backlight problems can be:
1. the lamp failure, becouse of long terms of using.
2. the transformer failure(low quality, or(!) dead or old lamp(the initial current is very high and the transformer is burned))
3. PWM controller failure(VERY rarely)
4. lack of backlite_ena signal, or 5v voltage for PWM working or lack of ACBAT_SYS voltage(battery voltage or AC adaptor voltage)
1. the lamp failure, becouse of long terms of using.
2. the transformer failure(low quality, or(!) dead or old lamp(the initial current is very high and the transformer is burned))
3. PWM controller failure(VERY rarely)
4. lack of backlite_ena signal, or 5v voltage for PWM working or lack of ACBAT_SYS voltage(battery voltage or AC adaptor voltage)