Trouble Shooting Chart
Oscillation from Microphone
Solution: replace U601
Solution: Replace C609
Solution: repair the faulty part
GO
NO
YES
NO
YES
NO
Feedback-Oscillation when switch
the Microphone output
Check point: the pin 2 of U601
on echo board
Observe: check the voltage is
Check point: Capacitors C605
to C610 at U601
Observe: check if there is any
poor soldering or short circuit
Check
point: capacitors
C602 to C604 at U601
Observe: check if there is
any poor soldering or short
circuit
4-10