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16.33 V 5.47V X 2 Linear Transformer fault

By on August 14, 2018
microwave oven repair ad fix singer











singer microwave oven repair no power

Customer sent to me this Singer SWD800EL23 Model Microwave Oven for repair with the complaint of no power symptom. Obviously the first component to check is the Main fuse.

I had to open the front cover panel in order to access the internal section. Take a look at the two photos below:

singer microwaveoven repair

open microwave oven front cover

Once the front cover was removed, I could see the high voltage transformer and the main fuse was tested good. This indicated there was no serious short circuit otherwise the main fuse could have open circuited.

high voltage transformer microwave oven

microwave oven main fuse

To cut the story short, I checked on the linear transformer (not high voltage transformer) which was located in the power supply/mainboard. There was no output AC voltage  from the transformer when tested with my AC voltmeter.

I further tested the transformer primary winding off board and found it to be open circuited (no resistance value)- see the photo below:

check microwave oven main fuse

Since I do not have this ready part, I searched from the internet and managed to find one. The brand name is  Galanz which is also famous for manufacturing Magnetron.

microwave oven repair singer

Once the new transformer is fixed and powered on, I could see that the power was fine by looking at the panel display:

microwave oven fix

repair and fix singer microwave oven

So in order to check if it is fully working we have to test the microwave oven by putting a cup of water and heat it. The result was good and I concluded that it was fixed and no further test is required.

fix microwave oven repair

Conclusion- Microwave oven just like any other electronic equipment where you need to know how the equipment functions before you start to repair it. If you want to learn how to check and test the linear transformer, main fuse and many other electronic components, you can check out Jestine’s ebook here.


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

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  1. Azaria

    August 14, 2018 at 12:48 pm

    Good work master

  2. Justice (City of Durban --South Africa)

    August 14, 2018 at 1:04 pm

    I do a lot of microwave repair but never came across this fault. Thank you for this interesting article ,was so curious to follow your logical repair steps.

  3. Albert van Bemmelen

    August 14, 2018 at 2:35 pm

    Interesting and good explained repair. The microwave oven in this article has at least a decent long living display. Most microwave displays have gas tube displays like in the old VCR recorders that deteriorate in time and are harder to read after years of service. And replacing those is almost impossible because of the display symbol differences between the many manufacturers of microwave ovens.

    • suranaga Electronics

      August 14, 2018 at 7:11 pm

      Thank you Mr.Albert.

  4. Parasuraman

    August 14, 2018 at 3:48 pm

    Excellent information shared! Thanks!

  5. Robert Calk Jr.

    August 14, 2018 at 4:07 pm

    Good job, Suranga.

  6. Yogesh Panchal

    August 15, 2018 at 12:32 am

    Good Job! Suranga

  7. Mihai

    August 15, 2018 at 12:57 am

    Thanks for sharing your experience !

  8. Ali rıza

    August 15, 2018 at 4:28 am

    Thank man.

  9. Haren Barsaikia

    August 15, 2018 at 5:46 pm

    Very nice, good job done.

    Thanks for sharing.

  10. Humberto

    August 16, 2018 at 12:16 am

    Good job Suranga, as usual. I really enjoy reading your articles.

  11. Ulises Aguilar

    August 16, 2018 at 11:27 am

    good job Sir

  12. Henrique Jorge Guimarães Ulbrich

    August 19, 2018 at 11:14 pm

    Great and fast, Suranga. As the other works you´ve performed. As Mr. Justice said above, it´s not common problems with transformers.

  13. ulises Aguilar pazzani

    August 5, 2019 at 11:27 am

    Good job Mr Bandara


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