A1706 820-00239 No picture via LCD but external works - Not Flexgate

[it-solve]

I got this A1706 820-00239, which had a screen issue. Probably one of my test screens is problematic as after connecting it I lost the internal picture, tested other screens still same.
Torch shine through it, to check if its only BL but cant see anything.

It turns on and chimes, capslock is responding but no internal picture. External works with disconnected LCD.

It must be related to LVDS, as happened when testing screens. LVDS has no damage. Where to check first? Tried PRAM reset, SMC reset. LCD matrix usually turns black, this one doesn't seem to turn black at all.

20V 0.345A with connected different test lcd

PP5V_S0 - 5.15V
PP3V3_S0SW_LCD - 0V
PP5V_S0_ALSCAM_F - 5.15V
PP5V_S0SW_LCD - 0V
PANEL_P5V_EN - 0V

u8510
PANEL_FET_EN_DLY - 0v
EDP_PANEL_PWR_EN - 0V
PM_SLP_S3_L - 3.3V


This U501, R5351, and CC728 area looks a bit weird, but I think it's flux. Dont see any liquid damage anywhere.

The only anomaly is this area on the backlight cover which seemed ripped off when fitting in the factory and perhaps introduced something through 8,9,0 keys.

 

[2informaticos]

3V3_S0SW_LCD is required for the image.
It must come on at least in the first few seconds (when machine chimes).
DP_INT_HPD should come high at same time.
Check diode mode to ground on EDP_INT lines of J8500; pay atention at pins 1 & 3.

BTW, there is EDP, not LVDS!

 

[it-solve]

j8500
All EDP_INT_* lines 0.234Vdc range except EDP_INT_AUX_N (pin 1) which is 0L

 

[2informaticos]

That's a good reason for no video at all, on internal LCD.
Broken trace, or CPU eDP output is fried.

BTW, stop posting "V" after diode mode readings.

 

[it-solve]

Thanks for your help