Earliest Led Tv Backlight Failure Yet Please Read.

[ReeceyBurger123]

Here I have this classic example of Vestel shit excuse the French. This is a hitachi brand rebadged Vestel crap 24" Led backlight lcd tv just 6 months old (5 months and 3 weeks to be exact) and already failed because its a Vestel and they truly are not built to last. So normally these tvs when they fail at this age they have gone past the bathtub stage in their product life as they have very little life span, normally the diodes on the psu will blow causing no standby or the firmware will go copout and cause the standby led to flash usual simple faults. Now there is a massive known fault that I have seen over 15 Vestel sets alone with the stupid and very annoying failure that im about to describe. The led bulbs them selves are actually failing. Most led tvs and especially these are wired like classic christmas lights so one bulb out all out, some full array sets will still run the rest of the bulbs even if one fails because they might be wired in parallel but these cheap Vestel's wire the bulbs in series so if one fails the whole strip wont light up, and of course if the psu, mobo or led driver detects a massive change in current it will not fire any of the bulbs. This hitachi come to me with sound no pic expected tcon or mobo but no, backlight wont come up. Opened the panel to find at leat 2 the tiny little smd leds burnt to a crisp leaving browning one the led strip with huge split marks in the centre of them. Now the huge fault and one of the main reasons why these bulbs fail is due to heat, the leds are hard working tiny devices that keep all the heat to themselves which as we all know electronic devices dont like heat. They do get cooled through transferring heat to the chassis of the tv and to the copper on the strips, but this tv did not have a metal chassis but a cheap plastic one which as we know plastic is not a good heat conductor and will not allow the leds to cool efficiently which is why the leds in this set blew up after 5 months of light use because of heat. When they get too hot the whisker in them either bridges and shorts causing the rest of the led to shatter and then fail and not pass any voltage. No why am I making this massive rant thread, the reason is because alot of the time the strips are not repairable due to the way they are assembled, I guess that they solder the leds onto the copper of the strip then add a VERY strong and thick type of pcb layer over the solder joints so that you can not access the solder to be able to replace the whole diode rather than just replacing the strips. Trust me I have tried peeling back this pcb adhesive stuff and have no luck repairing the original strips and im quite decent at soldering if I dont say so my self, making the strips almost impossible to repair. So overall my point is that I hate led tvs because they dont last Ive even seen the good high end ones like lg and panny have the leds fail after some years of use but Vestel takes the lead for blowing leds and all diodes and the bitch is these cheap Vestel strips are not repairable so you then have to find replacements at least in the high end ones you can repair the strips. Not built to a cost but built to fail and not be economically repairable. Vestel your tvs suck and I hope you go out of business and never return, yeah I guess they do keep my tv repair business going but they are a bloody nightmare so I still hate them. So in general avoid led tvs they suck and are not the way forward.

[mmartell]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

I think I can beat that story. This one was seen on display at a local Walmart. Harder to see in the pic than in person but the upper left quadrant is darker than the rest of the screen.

And oh ya, it's an LG 4k !

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Wow wander how old that set is ???

[stj]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Reecey, got any foto's of the led and surrounding area?

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

I will get you some today Stj, they might not be uploaded until later because I dont have wifi at my unit yet.

[flocko]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Bulb are thing that you plant in the ground ? lamps are the things that light up. one of the first things that I was picked up on when I was a young lad in collage some 53 years ago , but I do think we are just seeing the beginning of these LED lamp faults with a lot more to follow Flocko

[stj]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

conversion kits are fine,

the problem is the led tv's dont use enough leds, they just overdrive them to save money.
the kits stack the leds end2end - they use so many that you dont need to overdrive them.

[tom66]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

This is pretty typical. If the LEDs don't go the panel will. The power levels are low enough now that power supplies are cheap enough to build reliably - there's little saving to be made there now. Failures come in the complex areas to save money on: panel, LEDs, flash memory, soldering under CPU etc.

