LG 43UF640V backlight good but black screen and no sound

[totof]

Good morning.
I have a problem with my LG Smart 43UF640V TV. It starts, the backlight comes on but nothing is displayed on the screen and there is no sound.
I thought it was a TCon problem and ran various tests. If I disconnect one or the other of the cables from the tcon to the panel then the screen is white on the side where the cable is disconnected and black on the other side. If the two cables are disconnected the screen is completely black.
In the 4 configurations I measure exactly the same voltages on the tcon card (model V15 43UHD TM120 Ver0.4) :

HVDD : 7,28 V
VGL1 : -4,99 V
VGL2 : -9,96V
VCOM1 : 5,71V
VCOM2 : 5,69V
VGH_ODD and VGH_EVEN : switch between 27,96V and -9,94V
VDD : 14,45V
VCORE : 1,21V
VCC18 : 1,8V

These voltages seem correct to me and so I don't know if the problem could be the panel, the tcon or the motherboard. Do you have any advice to help me with my research ?

Thanks

[Bholu]

hello friend this fault comes with y line shorting u need to locate ckv ckv1 ckvb ckvb2 stvp points they are always go through right and left source pcb to the glass.first cut right side if picture ok then good or picture is not good you need to jumper them and cut other side lines.try this

[totof]

hello friend this fault comes with y line shorting u need to locate ckv ckv1 ckvb ckvb2 stvp points they are always go through right and left source pcb to the glass.first cut right side if picture ok then good or picture is not good you need to jumper them and cut other side lines.try this

Thank you Bholu for your help.
I don't found ckv ckv1 ckvb ckvb2 stvp points but I found service manual for my TV and signal name are different (see the attached document).

[Bholu]

These are the ckv lins first of all block right side then try left side check it one by one with the help of cello tape.

[totof]

I blocked all CLK signals, one by one, on each left and right side, and screen remains always with no video.
Just to notice that for CLK4 signal half of the screen is black deep.

[totof]

Is somebody has another idea to help me to determine the origine of the problem ?

[Diah]

try replace t-con incase only you have sound

if no sound then the issue at maunboards

[totof]

Thank you Diah.
There is no sound and when I disconnect only one nappe between tcon board and lcd panel I have no video, even on the side still connected to the lcd panel.
I don't know how to check the mainboard. Maybe it can existe a debug port.

[Diah]

Thank you Diah.
There is no sound and when I disconnect only one nappe between tcon board and lcd panel I have no video, even on the side still connected to the lcd panel.
I don't know how to check the mainboard. Maybe it can existe a debug port.

in general what you did to disconnect half screen and it show for you half white mean communication and panel with t-con are fine..... NO sound mean the fucking mainboards didn't work at all. so no signal to damn T-CON.

so why you go to involve with VG and CK... hope you are just testing didn't damage parts.

[Diah]

hello friend this fault comes with y line shorting u need to locate ckv ckv1 ckvb ckvb2 stvp points they are always go through right and left source pcb to the glass.first cut right side if picture ok then good or picture is not good you need to jumper them and cut other side lines.try this

welcome in this forum... but please DON'T JUDGE WITH OUT EXPLANATION;: SERVICE MANUAL AND SCHISMATIC COVERED THE NET OVER ALL::: HERE NEEDED ADVICE WITH EXPLANATION SO OTHER WILL LEARN AND FOLLOW:

[totof]

Finally I was wrong and there is sound on the TV.
I checked all the resistances and capacitances on the panel PCB and nothing abnormal (no short circuit, 3 resistance values noted: 0 ohm, 30 ohms and 100 ohms).