Oki B4100 - Manual (Page 251)

40055101TH Rev.4 251 /
7.1.13 High-speed Modem Test
Modem's signal appears
across
CN3 (WN5)?
Start
TX
Which mode, TX or RX?
Yes
Return to section 7.1.1
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)
No
Solved?
Yes
Replace WN5 Board.
Replace MCNT Board.
TX End
Signal route:
CN3-15, 16
→Τ1−3, 1→
CN1-3, 4
RX
Modem's signal appears
across L1 and L2?
Replace MCNT Board.
No
A
Possible cause:
CML signal
Yes
No
Signal route:
IC8-26 to 33 (AD0 to AD7)
→
IC8-1, 2
→
IC12-7 (S)
→
CN10-A8, B8 (S)
→
CN1-3, 4 (S)