Lenovo S145-15IWL nm-c121 black screen

[Jokerx84]

Hello!
I would like help with a Lenovo S145-15IWL nm-c121 motherboard, there is no picture on the display, but there is hdmi!
With display, lvds no problem!
The lid has been hit hard, it hasn't worked since!

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

Do you mean display via hdmi on external monitor is ok but no display on internal screen??

If yes, is there dimm display on internal screen-means image is there but no backlight??
Have you tried a known good working screen??
LID SWitch checked??

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

Do you mean display via hdmi on external monitor is ok but no display on internal screen??

If yes, is there dimm display on internal screen-means image is there but no backlight??
Have you tried a known good working screen??
LID SWitch checked??

No backlight, no faint image, just black screen, it worked on another laptop!
I also checked the cover switch, that's good too!
Sorry for the bad English!

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

Measure voltage(JEDP1) on following pins
Pin 1-2
Pin 15
Pin 16

Voltage on all pins of U3301

Be careful while measuring on JEDP pins. Your probe should be needle sharp.

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

Measure voltage(JEDP1) on following pins
Pin 1-2
Pin 15
Pin 16

Voltage on all pins of U3301

Be careful while measuring on JEDP pins. Your probe should be needle sharp.

pin 1-2=20.1V
Pin 15=3.3V
Pin 16= 0V

U3301
pin1=0
pin2=0
Pin3=0.1
pin4=0
Pin5=3.3

[Techtiger]

Re: Lenovo S145-15IWL nm-c121 black screen

pin 1-2=20.1V
Pin 15=3.3V
Pin 16= 0V

U3301
pin1=0
pin2=0
Pin3=0.1
pin4=0
Pin5=3.3

Enable single is missing from PCH to output LCDVDD U3301 pin4 check again

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

As@techtiger has mentioned, you've missing EN signal on pin4. Without this EN signal, you wont get any voltage on pin1. This is a common fault on many mb's. What's the resistance on Pin1 of U3301?? If the resistance is low, remove U3301 and check resistance on pin1 again. If resistance is ok on pin1, then jumper Pin5 to Pin1(U3301 removed).
Hope this works for you.

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

Update about the post#7 and then we need to fix missing voltage on PIN16 of JEDP1 as well. Voltage at Pin16 is also a must requirement.

PS: Probably you wont get display even after taking steps at post#7 but we can still fix it. Just give feedback and follow correctly. If you dont understand what i've said, feel free to write.

[raajkumar]

Re: Lenovo S145-15IWL nm-c121 black screen

I had similar issue on same board. I flashed bios with new one. power led is blinking. all other voltages are coming but only cpu_Dramrst is showig 0v.

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

As@techtiger has mentioned, you've missing EN signal on pin4. Without this EN signal, you wont get any voltage on pin1. This is a common fault on many mb's. What's the resistance on Pin1 of U3301?? If the resistance is low, remove U3301 and check resistance on pin1 again. If resistance is ok on pin1, then jumper Pin5 to Pin1(U3301 removed).
Hope this works for you.

U3301 pin1=26.1kohm

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

I had similar issue on same board. I flashed bios with new one. power led is blinking. all other voltages are coming but only cpu_Dramrst is showig 0v.

i flashed more bios and kbc and even kbc was a replacement

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

U3301 pin1=26.1kohm

Go ahead and jumper pin5 to pin1(U3301 removed)

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

Go ahead and jumper pin5 to pin1(U3301 removed)

jumper, no change

[JaroTech]

Re: Lenovo S145-15IWL nm-c121 black screen

Hi, just to be sure for the lid switch, you have 3.3 volts on pin 3 of U3601.

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

hi, just to be sure for the lid switch, you have 3.3 volts on pin 3 of u3601.

3.25v

[JaroTech]

Re: Lenovo S145-15IWL nm-c121 black screen

I don't doubt what you said before, it's just that we both check the value of the lid switch the same way.

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

jumper, no change

I expected this and have told you so. Now focus on pin16. What is the resistance on pin16?? If resistance is ok then try injecting 3V on pin16 and see if screen glows. If you dont have a dc supply to inject voltage, you can jumper between pin15-16. But before proceeding with either way, do remember to check resistance on pin16.

PS: I had the exact same fault on hp LA-D704 and fixed by removing UG1(Same as U3301 in your case) and jumpering IN-OUT pins and then shorting pin15-16(in my case perhaps pin 23-24)

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

I expected this and have told you so. Now focus on pin16. What is the resistance on pin16?? If resistance is ok then try injecting 3V on pin16 and see if screen glows. If you dont have a dc supply to inject voltage, you can jumper between pin15-16. But before proceeding with either way, do remember to check resistance on pin16.

PS: I had the exact same fault on hp LA-D704 and fixed by removing UG1(Same as U3301 in your case) and jumpering IN-OUT pins and then shorting pin15-16(in my case perhaps pin 23-24)

pin16=76kohm

unfortunately i don't have a dc power supply

possibly jumper R3314?

[mcplslg123]

Re: Lenovo S145-15IWL nm-c121 black screen

Instead of jumpering R3314, put a 0 Ohms resistor there.

[Jokerx84]

Re: Lenovo S145-15IWL nm-c121 black screen

Instead of jumpering R3314, put a 0 Ohms resistor there.

I did, no change