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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Source for LED backlight strips?
Looking for a reliable UK supplier for these. I don't have a part number
but have the panel type number, it's in a 50" LG TV. Kenny Cargill |
#2
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Source for LED backlight strips?
On 17/05/2016 07:47, Kenny wrote:
Looking for a reliable UK supplier for these. I don't have a part number but have the panel type number, it's in a 50" LG TV. Kenny Cargill Is it possible to wire bypass the failed one, and then would there be an observable weak spot in the illumination? |
#3
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Source for LED backlight strips?
I had considered trying to repair individual LED's but decided against it, I
have experience of repairing older type TV's but not this type. I have looked at Youtube video of dismantling these and found it a bit daunting, especially as it's 50". Have found one source, CHS listing kit at £180 and a Canadian source at the equivalent of £80 but it doesn't say if it's new or used, have mailed them to ask. http://www.usefulparts.com/tv-parts/...-for-lg-led-tv "N_Cook" wrote in message ... On 17/05/2016 07:47, Kenny wrote: Looking for a reliable UK supplier for these. I don't have a part number but have the panel type number, it's in a 50" LG TV. Kenny Cargill Is it possible to wire bypass the failed one, and then would there be an observable weak spot in the illumination? |
#4
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Source for LED backlight strips?
Yes, bypassing the failed LED will allow the rest of the string to work. Depending on the diffusers used and the pattern of the lens over the LEDs, dead LEDs can be obvious or difficult to pick up. Since the back light driver board monitors current, it reduces the voltage to keep the drop across the remaining diodes within "safe" margins.
Unfortunately, these LED TVs drive the LED string well beyond the safe limit of the LEDs. Often, you'll find several LEDs already shorted in addition to the offending open one. In late model Samsungs, you'll find more shorted than working in many cases. Just did a 2012 46" that had 32 dead out of 44.. You can buy a metric ****load of LEDs out of China for cheap and replace the individual LEDs using a hot air station. Some companies offer a firmware upgrade which reduces the drive to the array. Adjusting the customer controls will achieve the same thing, but I've found that for many reasons, the customer adjustment ends up in default, and that means 100% for the back light setting. I modify the LED drive circuit to reduce the back light by 30 to 40 % at a maybe 10% or so decrease in brightness. No one complains and they don't come back. |
#5
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Source for LED backlight strips?
"Kenny" wrote in message om... Looking for a reliable UK supplier for these. I don't have a part number but have the panel type number, it's in a 50" LG TV. My experience with this was finding a TV in the flats bin room that was made by a well known Turkish company (Vestel). Apparently LED failure is one of a long list of stock faults..................................... Unfortunately I cracked the LCD panel putting it back together, but I learned a fair bit from the excercise. Each LED had a plastic lens extruded on, I had to melt these with a soldering iron to peel them off. The iron wouldn't shift the SMD LEDs. It took a modeler's pencil blowtorch to shift the dud LED chips, after that I used a small roll of emery paper to clean off some solder resist and attach some power LEDs I had to hand. You can re-touch the PCB around the replaced LEDs with correction fluid. If its a Vestel - you'll probably find a few more LEDs that tested OK have given up.............................. |
#6
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Source for LED backlight strips?
"Ian Field" wrote in message ...
"Kenny" wrote in message om... Looking for a reliable UK supplier for these. I don't have a part number but have the panel type number, it's in a 50" LG TV. My experience with this was finding a TV in the flats bin room that was made by a well known Turkish company (Vestel). Apparently LED failure is one of a long list of stock faults..................................... Unfortunately I cracked the LCD panel putting it back together, but I learned a fair bit from the excercise. Each LED had a plastic lens extruded on, I had to melt these with a soldering iron to peel them off. The iron wouldn't shift the SMD LEDs. It took a modeler's pencil blowtorch to shift the dud LED chips, after that I used a small roll of emery paper to clean off some solder resist and attach some power LEDs I had to hand. You can re-touch the PCB around the replaced LEDs with correction fluid. If its a Vestel - you'll probably find a few more LEDs that tested OK have given up.............................. https://www.youtube.com/watch?v=Bf5T2wwtydY This is the video I watched, it's for a 47" LG, mines 50", I don't have the space to work like that and wouldn't feel confident dismantling the screen anyway. Local shop say they'll look at it and give me an estimate so that's probably what I'll do, thing is this TV is only 2 years old and the same fault may recur. I've decided to buy a 55" Sony with 5 year warranty and giving the LG to a family member if they want to pay for the repair. |
#7
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Source for LED backlight strips?
"Kenny" wrote in message
om... "Ian Field" wrote in message ... "Kenny" wrote in message om... Looking for a reliable UK supplier for these. I don't have a part number but have the panel type number, it's in a 50" LG TV. My experience with this was finding a TV in the flats bin room that was made by a well known Turkish company (Vestel). Apparently LED failure is one of a long list of stock faults..................................... Unfortunately I cracked the LCD panel putting it back together, but I learned a fair bit from the excercise. Each LED had a plastic lens extruded on, I had to melt these with a soldering iron to peel them off. The iron wouldn't shift the SMD LEDs. It took a modeler's pencil blowtorch to shift the dud LED chips, after that I used a small roll of emery paper to clean off some solder resist and attach some power LEDs I had to hand. You can re-touch the PCB around the replaced LEDs with correction fluid. If its a Vestel - you'll probably find a few more LEDs that tested OK have given up.............................. https://www.youtube.com/watch?v=Bf5T2wwtydY This is the video I watched, it's for a 47" LG, mines 50", I don't have the space to work like that and wouldn't feel confident dismantling the screen anyway. Local shop say they'll look at it and give me an estimate so that's probably what I'll do, thing is this TV is only 2 years old and the same fault may recur. I've decided to buy a 55" Sony with 5 year warranty and giving the LG to a family member if they want to pay for the repair. Update on this, was very careful dismantling the screen and using a variable power supply found a duff LED on 2 of the 12 strips. Easily found using the part no. on them, expensive at £25 each. I've reduced the backlight current to hopefully make them last longer, it seems LG set the default at maximum! It wasn't as difficult as I had expected and if doing it again I'd try replacing individual LED's, I have a few spares now. |
#8
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Source for LED backlight strips?
I just did a 47" LG repair and was surprisingly straightforward. I followed the video (was a very similar TV) and took around hour and a half. Having a friend to help you is great though especially when lifting the LCD out of the frame.
The room I needed was a small (single) bed and a little table to place the TV when disassembling it. Only one led had blown so I ended up just short circuit'ing it. You can tell a bit that the background is darker but worked well. |
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