Author Topic: LG 50LF580V - Flashing backlights.  (Read 240 times)

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Turnip

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LG 50LF580V - Flashing backlights.
« on: August 19, 2018,10:35:31 »
Hi folks,

Have one with a continual backlight flash. Note OSG info but haven't the time to read it before display cuts. Seems 5 strips connected 2 and 3 strips in series to two P/I feeds.

Checked screen with tester where one shows 90v and the other 144v so suspect a couple of duff Leds on the 90v side as the figures don't add up.

Thought mention as Guess someone has had the problem before, and the screen is a bit big and fragile to take off for fun.

Any thoughts ? - Chris

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LG 50LF580V - Flashing backlights.
« on: August 19, 2018,10:35:31 »

downunder

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Re: LG 50LF580V - Flashing backlights.
« Reply #1 on: August 20, 2018,05:24:00 »

Hi Chris,

I'd be more inclined to suspect the LEDs on the 144V feed, however, the LED strips in these have a joiner near the centre of each dtrip. These are inclined to be problematic. Just a thought, but I can see a display panel coming off.


Bruce

Turnip

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Re: LG 50LF580V - Flashing backlights.
« Reply #2 on: August 20, 2018,11:23:01 »
Hi Bruce,

Do you care for a bet as to which string has the duff budgies ?

Waiting for the cust to sign the 'shit or bust' certificate, as they can get peeved even after a verbal OK if things go wrong and I catch an edge against something I didn't notice.

After some early disasters, sorted a large sheet of plywood that I shove underneath. It even has a lip so the screen can't drop off while I'm looking for somewhere to rest it whilst sorting the diodes - Chris.

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Re: LG 50LF580V - Flashing backlights.
« Reply #2 on: August 20, 2018,11:23:01 »

sinclairtv

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Re: LG 50LF580V - Flashing backlights.
« Reply #3 on: August 20, 2018,13:52:28 »
If its got the 6v LEDs, Im finding that some types are brighter when replaced and will shine through. Pain in the neck when the set has to be boxed back up to discover this. I use the old cardboard of a large set to rest the screen on along with a sucker to lift a corner on to the cardboard

Turnip

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Re: LG 50LF580V - Flashing backlights.
« Reply #4 on: August 21, 2018,12:30:50 »
Thanks Sinclair,

Had an issue with a top lit screen, where replaced dodgy leds (rather than the whole lot) where cust complained as the heat had distorted the diffuser sheets giving a vague wedge pattern down the first two inches on certain pictures.

Suspect if I'd replaced the sheets the other way up - Guess learning curve.

Had one in today with a smashed screen where the edge lit Led assembly was mounted LHS - Seems sensible but didn't survive the brick.

Tend to use a bit of plywood, though with 60 inch sets, I'm in trouble as ply sorts 50 inch. Early failures were due to catching the screen on something, and chipping off a corner - Mind you, that was last year, not lost one since - Chris.


sinclairtv

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Re: LG 50LF580V - Flashing backlights.
« Reply #5 on: August 21, 2018,16:55:33 »
I'm not trying to repair edge lit types. I don't see how to replace individual leds and trying to get whole strips is to time consuming.

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Re: LG 50LF580V - Flashing backlights.
« Reply #5 on: August 21, 2018,16:55:33 »

downunder

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Re: LG 50LF580V - Flashing backlights.
« Reply #6 on: August 22, 2018,03:25:32 »

Hi Chris,

We live and learn with panels - suspect all of us have cracked the odd panel. My early disasters happened when the outer frame that the panel

snuggles into wasn't true. OK till you screw the metal frame on.                                Bruce

Turnip

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Re: LG 50LF580V - Flashing backlights.
« Reply #7 on: August 22, 2018,10:38:25 »
Hi Sinclair,

Not done too many edge-lit yet, but found it not much of a problem after heating the heat sink a bit, where the double sided tape that holds the strips peels off quite easily - change duff Leds and use more double sided tape. Guess there might be an issue if the aluminium strip holding the Leds gets a bit bent, as tape won't hold it.

Hi Bruce, well said. Like some I didn't check clearance and broke a couple - As embarrassing as when a cat makes a nifty leap, misses, and slopes off without a word.

My LG is turning out to be fun - One S/C Led on the two strip, three strip OK. Fitted a 6v Led of the sort I've used before on LG and it didn't work. Tried another and the same. Matched up soldering the larger pad on the Led to the larger pad on the strip, then realised they've swapped it about reversing polarity. Wouldn't mind as could fit the Led lower so it doesn't short out, but then there's the issue where if the lens is placed a micron off, folks complain.

Had a look on Ebay, but every seller who mentions anything, sells the same Leds I've got - All fun - Chris.

 

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