Xerox WorkCentre XK50cx, Service Manual

Page: 62 / 109

5-6
Troubleshooting
PROBLEM ITEMS TO BE CHECKED HOW TO SOLVE
TEL LINE
CANNOT BE
ENGAGED
(NO DIAL TONE)
Cannot MF dial
MF dial is
possible but not
DP dial.
Defective fax
transmission
Defective
automatic fax
reception
• When you press “ OHD” key:
a) Check line cord connection.
b) Check MAIN LIU harness, and P1(LIU
PBA).
c )Check relay operation of LIU PBA : Is
the control signal of CN8-7(main) low?
• Check CN8 (main PBA), MAIN-LIU
harness, and P1 (LIU PBA)
• Check DP control signal of CN8-11 of
MAIN PBA and the circuit around R15.
U6 and Q2 of Liu PBA.
• Check CN8 (main PBA), MAIN LIU
harness, and P1(LIU PBA).
• a) Is the external phone hooked off?
b) Is the output of US-4(LIU PBA) low?
• Check ‘hook off’ : Refer to ‘TEL LINE
CANNOT BE ENGAGED’ above.
• Check the control signals of CN8-11.
• Check transmission path : Check output
of CN8-3.4 and T2-4(LIU PBA).
• Check reception path : Check output P1-
1 (LIU PBA) and input of CN8-1(main
PBA).
• Is the ring checked?
Check ring pattern at U9-4 (LIU PBA).
CN 8-9.
• Refer to ‘Defective Transmission.’
• a) insert it correctly into the connection
jack called “line”.
b) Replace defective parts.
c) Replace main PBA IF the control signal of
CN8-7(main) is high.
Replace LIU PBA if high but phone line cannot
be connected.
• Replace defective parts.
• Replace LIU PBA.
• Replace defective parts.
• a) Hook on the external phone correctly.
b) 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 P1-1(LIU PBA) is not
confirmed.
Replace main PBA if CN8-1(MAIN PBA) is not
confirmed.
• Replace LIU PBA if it cannot be checked.
• Refer to ‘Defective Transmission’.
5-3 FAX
5-3-1 FAX/TELEPHONE Precautions