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Can a bad diode cause a kenmore microwave m # 721.80012401 not to heat?

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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

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SOURCE: No heat but everything else works

Sounds like the magnetron has failed. This is the component that produces the microwaves that heats the food.

The cost of the magnetron is about 95% of the cost of a microwave oven. Most people don't, for this reason, replace the magnetron, they replace the whole oven which is probably what you will end up doing.

There is a possibility that the circuit that provides power to the magnetron is faulty and you need to take it apart, find the proper electrical leads and test them with a volt meter. To do this you have to remove it from its mounting and take it apart. It is a fairly lengthy process however.


Posted on Apr 26, 2009

  • 9098 Answers

SOURCE: Maytag MMV5156AAS Microwave won't heat and has hum/buzz.

A failed diode isn't the most common failure, but it happens. And sometimes it's due to bad magnetron or a bad connection.

If the capacitor fails, it almost always shorts, which results in a blown fuse whenever you hit "Start" to run the microwave.

The magnetron on this model should have a 5-year warranty, in case that's relevant. Your owner's manual is here.

We have the service / repair manual for this model and have uploaded it to our site here to help you.

It will give you safety info, step by step help in disassembly, troubleshooting tips, and part numbers.

Here are some links you or someone you know can use for test help, but read their safety warnings first:
(if it's not shorted or burned, it's probably okay)

There should also be a "mini-manual" (tech sheet) hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting, testing, and locating components.


At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

You can find helpful exploded view diagrams and order parts here.

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

Posted on Jun 30, 2009

  • 1126 Answers

SOURCE: need installation instructions
I could only find the owners manual. Hope this helps.

Posted on Sep 03, 2009

  • 5568 Answers

SOURCE: Microwave does not heat

There is also very likely a fuse for the magnetron circuit as well. A failed magnetron could well destroy the diode that supplies the high voltage DC for it.

Posted on Oct 17, 2009

  • 48 Answers

SOURCE: Replaced bad diode in ge microwave only to have

Replace the magnetron and high voltage capacitor and diode and you wont have any issues. Make sure you clean any burned carbon residue from the area where the mag tube is installed.

Posted on Nov 13, 2009

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1 Answer

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

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Kenmore elite microwave not heating

This a common issue and caused by one of three things, magnetron, "heats food" cracked high voltage diode, and a shorted high voltage capacitor.

Mar 23, 2012 | Kenmore Microwave Ovens

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Kenmore microwave model# 401.8504 will not heat

There are 3 likely causes, the magnetron "heats food" the high voltage diode "sometimes cracks" or the high voltage capacitor "usually shorts"

Mar 13, 2012 | Microwave Ovens

1 Answer

I have kenmore microwave model 721.80012401 it does not heat, I checked the magnetron thermostat, capacitor and the only thing that does not check out is the diode,can the diode cause this problem?

yes your diode can keep it from heating but it usually makes a loud growling if diode is bad. there is also another thermal disc on the other side of the oven that could be open. usually can see it in a hole in the plastic with 2 wires. if there is continuity on both this and the mag thermal, you may have a bad magnetron

Feb 11, 2012 | Kenmore 63252 Microwave Oven

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Our Kenmore microwave oven recently stopped heating. The lights, turning plate and controls all work but with no cooking is occurring. The last time I attempted to heat something up I heard a cracking...

The most likely cause is a bad magnetron, "heats food" the other two possibilities are the high voltage capacitor and diode. The cost to repair will a approach a new microwave oven.

Apr 08, 2011 | Kenmore 80412 Microwave Oven

1 Answer

Kenmore microwave model numbr 72180039700 does not heat anything

The cause will be one of three things, the magnetron "common problem" or the high voltage capacitor and diode. If the magnetron turns out to be the problem, it will be cheaper to replace the microwave oven.

Mar 10, 2011 | Kenmore Microwave Ovens

1 Answer

The microwave comes on and seems to cook but does not cook . It makes a very loud humming noise and the turntable goes around but there is no heat to cook anything.

you either have a bad magnatron, that is trying to heat but won't or you could have a capacitor or diode (rectifier) that is bad. if you order a magnatron replace capacitor and diode (rectifier)

Feb 24, 2011 | Kenmore Microwave Ovens

2 Answers

Makes a humming noise wont heat

If its making a humming noise, that means the diode is bad and should be replaced. Once replaced the microwave will begin to heat again.

Feb 11, 2011 | Kenmore 62622 Microwave Oven

1 Answer

Microwave won't heat

The two possible causes are a faulty door switch and a bad magnatron. You can pull the top cover off of the unit and check all of the door switches (there are 2-6 of them all on a common rail, me normally closed)). If the door switches all check out, replace the magnatron, diodesmag-glass_10x10.gif, and capacitor

Oct 28, 2008 | Kenmore 62622 Microwave Oven

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