contact General Electric toll-free at (888)-240-2745 from 8 a.m. to 8
p.m. ET Monday through Friday, and 9 a.m. to 3 p.m. ET Saturday, or
visit GE's Web site at www.geappliances.com. For additional information
on Kenmore units, contact Sears toll-free at (888) 679-0282 from 8 a.m.
to 10 p.m. ET Monday through Saturday, or visit Sears' Web site at
www.sears.com

To see this recall on CPSC's web site, including pictures of the
recalled product, please go to:
http://www.cpsc.gov/cpscpub/prerel/prhtml08/08110.html


Kenmore

NEWS from CPSC
U.S. Consumer Product Safety Commission
Office of Information and Public Affairs
Washington, DC 20207

FOR IMMEDIATE RELEASE
December 5, 2007
Release #08-110

GE's Recall Hotline: (888) 240-2745
Sear's Recall Hotline: (888) 679-0282
CPSC Recall Hotline: (800) 638-2772
CPSC Media Contact: (301) 504-7908
General Electric Media Contact: (888) 240-2749

General Electric Recalls Microwave Combo Wall Ovens Due to Fire Hazard

WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in
cooperation with the firm named below, today announced a voluntary
recall of the following consumer product. Consumers should stop using
recalled products immediately unless otherwise instructed.

Name of Product: Built-in Combination Wall and Microwave Ovens

Units: About 92,000

Manufacturer: GE Consumer & Industrial, of Louisville, Ky.

Hazard: The door switch in the microwave oven can overheat and ignite
plastic components in the control area, posing a fire hazard to
consumers. The lower thermal oven does not pose a hazard.

Incidents/Injuries: GE is aware of 35 incidents of minor property damage
and one incident in which a fire damaged adjacent kitchen cabinets. No
injuries have been reported.

Description: The recall includes GE combination microwave and
conventional built-in wall ovens sold under the following brand names:
GE, GE Profile(r) and Kenmore. The ovens were sold in white, black,
bisque and stainless steel. The brand name is printed on the lower left
corner on the front of the microwave door. The following model and
serial numbers can be found inside the microwave oven on the left
interior wall.

Recalled GE / GE Profile Models:

JKP85B0A3BB, JKP85B0D1BB, JKP85W0A3WW, JKP85W0D1WW,
JKP86B0F1BB, JKP86C0F1CC, JKP86S0F1SS, JKP86W0F1WW,
JT965B0F1BB, JT965C0F1CC, JT965S0F1SS, JT965W0F1WW,
JTP85B0A2BB, JTP85B0A3BB, JTP85B0A4BB, JTP85B0A5BB,
JTP85B0D1BB, JTP85W0A2WW, JTP85W0A3WW, JTP85W0A4WW,
JTP85W0A5WW, JTP85W0D1WW, JTP86B0F1BB, JTP86C0F1CC,
JTP86S0F1SS, JTP86W0F1WW, JTP95B0A2BB, JTP95B0A3BB,
JTP95B0A4BB, JTP95B0A5BB, JTP95B0D1BB, JTP95W0A2WW,
JTP95W0A3WW, JTP95W0A4WW, JTP95W0A5WW, JTP95W0D1WW

Serial number begins with:

AZ, DZ, FZ, GZ, HZ,
LZ, MZ, RZ, SZ, TZ,
VZ, ZZ, AA, DA, FA,
GA, HA, LA, MA, RA,
SA, TA, VA, ZA, AD,
DD, FD, GD, HD, LD,
MD, RD, SD, TD, VD,
ZD, AF, DF, FF, GF,
HF, LF, MF, RF, SF,
TF, VF, ZF

Recalled Kenmore Models: (All model numbers start with 911)

41485991, 41485992, 41485993, 41485994, 41489991, 41489992,
41489993, 41489994, 49485992, 49489992, 47692100, 47699100,
47862100, 47869100, 47812200, 47813200, 47814200, 47819200,
47792200, 47793200, 47794200, 47799200

Serial number begins with:

0, 1, 2, 3

Sold at: Department and appliance stores from January 2000 to December
2003 for between $1,500 and $2,000.

Manufactured in: United States

Remedy: Consumers should stop using the microwave oven immediately.
Consumers should contact GE regarding their GE/GE Profile micro-oven
combo or Sears for their Kenmore unit. GE is offering a free repair or
rebate on a new product, a $300 rebate toward the purchase of a new GE
brand unit, or a $600 rebate toward the purchase of a new GE Profile
brand unit. Sears is offering a free repair or $300 rebate toward the
purchase of a new Kenmore brand unit. Consumers can continue using the
lower thermal oven.

Consumer Contact: For additional information on GE /Profile units,
contact General Electric toll-free at (888)-240-2745 from 8 a.m. to 8
p.m. ET Monday through Friday, and 9 a.m. to 3 p.m. ET Saturday, or
visit GE's Web site at www.geappliances.com. For additional information
on Kenmore units, contact Sears toll-free at (888) 679-0282 from 8 a.m.
to 10 p.m. ET Monday through Saturday, or visit Sears' Web site at
www.sears.com

To see this recall on CPSC's web site, including pictures of the
recalled product, please go to:
http://www.cpsc.gov/cpscpub/prerel/prhtml08/08110.html



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