Hi
Lenovo Y520, U9 -> SY6288C20 that provide +LCD_VDD -> 3.3V is burnt and has probably damaged the pch via the enable pin.
I replaced both u9 and the pch , the system boots but only displays via hdmi port. The problem is pin 8 which manages the backlight, remains at 0V and therefore disables the backlight.
This signal (bkoff#) must be at 3.3v and comes from pin 113 of the EC. Even reprogramming the bios the situation does not change.
I noticed that there is a 10k resistor RE36 (not in place by default) (for test ?) which supplies (through the RE36 RE40 resistor divider) the
3.3v to BKOFF# line. I disconnected pin 113 of the EC (to be safe) and added RE36 . Now the lcd turns on and displays.
I was wondering if this is a known issue and does replacing the EC solve the problem?
thanks for your attention
Lenovo Y520, U9 -> SY6288C20 that provide +LCD_VDD -> 3.3V is burnt and has probably damaged the pch via the enable pin.
I replaced both u9 and the pch , the system boots but only displays via hdmi port. The problem is pin 8 which manages the backlight, remains at 0V and therefore disables the backlight.
This signal (bkoff#) must be at 3.3v and comes from pin 113 of the EC. Even reprogramming the bios the situation does not change.
I noticed that there is a 10k resistor RE36 (not in place by default) (for test ?) which supplies (through the RE36 RE40 resistor divider) the
3.3v to BKOFF# line. I disconnected pin 113 of the EC (to be safe) and added RE36 . Now the lcd turns on and displays.
I was wondering if this is a known issue and does replacing the EC solve the problem?
thanks for your attention
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