Fax - Xerox WorkCentre Pro 412 Service Manual

Maintenance & Troubleshooting

7-4 FAX

7-4-1 FAX/Telephone Precautions
PROBLEM
TEL LINE CAN-
NOT BE
ENGAGED
(NO DIAL TONE)
Cannot MF dial
MF dial is possi-
ble but not DP
dial.
Defective FAX
transmission
Defective auto-
matic FAX recep-
tion
7-12
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
output 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 Trans-
mission.'
August 2001
HOW TO SOLVE
a) Insert plug into the socket
named "line".
b) Replace defective parts.
c) Replace main PBA IF the con-
trol signal of CN20-7(main) is
high.
Replace LIU PBA if high but
phone line cannot be con-
nected.
• 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 sig-
nals of CN8-11 (MAIN PBA) is
low.
• Replace main PBA, if abnor-
mal.
• 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 Trans-
mission'.
WorkCentre Pro 412
Launch Issue