Return Of An LED TV Model Samsung UA24H4003AR
I have written an article about this TV under the caption ‘WHAT WILL BE THE SYMPTOM WHEN VGH IS MISSING IN LED TV? – SAMSUNG UA24H4003AR’, which is yet to be published as I write this article. This TV first visited me in May, 2023 with VGL missing case and I fixed a board to supply VGL/VGH etc. externally. More details are there in that article.
Subsequent to this, the TV was brought for checkup a couple of times as the customer was saying that it went off suddenly and sometimes restarted. But on testing it in my house for even three days, no such problem was noticed. Then I visited their home and checked their electrical fittings. The fittings were very old and in bad shape in that rented house and far from any acceptable standard. He himself found out that there was loose contact in the mains switch too! So, the AC input to the TV was unstable, because of which it was getting tripped.
I never heard again from him until in October, 2023 he brought the TV again stating that it was restarting, which was confirmed by me on testing too. I opened the TV and after thorough cleaning, brought it in to study what goes wrong. On removing the Power Supply board and studying, I saw a lot of burnt marks on the board, picture of just one is being given below for information:
Apparently the intermittent loose contacts in the electrical supply had done enough damage to the PS Board. Even the negative contacts of the electrolytic capacitors looked strained with dark marks. I replaced all of them, upon which the PS was stable. But the 3.3V IC in the Mother Board, which I had tapped for providing power supply to the VGL/VGH booster board, was getting extremely hot and the display was getting off after a few minutes. So, after studying the following circuits in the web, I provided a 7805 IC with LM1117 3.3V connected to it and tried.
But this did not solve the problem as the LM1117 was getting terribly hot and shutting down.
So, I fixed it on a Copper clad board, assuming that it could dissipate the heat and the IC will then be within the tolerable temperature:
But that also did not work out and then I checked the Ampere drawn by the load and it was:
Though the current rating of this IC is 800mA, as you can notice it was at the brim with 0.646A. When graphics in the picture adds the load, this might be overshooting the barrier and shutting itself. So, the next step was to provide the following board, which is rated to handle around 3A load.
I gave the 13V input and shorted the 3.3V to get the desired voltage and fixed the board on the PS Board and wired it to the booster board.
Then the TV was found working very well without any hitch and it was tested for many hours.
Mission accomplished after experiments and learning to have the satisfaction getting collected.
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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Imoudu.O
February 12, 2024 at 3:16 pm
I appreciate your experiment,i once did such experiment few months ago with 7805 voltage regulator and it got hot because over 1 ampere pass through it, but i couldn't repair the device because no supporting boards available for me to use.Come to think of it, you suppose to be a visiting lecturer in one of your state universities Ooo!
Thanks for sharing sir, have a nice day.
Parasuraman S
February 12, 2024 at 4:50 pm
No, dear, I am not a visiting lecturer. I am a student still and wish to learn more and more from technic classes and other forums. Many thanks for your comments, dear!
Albert van Bemmelen
February 12, 2024 at 3:32 pm
Again very odd problems keep happening in TV repair land. Luckily you always find a way to solve those unexpected issues.
To me TV repair is something I only did a few times successfully myself in the past because I hardly see any defect specimens to repair. But to gain more knowledge and trying to keep up in this field I recently did pre-order Kent Liew's new v 8.0 LED TV e-book to add to my collection of e-books on TV repair.
Parasuraman S
February 12, 2024 at 4:52 pm
Many thanks for your expert comments and share. The book you ordered is a very good one. But unfortunately, I am not able to buy it now.
Waleed Rishmawi
February 12, 2024 at 4:30 pm
very good repair. you are the man for such jobs, so keep up the good work. where do you buy these boards from? could you please send me a link. thanks and have a blessed day
Parasuraman S
February 12, 2024 at 7:48 pm
The boards are bought locally from electronics shops. These are available here. I keep stock of a few. Many thanks for your comments!
Yogesh Panchal
February 13, 2024 at 3:25 pm
Good fix! Sir
Now a days Circuit works on Low Voltage with high ampere,in ATX SMPS 3.3v & 5V are rating 25A.....so sometime normal LDO/ Regulators will not work with same voltage.
Parasuraman S
February 13, 2024 at 9:41 pm
Many thanks for your comments and guidance!