LG 47lw5700 back light no video

[microvibe]

I have LG 47lw5700

Initial issue
I get red standby press button turns blue backlight comes on but no video.
I have 12v both sides tcon fuse.
Pin out voltage
NC 0v error
12v 11.98v pwm
12v 11.98v n. C.
12v 11.98v drv on
Gnd vsync
Gnd gnd
3.5v 3.48v
3.5v 3.48v
Gnd
Gnd
24v 24.1v
Pwr on 3.48v

If I unplug cable on left tcon to panel picture comes up on screen TV functions fine on that half. Is it a bad panel or tcon

[budm]

Re: LG 47lw5700 back light no video

'If I unplug cable on left tcon to panel picture comes up on screen TV functions fine on that half'
Bad panel.

[microvibe]

Re: LG 47lw5700 back light no video

Damn thought maybe tcon or main guess nothing on the panel board could cause that . The board that connects to tcon from panel. When left disconnected it just stays white other side has picture. If I disconnect panel cable while TV on it gets some lines flicker.

[microvibe]

Re: LG 47lw5700 back light no video

Found this corrosion on the board that's attached to the panel. Possible this could be causing problems? And panel still good.
Cleaned it up but when I was probing psu to main pinouts I shorted 24v to ground now plug in relay clicks on psu I still have all voltages coming out of psu but no red standby does nothing when power button pressed. Would this panel be used in a LG 47lh30 or 47ld520?

[budm]

Re: LG 47lw5700 back light no video

One of those LCD panel with tab bonding board on the bottom edge of the panel, people just spray the cleaner on the screen and it drips all the way down to the boards and ruin it.

[microvibe]

Re: LG 47lw5700 back light no video

So not worth me trying to fix main board then. That corrosion ruined the panel

[Brokit]

Re: LG 47lw5700 back light no video

My 42LS570S displays half a good picture when I unplug the ribbon from the right side of the Tcon and a replacement Tcon did not fix the fault. The tab bonding board connected to the screen also shows sign of corrosion, probably due to liquid damage as above. The damaged board looks like it contains caps and resistors and the board its self and the bonded tabs look ok. I have found the LG specification sheet for the screen and board and replacements (left and right pair)are available if you do a search. I would like to attempt to replace the damaged components on the damaged rhs board but I am unable to find the circuit diagram stating the values of the components. The board is P/N 68705-13538 DESC - V12 42FHD Right Ver 1.0 H/F. Does anyone know/have any information on this board?

[simo]

Re: LG 47lw5700 back light no video

i fixed one like this model, with the same problem, it was mainboard problem, i got a backlight but no picture, i did a CPU reflow,and i put a small fan to avoid any overheating in the futur, the Tv still working right now, it has been for 10 months ago, you can try with heatgun, just remove big balck heatsink and heat up a little bit the Bga chip,

[microvibe]

Re: LG 47lw5700 back light no video

The video displays fine if one ribbon going to corroded tab bond board removed. Not main board. It has just bit corrosion I think I am going to clean it up starting probing caps comparing to other side . But right now I shorted 24v on main by mistake trying to fix that

[Brokit]

Re: LG 47lw5700 back light no video

42LS570S Does anyone have the circuit diagram stating the values of the resistors and capacitors on the board P/N 68705-13538 DESC - V12 42FHD Right Ver 1.0 H/F. Does anyone know/have any information on this board?

[microvibe]

Re: LG 47lw5700 back light no video

Would anyone know what other model uses this panel. I think I toasted this main board and there to pricey to buy for testing . I can get a little of 47-50" broken screen don't know what models tcons and main boards would Jimmy rig to test this panel.

[Brokit]

Re: LG 47lw5700 back light no video

I have the service manual for the 42LS570s but the title of the manual says it covers the 42LS570S,570T-ZB,42LS575S,575T-ZD as well. The main board number is EBT62013872 just in case your 47lw5700 uses the same board.
Have you tried a search for the 47lw5700 service manual. It may include other compatible models for your main board.

[Brokit]

Re: LG 47lw5700 back light no video

https://www.electronica-pt.com/esque...s-lb12c-26443/

47lw5700 service manual

[microvibe]

Re: LG 47lw5700 back light no video

Shows only 2 models but I know 55lw5700 same main board. How would you search where the panel itself is all used in

[Brokit]

Re: LG 47lw5700 back light no video

I would suggest doing a google search for the board number and see what results turn up. Sometimes websites selling spares list the compatible board models on their site.