5KV 0.7 Amp fuse replaced to restore the heating factor in a microwave oven. Model: Normandy
A china made microwave oven was brought to my shop with the complaint it does not heat up the food. In a case like this usually two reason why no heat produced in a microwave oven.
– Bad magnetron
– A blown fuse between the main capacitor and the magnetron.
– Bad magnetron and bad fuse
It looks really new and but still, checking it is essential to find out the problem.
As seen, the magnetron, main power transformer, and the capacitor. First step it to discharge the main capacitor. Discharging is done by using two screw drives and touching the two main terminators of the capacitor. A very good idea is to wear gloves when discharging the capacitor. It is very dangerous to work on microwave ovens with the main capacitors still charged.
Checking the magnetron was my first priority. Put the meter to ohm setting and check the reading between the magnetron and its metal body. If you get any reading, the magnetron is faulty. As you can see, it is ok. In some cases, it does not show reading but still there might be a chance that it is faulty.
In my experience, I come across a lot of blown fuse due to electrical problem at home or just bad magnetron.
These fuses can handle up to 5k V but they come in 0.7 amps to protect the magnetron. Some technicians replace this fuse with another one but higher value. My advice to you always use the specified value otherwise, you will have problems
As expected, it was a blown fuse. I have a lot of these fuses at my shop and right away I replaced it with an intact one. Always test the microwave oven after replacing the fuse. It might be a bad magnetron showing good reading on the meter yet, will blow the fuse again.
In my case, the replacement of the fuse fixed the issue. 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.
P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.
Note: You can check his previous repair articles in the link below:
https://www.electronicsrepairfaq.com/welding-machine-repaired-model-inc-comma-2003
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Jestine Yong works as an Electronics Repair Lecturer in Kuala Lumpur Malaysia and his training website is http://www.NoahtechElectronicsTraining.com. You can check out his repair blog at http://www.JestineYong.com
12 comments on “5KV 0.7 Amp fuse replaced to restore the heating factor in a microwave oven. Model: Normandy”
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Very educative service tips indeed! Thanks for sharing!
I am working on a microwave oven which was not heating, all components seems to be working except the magnetron which look dark tip.there is a resistance between its terminal 0.2ohms and there is no reading between terminal to ground how do I test the magnetron if it is ok or not?sir please I need help to on how to properly test magnetron.thank you.
From your measurements, the magnetron appears ok. For some info on how to test a magnetron go to http://www.microtechfactoryservice.com/mag_test.html
I had a similar problem and it was the magnatron. The tip had a hole burnt in the side.
I replace the magnatron and fuse and all is fine.
Good job, Waleed. I had to order some of those fuses from China. They don’t look like normal fuses.
Good technical information shared. Thank you..
thanks very informative for learner technitions.
Thank’s for sharing Waleed !
To check the magnetron operation please take care of high RF radiation so
just lets have low power gas bulb in heating area.
HELLO EVERYBODY
I need your help please with my microwave. it’s Daewoo kog-134k
the problem is that the standby transformer keeps blowing up.
the first time I had to buy the whole control panel because I did not find a replacement to the transformer(631fs low voltage transformer).
I could not know the reason that damaged the transformer.
the new one worket fine for only two days then it blows up also.
please help
thank you
What causes the microwave oven the emit sparks? Even after painting the inside area.
Hello I am working on a Metrowealth microwave oven which was not heating the first time I plug into the power outlet, I check the different components and found out the fuse busted all other components seems to be working including the magnetron which shows resistance between its terminal 0.2ohms and there is no reading between terminal to chassis. I already replaced the fuse and test again, it produces sounds and weak vibration which shows the magnetron is already working but still it doesn’t heat up food. What might be the other problem/s? Sir please I need help on how to fix the problem. Thank you!