This board was liquid damage, no power, with the lcd flex burned, connector on the board is intact.
I Fixed the liquid and managed to get the board to boot, however there is backlight but no image. I tested different screens known to be working.
I also ruled out lcd flex cable, ssd, pram and bios.
The board fully boots and it can even display an image on external monitor. I checker the SMC_LID signals and compared to anoher board and they are good, althought If SMC_lid was tripped I would normally not see a backlight.
Here are the signals and power rails I measured:
PP3V3_S0SW_LCD: 3.3V
PPVOUT_S0_LCDBKLT: 49V
PP5V_S0SW_LCD: 5V
PP5V_S0_ALSCAM_F: 5V
LCD_IRQ_L: 0V (same on known working board)
DP_INT_HPD: 3.28V
BUF_EDP_PANEL_PWR_EN: 3.3V
TCON_BKLT_PWM: 2.746V
EDP_BKLT_PWM: 3.039V
I2C_TCON_SDA_CONN: 3.3V
I2C_TCON_SCL_CONN: 3.3V
EDP_INT lines Voltage / diode mode reading:
EDP_INT_ML_P<0>: 0.47V / 0.210
EDP_INT_ML_N<0>: 0.47V / 0.210
EDP_INT_ML_P<1>: 0.47V / 0.210
EDP_INT_ML_N<1>: 0.47V / 0.210
EDP_INT_ML_P<2>: 0.47V / 0.210
EDP_INT_ML_N<2>: 0.47V / 0.210
EDP_INT_ML_P<3>: 0.47V / 0.210
EDP_INT_ML_N<3>: 0.47V / 0.210
EDP_INT_AUX_P: 0V / 0.210 (same on known working board)
EDP_INT_AUX_N: 3.3V / 0.210
I suspect the cpu went bad via some edp pins on J8500 but I am here to try anything I may not think about.
I have no more idea. Thanks!
I Fixed the liquid and managed to get the board to boot, however there is backlight but no image. I tested different screens known to be working.
I also ruled out lcd flex cable, ssd, pram and bios.
The board fully boots and it can even display an image on external monitor. I checker the SMC_LID signals and compared to anoher board and they are good, althought If SMC_lid was tripped I would normally not see a backlight.
Here are the signals and power rails I measured:
PP3V3_S0SW_LCD: 3.3V
PPVOUT_S0_LCDBKLT: 49V
PP5V_S0SW_LCD: 5V
PP5V_S0_ALSCAM_F: 5V
LCD_IRQ_L: 0V (same on known working board)
DP_INT_HPD: 3.28V
BUF_EDP_PANEL_PWR_EN: 3.3V
TCON_BKLT_PWM: 2.746V
EDP_BKLT_PWM: 3.039V
I2C_TCON_SDA_CONN: 3.3V
I2C_TCON_SCL_CONN: 3.3V
EDP_INT lines Voltage / diode mode reading:
EDP_INT_ML_P<0>: 0.47V / 0.210
EDP_INT_ML_N<0>: 0.47V / 0.210
EDP_INT_ML_P<1>: 0.47V / 0.210
EDP_INT_ML_N<1>: 0.47V / 0.210
EDP_INT_ML_P<2>: 0.47V / 0.210
EDP_INT_ML_N<2>: 0.47V / 0.210
EDP_INT_ML_P<3>: 0.47V / 0.210
EDP_INT_ML_N<3>: 0.47V / 0.210
EDP_INT_AUX_P: 0V / 0.210 (same on known working board)
EDP_INT_AUX_N: 3.3V / 0.210
I suspect the cpu went bad via some edp pins on J8500 but I am here to try anything I may not think about.
I have no more idea. Thanks!
