Tone (Tel/Fax) Send Test - Oki OKIFAX4550 Maintenance Manual

7.15

Tone (TEL/FAX) Send Test

Start
Connect oscilloscope probe
across the line terminals
L1 and L2.
Perform TONE (TEL/FAX)
SEND TEST. (See 6.13.)
Pseudo-Ring Back Tone
signal appears
across L1 and L2?
Yes
End
Return to section 7.1
41309401TH Rev.4
Note: The pseudo-ring back tone is sent to the
No
MF signal appears across CN10-A4
(S) and CN10-B1 (0V) of MCNT board?
Yes
Replace NCU Board.
Yes
Solved?
No
Replace MCNT Board.
telephone line for TEL/FAX automatic
switching.
No
Replace MCNT Board.
Signal route:
<46F>
IC8-87 to 95 (D0 to D7)→
IC8-28, 29→IC12-7 (S)→
CN10-A4 (S)
<R46>
IC6-87 to 95 (D0 to D7)→
IC6-28, 29 → IC10-7 (S)→
CN10-A4 (S)
Possible cause:
CML signal
237 /