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This CRT TV Took Another Blow But Restored – ONIDA ULTRA SLIM CO21SBL300B

By on July 22, 2023
This CRT TV Took Another Blow But Restored – ONIA ULTRA SLIM CO21SBL300B







Those of you who are interested can see my previous article to know the history of the set:

The first visit of this TV was in August, 2021 and second visit now in April, 2023. The problem reported was that the TV became dead after a lightning strike. After opening and cleaning the set, I saw the fuse was blown and also observed a 4.7mFD/350V cap near the LOT bulged, and Capacitor 152/2KV exploded in the SMPS area.

Even one leg of the 4.7mFD cap had got loose. The PTC was also found darkened. The other components had survived the surge.

burnt capacitor

With the consent of the customer, I went ahead and replaced all the electrolytic caps in the TV this time along with the PTC. The entire board was retouched with fresh solder as a routine maintenance.

The TV worked very well after all these time consuming exercises, causing another gratified satisfaction finding its way home!

crt tv repair



This article was prepared for you by Parasuraman Subramanian from India. He is 72 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 article on Voltage Surge Blew Transformer Of BPL M9903-H Two Converted To Three-In-One




  1. Anwar Yunas Shiekh

    July 22, 2023 at 8:35 am

    Impressive, but I find CRT TVs too expensive to run

    • Parasuraman S

      July 22, 2023 at 11:49 am

      Yes, power consumption might be high. But many customers prefer to watch telecasts and videos on CRT TV instead of the latest LCD/LED TVs. I have many customers like that! Many thanks for your comments!

  2. Waleed Rishmawi

    July 22, 2023 at 1:58 pm

    yea, the joy of capacitors replacement..LOL. I am sure you had a lot of fun doing it. thanks for sharing and have a blessed day.

    • Parasuraman S

      July 22, 2023 at 4:03 pm

      Yes, my hands itch to replace old electrolytic capacitors from boards, whenever I see them! (LOL) Many thanks for your comments, dear friend!

  3. Albert van Bemmelen

    July 22, 2023 at 2:12 pm

    I agree with Anwar. And because of limited space at home I already scrapped this week a perfectly good working 60 Watt portable inch color tv and a good 17 inch Philips monitor. Including two old bad and hardly used printers. One matrix printer and one old inkjet Brother Fax printer that was completely dryed out. Of course I saved most of the components but brought the large crt tubes to our town's depot. And I now got space for 3 flatscreen monitors.

    • Parasuraman S

      July 22, 2023 at 4:08 pm

      Like many other things that occupy the house, whether we like it or not, there are some guys who are bent upon holding on to the old CRT TVs, come what may! I too got relieved of my BPL 29" Colour TV in excellent working condition and look wise too, donating it to my School during Covid period, when many students were given TVs for study from home. I find my table giving us more space to keep things and do some desk work. Many thanks for your expert comments and sharing experiences.

  4. Tito Kanshulu

    July 24, 2023 at 1:03 pm

    Impressive repair Sir. Thanks

    • Parasuraman S

      July 24, 2023 at 11:17 pm

      Many thanks!

  5. Yogesh Panchal

    July 24, 2023 at 3:02 pm

    Good Job! Sir,
    I used Sharp color TV for almost 25 years without any problem. but when it failed I scarp it off because of Unavailability of spares.

    • Parasuraman S

      July 24, 2023 at 11:18 pm

      That is sad! If the tube was ok, you could have tried your best to bring back the board to working condition or else used a China Kit. Many thanks for your comments and sharing experience.


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