Samsung FACSIMILE SF40 Service Manual page 22

Chart 9 No Receive
Called machine
Auto answer? Receive data?
See chart 7
Check Tx/Rx
Check tel-line signal from P4-6
to P4-1
NO
Replace main
board
Chart 10 No Dial Tone
Lift handset
from fax
NO > Replace LIU
board
Dial tone
~ O.K?
Dial tone
O.K?
YES
YES
NO
Replace main
board
21