Casio PX-780 Service Manual page 21

4-18. Printer NG
Battery volvage
6.0V?
NG
Low Battery
4-19. Key Backlight NG
Check the connection
of CN16.
NG
Connector is loosely
connected.
4-20. MCR NG
Check the connection
of CN14.
OK
Check the connection
of CN19.
NG
Connector is loosely
connected.
OK
FFC
damaged?
No
OK
FFC
damaged?
No
OK
Replace Printer,
check again.
NG
Yes
Replace KEY PCB,
check again.
No
FFC is defective.
Yes
Change it and check
again.
Replace MCR PCB,
check again.
NG
– 19 –
OK
Printer is defective.
MAIN PCB is defective.
FFC is disconnected.
OK
KEY PCB is defective.
MAIN PCB is defective.
OK
MCR PCB is defective.
MCR Head is
defective.