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Microwave Oven Not Heating Properly- Easy Solution

By on August 9, 2016
microwave oven not heating









microwave oven

Customer sent to me a Campomatic brand microwave oven with the complaint of not heating properly.  What I did was to put in a cup of water and set the timer to 20 seconds and let it run.

True enough, after the timer was off, I opened the cover and found that the water inside the container was still not hot (no heat).

fix microwave oven

Since the microwave was not working, I decided to open up the cover and check the components. I tested the fuse, high voltage diode, high voltage capacitor, magnetron, door switch, transformer and etc and found that all seems to be working fine. You can refer to the block diagram of the oven that I have drawn.

no heat in microwave

microwave oven schematic diagram

There is one thing that I have not tested yet and it was the PCB components. So the first component I checked was the 12 volt DC relay. I soldered it out and tested it using an external dc power supply. I was surprised to see that actually the relay did not click when the power was applied and this indicated the relay was as fault.

how to repair microwave

microwave oven relay not working

I replaced with a new relay and put a cup of water and set the timer again to 20 seconds.

microwave oven not heating properly

After 20 seconds, I touched the water with my finger and the water was warm and this proven the microwave oven indeed was working fine.

not heating microwave oven

So in conclusion, I just replaced a relay and the no heat problem solved. For your information, not all microwave problems are related to this relay. It can be other components that can breaks down like a defective magnetron and etc.

Note: If you are not a repairer, it  is not recommended to repair it. Send to someone that has the experience in fixing the oven.

microwave heating problems


This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.

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Note: You may check out his previous repair article in the below link:

and other microwave oven not heating repair article by Parasuraman and Waleed below:




  1. Albert van Bemmelen

    August 9, 2016 at 2:23 pm

    Very nice detailed presentation of your repair Mr. Suranga. And besides the successful repair also very informative for other MicroWave repair cases!

    • chris

      September 6, 2016 at 7:21 am

      Thanks Very helpful and clear explanation..

  2. Yogesh Panchal

    August 9, 2016 at 3:03 pm

    Good Repair! Suranga

  3. Waleed

    August 9, 2016 at 4:32 pm

    usually when I repair a microwave oven with no heat problem, I usually check the power getting to the power transformer. if I am getting power there, I check the fuse and the magnetron, if not I go backward to the power panel. it would save time and effort on the repair.
    thanks for sharing your repair tips.

  4. Parasuraman S

    August 9, 2016 at 5:06 pm

    Very informative! Good job!

  5. Anthony

    August 10, 2016 at 6:21 am

    Good repair as always Suranga !

  6. Luciano Khware

    August 10, 2016 at 2:34 pm

    Congratulations Mr Suranga Bandara, professional fault finding technique. Thanks for the oven block diagram which makes it more clear.
    Keep it up!

  7. Chaminda J

    August 12, 2016 at 4:21 pm

    Thank's for sharing suranga.
    Very useful & Greet job.

  8. Benjamin E.

    August 31, 2016 at 8:58 pm

    Be careful with these microwaves. I had someone give me a similar one (looked pretty much the same on the outside and inside, including the PCB).

    The power relay (Marked "Galanz") had not only failed, but caught fire too!

  9. Ulises Aguilar Pazzani

    October 6, 2016 at 10:48 am

    Good Job Mr Suranga

  10. Charlie

    July 6, 2019 at 9:13 pm

    Very good tutorial

    Is not called "Condenser" >CAPASITOR<<


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