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156
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KX-F910BX
7-5. AUTO DISCONNECT CIRCUIT
(1)Function:
This circuit is used to detect the fact that another telephone connected to the same line is OFF-Hook while the unit is in the
time of TEL/FAX’s arrival bell ringing operation.
(2)Circuit Operation:
Tip (Ring)
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D101
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Q101
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C107
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D102
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R114
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Q102
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PC103.
During this interval C107 charges and the base of Q102 becomes high, and PC103 pin(2) becomes low, causing PC103 to
go ON. If a parallel-connected telephone or external telephone is put into an OFF-HOOK status,, charge ceases to flow
C107 and the base of Q102 becomes low, causing PC103 to go OFF.
When a line is connected, Q102 and PC103 go ON, causing pin 5 of IC151 to go low. When the line is disconnected, Q102
and PC103 go off, causing pin 5 of IC151 to go high.
7-6. TAM INTERFACE CIRCUIT
This circuit is for to switch between FAX receiving and external TAM’s message recording automatically.
This circuit consists of EXT. TAM OFF-HOOK detect circuit, Monitor Transformer, Multiplexer, Amplifier, VOX detect circuit.
In details please refer to page 142. TAM INTERFACE SECTION.
7-7. LINE AMPLIFIER AND SIDE TONE CIRCUITS
(1)Circuit Operation
The reception signal received as output from the line transformer T101 is given as input to R202, C205 to IC201 pin (6), and
it is inputted to the reception system at an amplifier gain 10.1 dB from pin 7.
The transmission signal given as input to IC201 pin (2) via R210, C203 is amplified to about 15 dB, It is outputted form pin 1
of IC201 and it is transmittted to T101 via R201, C202,T101. Without side tone circuit, the transmission signal here would return
completely to the reception amplifier via R201, C202. Here, the signal output from IC201 pin (1) passes through C218, R203,
R204, C207 and enters the amplifier IC201 pin (5), and this is used to cancel the return part of the transmission signal.
This is the side tone circuit.
Transmission Signal: C203
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R210
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IC201(2-1)
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C202
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R201
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T101
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TEL LINE
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C218
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R203
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R204
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C207
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Reception Signal: TEL LINE
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T101
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R202
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IC201(5,6-7)
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C210
(Side Tone)
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