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Replaced PS Board In Revisited Samsung LED TV Model LA32D451G3

By Jestine Yong on January 6, 2024

Those of you who have not read my earlier article may kindly do so as I will be focusing only on the problem reported this time and rectification done.

https://jestineyong.com/voltage-surge-shorted-two-mosfets-and-blew-the-fuse-in-samsung-led-tv-la32d451g3/

This TV which was attended to in March, 2023 returned in June, 2023 after a gap of only three months. This time the complaint was intermittent on/off and later fully dead. The customer also told me that there was loose contact in the non-standard type three pin plugs, as it was inserted with an adaptor which tends to get loose after sometime because of poor quality.

The Mosfets were found shorted along with SMD components on the LCD driver side and my attempts to revive it by replacing defective components were futile, by which time, the tracks were all in bad condition. After frequent consultations with my techie friends, I opened the back light case and looked for any dark contacts in the LCD holders or dark marks on the LCDs. I could not find any and everything looked quite clean:

I looked for any defective components in the driver board and checked the transformers for any shorts too. I could not find any. I tried using an LCD Driver that I had but did not succeed as it was not having enough power to drive the 32” type load. The external driver was connected to the contact ends for which, I had removed the transformers from the original driver board, to isolate the high voltage output.

The required driver was not available in the market. Hence, the final decision was taken to replace the PS board. When I posted the model and picture in the salvaged working board Whatsup group, I got a response from one in Gujarat and I verified the credentials through my contacts there and found it to be reliable. I placed the order not only for the PS Board but the LCD driver board as well, to avoid a possible mismatch.

We cannot take the risk of burning the LCDs due to some mistake, which then would call for entire backlight replacement with LED type, increasing the repair cost to beyond customer’s budget for this very old TV.

I got the board, which was equivalent, but with slightly different voltage outputs. I wanted BN44-0438A, but got BN44-0438B, in which the Driver Mosfets were not SMD type and were fixed on the top side. The output had one point for providing supply to Audio IC. The LED driver side was however ok. So, I had to remove the pins from the connector and re-insert them in the place where it was required to match the input to mother board.

As you can see from above two pictures, the original board had no 18V outputs, but the replacement received had 18V at pins 5 & 7. That’s why I had to remove these two pins from its sockets. Rest everything was in perfect place. Then I removed the driver board and fixed the replacement received and connected the PS Board to it and applied power. I was glad to see that the backlight was getting on without connecting it to mother board, which was typical to Samsung.

Then switched off power, waited until the developed voltages were drained and then connected the PS to the mother board. When I applied power, the TV was found working very well. I replaced the three pin power plug as desired by the customer to avoid loose contacts in future. I tested the TV for three days before giving delivery to customer. Mission accomplished with satisfaction getting added to collection!

This article was prepared for you by Parasuraman Subramanian from India. He is 74 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 Crystal Oscillator Found Defective In LLOYD Air Conditioner Remote Control

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LED TV Repair

14 Comments

Waleed Rishmawi

January 6, 2024 at 1:51 pm

Good job on the repair my friend. I am surprised there are still boards out there for LCD TV’s because I tried to find one for a tv I was trying to fix but could not find. Have a blessed day and thanks for sharing

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- Parasuraman S
  
  January 6, 2024 at 4:48 pm
  
  Many thanks dear! The old boards and other spares parts are available through a whatsup group. Any technician can buy it on a bargaining price. The old parts are sold even by scrap dealers, who rip open all sorts of TVs and store the parts with make and model number.
  
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Babu M S

January 6, 2024 at 4:19 pm

Very very good job sir. your taking lot of pain to restore such a tv and making customer to happy. Thank you very much for sharing.

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- Parasuraman S
  
  January 7, 2024 at 10:52 am
  
  It is the passion that drives us all! Many thanks for your comments!
  
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Albert van Bemmelen

January 6, 2024 at 5:24 pm

These difficult board replacements are not without risk especially when they look the same but use other connector socket voltages. And knowing this old TV now already is fixed for the third time the question remains if it is worth it if a set keeps going out of order so many times in a short time?
It again shows your firm determination and confidence in these matters!

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- Parasuraman S
  
  January 7, 2024 at 10:54 am
  
  In India, generally people get attached to all devices and always prefer to get it repaired. The use and throw system has not fully set in, except with very rich people, who just don't bother. Many thanks for your comments and observations!
  
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Yogesh Panchal

January 6, 2024 at 6:06 pm

Good Job Sir,
Modification / Replacing the board need more study & Observation or it will lead journey to some other direction ......

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- Parasuraman S
  
  January 7, 2024 at 10:55 am
  
  Very true, Yogesh! That provides an opportunity to learn and fine tunes our focus and concentration! Many thanks, dear!
  
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Imoudu.O

January 7, 2024 at 4:41 am

You removed pins 5 & 7 from the new board, and the original board had pins 1,3,5,7 as 13V,so having removed pins 5&7, then how did the new board work without having 13V on 4 pins(1,3,5,7) just like the original ps board.Thanks

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- Parasuraman S
  
  January 7, 2024 at 10:58 am
  
  The Pins of 13V are joined together. The 13V DC output is single. Separate wires are provided, I think, for taking the load. But it does not matter much! Many thanks for your comments and keen observation!
  
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Mark

January 7, 2024 at 1:18 pm

Another job well done Parasuraman!

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- Parasuraman S
  
  January 7, 2024 at 8:11 pm
  
  Thanks dear!
  
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R Lamparter

January 7, 2024 at 11:16 pm

I always enjoy reading your repair articles.

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- Parasuraman S
  
  January 8, 2024 at 5:09 pm
  
  Glad to know! Many thanks for your comments!
  
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