LG 47LN578V - Brief Backlight flash on power up.

[budm]

Re: LG 47LN578V - Brief Backlight flash on power up.

is this the one on EBAY?
http://www.ebay.com/itm/252260850432...432%26_rdc%3D1

There are many 3528 PLCC-2, which one that you use?
3528 1210 PLCC-2 so far that I found has If of only 30mA, I am looking for >150mA (which is most drive current is for the backlights) or more for at least 1/2W LED. I found LG INNOTEK but they want high qty.

[RobbieC]

Re: LG 47LN578V - Brief Backlight flash on power up.

i had a good look through them all - all similar to this http://www.ebay.co.uk/itm/50x-XENON-...HHYtHEAF0DjH8A
my concern was all the forward current were rated at 20mA max which i'm guessing is much lower than spec.
Personally I am leaning to these @ 200mA http://uk.rs-online.com/web/p/products/897-8737/
or maybe these at @ 300mA http://uk.rs-online.com/web/p/products/897-8784/

[budm]

Re: LG 47LN578V - Brief Backlight flash on power up.

Those 3528 are rated around 30mA which is not going to make it.
3535 in your link () will be better but not sue if it will fit the footprint on the PCB.

[flocko]

Re: LG 47LN578V - Brief Backlight flash on power up.

Hi Budm + Robbie the ones that i got were from www.wayjun.com. was some time back but still have some left,but unable to find invoice and no numbers on them, sure i am right that they were rated at 200mA 3-5v max 3528 PLCC-2 bright white they had all the data on line

[michael dranfield]

Re: LG 47LN578V - Brief Backlight flash on power up.

You can buy these led lights from a company called charles hyde and son in pocklington , I ordered a set today for a smaller version of this model, dont waste you money buying second hand ones on e bay as the best of there life will allready be gone, unless you can source some from a brand new set which has been damaged in transit.
However you have to buy the whole set of 12 and if you dont have an account the 12 will set you back £96.49.

[michael dranfield]

Re: LG 47LN578V - Brief Backlight flash on power up.

Tip : If you don't have a stencil for what you need get a universal one and place it over the BGA chip... Get a tea candle (Ones in the metal case) and let it melt... Using a cocktail stick/toothpick fill the holes that are not needed in the stencil with wax. Make sure you skim over the stencil afterwards to make sure its flush. VOILA custom stencil. Easy to clean off with boiling water too

Last time I did a BGA and did not have the correct stencil I put all 208 balls on by hand with a pair of tweezers, flux the BGA first with thick sticky flux so the dont all roll of if you sneeze though !

[RobbieC]

Re: LG 47LN578V - Brief Backlight flash on power up.

I was dubious about the footprint for the 3535 too! Unfortunately I couldn't find too many alternatives for a similar spec. My interpretation was that the ideal layout would have the pads with only a small gap (0.6mm) between but that they should be ok with the existing ones..... I ordered them yesterday with delivery this morning so will see. For only £7 (USD 10) I can live if they wont fit

[chrismurphy]

Re: LG 47LN578V - Brief Backlight flash on power up.

see my post https://www.badcaps.net/forum/showthread.php?t=51847

[RobbieC]

Re: LG 47LN578V - Brief Backlight flash on power up.

So this is the footprint. Was hoping for more 'side' access to the pad but looks as though it needs to be sat on the pad from above.
I intend to be using a hot air station from below so shall see!

It appears there are 2 bits on each pad which wrap up the side of the led which you could use for soldering but they are thin and wouldn't like to guarantee to be a good enough connection.

[stj]

Re: LG 47LN578V - Brief Backlight flash on power up.

the larger pad is the actual base of the reflector and acts as the heatsink - or the link to one.

[rossoreed]

Re: LG 47LN578V - Brief Backlight flash on power up.

I replaced 5 failed LEDs with these from Radiospares (part ref 697-3759), and although they got me back viewing again over Xmas, the colour is wrong, they create pale green shading on the screen.
How are you re-attaching the LED lens? I used clear silicon, which again was probably a mistake as the light spread is not even.

Paul

[RobbieC]

Re: LG 47LN578V - Brief Backlight flash on power up.

