LG 55LW5590 no display, no backlight

[unimatrix93]

Dear forum, I trying to fix up my LW 55LW5590 TV.

The original board has graphical artifacts, so I odered a new one from Aliexpress.

But with this board, the TV's backlight, nor the display won't turn on.
The stabdly led turns white when I touch the power button, but nothing happens.

I tried moving IC5202 and IC601 to the new board, but nothing changed.

[Davi.p]

Put the original board (we are talking of witch board?) and post photos of the video appearance, then we can judge if new board must work or not, generally appears you got the wrong board, LG ones have usually 3 codes and must match all ones

[unimatrix93]

Put the original board (we are talking of witch board?) and post photos of the video appearance, then we can judge if new board must work or not, generally appears you got the wrong board, LG ones have usually 3 codes and must match all ones

I don't have the original board anymore, but I do have photos of it's stickers/codes:


The original board produced purple artifacts all accros the display. However the spinning LG logo and everything else worked perfectly. The problem was caused by the dying URSA5 Extrenal FRC IC. Cooling it with an active fan and bigger heatsink helped the artifact temporarely.

[Davi.p]

EBT... is one of the codes, i think this is the most important because it identifies the softwares, artifacts of witch shape? wasn't them circle shape and faded? in that case bad.leds can be..

[unimatrix93]

EBT... is one of the codes, i think this is the most important because it identifies the softwares, artifacts of witch shape? wasn't them circle shape and faded? in that case bad.leds can be..

No they were blocky purple like graphical glitches.

I think I forgot to transfer IC602 from the original board, can this kind of IC be reprogrammed by Ch341A?

[Davi.p]

write me the printing on it..

[unimatrix93]

write me the printing on it..

The printing on IC602? It's F0514A.

[Davi.p]

It is a standby IC, there's no need i think, unless the remote has some keys not working or scrambled..

[lotas]

F0514A - micom Renesas UPD78F0514A

[lotas]

It is a standby IC, there's no need i think, unless the remote has some keys not working or scrambled..

It just gives commands to turn on the backlight, t-con, dc/dc convectors...

The processor often suffered on this chassis.

[unimatrix93]

It just gives commands to turn on the backlight, t-con, dc/dc convectors...

The processor often suffered on this chassis.

But it has internal flash memory or it doesn't mattery which software is on it?

I was suspecting the CPU too. Should I try the "oven method" and see if it helps?

[Davi.p]

Have you got the schematics?

[lotas]

Have you got the schematics?

Yes, here you go.

[lotas]

Try heating the processor with a hairdryer, turn it on a little when it cools down and see.

[unimatrix93]

Try heating the processor with a hairdryer, turn it on a little when it cools down and see.

I have a hotair soldering station, a 858 clone.
What temperature and air settings should I use?

[lotas]

Yes, set it to 350 + warm it up, this method will not fix it, only for the location that the problem is there...
Sometimes a full reboot helps, sometimes replacing the processor, but you won’t find a new one that works...

[Davi.p]

sorry it is on post #1 (i'm at work, if master see me...) , page 52 , point n.2 =micom for key/IR...

Lotas, old board is not present, new board is sold as good, no need to reflow, probably stickers doesnt match, is it right unimatrix?

Post here the EAX code of main board, i search a picture, i point you the memories to swap, surely the NAND flash (TSOP48 package)

Where is the FRC IC? i see none on the picture of Service manual.. only Processor

[lotas]

page 52 , point n.2 =micom for key/IR...

Sometimes you need to look at diagrams to see what micom is responsible for...

[unimatrix93]

sorry it is on post #1 (i'm at work, if master see me...) , page 52 , point n.2 =micom for key/IR...

Lotas, old board is not present, new board is sold as good, no need to reflow, probably stickers doesnt match, is it right unimatrix?

Post here the EAX code of main board, i search a picture, i point you the memories to swap, surely the NAND flash (TSOP48 package)

Where is the FRC IC? i see none on the picture of Service manual.. only Processor

This is the original board EAX:

And this is the new one:

You are right about the EAX, it's doesn't match.
The FRC IC is under the black heatsink next to the LVDS connectors.

I already swapped the TSOP48 package next to the CPU, a Toshiba IC. I removed it back then from the original board for saving it.

[Diah]

buying complete boards from aliexpress not a good idea... because they don't have working one...most all mainboards or power boards etc are parts didn't passed "QC" quality control at the manufacture so they sell it as used or some write as new... but 90% of them have fault.