High-Speed Modem Test - Oki OKIOFFICE44 Service Manual

7.1.13 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 (WN5)?
No
Replace R44 Board.
Troubleshooting
RX
A
Yes
TX End
Yes
Replace WN5 Board.
Solved?
No
Replace R44 Board.
Signal route:
IC8-26 to 33 (AD0 to AD7)
IC8-1, 2 IC12-7 (S) CN10-A8, B8 (S)
CN1-3, 4 (S)
7 - 20
Signal route:
CN3-15, 16
CN1-3, 4
Yes
Possible cause:
CML signal
Return to section 7.1.1
OKIOFFICE 44
Service Manual, P/N 59276801