Bad High Voltage Capacitor In Microwave Oven
This microwave oven was brought to me with the complaint that it was not heating up, though all other control functions worked well and further that it was returned by a repair shop stating that the big transformer was defective and a replacement could not be found.
I opened the set and did a general cleaning before I investigated into the complaint. I found the secondary high Voltage/low AMP fuse blown. As per guidance given by technician friends, I disconnected all the wires of the main driver transformer and connected its primary to 230V AC directly through a 200W Series Bulb and looked for the output. The Bulb lit indicating that there could be a short in the primary.
When I shared the snap and the details, one of my friends called me up to inform that the TX might draw high current and the bulb would indicate a short. He asked me to check the capacitor for any short. I checked and found that the capacitor was dead short! I replaced the capacitor as well as the protection diode connected to the ground and then reconnected all the wires back and tried. I also replaced the fuse and checked for any short in magnetron before switching on. Yes, the oven was working well, though the question remained how and why the shop said that the TX was defective! (I know them well and they are professionals in electronic servicing. So, it could be a freak mistake, but to my advantage! When the customer told me about that shop, I had immediately replied to him that the shop is known to be professionals and their finding could be right, but anyhow, I shall recheck! We should never accuse anyone or criticize another shop or technician to a customer. Even if the customer brings a set to us accusing another one, we should correct their attitude.
Whenever a customer approached me with a problem in the set and expressed dissatisfaction about a service done by another, I tried my best to educate how things are from a technician’s side and have only justified and never join the customer’s comments. It is a bad practice and might degrade us!) Here are a few pictures to help those who might be curious to see the inside of a microwave oven. As I forgot to click the oven in working condition, I requested the customer to send me a picture, which he did obligingly.
Defective Capacitor and Diode
Oven in working condition
The work was completed with a thrill and a satisfaction that happily jumped into its collection bag!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous repair article below:
https://jestineyong.com/modified-capstan-wheel-base-support-in-panasonic-two-in-one/
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Albert van Bemmelen
February 24, 2020 at 7:49 pm
Thanks to your expertise any person can enjoy a hot dinner while watching his tv or listen to his radio after you had fixed any of those devices in no time!
Parasuraman S
February 25, 2020 at 10:01 am
Vow! That's a very boosting compliment! Many thanks!
Robert Calk Jr.
February 24, 2020 at 7:59 pm
Good job, Parasuraman!
Parasuraman S
February 25, 2020 at 10:03 am
Many thanks!
Allan
February 24, 2020 at 8:16 pm
Himy friend,
I salute you for your splendid attitude towards other repairers. We need to help each other. Great repair my friend.
God Bless
Parasuraman S
February 25, 2020 at 10:03 am
Many thanks! Generally talking ill of others, especially in their absence is not a good habit!
Imoudu Onwumah
February 24, 2020 at 10:17 pm
Good repair work.What is TX .l've tried to repair a couple of microwave ovens ,but I never succeed. Well,I am looking forward to be like you in repairs in future.Well done.
Parasuraman S
February 25, 2020 at 10:00 am
TX is a short form used for Transformer.
Don Oser
February 25, 2020 at 5:14 am
Good of you not to bash the other repair shop. It feels so good to repair defective items. Saves the customer money and keeps the unit out the landfills. Thanks for sharing these repairs.
Parasuraman S
February 25, 2020 at 10:06 am
Many thanks! We have to always see good of others and resist the urge to talk bad, as we cannot see things from their angle or view and know what made them do so!
Waleed Rishmawi
February 25, 2020 at 2:44 pm
a job well done my friend. Technicians are humans and we do make mistakes that is why when never look down on other technicians but we fix things that others could not fix and therefore, you are gaining that customer by the good repair job that you did. thanks for sharing.
Parasuraman S
February 25, 2020 at 5:27 pm
Many thanks! Yes, you are right! We gain from others' misfortunes and that is how the nature is due to some unknown reasons! But we should also be aware that a few of our customers would not have come back to us, after something failed at their end and they took it to some other with more or less same remarks or more, even though the failure could have nothing to do with our service! World is full of variances!
Humberto.
February 26, 2020 at 8:24 am
Hi Parasuraman, good repair, as usual. By the way, all the techs should have a professional ethics, as you commented previously.
Parasuraman S
February 26, 2020 at 11:57 am
Many thanks! Yes, you are right. Professional ethics should be there.
Henrique J. G. Ulbrich
February 27, 2020 at 4:12 am
Very good, Parasuraman. I appreciate your ethics very much. I do the same. Just one doubt: You inform that all the transformer wires were disconnected. Therefore, in this way the shorted capacitor became out of transformer circuit, and considering the transformer was in good condition, there was no condition to the series bulb to lit.
Parasuraman S
February 28, 2020 at 6:56 pm
Many thanks! The bulb will lit as the transformer draws current due to its special winding on the primary. It won't glow brightly, but the bulb will certainly glow mildly. But that is how it is and it worked well after assembly.
Tito Kanshulu
March 2, 2020 at 6:56 pm
That's a very interesting work Mr Parasuraman and quite encouraging to hear your side of advice on the customer
Parasuraman S
March 5, 2020 at 12:02 pm
Many thanks!
a b
November 15, 2021 at 10:57 am
The "protection diode" you mention is not a protection device. It is an essential part of the half-wave voltage doubler.