Troubleshooting - Casio ap-21 Service Manual

1. No power
Replace main PCB.

TROUBLESHOOTING

Check fuse F401.
Is F401 blown up?
Check fuses F402, F403, and
F404.
Are the fuses blown up?
Measure output voltages of
the transformer.
Yes
Are the voltages 21.6 V AC
and 8.4 V AC?
Check the power switch.
Is it OK?
Check position of voltage
selector.
Is it OK?
Replace the transformer.
— 11 —
Yes
No
Yes
No
No
No
Yes
No
Yes
Replace F401.
Replace F402, F403, and
F404.
Replace the power switch.
Set the voltage selector at
proper position.