Oki B 4100 Maintenance Manual page 474

3-2 TEL-W2F circuit diagram
Note: Each country's hardware parameters comparison table refer to page A3-82 ~ 83.
1) Speech IC
General functions of the speech IC are as follows:
• Basic speech functions included.
• Separate receive pre-amplifier with signal output terminal
• Separate receive power amplifier input terminal, cause it is possible to mixing input.
• Balanced input for microphone input to provide immunity to common mode noise.
• MF pre-amplifier input terminal is possible to mixing input.
• Dial pulse waveform improvement circuit included.
• Manual pad function included.
• The transmit, receive, and DTMF amplifier are provided with AGC in accodance with
2) Sending Level Adjustment
The sending level is determined by the circuit section formed by resistors R55, R56,R57
and R58, and the bits of R110-R114 connect the resistors in parallel. The sending level is
maximum when all the bits of R110-R114 are set to "Mount", and minimum when all the
bits of R110-R114 are set to "Not mount".
3) Receiving Level Adjustment
The receiving level is determined by the circuit section formed by resistors R34, R35, R36,
R37 and R38, and the bits of R101-R105. The receiving level is minimum when all the
bits of R101-R105 are set to "Mount", and maximum when all the bits of R101-R105 are
set to "Not mount".
4) Sending Frequency Response Adjustment
The circuit section affecting the low range level of the sending frequency response is
formed by capacitors, C35 and C36, which are connected in series to the section in front of
a transmitter.
Note: When the fequency response is changed, the sending and receiving levels may be
5) Side Tone Adjustment
Adjustment is unavailable.
6) DC V-I (voltage-versus-current) Characteristics Adjustment
Adjustment is unavailable.
7) Return Loss
Adjustment is unavailable.
8) AGC (automatic gain control)
Adjustment is unavailable.
40055101TH Rev.4
the line current.
changed. Verify the sending and receiving levels after adjustment.
474 /