Shorted LED Lights In An LED TV Repaired. Model LG
A friend of mine brought this LED TV for repair. It is an LG TV and to be honest with you, I really hate LG product.
They work fine but when they break down, the parts are too expensive.
When I powered the TV set, there was a red LED light coming on but there was no picture. I took the screws off and here is what I found.
As seen, power supply, main board and the T-con board, hidden under the TV stand.
This is the model number of the device. From my experience and I have seen so many of this kind of problems. It is the LED lights inside. When there is even one LED light shorted it effects the whole lights in there causing to have a black screen.
To make sure that the LED lights are bad, you need to go to the power board and check the 24 volts out. If these 24 volts are there, usually, the LED lights inside the panel are shorted and it has to be checked and replaced.
This is what inside a LED TV panel looks like. All these LED light has to be checked for short. The best way to do that is to set your meter on diode mode and touch the positive and negative on the LED strip and the Light should come on.
If the LED light did not light one, it is shorted and need to be replaced. It is an easy way to do it but it is a long process because you have to check all of these LED lights.
I took the white reflector to expose the LED Lights to be checked. Many technicians replace the shorted LED light strip and that cost a lot of money. My customer wanted the cheap fix because he wanted to give this TV set to his kids to be used with play station. So with that in mind, I came with a different way to fix this. I found about four lights shorted. Once I soldered all of them off the board, I added a tiny wire across the terminal of the LED light. In other words, cancelled the light but made it a connection to the next light in line. Once I did that, all the remaining lights came on.
The idea here is to make the whole panel come on without a black spot to be found on it. In other words, if I have two bad LED light in a row, I will have a problem lighting that spot because two shorted lights, will give you a black spot and that is what we are trying to avoid. In this case you will have to add LED light or replace the whole light strip.
Here is a bad LED light. The scratch mark indicates the volt meter spots to test the lights. I took the plastic diffuser off to replace the light.
Here is the result. Mission Accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
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Robert Calk
October 31, 2017 at 12:10 pm
Good job, Waleed. Nothing wrong with saving the customer some money.
abigail karonga
October 31, 2017 at 1:38 pm
Thank you so much for excellent repair report to suitecustomer's pocket.
kirui
October 31, 2017 at 3:48 pm
I believe you mean the LED is open rather than short. Since you a putting a jumper wire to connect the LEDs that are fine and removing the faulty one. The jumper is equivalent to a short.
Waleed Rishmawi
October 31, 2017 at 5:44 pm
kirui: yes you are right they were open..my bad
Shingirai Magaso
December 12, 2017 at 7:32 pm
You are correct
Mike B
October 31, 2017 at 4:01 pm
Just asking, if the LED's are shorted why is it neccssary to bridge them out?
Waleed Rishmawi
October 31, 2017 at 5:44 pm
Mike B: sorry, the LED were open..my bad
Waleed Rishmawi
November 3, 2017 at 6:10 pm
Mike B: if one is open, the rest of the strip will be open as well. so I bridge them out so the strips will get power and come on
Parasuraman
October 31, 2017 at 4:16 pm
Good informative article! Thanks for sharing!
Chance
November 1, 2017 at 12:45 am
l always have been wonderling how much maximum voltage these led can handle
IVAN1
November 1, 2017 at 1:17 am
HOLA Parece un problema común en las pantallas led Entiendo que todos los led están en serie y que la caída de voltaje ,originada por el led
faltante es absorbida por el resto de los led .eso aumentaría la corriente por la serie: lo que podría originar envejecimiento en los led ¿Se podría poner un diodo zener de 3.2 voltios en reemplazo del puente de alambre? Gracias Reciban un gran saludo desde CHILE
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HELLO It seems a common problem in the led screens I understand that all the LEDs are in series and that the voltage drop, originated by the led
missing is absorbed by the rest of the led. Would increase the current through the series: what could cause aging in the led Could you put a zener diode of 3.2 volts in replacement of the wire bridge? Thank you. Greetings from CHILE
Waleed Rishmawi
November 2, 2017 at 3:29 pm
Ivan1, i never tried that before and I will think about it the next time I do that. thanks for sharing
Shingirai Magaso
December 12, 2017 at 7:41 pm
The supply is designed to provide constant current, if you increase the number of lights, the overall voltage across all the LEDs will increase. If you decrease the number of LEDs, the overall voltage across all the LEDs will decrease which means that the voltage across each LED is not altered by adding or removing some of the LEDs because the supply is driving constant current through the LEDs.
