Mulja tv repair portal
Equipment Repairs => LCD TV forum => Topic started by: Turnip on March 28, 2018,12:36:29
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Hi folks,
Sound but no back light - Guess Screen Leds, but noted 15 conductors from P/I to screen.
Seems a bit excessive, but note screen Leds are an issue, as plenty on Ebay and look like LG 3v Leds used with Vestel screens.
Guess when taken apart will suss those 15 conductors, hopefully - Chris.
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Hi Chris,
I note that Samsung and LG are using these multi-pin connectors for the LED drive, especially in larger screens.
Essentially most of the wires are paired for each parcel of LEDs, eg. 1+, 1-, 2+, 2-, and so forth.
With your trusty LED tester, using the legend near the plug, you should be able to check if each pair produces light, and each pair uses
the same voltage as per readout on the tester. On the other hand, you could take the panel apart. All in a day's work. Bruce
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Thanks Bruce,
Took screen apart finding five strings of nine leds. Found nine leds S/C. Thought try use a standard 3v of same dimensions to discover the print doesn't match the led unless soldered in the wrong way around, where of course it doesn't function.
If soldered in the right way the led shorts out the pads. Noticed some on Ebay for 42 inch Sammys, and they look the business.
China does quite a lot but with no close up pictures, and from a distance they all look the same. Early days I guess - Chris.
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If Chris was wanting to be nice he couldve nipped up to China and took better pics of them.
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So true, but Bruce is nearer by a few yards - Chris.
In the event got the ten Sammy Leds in the post today and used most of 'em without over cooking even one. They're sort of nice as a top central spot indicates positive (two at the bottom for negative) so you don't have to keep checking the underside while they flip about as you try get 'em sorted on the strip.
Downside - Strip seems to be glass fibre, and doesn't conduct heat so well - Which might explain premature failure, especially as the strips aren't stuck to the metal back plate - Just slotted in.
Did the usual where you snip from the top and clean up with solder wick, add a little LMP then place the Led and hold over heat 'till the solder melts, then quickly cool the strip with anything handy - Spit on a finger seems to function, as always available - Chris.
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Hi Folks,
Thought mention outcome - New Leds a little more Blue than originals. Lenses just like the sort used on LG strips used by Vestel - The rather flat round ones where if you get them more or less centralised over the LG Led it's OK.
Not with these Sammy Leds, as on reassembly there were light and dark patches most everywhere using a White or coloured blank screen. Normal viewing mostly unnoticeable unless customer picky.
Checking each individual replaced lens on a display screen seems time consuming, especially if you've taken off a lot to find the duff Leds.
Fun though - Chris.
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hi chris i've got the same tv with just 1 led blown, can i use an lg one that's all i've got at the minute, also can't seem to find leds for this tv only the strips thanks
shaun
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Hi Shaun,
No - The LG leds are the wrong way up, need sort genuine Sammys, notice two sources on Ebay.
Noticed also that with LG the lenses aren't any problem but with Sammy Leds they are.
Guess it's good to try displaying on filters before reassembly, strip a time - Chris
Set came back after a few days where another Led had popped, also plugs and sockets on strips were dubious so hard wired the lot.