35
MCU
Start
Normal power-on alert
tone?
Speaker works well?
Yes
No
Yes
No
MCU clock crystal X601
works well?
MCU operating voltage
VCC works well?
Yes
No
Check U606
Replace X601
No
Yes
Check whether other
control pins control well.
MCU works
well
Yes
No
Check pin
connection or
recording
programme
Replace the
speaker