Kevork
November 1, 2017 at 7:45 am
Hi, Mr.Waleed Rishmawi.Nice job, but I suggest , on coming repairs , try to show the approach with connecting a wire for continuity from one Led to the other one ,with picture , that would be a fantastic explanation for the repair . This way , your followers will be amazed, and will be very pleased . I thank you , and wait you for new repairs. Your follower , Kevork.
Waleed Rishmawi
November 2, 2017 at 3:31 pm
Kevork: I think you misunderstood the wire connecting here. I make a wire short between the two pins of the actual LED light not with another LEd light in the strip..
Walt
November 2, 2017 at 8:22 am
Howdy, I am an electronics tech. I service many units with LED issues, shorted and open both. I would not recommend shorting the pads on the bad LED's, this will only increase the stress on the rest of the string even if it works at all. I have found at times even one shorted will cause the power supply to kill the power due to excess current. I have replaced LED's in many brands and have had very good luck. The main thing that gets troublesome at times is getting the LCD panel out as many are put in with glue strips. One piece of advice to all, if the unit is so equipped in the menu, turn the back light setting to around 75% of full. Decreasing the power level to the LED's will greatly decrease failures, and cause very little difference in video if any.
Walt
Menahem Yachad, Jerusalem, Israel
November 2, 2017 at 5:05 pm
Excellent evaluation, but not solved correctly.
The reason that the LED's failed in the first place, is because of an unstable PSU, likely delivering higher than approved voltage/current.
So removing LED's from the circuit, just increases the current on the remaining LED's.
Therefore, your customer can expect the remaining LED's to fail again in a short time, leading to unsatisfaction with your work - that is a pity.
The correct fix would be to
1. Rebuild the PSU to specifications, and
2. REPLACE all open LED's (no need to replace the whole strip).
That is a long-lasting fix, delivering best value to the customer.
Waleed Rishmawi
November 3, 2017 at 6:16 pm
Menahem: thanks for your input. I usually replace all the strips in the LED TV but this one, the customer did not want to spend a lot of money on it so that is why I did that. I usually explain that to the customer. I besides, I have done that before many times and so far i did not have any complain from the customers.
Zibbo
November 17, 2017 at 3:28 am
This is very true, I learnt that the hard way when the TV I had fixed by removing 2 burnt LED's came back after a month with the same problem!
Robert Calk
November 3, 2017 at 5:31 am
I keep my TV at about 65%, and my laptop at 50%.
Waleed Rishmawi
November 2, 2017 at 3:35 pm
Walt. I do not usually short the bad LED light but I do so because sometime I do not have the full LED strip or the customer can not handle the replacing of all the LED strips. I have done this before many many times and so far I did not have any problem with this method whatsoever. I did not bother to turn the light setting in the menu and so far I did not have a complain. I thank you though for the information presented here. God bless and have a good day.
Walt
November 2, 2017 at 10:50 pm
Howdy, Mr. Waleed. Thank you for your response. I also run into cost and mostly availability issues with the strips. I have serviced many of these units over the past several years. As I have been servicing equipment for 40 years soldering comes second nature to me. I have never replaced a strip just the individual LED's that are defective. It is tricky, but after doing so many it has become easy to do. As for the response about the PSU, I have only had one with an issue and it was just the opposite of over driving. The current against the specs on the LED's is typically in line with the LED specs on the units I have serviced. If you are familiar with butane hot air solder units, I'm sure you are. I remove the LED's with that and then just float the new LED's with a fine tip soldering iron set to 800. Just a few quick touches and it is done, of course three dabs of high temp glue to put the lens back in place. I have many out there from close to two years now still working, so I guess I must be doing fine with my repairs. Only one call back in all that time. Thank you and God Bless as well. Walt
Yogesh Panchal
November 3, 2017 at 12:16 am
waleed
thanks for sharing your experience.
Albert van Bemmelen
November 3, 2017 at 4:38 pm
Interesting repair, but I agree that replacing the open white leds instead of just shorting them must be the only and correct way to repair such backlight failures. I still do not understand how you say you solved the now open spots that still contain the now dark defect leds?
Waleed Rishmawi
November 4, 2017 at 3:42 pm
albert: by making sure that every other LED light is on other wise you will have dark spots on the screen display. if i have a strip of light that has two bad LED light in a row, I will have to replaced the whole strip or just replace the actual LED light on that bad spot. I hope this answer your question. thanks for sharing