Tone (Tel/Fax) Send Test - Oki B 4100 Maintenance Manual

7.2.15 Tone (TEL/FAX) Send Test

Start
Connect oscilloscope probe
across the line terminals
L1 and L2.
Perform TONE (TEL/FAX)
SEND TEST. (See 6.12.)
Pseudo-Ring Back Tone
signal appears
across L1 and L2?
End
40055101TH Rev.4
No
Yes
MF signal appears across CN6-A8, B8
(S) and CN6-A12, B12 (0V) of MCNT board?
Replace NCU Board.
Yes
Replace MCNT Board.
Return to section 7.2.1
Note: The pseudo-ring back tone is sent to the
telephone line for TEL/FAX automatic
switching.
Yes
Replace MCNT Board.
Signal route:
IC12-7 IC29-13
IC29-3 IC30-1
CN6-A8, B8 (S)
Signal route:
CN3-15, 16 T1-3, 1
CN1-3, 4
Solved?
No
Possible cause:
CML signal
No
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