Oki OKIFAX 5400 Maintenance Manual page 343

TELU/TEL-W2/TEL-W1/TEL-W2D/TEL-W2F
3-5 TEL-W2F circuit diagram
Note: Refer to each country's hardware parameters comparison table.
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40838301TH Rev.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 the line current.
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".
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".
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 changed. Verify the sending and receiving levels after adjustment.
Side Tone Adjustment
Adjustment is unavailable.
DC V-I (voltage-versus-current) Characteristics Adjustment
Adjustment is unavailable.
Return Loss
Adjustment is unavailable.
AGC (automatic gain control)
Adjustment is unavailable.
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