Stubborn Panel Short Left Unresolved In VU LED TV 55K160GAU
This is a story that proved the old adage ‘life need not be all on roses!’ It applies to our technicians’ field too! This TV was brought to me as per recommendation by a techie friend from a person living in my neighborhood. The condition of the TV when brought was like this:
The first step was to check the voltages and I found the following:
I posted this in my techie group and got some suggestions.
To begin with the advice was to cut the LC1 and LC2 lines coming out of the IC, which I did:
Picture was very good and clear:
The inside of the TV is being given for those who might be interested: (Please use cntrl+scroll to zoom)
All was well for a few minutes, until small horizontal lines started appearing at the bottom and dancing and increasing slowly to almost half of the screen. In came further advice from my techie friends. This time, the instruction was to apply VGL to LC1 and VGH to LC2 on the sides that go to the panel and if there was no improvement, shift these and see. Well, the same problems continued, though there was some slight improvement.
Then the next step advised was to remove the LVDS cable from the T-Con board one by one and locate which side was clear and which side had the problem. On checking like this, the problem was located to right side of the screen. So, I was instructed to cut the CKVB1 and CKVB2 at the extreme end where it goes to the panel and if the problem is not solved, just to short these two lines, which I did:
The problems still remained unresolved! Then the next instruction was to cut the data lines that go the panel and if problems continued, short all those lines on the panel side, which again I did step by step:
Well, the VU TV seemed to be amused in continuing with the problems. So, my techie friends concluded that the panel was internally short and even though there were methods to short and burn these by applying high voltage, it might not last longer and advised me to give up, which I was only happy to do after spending several eye straining strenuous hours spent on this, which lasted for more than a week!
So, dear friends, that is why I said, our life is not all on roses always! You might ask whether any satisfaction got added; yes, indeed, as I did what best I can, self-learning a lot and lot in the process, which counts more than the time spent! So, satisfaction coated with a big relief got collected! (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 Restored A CCTV Power Supply With A Perfect Output
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PV Beveren
June 11, 2023 at 8:08 am
I has a similar issue of black verical lines on a plasma big TV screen.
Consulting YT, I found a video with a simiar proble.
it appears a row of small contacts along the bottom of the screen start to lose contact due to inside frame shrinkage to switch contacts over time.
Several rows of electrical tape along the bottom of the screen, between the frame and the contacts or switchs, to force the contacts to make better contact, seemed to have fixed the problem.
It has been 3+ years and so far, so good.
Parasuraman S
June 11, 2023 at 9:12 pm
I'm very glad to hear this novel method to solve a problem! Many thanks for sharing!
Charles DAlessandro
June 11, 2023 at 9:20 am
After many years in doing repairs in electronics one must learn the word condemn its a seven letter word that we sometimes avoid. Because we don't want to show the customer that we are not interested in the repair but after all the effort will the customer be pleased with the result. AND THE BILL may be not. In fact scraping the TV and saving the boards is sometimes a waste if you run into the same model for repair the boards may not work. Due to the fact they use off the shelf parts they may look the same take the back off and your scratching your head ??????? what the hell. I have a sony screen in one a samsung in this one.
Parasuraman S
June 11, 2023 at 9:13 pm
Many thanks for your comments and sharing your experience!
Francisco Maciel Barba
June 11, 2023 at 9:39 am
Just a comment: many times we spend hours and days trying yo solve issues. Some times we solve them so we feel SUPER... Like a hero!
Some other times we can not solve issues; but, we just spend time to have learned we are READY for the next round !
Congratulations. Failing means learning
Parasuraman S
June 11, 2023 at 9:13 pm
Many thanks for your comments and soothing words!
Albert van Bemmelen
June 11, 2023 at 4:47 pm
Reading about your incredible tough stubborn panel repair story only reinforces my conviction not to embark on major difficult TV repairs that involve such large and defect LCD panels.
I however recently fixed one of those cheap affordable 0.96 inch two color oled displays that suddenly no longer worked in this project I made several times successfully, See here:
It is a tiny micro component tester that tests all components except zenerdiodes. Including giving ESR e-cap values next to their capacity, plus tests coils, thyristors, triacs and naturally transistors with giving their HFe value.
I was able to completely fix the failing 0.96 inch Oled display by reconnecting one of the flatcable connections that was broken to the Oled panel. Which was found by comparing all connections with that of another good Oled display.
Parasuraman S
June 11, 2023 at 9:16 pm
Vow! That's a good instrument tool! Many thanks for sharing and comments!
Albert van Bemmelen
June 11, 2023 at 11:08 pm
PS: Testing triacs and thyristors with this tiny micro component tester is limited to most low gate activating triodes upto about 6mA gate current max.
And most zeners can't be tested because of the low probe testing voltage.
Also always make sure to discharge any capacitor prior to measuring it to prevent the Atmega micro 328P module from blowing up its inputs!
Parasuraman S
June 12, 2023 at 9:35 pm
Many thanks for your inputs and advice!
Waleed Rishmawi
June 12, 2023 at 4:05 pm
I have many TV issues just like that and I did not even bother with it. it is just too much work and many hours spent and the customer is not even willing to pay for that time spent trying to fix the tv. thanks for sharing and have a blessed day
Parasuraman S
June 12, 2023 at 9:36 pm
Yes, I agree with you, dear! But I take up such cases to learn!
Zahedi FARJAN
June 22, 2023 at 4:16 pm
Dear sir I have a hisense tv the p supply blown up I have been able to pinpoint the problem.but there is an smd resistor which has been blown up but am unable to read its value.model no of tv 39n2177pw.main board model RSAG7 820.7416/ROH it's on the neg part of cap 120uf 450v.an resistor r 827
Hope I will get an answer
Regards
Z.FARJAN
Yogesh Panchal
June 25, 2023 at 12:37 am
Good repair! Sir