VDR Saved ONIDA Ultra Slim CRT TV MODEL CO21SJQ350BR From Extensive Damage By Lightning
This CRT TV had visited me in July 2015 and those who have missed this article may please follow this link:
Once again this was brought in in August, 2022 reporting that the TV became dead due to lightning strike. The voltages in their house surged up blowing many appliances including this TV. I opened the TV and cleaned the inside thoroughly, after which the customer himself moved the heavy TV to inside my house and left.
On inspection of the board, I saw one 250V cap bulged near the FBT, the fuse was blown and the VDR was found cracked and shorted. I replaced the VDR with an almost equivalent one.
You can check the datasheet of 14D471K here:
14D471K pdf, 14D471K Description, 14D471K Datasheet, 14D471K view ::: ALLDATASHEET
Then applied power and still the TV was dead and the full voltage remained in the Tank Capacitor which itself is an indication that switching was not taking place. If switching was taking place, oscillation will continue until the voltage drops to a low level. After combing the primary and secondary area for any defective component, I decided to replace the STR W6556A and see.
I connected a 100W bulb as load in place of the LOT by pulling out one end of the jumper wire that goes to the primary winding and gave power. Got the following result:
The output of 110V DC was good and I put the jumper back (of-course after removing the plug, discharging the tank capacitor!).
Then loaded the PCB to the CRT and checked. The TV came on with good blue screen. I then fed a video signal and was glad to see a good picture.
I allowed the TV to be on for several hours before putting the back cover and calling the customer to pick it up.
Mission accomplished quickly without forgetting to add satisfaction to the collection bag!
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 Servicing Four Radios, SONY ICF7600AW – PHILIPS RL118 – SANGEAN SG700L – PHILIPS PRESTIGE 556
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Andrew F. Ali
March 11, 2023 at 9:23 am
With experiece you can go straight to the defective components.
Excellent work.
Parasuraman S
March 11, 2023 at 9:01 pm
Many thanks for your expert comments!
Waleed Rishmawi
March 11, 2023 at 3:34 pm
another success by an experienced technician. keep up the good work my friend. I am just amazed that people are still using CRT tv's but it is still an amazing detective work repair. have a blessed day.
Parasuraman S
March 11, 2023 at 9:02 pm
Many thanks for your comments and admiration! Yes, people are still using CRT TVs.
Albert van Bemmelen
March 11, 2023 at 4:39 pm
Old tv or not doesn't really matter if they are still working and appreciated. Like those old crt screens still used in arcade videogame machines. Everything goes old in time but still can be fixed. With here interesting given technical data in the process about the used replacement VDR. And VDR's are still often used in other equipment these days.
Parasuraman S
March 11, 2023 at 9:03 pm
Many thanks for your expert valuable comments!
Lanno
March 13, 2023 at 3:18 pm
The 2 reasons why I don't use CRT tvs anymore is because the last one (a JVC made in UK in the '90's) had hardly any colour left and because 3 years ago I was given a big faulty Samsung plasma and a midsize Hisense LED one, all within 2 weeks. The first one needed a $50 secondhand board and the second one only a bit of 240V AC.
The only problem is that the JVC had a much better sound !
Parasuraman S
March 13, 2023 at 11:53 pm
Very interesting to hear! Many thanks for your comments!
Yogesh Panchal
March 17, 2023 at 4:30 pm
Good fix! sir.
Parasuraman S
March 17, 2023 at 11:33 pm
Many thanks!