Backlight And Remote Sensor Issue Resolved In Samsung LED TV Model 39EH5003
This TV was brought by a recently added regular customer. According to him, the TV was not having a display while sound was ok and it was lying with him for a very long time unattended. I took it up for opening, cleaning and troubleshooting as soon as I got free time to look into it.
Since I heard sounds of some loose parts inside the TV while handling it, there was no need for me to do any checking as I understood these could only be the domes of the LED fallen off inside the front panel. This is quite common and it was found to be true later when I opened the front frame, removed the panel, sheets and the reflector and moved it to my son’s bedroom, as he was away.
The scaler boards were taped safely and securely to the panel for such movement (Please see last picture below this paragraph) and I used a thick thermocol sheet to insert and detach the panel lest it should break like potato chips. I put some marks on the sheet in the extreme lowest corner to identify the top and its position. I marked I, II, III & IV and put four line marks at the corner of the metal sheet. (Please see arrows in the third picture below.)
Finally, I could see the LED strips at the bottom of the metal frame. There were a lot of loose domes of the LEDs, which have fallen off due to excessive heat, wear and tear. Picked up these domes, removed the tape stuck to hold all the strips in place, and slid off the strips one by one. There were totally 10 strips with six LEDs in each, making it a total of 60 LEDs for this 39” TV. The LED was of 3V, which I could make out after testing a few of them one by one, out of which two were ok. Picked up the strips and put it in a bag so that another shower of domes can be collected inside it instead of spilling it over. (The domes that have fallen off are marked in the picture below)
Went to the only two electronic shops in the town and unfortunately one shop had only 8 strips instead of 10. The other shop did not have it. But he took it for fetching exact replacement. But he too reported the next day that these were not available. I provided measurements and sought availability with a few dealers in other towns. But none of them had. Then went back to the first shop and requested him to help me, who was kind enough to fetch it the next day. I went there on my return from the hospital and picked it up. Took up the job of fixing the strips in its place as soon as I got free and then applied power to see the light glowing delightedly!
As mentioned by me many times in my previous articles, Samsung backlight would get on even without connecting the mother board. So, it is easy as otherwise, without connecting the panel, the mother board would not get on. Ofcourse we would test each led strips before fixing. But we need to see how bright the light is and do necessary adjustments if necessary. Thanks to Samsung for this facility on their TVs.
I reassembled the TV once again following the markings already made and finally moved the panel from my son’s room to my service room taking care not to cause any damage by bumping on the walls or doors when I walked, because of the sway I have! Then applied power and was pleased to see the TV getting on with its own menu display. The customer had not brought the remote control, because of which I used a universal remote. But there was no response to RC commands. Then I went to the market again and bought an RC unit of Samsung and tried. But even then, it did not work. The Joy stick which housed the IR unit was removed and checked. There was a four pin SMD IR in it. The first and last pins were grounded. The second pin was connected to B+ and the third pin was the IR that went to the uController. The voltage was showing around 1V instead of 3.3V that should have been there. So, I removed the sensor unit and checked.
There was a short with few ohms on the supply pin. So, I removed the sensor. Then also the voltage was dropping. So, I removed the SMD cap also. Both the sensor and cap were short.
Since I did not know the value of this SMD Cap, looking at the size, I just used 1uF SMD cap. The SMD sensor with four pins was not available in the market. So, I fixed a small three pin sensor, the first of which was IR, the second was ground and third was the B+. I drilled three holes on top of the frame near the slot for sensor and inserted the IR into it and bent the leads at the other side. Then wired the three legs to the appropriate places on the joy stick module. I used thin flexible wires so that these did not tear off the tracks. Let us have a look at this arrangement:
Then the RC unit was working very well and I could do adjustment of contrast, brightness, sharpness, color and backlight. I connected my VGA tester using a VGA to HDMI converter and gave the signal:
There were symptoms of internal shorting of panels, which were bizarre colors and shrinking of picture when patterns were changed. There were not easily noticeable lines too at the top to almost half way through. I informed this to the customer and let the TV on running with the usual Sherlock Holmes Movies, dialogues of which are already by hearted!
I tried to synchronize the lip movement with the dialogues memorized by me and I was amazed to see how much I could remember, which showed that Alzheimer’s is nowhere near! Here is the picture of the movie and that of the superannuated LED Strips:
Mission accomplished providing a lot more learnings, causing the satisfaction to jump into the collection bag without waiting for any nod!
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 Restored SYSKA LED Tube Light Model SSK-SQ2001
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Humberto
June 1, 2025 at 7:47 pm
Thanks for sharing this article, Parasuraman. You are a real Master ⭐
Parasuraman S
June 1, 2025 at 8:16 pm
Thanks for your continued support, dear Humberto!
Albert van Bemmelen
June 1, 2025 at 9:02 pm
I'm sure that Alzheimer will never be part of your articles! Although checking your typing result may need some attention here since 2 sentences were wrongly mixed, where you wrote "Then I went to the market again and bought an RC unit of Samsung and tried. But even then, it did The new strips fixed in place not work". (lol)
But even Sherlock Holmes himself would be proud on seeing his screen picture on another fine fixed television!
Parasuraman S
June 2, 2025 at 8:15 am
Many thanks for your keen study, observation and comments, as usual, dear Albert! Typo errors are very difficult to find inspite of reading and re-reading!
Parasuraman S
June 2, 2025 at 8:58 am
Dear Albert:
After you pointed out this error, I checked my copy and did not find any error. The sentence was correctly 'It did not work'. But when I wanted to write an email to Jestine Yong, and tried copying that portion, the error surfaced! A funny bug while converting word to pdf at my end, I presume. Anyhow, I have requested Jestine Yong to correct it.
What a strange error!
Mark J
June 1, 2025 at 11:39 pm
Parasuraman another great repair. I always look forward to your articles. Thank you for sharing.
Parasuraman S
June 2, 2025 at 8:18 am
Many thanks, dear Mark!
Imoudu
June 2, 2025 at 2:41 am
Thanks for sharing sir, that remote control type seems strange to me,haven't seen it before.
Parasuraman S
June 2, 2025 at 8:19 am
Don't worry, you may get one soon! (LOL) Many thanks, dear Imoudu!
Waleed Rishmawi
June 2, 2025 at 1:53 pm
professional work as always. these panels are very thin and break easily and that is a good idea to keep it away safe till the job is done. thanks for sharing be blessed my friend.
Parasuraman S
June 2, 2025 at 5:10 pm
Many thanks for your comments, dear friend!
Yogesh Panchal
June 2, 2025 at 2:43 pm
Good Job! Sir
LED Domes are always problem in some brands Like Samsung / Sony & others some are having proper Locking notch on dome which can stay firmly on the LED.
Good Modification of IR Diode as well.
Parasuraman S
June 2, 2025 at 5:11 pm
Thanks, dear Yogesh Bai!