Funnily enough that is exactly my experience! So my previously fixed tv died again. Stripped and saw no obviously (new) dead led but 1 string was obviously not flashing at all at startup. Narrowed down by swapping the r1 r2 l1 l2 combos until the other string failed. Then popped off the led lens to work along. Curiously, on my multimeter in continuity mode which beeps, i can just manage to get a working led to light which helped no end identify the issue. One of the led's which had previously failed shorted had popped and was open. Cool, set meter into current mode and measure current. Voila set backlights working again - albeit with dead ones still in existence.
Interestingly, screen is brightest just after powerup at a whopping 400mA over the string, this settled to ~140mA based @ a backlight of 30 iirc. That proved, I still had 9 dead leds from before. I had the repalcement led's linkedf rom above from rs as a repalcement so set about pulling of lens and removing dead led with hot ait staion (Aoyue 908). 2 were problematic in that they were somewhat welded to the pad and took some force with a soldering iron. 2nd problem was that the larger heatsink on the pad is the anode and on the replacement led is the cathode. This mean the led position is moved approx 2 mm down form where it was originally intended. This was a pain for a few as there were obvious shorts which needed reworking. Eventually, all failed 9 were replaced having then also removed several adjacent led's to test continuity in the string.
Next part reassembly - this turnewd out to be hard. As I had removed nearly half of the 54 led lens via trial an error and faultfinding i intended to reglue them back. Ok this kindof worked using superglue however
1: the lens were mixed up so not going back to original source so legs may have broken is different locations
2: The new leds were actually now lower than originally located so this meant the lens didnt fit correctly either.
Also re-assembly showed many lens were out of position and simply fell off. Pikey fix was to attach with clear sellotape. This worked to a fashion, re-assembled and made sure diffuser panels were ok then powered up. Result was massive bleed from all over the place. The 9 led were actually brighter and marginally different colour than original, 2nd the lens alignment makes a huge difference to baclight continuity.
I was stuck and had removed too many lens to do anything so I reassembled and put tv back into front room where the final results annoyed the hell out of me.
Pic below is finally assembled tv showing a test pattern from openelec (kodi).
The 9 different colour patches obviosuly show where the new leds are, then the other halo marks are original led's which have misplaced lens.
These are 6500k led's rated at 300mA and 70 cri. These look too bright and the wrong colour. I thinkt hey are 52 lumen too. Maybe closer to 7000k is required.
Also ideally, heatsink pad needs to be reversed.

Major issue is lens reattaching. I would love to know how anyone has correctly done this ? I can only suggest using some kind of washer ? which will keep them alaigned correctly but i guess would need to be a specific thickness.

[RobbieC]

Re: LG 47LN578V - Brief Backlight flash on power up.

You can buy these led lights from a company called charles hyde and son in pocklington , I ordered a set today for a smaller version of this model, dont waste you money buying second hand ones on e bay as the best of there life will allready be gone, unless you can source some from a brand new set which has been damaged in transit.
However you have to buy the whole set of 12 and if you dont have an account the 12 will set you back £96.49.

Just looking at that - seems semi reasonable if new but be interested to see what anyone with an account gets. I guess that must be the LG standard replacement - now just need a friendly one... !

http://www.chsinteractive.co.uk/elec...-more-info.htm

[flocko]

Re: LG 47LN578V - Brief Backlight flash on power up.

Check out eBay UK item number:252260850432 the easy way to repair LED strips,does not look such a bad option now then? why did you have to take all the lens off to check the LEDs ,scratch off the solder mask to the left and right of the LED to be tested test with meter in diode mode or two AA cells with a 470ohm resistor

[michael dranfield]

Re: LG 47LN578V - Brief Backlight flash on power up.

Just looking at that - seems semi reasonable if new but be interested to see what anyone with an account gets. I guess that must be the LG standard replacement - now just need a friendly one... !

http://www.chsinteractive.co.uk/elec...-more-info.htm

£74.22 if you have an account, and cheaper than a new screen !
Serach Datasheet ST MICRO part number LBP01 , if you want to mod your new strips , this device can be bought from Farnell components in leeds for about 54p each.

[RobbieC]

Re: LG 47LN578V - Brief Backlight flash on power up.

Hmm thats not bad at all - works out at under £7 per strip for new led's. Worst case scenario is buy a set and sell the old ones on.

@Flocko - yeah hindsight is a wonderful thing as I was unaware of how critical the lens is. Bit of trial and error now needed for a spacer / washer to get the height and alignment right. Replacing one / all with used led's isnt a viable option imho.

If i was to fully rewind, i would have just pulled all the dead led's i had previously and short them as they seem to be the ones which will fail open circuit thus killing the string.

As it is, I have a few lens to work out how to align properly, then either live with or remove the 9 which are the wrong colour. Or buy a new set which should gaurantee the set for a good 2 years if the backlight is set low for all inputs.

[flocko]

Re: LG 47LN578V - Brief Backlight flash on power up.

£74.22 if you have an account, and cheaper than a new screen ! Not after you add Vat+ delivery ? so what would you invoice a customer for this cheap job? your parts markup, labour/collection and delivery.i have worked out what i would have to charge, and do not think i would have many takers and would soon be out of work

[flocko]

Re: LG 47LN578V - Brief Backlight flash on power up.

Robbie shorting out the LEDs is why the others failed ? have a look at the data of a LED string driver IC to see how they work for a better understanding (this is one of the ones that are fitted to Vestal power boards MP3394S its a four string but can be adapted to run more strings ) that i also do a repair kit for.

[michael dranfield]

Re: LG 47LN578V - Brief Backlight flash on power up.

Check out eBay UK item number:252260850432 the easy way to repair LED strips
.

Looks just like some old LED s that have been cut from a strip with a bit of wire soldered on, what we in the trade called a bodge .

[michael dranfield]

Re: LG 47LN578V - Brief Backlight flash on power up.

£74.22 if you have an account, and cheaper than a new screen ! Not after you add Vat+ delivery ? so what would you invoice a customer for this cheap job? your parts markup, labour/collection and delivery.i have worked out what i would have to charge, and do not think i would have many takers and would soon be out of work

price is including VAT and delivery , plus £30 fitting job done for £100.however at the rate new sets are falling by you wont get many people spending £100 on a repair these days.