Tip & How-To about Microwave Ovens

Microwave ovens that are not heating - All models

The microwave heating in all microwave ovens is done by an component called a magnetron - its usually is quite durable and can last for years.

To see an image of what they generally look like, check out http://www.upv.es/gcm/docente/images/mag_section.gif

However it can fail and being a sealed item is not repairable.

A simple test is - try and microwave heat a half glass of water for 1 minute - no hot water means no microwave energy is being produced.

A replacement magentron may be available for your oven - but when you consider
1. the cost of the part (if still available) and
2. the labour cost to have it replaced and
3. the time you will be without a microwave - then it makes sense to just go buy a new one. It will be new - cheaper than what you originally paid, have a 12 mth or more warranty and probably have more features than your old one did.

Grill and Convection features:
If you have an microwave oven which also has an inbuilt grill and convection features then these elements can fail also. They are replacable, are generally far cheaper than magnetrons and it may be cost effective to have a failed element replaced (they are a similar sort of element to what you find in an ordinary stove oven)

NOTE: Non qualified persons should NEVER ATTEMPT REPAIRS to a microwave oven - failed magnetron or other fault. There are very dangerous voltages associated with its both its operation and in surrounding components - these voltages may still be there even with the machine unplugged plus the actual radiation of microwave energy may no longer be directed as normal to inside the oven - it may go for you!

Despite there being safety interlocking features built in to protect the user in normal operation, play around inside the oven case and there will be no protection, You may end up being the item being cooked in more ways than one.

If there is no replacement fuse apparent on the outside of the unit don't go looking for one inside.

If you must have it repaired TAKE IT TO A SERVICE CENTRE and get a quote for the total cost of repairs - never play with it youself.

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my microwave oven quit heating . No error message or any other problem. all buttons work fine just no heat

If it has a turntable that does move it usually means one of three things bad:

1. A diode many use for power purposes for the heating.

2. A circuit board called an inverter that powers the heating and controls the Magnetron.

3. A Magnetron which does the actual heating.
12_11_2012_3_08_28_pm.jpgTypical diode which cannot read shorted or open across.

12_11_2012_3_10_09_pm.jpgTypical Magnetron which usually cannot be tested by normal means but has to be replaced to know if good or bad.

Dec 11, 2012 | Kenmore Microwave Ovens

2 Answers

machine goes through the motions but water comes out cold

Hi,you have not stated how old this unit is ? I think they are supposed to last for 4-5 years but I've known some to break after just one year and others that worked great for 15 years or more.
Read more: What is the average life span (during normal use) of a microwave oven? ' Answerbag http://www.answerbag.com/q_view/1540053#ixzz1TQlW7RlH

Carbon Heating Lamp for microwave oven strong heat resistance. More than 6000hrs lifespan.
From a website...

7.3.7 Magnetron Life Expectancy

The typical life of a magnetron tube is approximately 2000 hours of operation. Some factors that can diminish the life of a magnetron are: 1) no-load operation, 2) operating with too much metal in the cooking cavity, 3) line voltage consistently too low or too high, 4) improper phasing, 5) improper installation or removal, 6) replacing associated high-voltage components with substitutes that are incompatible with the system design, 6) continual operation at the upper limit of its heat tolerance due to inadequate air circulation, 7) obstruction in the wave-guide, 8) failed stirrer operation.


We use ours about 15 mins a day which would mean 2000 hours would be reached in 22 years but as they say there are a lot of factors which may reduce its life. The design and parameters of the oven will make a considerable difference. E.G. A highish power magnetron always underrun will last much longer than a smaller one run at its max ratings.

A restaurant might reach 2000 hours in only a year or so and industrial machines whether for cooking food or other processes will require frequent magnetron replacement.


Jul 28, 2011 | AEG Microwave Ovens

2 Answers

sharpe model R-1480 not heating (it sounds a little louder)

A loud sort of "groaning" noise and no heat is the sign of a bad magnetron tube. The magnetron is the microwave source, and when they go bad it's usually time to replace the oven. Most microwave repairs, especially a magnetron replacement, should be left to professionals. There are lethal voltages under the cover, and the chance of microwave leakage if the repair isn't done properly. With the price of a replacement tube and labor for the repair, it's often doesn't cost much more (and sometimes even less!) to buy a new oven.

Sorry I can't give you a more positive answer, but thanks for using Fixya!

Oct 31, 2010 | Sharp R-1480 Microwave Oven

1 Answer

Model MS 2327 B, works but is not heating up anything

This is a very common fault on microwave ovens and is usually caused by a failed magnetron. This is the device which produces the microwaves and it is the single most expensive component. Magnetrons don't really have a fixed lifespan, they can last for twenty years or more or can go pop the first day they're used.

Replacement is usually straightforward (make sure to obtain a new microwave collar as the old one cannot be re-used safely) but rarely cost-effective. Unless the oven remains under warranty it's always far quicker and usually much cheaper to replace the oven, especially as yours is a budget model.

Sep 10, 2010 | LG LMV1680ST Microwave Oven

2 Answers

advantium -- wont cook

The solution to this problem is to replace the magnetron. I had the same symptoms, and I got a used magnetron and replaced it. It takes some advanced electrical skill, and you have to disassemble the oven all the way to the inside stainless steel. I have the same exact model, manufactured in November of 1999.

Jan 13, 2008 | GE Advantium SCA2001BSS Microwave Oven

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