4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

[r ez a]

hello friends
this board came with dead kbc, i replace it and its alive now
hdmi display is good but there is no lvds
i tried new bios,led and led cable
LCDVDD_EN=v0 and 36Ω
if i jump pin 3 and 4 of u4901 led will turn on just black
i see activity on edid

any idea?
should i try new kbc?

[mon2]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

Link or post a schematic.

[r ez a]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

Link or post a schematic.

here it is

[mon2]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

Resistance to ground of LCDVDD_EN is 36 ohms?

That is very low.

Measure the voltage to ground of

LCD_SMBCLK_C
LCD_SMBDATA_C

Pin 11 of Lvds connector
Pin 25 of Lvds connector
Pin 26 of Lvds connector

If the resistance to ground is very low on lcdvdd_en then consider to remove u4901 and measure again. No power when measuring in resistance or diode mode.

[r ez a]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

Resistance to ground of LCDVDD_EN is 36 ohms?

That is very low.

Measure the voltage to ground of

LCD_SMBCLK_C
LCD_SMBDATA_C

Pin 11 of Lvds connector
Pin 25 of Lvds connector
Pin 26 of Lvds connector

If the resistance to ground is very low on lcdvdd_en then consider to remove u4901 and measure again. No power when measuring in resistance or diode mode.

i measure resistance when it was plugged
when its totally off its 100k ohm

DISP_OFF#= 0V
LCD_SMBCLK_C =3.3V
LCD_SMBDATA_C=3.3V

[mon2]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

DISP_OFF#= 0V

The logic board is requesting the lcd display to remain OFF.

Check if the status changes with the top lid or angle of the opening.

There should be a lid sensor on board as well.

Toggle the hotkey used for int or ext display to see if this voltage changes.

[r ez a]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

i have another same motherboard and it work normally in same situation
currently LID_SW# =1V
after i remove D4901 :
LID_SW#= 3.3v
DISP_OFF#=0V
LCDVDD_EN=0V
LCD_BL_EN=0V

im facing wierd problem here
schematic and pcb are different
DISP_OFF# goes to pin 21 not 11

and CAM_USB_10+ that must be on pin 21 is on pin 11:|
LVDS Socket is 40 pin but pin 30 to 40 are not ground same as schematic, it's numbering doesn't make sense

[r ez a]

Re: 4540 (Rocky_Intel_MB, 11243-1 (48.4SI01.011)) No LVDS

i put all parts back and its working now:|