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Why do backlight LEDs burn out and go blue?
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PlainName:

--- Quote ---I do not know if people are afraid to post such information to protect from potential identification, or if people think that no one knows the device anyway. Or, and i am afraid that this is actually the most likely, if people are just too lazy.
--- End quote ---

No doubt a combination, but sometimes it's not knowing what info is relevant. In some other forums, people post 100K-worth of log output, 99.99% of which is of no use and just obscures the relevant part. I suppose in some ways it is akin to quoting - IMO a succinct quote of the section being addressed is far better than the full quote and then trying to work out which is The Bit being dealt with.

But we also see quite comprehensive descriptions which include fixes that can't be used for some reason (usually quite sensible) and yet at least a couple of responses will be to use those specific fixes. Sometimes you can't win.
PlainName:
And... it pains me to say so but eti did actually ask a generic question (why do LEDs burn out) and perhaps his only fault is to include a specific example. So with a quick reading (mea culpa) one might assume he is asking what's wrong with his TV, whereas in fact he is asking why backlight LEDs in general go like that.

The answer would seem to be that stick-on phosphor patch, which is something I didn't know about so I am grateful for the question coming up!
Cerebus:

--- Quote from: Ranayna on November 08, 2021, 10:20:41 am ---Post as much information about the issue you want help with as you can.
People cannot read minds, even here  :-//

--- End quote ---

The problem is that some people are quite good and do all that, even to the point of meticulousness, but then there are certain individuals who just seem congenitally incapable of actually reading it and shoot off at some tangent.

For a very simple example, I just read a thread where someone says "I want to buy an upmarket-brand-name model XYZ scope; can anyone recommend an upmarket-brand-name dealer in my-area". The very next poster says "You should get a downmarket-brand model ABC!".  :palm: Do we really need to start making people sit a reading comprehension test before they're allowed to post?

I'm not saying that's what's happening here, in fact it's not, but it just goes to show that some people are so dumb, or determined to just go their way, that clearly and completely stating the problem/issue for discussion/question isn't a foolproof way of getting a sensible discussion/answer. I've noticed that quite a lot of the people who derail things in this way have self-congratulatory superlatives like 'guru', 'expert', 'master', 'wizard' and so on in their chosen user names. I think the implications are quite self-explanatory.
eti:

--- Quote from: Cerebus on November 10, 2021, 12:33:23 am ---
--- Quote from: Ranayna on November 08, 2021, 10:20:41 am ---Post as much information about the issue you want help with as you can.
People cannot read minds, even here  :-//

--- End quote ---

The problem is that some people are quite good and do all that, even to the point of meticulousness, but then there are certain individuals who just seem congenitally incapable of actually reading it and shoot off at some tangent.

For a very simple example, I just read a thread where someone says "I want to buy an upmarket-brand-name model XYZ scope; can anyone recommend an upmarket-brand-name dealer in my-area". The very next poster says "You should get a downmarket-brand model ABC!".  :palm: Do we really need to start making people sit a reading comprehension test before they're allowed to post?

I'm not saying that's what's happening here, in fact it's not, but it just goes to show that some people are so dumb, or determined to just go their way, that clearly and completely stating the problem/issue for discussion/question isn't a foolproof way of getting a sensible discussion/answer. I've noticed that quite a lot of the people who derail things in this way have self-congratulatory superlatives like 'guru', 'expert', 'master', 'wizard' and so on in their chosen user names. I think the implications are quite self-explanatory.

--- End quote ---

I shall freely admit my propensity to rocket off at tangents, it’s a lateral thinking trait of mine 😁 for which I make no apologies whatsoever; it’s a function of how my mind works. I am sorry if I’ve confused anyone, especially the “experts” <bows with great humility> 😉😉

I agree regarding those using the cliched superlatives in their surnames, and will quote a phrase I once heard, regarding one naming oneself an “expert”:

“An ex is a has-been, and a spurt is a drip under pressure.”😛

I find humility wins every time, and I feel that maybe a great deal of personal insecurity leads some people to feel a need to establish their prowess by over-compensating, when, in fact, talent and gifting can speak for itself FAR louder than any superficial, somewhat boastful moniker.

station240:

--- Quote from: eti on November 06, 2021, 12:40:45 am ---I beg to differ. Google "LG TV blue picture fault" and count the endless results that show engineers replacing the backlight strips that have gone blue.

--- End quote ---

Ah there is a difference between a service technician/engineer and engineers in general.
engineer: That's can't happen, (assumes customer is an idiot), spends ages on other random guesses before giving up.
technician: (takes one look at the set) Yup had one of those in last month, backlight LEDs have failed and gone blue.
Still you'd think engineers would know white LEDs are just blue ones with a phosphor layer added.

I've got a LED backlight and PSU here, after some reverse engineering I found how to turn the LEDs on without the control board.
But turns out if you drive them 100% (no PWM signal), they all turn blue after a few hours, but leave them off for a few days and they go back to white.
Obviously that can't happen if the phosphor layer falls off entirely. Bad bonding material perhaps ?
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