Troubleshooting Flow Chart
MCU
Start
Normal power-up
alert tone?
Yes
No
Normal speaker?
Yes
Normal MCU
VCC?
Yes
Normal MCU
X601?
Yes
Other control pins
are normal?
Yes
MCU is OK
No
Replace it
Check U601,
No
U602, U604,
and U606
No
Replace X601
Check pin
No
connection or
reburn the
program
40
Service Manual