Oki B 4100 Maintenance Manual page 296

Test other fax machine under the same
conditions, especially concerning Step 1-4.
The hardware of the troubled fax machine
may be damaged.
Go to 7.13 (High-speed Modem Test)
to localize the cause.
Description: Protective tone is 1700 Hz/200 ms.
40055101TH Rev.4
A
Do they transmit normally?
Yes
This signal is added to training signal to protect the training signal against echo
as follows.
TX TR
Protective tone
1700 Hz/200 ms
No
Check the line and the network.
Note: Even if the high-speed modem test
results in success, 300 bps signal route
remains unchecked. In that case, the
most suspected unit is MCNT Board.
message signal
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