LG 42LW4500 distorted picture and bootloop

[khaahk]

Hi
power rails seem ok.
Added picture and video.

Reseated all connectors, did a reflow of main cpu LGE1027DC.
No change.
Tcon or mainboard? Any ideas?

[attainteddragon]

Re: LG 42LW4500 distorted picture and bootloop

might be panel, but it could be tcon as well. disconnect a ribbon cable that goes from the tcon to the panel and see how it effects the picture, then do the opposite side.

does it effect the osd as well?

[khaahk]

Re: LG 42LW4500 distorted picture and bootloop

if TCON to panel one ribbon disconnected - one half picture white the other stays the same (with defects). The same with the other ribbon.

When i disconnect PL704 (41Pin LVDS Connector for FHD 120Hz)from main to tcon then picture shows the same defects but looks interleaved (white logo is striped).
When i disconnect PL703 (51 pin LVDS Connector for FHD 60/120Hz) from main to tcon then picture stays black.

OSD does not show up - reboot happens too fast.

[attainteddragon]

Re: LG 42LW4500 distorted picture and bootloop

if the screen is the same with either side disconnected, then your panel should be ok.

i missed the bit that said it was in bootloop. i would be looking at the main board then.
not sure if i can be much more help on this one. have you tested the voltage regulators?

[dskall]

Re: LG 42LW4500 distorted picture and bootloop

Heat/cool small sections of mainboard to see if it will come on. Looks like some noise maybe cap or regulator going bad.

[khaahk]

Re: LG 42LW4500 distorted picture and bootloop

Will give it a try, thanks everybody for ideas.

[khaahk]

Re: LG 42LW4500 distorted picture and bootloop

In the end had to change the mainboard (bootloop disappeared) but the picture had different kind of vertical lines. After changing tcon - everything is fine.

[attainteddragon]

Re: LG 42LW4500 distorted picture and bootloop

sucks that you had to change both boards, but great that it is working again.

enjoy.