Size of Backlight LEDS ?


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Size of Backlight LEDS ?

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Southerner1959
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Nov 5, 2015, 10:43 AM

Post #1 of 7 (1363 views)
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Size of Backlight LEDS ?	Can't Post

It would seem that some of the LEDs for the backlight inside my LG Television has failed.

It looks very tricky to get the screen apart to replace them, so I don't want to leave it in pieces.

Can anyone therefore tell me what size the LEDs are?

And the current rating I should be looking for?

I can see Surface Mount LEDs anything from 1mm to 5mm square.

Also there are lots of different "White" colours available - does anyone know what type sets use?

jts1957
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Nov 5, 2015, 6:58 PM

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Re: [Southerner1959] Size of Backlight LEDS ? [In reply to]	Can't Post

Your local recycler may be able to provide a Same brand - SIMILAR panel size model of a similar vintage, and even if NOT the same backlight technology, it would give a screen to 'practice' disassembly / assembly on/with. Be careful with the tabs as pointed out in video, they can detach with surprisingly little pressure. Try NOT to pick up the TFT glass panel by the corners. It may help to have two persons for larger screens.

Bring a smart phone and research the model numbers that recyclers have to confirm backlight technology. (Edge vs whole panel array.)(Google Model number with CNET can give basic specs.)

The closer the Brand, screen size and vintage, the more likely a 'match.' Just bear in mind that donor set probably has bad LEDs too.

The LEDs in a used set will match the ones in your set better than brand new ones in regards to operating hours, reduced brightness, etc. Just remember to reduce the duty cycle of the LEDs.

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Southerner1959
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Nov 5, 2015, 7:26 PM

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Re: [jts1957] Size of Backlight LEDS ? [In reply to]	Can't Post

Thank you for replying . . . and I appreciate what you say makes sense.

The problem is that people don't throw these sets away when they go wrong . . . they sell them on Ebay . . . and there are none currently in this part of the country!

So I would have to buy new LEDs and fit those.

Even getting an idea of what size to get would be a help!

And do they use high current ones? ie 200 - 400mA, rather than the normal 20mA types?

jts1957
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Nov 5, 2015, 7:44 PM

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Re: [Southerner1959] Size of Backlight LEDS ? [In reply to]	Can't Post

IF you change ALL LEDs at once, even the working ones (for brightness, longevity match, etc.) then just need high current, same physical size. Mouser, Digikey.

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(This post was edited by jts1957 on Nov 5, 2015, 7:45 PM)

Southerner1959
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Nov 12, 2015, 1:05 PM

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Re: [jts1957] Size of Backlight LEDS ? [In reply to]	Can't Post

Well having dismantled the screen on this LG TV, I saw the LEDs are just 3mm square.

I couldn't find ANY that small that are high current, so just got some high brightness ones. (only 3 original ones have actually failed)

However . . . these are blowing straight away!

Having replaced the 3 blown ones again, this time they all went short-circuit, so all the rest are staying on OK now.

So I could now measure the current each string is taking . . . and it IS 400mA (I'm just amazed it's that high!)

I guess I'll have to get some 400mA LEDs, even though they are physically much bigger. Don't suppose it will make much difference . . .

(This post was edited by Southerner1959 on Nov 12, 2015, 1:20 PM)

Southerner1959
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Nov 14, 2015, 4:57 PM

Post #6 of 7 (1272 views)
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Re: [Southerner1959] Size of Backlight LEDS ? [In reply to]	Can't Post

Well I eventually found some small (3mm) high current LEDS . . . got them fitted, and set is working OK.

However . . . you can clearly see that the 3 I have replaced look quite yellow compared to the original ones.

They had a colour temperature of 4000 K

So I have now ordered some similar ones, with a 6500 K colour temperature . . . hoping they will be a good match. (this is all proving rather trial and error for me!)

Once I have found ones that are correct, I will post the details (they're available from RS Components in the UK in small batches, typically 2 - 5, and only about �1 each)

Southerner1959
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Nov 18, 2015, 11:29 AM

Post #7 of 7 (1246 views)
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Re: [Southerner1959] Size of Backlight LEDS ? [In reply to]	Can't Post

Well having replaced the 4000K ones that looked a bit yellow, I have now fitted 6500K ones, and they look a bit green!

Guess I need 7500K or even 10000K ones?

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