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KX-TS2388RUB/KX-TS2388RUW/KX-TS2388CAB/KX-TS2388CAW/KX-TS2388UAB/KX-TS2388UAW
4.2.
Circuit Operation
4.2.1.
Bell Detector Circuit
When the bell signal is input from LINE to T/R (when the telephone rings), the signal is output at the speaker via the following
path :
T/R
path :
T/R
R1/C1 D1/LED1 (small PCB) D3/D4 IC1 (pin8) IC1 (pin5) PC1 C5 SW2 (R7/R8/R9) T1 Speaker
4.2.2.
Dummy Ringer Circuit
When {AOH} button is pressed during incoming call (Caller ID AOH mode), dummy ring function will be activated.
The bell signal from LINE stops and Caller ID is received.
Set will keep on ringing by the dummy ring function until the handset is picked up / speakerphone is on.
The bell signal from LINE stops and Caller ID is received.
Set will keep on ringing by the dummy ring function until the handset is picked up / speakerphone is on.
The dummy ring signal is generated from IC801 via the following path :
(Speakerphone will be activated during dummy ring)
IC801 (pin 89)
(Speakerphone will be activated during dummy ring)
IC801 (pin 89)
R901 Q2 SW2 ( R11/R12/R13 ) C8 R615 C616 IC601 (pin 19) IC601 (pin 15) C618
Speaker
4.2.3.
Telephone Line Interface
4.2.3.1.
Circuit operation
• On hook
Q101 is OFF, on-hook condition where DC loop is disconnected and voice signal flow is cut.
• Off hook
During Off-Hook, pin 1_3 of SW101 and Q101 is ON, providing an off-hook condition (active DC current flow through the circuit)
and the following is the signal flow :
T
and the following is the signal flow :
T
POS101 L101 D101(+) Q101 R180 Q107 R119 D103 D101(-) L102 R
• Receiving signal flows:
LINE
Q101 R180 C109 C401 R401 L412 L401 Q401 C404 R405 R417 L405 C405 L406
Q402 C408 R413 L409 Q403 C410 VR401 SP (handset)
• Transmission signal flows:
MIC (handset)
C422 VR402 R423 C425 L421 R430 Q422 R429 C429 L107 Q107 Q101
R180
LINE
• Pulse Dial
A pulse signal switches repeatedly between high and low logic is output from IC801 (pin 73), on and off the line loop, generating
the pulse dial signal.
the pulse dial signal.
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