Oki OKIFAX 5400 Maintenance Manual page 337

TELU/TEL-W2/TEL-W1/TEL-W2D/TEL-W2F
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40838301TH Rev.1
Return Loss Adjustment
The return loss adjustment is performed by the installed C-R networks corresponding
to the individual country. For adjusting the return loss, select the corresponding C-R
network by the designated DIP switch and adjust the return loss by changing the values
of capacitors and resistors.
The dip-switch set to ON corresponds to the country as shown in the table.
Country
UK
Italy/Belgium
Denmark
Norway
AGC (automatic gain control)
AGC is a function for adjusting the sending and receiving levels automatically in
accordance with the line current values, so that the optimal communication level is
automatically set. The circuit section to determine the AGC characteristics is formed
by resistors R41 and R43 connected to the AGC terminal of the speech IC. The AGC
gain is high when the resistor values are small, and the AGC gain is low when the
resistor values are large.
Pulse Dialling
Changing the make-and-break ratio is determined by the dip-switch SW4-1 and 2.
• Setting SW4-1 to ON and SW4-2 to OFF corresponds to a 33% make ratio.
• Setting SW4-1 to OFF and SW4-2 to ON corresponds to a 40% make ratio.
MF dialling
The MF signal sending level is adjusted by the selection of resistors and capacitors
allocated for the individual countries by the dip-switch setting.
The dip-switch set to ON corresponds to the country as shown in the table below.
Country Dip-switch
UK SW2-1
Italy/Belgium SW2-2
Denmark SW2-3
Norway SW2-4
Increase the resistor value to lower the MF signal sending level, and decrease the
resistor value to raise the sending level. The difference between the high and low
groups of the MF signal is performed by changing the capacitance of the capacitor. The
allowable level difference between the high and low groups is (2±1) dB.
Manual Pad
The manual pad is used as a countermeasure by the ON setting of SW3-8 when
howling is occurs because of line conditions. (normally set to OFF)
Dip-switch Symbol (network)
SW1-5 R29, C21, R26
SW1-6 R30, C22, R27
SW1-7 R31, C23, R28
SW1-8 R76, C54, R77
Symbol Rated Value
C31, R38 -9 dBm/-11 dBm
C70, R39 -6 dBm/-8 dBm
C71, R80 -9 dBm/-11 dBm
C72, R81 -9 dBm/-11 dBm
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