Legion S7-15ACH6 No display but the laptop is turning on and booting

[yaso143]

hey can a iask anybody for ideas im currently checking a legion s7 laptop upon checking the laptop works fine but the lcd is completely black laptop's capslock responds when you click it and you can hear the windows startup tone i checked the board and the main power rail (16v on battery) and the 3.3v is present on the lcd connector of the motherboard so exposed the board of the lcd and check the voltages and found out led_en and pwr_led is missing voltages


my question what should be the voltage on led_en and pwr_led ?

[Vesko356]

my question what should be the voltage on led_en and pwr_led ?

Check the fuses first. Upload good quality image of the pcb. Classic test point names are PWM , LED_EN, VLED , LED_EN should be 3.3V, PWM is 3.3V at full brightness, VLED = main power rail. PWR_LED is most probably test point for 19V (or battery voltage if the charger is not connected) main power rail, but can be a brightness signal too, different manufacturers use different names, so to be sure test for continuity between this point and the 19V main power line fuse to find out.

[yaso143]

LED_EN (no voltage) PWM_LED(0.008v) VLED(16.5v) there are two fuses tested the and they have continuity

do you think its a lcd or edp issue ?

[Vesko356]

LED_EN (no voltage) PWM_LED(0.008v) VLED(16.5v) there are two fuses tested the and they have continuity

do you think its a lcd or edp issue ?

It's not the issue with the screen itself - you have both LED_EN and PWM_LED signals missing. Check the eDP cable for short and continuity, and the signals at the motherboard connector.

[yaso143]

here is the voltage found near the connector is there any voltage needed?

[Vesko356]

Link the schematic for your motherboard model. Random measurements here and there doesn't mean much.
Did you check the eDP cable?