Lenovo laptops power on but no display

Bturlea

Active Member
VIP PRO
Aug 27, 2019
8
1
Hello guys!

I have 3 different laptop with same problem: Lenovo ideapad 100( MB: NM-A681 ), Z50-70 (MB: NM-A272) and yoga 700. all of them power on, fan spinning, power light on, battery charging but no display.

Made some measurement on edp port and i found that +LEDVDD 20v, +3VS 3V, but nothing on +LCDVDD_CON, DISPOFF# and INVT_PWM.
I've tried replacing the display, programming bios and ec and no difference.

Can anyone explain to me how video start sequence works on lenovo laptops?
Any suggestion what to check?
 

Bturlea

Active Member
VIP PRO
Aug 27, 2019
8
1
Lenovo ideapad 100( MB: NM-A681 ) i've seen it working.
Left if on a side for 2 weeks as needed a new palmrest and after the part arrived and replaced, on first boot display didn't show picture but windows sound was there, and on secound boot no picture, no sound.