[SOLVED]820-2850 no backlight - no bklt_pwm

[ytesfay80]

I have this board that was sent in from another shop. It appears as if there was liquid damage but not in the area of the LCD connector or the LP8545.
I tested with another display I have and that one also had no backlight and I could see the flashing folder as well.
BKL_EN measured 3.11v but when I measured R9704(BKLT_PWM) I got 0.008v.

On Pin 40 of the LCD Connector I was getting around 24v on backlight.

I even ran a wire from pin 2 of R9731 to Pin1 of R9704 and when I measured BKLT_EN and BKLT_PWM they both measured 0v which looks like something is pulling those down.

Should I replace the LP8545 or should I ultrasonic the board to make sure the U9600 chip is not the issue?

 

[dukefawks]

Resistance to GND on PWM line? Remove R9704 to check which side the short is.

 

[ytesfay80]

Resistance to ground on PWM is 98kohms.

R9704 is not shorted to ground. In diode mode R9704 is 0.44v.

 

[dukefawks]

You can try to replace the 8545 and if that does not help remove R9704 and connect to 3V directly. I assume you did a few PRAM resets and such?

 

[ytesfay80]

I did the first two things you said to do and neither worked so I did a PRAM Reset and the backlight appeared and everything is working fine.

Thanks duke!