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Here you go chaps, photos show the chassis of the tv which is pink plastic and one of the burnt up led diodes as you can see the glass on it has shattered you can see that the others still have their yellow glass on and its not like its in the middle of the strip which normally is the hottest part but I have a large suspicion its because of heat.

[R_J]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Thats 1 bad led out of the 200 in that panel, and how many of those panels non't have a problem. if that 1 led was replaced the rest of the led's might out last the rest of the tv.

[tom66]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

The problem is while LEDs have a good overall lifespan exceeding 50,000 hours the early failure rate is quite high and if one single LED fails, the whole TV is usually unusable.

If the TV would operate with several LEDs out, there would not be a problem. There already exist antifusible zener devices which will short out failed LEDs allowing the rest of the set to continue operating with a minor drop in picture brightness. These would cost a matter of pence per LED to add to these sets yet manufacturers do not do this because it is not in their interest to increase lifetimes.

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Yeah im looking at what zeners to use thinking 100ma 2-3v just checking what voltage the booster on this works at normally 70-90v @4 a but this is different voltage and current.

[tom66]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

They would have to be rated at the LED forward voltage and power dissipation at Vf x I, where I is the LED current (around 20-100mA) and Vf is the forward voltage (around 3-4V).

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Just got to find the type I need and corrected my comment I put 100v and 3w lol doh, I will see what I need tomorrow as the tv is at my unit.

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Thats 1 bad led out of the 200 in that panel, and how many of those panels non't have a problem. if that 1 led was replaced the rest of the led's might out last the rest of the tv.

Unfortunately I highly doubt that, I recon that after I repair this it will be another month or 2 before its out again designed to fail.

[stj]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

looks pretty simple.
first, work out the size of the led's

then order a bunch of different ones from rapid.
http://www.rapidonline.com/Electroni...ace-Mount-LEDs

try them until you get one that gives the right brightness and colour.

you can change them with hot air - dont overdo the temperature or you will damage the lense.

[freakaftr8]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

I just ran into a 2012 samsung. Same problem with these cheaply made 3 strip backlight systems. Edge lit seem much more reliable. This design appears to be inherited by oncorp. A. Chinese design. The backlight strips are inadequate for efficent cooling and eventually overheat and blowout leds.

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

Well just repaired this set used a 3w zener at 90ma tv turns on and works now. However the picture looks horrible almost washed out like its too bright but the leds do dim on start up guess its just because the lcd is crap because its a Vestel panel looks like a blurry painting the colours fade depending on what angle you view the set im too used of my pioneer kuro. I guess that this is a case of you get what you pay for, pay £80 for a set this cheap its going to last 6 months and look like crap so renting a tv for £14 a month not worth it. Charged £20 for repair hopefuly get a few more months life out of it just goes to show how cheap and unreliable products are getting nower days.

[tom66]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

The VES315 etc panels look terrible. They do the gamma correction on the main board instead of at the panel level so you get loads of banding which makes everything look a lot like an oil painting.

You can change the dim setting under the Picture menu, backlight MAX is not that bright though. Nothing you can do it is optimised to be as cheap as they can get away with. Honestly I would leave it at MIN to try and preserve backlight lifetime.

[ReeceyBurger123]

Re: Earliest Led Tv Backlight Failure Yet Please Read.

The VES315 etc panels look terrible. They do the gamma correction on the main board instead of at the panel level so you get loads of banding which makes everything look a lot like an oil painting.

You can change the dim setting under the Picture menu, backlight MAX is not that bright though. Nothing you can do it is optimised to be as cheap as they can get away with. Honestly I would leave it at MIN to try and preserve backlight lifetime.

Exactly what I said to the owner keep the brightness low help save the life of those crappy leds. You are right as well it looks like an oil painting lol never seen a tv that looks so hideous in my life I dont know how people can stand to watch it also the sound quality is also horrible sounds scratchy and squeaky when ever bass is played, yet people will still swear that this junk has a good picture and sound quality. As you said you try to tell them not to buy it that its a pos but they do and dont listen, ohh well gives us technicians a tv to repair when they fail.