Panel Found Cracked On Restoring LG 47” 3D LED TV Model 47LM7610-TB
This TV was brought to me by hitherto unknown customer, on verbal recommendations in succession by two technicians in my town. After the first one recommended me, he had called me stating that the TV was in a place around 250 KMs away, and he would bring it during his next visit, as he was shuttling up and down between the two places as a part of his professional work. Though I offered to get it rectified through my techie friends in that place, he preferred to bring it to me, which actually surprised me. This was months back and he once again called me in between to remind me that he would bring the TV. The complaint reported was that the TV goes off after a few minutes of working. He made up his mind to bring it to me because of a second recommendation from another techie in my town, as he too was not able to find the cause. But weeks had passed before the TV was finally brought to me. On checking the TV in front of him, it was found dead.
He was honest to tell me that he had taken it to another techie and he was bringing it from there. Well, both the techies were very much known to one another very well; through inter actions about various problems we face in in our trouble shooting. I told him clearly that unless the TV is on, I cannot see the condition of the panel and I would not be responsible for any damages or scratches that would have happened while handling the TVs. He said ok and left to that faraway place. I think it was after a week, I managed to clear my table to accommodate this large and very heavy TV. I used a Vacuum cleaner to clean the outside of the TV before opening the back cover. Then cleaned the inside too likewise to avoid carrying this heavy TV outside, which might trigger another attack of low back pain.
I powered the TV and noticed that the output voltages were missing. On a close inspection of the power supply board, I observed that there was rust formation in many parts of the board. Jumper wires and legs of opto-couplers were rusted and in bad shapes:
I replaced the 817s and also the jumper wires and cleaned the board thoroughly using IPA. Did ring and ESR tests and looked for any defective components visually and using Multimeters. I could not find anything wrong. So, powered the board again and was glad to see output voltages present. This TV was of a peculiar type with a sub-uController IC fit on the reverse side of the power supply with several mosfets in an array to drive the edge LED backlights. There were two connections to the mother board for intercommunication between the PS and mother board. Similarly, there were two LVDS cables that went to the T-con boards.
After connecting the PS board to the mother board, when I applied power, the TV came on to my great relief. But I observed a crack on the right side of the panel and a deep scratch from that point to almost quarter of the screen. The top film was scraped by some sharp edge, perhaps after hitting on the side.
The damage looked menacing and I took snaps and video and sent it to the customer. I am sharing the following pictures to know how a small crack developed and slowly reached the other end of the screen followed by one more underneath doing the same:
But the picture was good, and the lines were not preventing view:
Due to winter weather, the crack developed on a daily progression and reached the opposite side. But picture did not tear off and we could view it well. With a lot of pressure from my side, the customer paid a visit after a few weeks, to look at the TV himself, when we sat together and discussed the next course of action. I had already combed my groups to check who all had a second hand working panel. Since this was a 3D frameless panel, the rate quoted was too high, which customer could not afford to buy due to a tight financial situation. So, it was mutually discussed and agreed that he would use the TV in that condition and allow it to die a natural death, in case it was already sentenced to be so!
As far as I am concerned, the work was completed to my satisfaction, as the intermittent on/off was solved and the TV worked very well for several hours in a day for several days. The customer paid my charges, which I made very nominal, because of the unfortunate events and his present financial condition. Mission accomplished qualifying the satisfaction to get a Passport and Visa for entry into the bag! (LOL).
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 Power Supply Modified In Philips Sound Machine Model AZ380/94
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Albert van Bemmelen
October 7, 2023 at 2:35 pm
It was obvious why this damaged tv was brought to you Parasuraman. Although it was quite unusual that the tv had been brought from a 250KM away long route. Luckily this heavy tv did not trigger any attack of lower back pain, which I happened to know all about myself too!
Parasuraman S
October 7, 2023 at 5:54 pm
Many thanks for your concern and comments!
Tito Kanshulu
October 7, 2023 at 5:04 pm
Was the problem with those rusted opto-isolators only, or there was something that caused the tv shut down upon being switched on? I am curious to know
Parasuraman S
October 8, 2023 at 7:34 am
Yes, only rusting of components which went unnoticed by the techies was the problem. Many thanks for your comments!
Imoudu.O
October 8, 2023 at 2:18 am
I wonder why other techies couldn't solve these problems. The way you explained repair work seems simple work to do, or is there any other complicated thing that the other techies couldn't detect or repair? Thanks.
Parasuraman S
October 8, 2023 at 1:19 pm
Yes, that's what I also thought. I asked them too, as they know me. But they gave some evasive replies without touching the truth; like 'I tried my best, I spent a lot of time, but could not find it' etc. As you know, we cannot afford to strain our relationships with techie friends and so I gave an impression that I just gulped what they told me.
Yogesh Panchal
October 16, 2023 at 11:36 pm
Good Job!Sir
Parasuraman S
October 17, 2023 at 8:41 pm
Many thanks!