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No Heat Up In Microwave Oven Repaired

By on November 28, 2019
microwave oven fix and repair











A guy from an organization located in Bethlehem brought this LG microwave oven for repair. This device comes on but it does not produce any heat. Usually, with this kind of issue, I check for three things, the Magnetron head, power or simply just an open fuse. Let us find out.

microwave oven repair

 This is the model number of this device.

Just few screws to come off and the cover was off to start the repair of this faulty device.

internal microwave oven

This is general view of the microwave oven from the side and as you can see, the main transformer, the capacitor, the fan and of course the magnetron on top. The first thing to do is to discharge the main capacitor which is a very important step to do otherwise you will get zapped with the high voltage stored in it.

how to repair microwave oven

These are the main transformer pins and it supposed to get 220 AC volts there otherwise the microwave oven will not come on.


In my case, the microwave oven was coming on therefore; the 220 AC volts were present here.

220 volt present in micro wave oven

These are the two terminals of the magnetron and I am checking here if it was faulty or not. I did this checking by setting the multi meter on ohms and one probe on the body of the microwave oven and the second probe is touch one of the pins of the magnetron. If you get any ohms reading here, the magnetron is faulty and needed replacement but in my case, the magnetron was ok.

microwave oven fuse

The third step to check the main fuse that connects one of the capacitor pin to the center tap of the transformer. I have come across many microwave ovens that do not heat and the main cause would be this fuse.

microwave oven fuse replaced

When I popped open the case of the fuse, I found out it was open and needed to be replaced. I did not have the same fuse ratings but for the sake of testing I added a thin wire there to make sure there are no other bad components in this microwave oven that needed attention.

microwave oven fuse replaced and repair

As you can see here one side of the fuse is connected to the main capacitor and the other side is connected to the center tape of the main power transformer. And as I mentioned before you need to discharge this capacitor before doing any kind of work on it.

I put everything back together and tested the microwave oven and it passed the test. I will not in any way give it back to the customer without replacing the fuse there with an original one. I will pay a visit to a local electrical store and get some as soon as possible.

Mission Accomplished.

This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

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Note: You can check his previous repair articles in the link below:




  1. Parasuraman S

    November 28, 2019 at 4:24 pm

    Good job there!

  2. Albert van Bemmelen

    November 28, 2019 at 4:35 pm

    Luckily the transformer and HV diode, and also the capacitor tested good after the fuse was replaced. Otherwise you needed to measure those and replace any bad part too. And you of course also had measured the low resistance (~3 ohm) between both magnetron tube pins. Else emitting electrons could not generate by the microwave glow filament.

  3. Waleed Rishmawi

    November 28, 2019 at 9:25 pm

    Albert: the fuse go out so often because our electrical system go out many times during the day. I have seen many cases like that before. I never had an issue of plowing parts after the replacement of the fuse. all is well. have a blessed day

  4. Ulises Aguilar

    March 30, 2020 at 11:41 am

    grate job Sir, take care

  5. Ivan

    April 12, 2020 at 7:33 pm

    for sure I was blue about that type of micro oven, and 2weeks back someone brought it for me and I was blue about it, but now am very sure I can fix it , thanks alot sir

  6. Bongani

    November 26, 2020 at 12:27 am

    How to discharge that big Cap.?


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