Solutions for indicator light light-up problems

1. Check the circuit of indicator light, whether the low level from MCU output to triode is normal --- High level 3.3V and low level 0V goes opposite when switches,  if it’s abnormal, check whether broken circuit or Rosin joint happened between circuit and MCU;

2.+-3V Check whether the supply voltage of triode is 5V, and triodeoutput is normal, Measure the Voltage of the two end of indicator light to seewhether it is +-3V,

3. Check whether disconnection happened between main board socket and the key, or circuit board.  and whether short circuit happens upon thecircuit board against the ground.

4. Change the indicator light when necessary.