No Working
Y
N
N
Y
N
I2C BUS
wokring if
OK
Power supply if
OK
LED if Lighting
check 3 control
voltages(power-
on/off,panel-on/off,on-
pback,) if OK,
check 5vstb voltage
if OK
Check the relevant
circuitry,e.g.power
supply B.D
check
relevant
circuitry
check working conditions of U300 if OK
crystal/Reset
circuitry working if
OK
U301/U302/U305 power
supply and SCL/SDA
Fig1. No Working
