820-00426 no backlight

[ajdoc]

Small liquid damage on J5250 and R6323.

There is no backlight (there is data on LCD).
PPVOUT_S0_LCDBKLT = 0V (1.1V in diode mode)
PP5VR3V3_SW_LCD = 5V

Connected known good display assembly and same issue.
Ext display works and internal display is detected in macOS.

Replaced J5250, C5250, R5250 and same issue.

Power button is not working, connected new keyboard and still same issue so I think there is some issue with lid sensor?
It think lid is closed so power button is not working and thats why there is no backlight.

SMC_LID = 5V

With LCD attached and machine powered i do get
(pin 5) PP3V3_S0_EDP_SW = 3.3v
(pin 8 ) LCD_BKLT_PWM_R = 2.09v
(pin 9) LCD_HPD_CONN = 3.3v
(pins 28-30) PP5VR3V3_SW_LCD = 5v.

BKL_EN_R = 3.3V


When board run on charger I can't shut down with power button but can't turn on so I am sure it will be something with lid sensor etc.

Any hints/ideas?

 

[2informaticos]

"SMC_LID = 5V"
Are you sure about this?
SMC doesn't accept 5V on inputs; and that signals is pulled-high to 3V42_G3H.

Check triggering SMC_ONOFF_L, instead of using power button.

 

[ajdoc]

Sorry, SMC_LID = 3.3V

SMC_ONOFF_L - can turn ON and OFF without any problems.

 

[ajdoc]

Q7701, Q7706 had solder balls around so replaced them and new U7701 and backlight works

Keyboard was faulty as well so thats the reason why power button was not working.