High-Speed Modem Test - Oki OKIFAX4550 Maintenance Manual

7.13

High-speed Modem Test

Start
Connect oscilloscope probe
across the line terminals
L1 and L2
Perform H-MODEM SEND
TEST for the transmitter and
H-MODEM REC TEST for
the receiver. (See Fig. 6.9.1)
Which mode, TX or RX?
TX
Modem's signal appears
across L1 and L2?
No
Modem's signal appears
across
CN3 (NCU)?
No
Replace MCNT Board.
41309401TH Rev.4
RX
A
Yes
TX End
Yes
Replace NCU Board.
Solved?
No
Replace MCNT Board.
Signal route:
<46F>
IC8-87 to 95 (D0 to D7)→IC8-28, 29 →
IC12-7 (S)→CN10-A4 (S)→NCU Board
<R46>
IC6-87 to 95 (D0 to D7)→
IC6-28, 29 → IC10-7 (S)→
CN10-A4 (S)→NCU Board
Yes
Possible cause:
CML signal
Return to section 7.1
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