nm-c171 rev:1.0 s145-ast backlight proplem

[sonerpc]

On the s145-ast lenovo laptop with nm-c171 rev:1.0 motherboard, the image appears without illumination. When I look carefully, I can see the lenovo text. I downloaded the bordviewer and the schematic from the badcaps family, but which voltages should I measure? 20 volts come out from both ends of the fuse.

[Bonzas]

Measure this pin voltage on JEDP1 :
1) +LEDVDD ( 19v )
2) DISPOFF# ( 0v = active low )
3) INVT_PWM ( 3v )
4) LCDVDD_CON ( 3v )

but before doing that. if it's me, i'll try with another lcd

[sonerpc]

Measure this pin voltage on JEDP1 :
1) +LEDVDD ( 19v )
2) DISPOFF# ( 0v = active low )
3) INVT_PWM ( 3v )
4) LCDVDD_CON ( 3v )

but before doing that. if it's me, i'll try with another lcd

I tried it with another LCD panel. The result did not change. I will check the voltages you mentioned.

[sonerpc]

Measure this pin voltage on JEDP1 :
1) +LEDVDD ( 19v )
2) DISPOFF# ( 0v = active low )
3) INVT_PWM ( 3v )
4) LCDVDD_CON ( 3v )

but before doing that. if it's me, i'll try with another lcd

INVT_PWM ( 3v ) There is no voltage on this pin. There is no 3v signal. There are other voltages you mentioned.

[Bonzas]

If you brave enough, remove R19 and make jumper on invt_pwm side from 3vs. But make sure no short on invt_pwm pin

[Maestro Electronics]

its can be backlight lcddriver

[mon2]

Does pin 4 (EN) of U7 have a voltage? U7 may be defective.

[sonerpc]

If you brave enough, remove R19 and make jumper on invt_pwm side from 3vs. But make sure no short on invt_pwm pin

There is no short circuit, but how should I do it? Can you give me some more information, where is r19?

[Bonzas]

There's boardview on here

https://www.badcaps.net/forum/troubl...52#post1759252