Xerox WorkCentre Pro 412 Service Manual page 184

Maintenance & Troubleshooting
7-4 FAX
7-4-1 FAX/Telephone Precautions
PROBLEM
TEL LINE CANNOT BE
ENGAGED
(NO DIAL TONE)
Cannot MF dial
MF dial is possible but
not DP dial.
Defective FAX transmis-
sion
Defective automatic
FAX reception
7-14
ITEMS TO BE CHECKED.
• When you press the "OHD" key:
a) Check line cord connection.
b) Check MAIN LIU harness, and
CN1(LIU PBA).
c) Check relay operation of LIU PBA:
Is the control signal of CN20-
7(main) low?
• Check CN20 (main PBA), main-LIU
harness, and CN1 (LIU PBA)
• Check DP control signal of CN20-
11 of MAIN PBA and the circuit
around R15. U6 and Q2 of LIU
PBA.
• Check CN20 (main PBA), main LIU
harness, and CN1(LIU PBA).
• Is the external phone off the hook?
• Check 'hook off': Refer to 'TEL
LINE CANNOT BE ENGAGED'
above.
• Check the control signals of CN20-
11.
• Check transmission path: Check
output of CN20-3.4 and T2-4(LIU
PBA).
• Check reception path: Check out-
put CN1-1 (LIU PBA) and input of
CN20-1(main PBA).
• Is the ring checked?
Check ring pattern at CN1-9 (LIU
PBA).
• Refer to 'Defective FAX Transmis-
sion.'
3/03
HOW TO SOLVE
a) Insert plug into the socket named
"line".
b) Replace defective parts.
c) Replace main PBA IF the control
signal of CN20-7(main) is high.
Replace LIU PBA if high but
phone line cannot be connected.
• Replace defective parts.
• Replace LIU PBA.
• Replace defective parts.
• Replace LIU PBA if low.
• Refer to 'TEL LINE CANNOT BE
ENGAGED' above.
• Replace main PBA, if the signals of
CN8-11 (MAIN PBA) is low.
• Replace main PBA, if abnormal.
• Replace LIU PBA if CN1-1(LIU
PBA) is not confirmed.
Replace main PBA if CN20-
1(MAIN PBA) is not confirmed.
• Replace LIU PBA if it cannot be
checked.
• Refer to 'Defective FAX Transmis-
sion'.
WorkCentre Pro 412, FaxCentre F12 &
WorkCentre M15/M15i