Service manual

Troubleshooting
Samsung Electronics 4-17
4-6-2 FAX(only SCX-5312F)
4-6-2-1 FAX/TELEPHONE Precautions
PROBLEM ITEMS TO BE CHECKED. HOW TO SOLVE
TEL LINE CANNOT BE
ENGAGED
(NO DIAL TONE)
• When you press “ 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?
a) insert it correctly into the connection
jack called “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.
Cannot MF dial • Check CN20 (main PBA), MAIN-LIU
harness, and CN1 (LIU PBA)
• Replace defective parts.
MF dial is possible but
not DP dial.
• Check DP control signal of CN20-11 of
MAIN PBA and the circuit around R15. U6
and Q2 of Liu PBA.
• Replace LIU PBA.
Defective fax transmis-
sion
• Check CN20 (main PBA), MAIN LIU
harness, and CN1(LIU PBA).
• Is the external phone hooked off?
• 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).
• 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.
Defective automatic fax
reception
• Is the ring checked?
Check ring pattern at CN1-9 (LIU PBA).
• Refer to ‘Defective Transmission.’
• Replace LIU PBA if it cannot be checked.
• Refer to ‘Defective Transmission’.