20.3. Telephone Line Interface
<Function>
- Bell signal detection
- Clip signal detection
- ON/OFF hook circuit
- Audio circuits
Bell signal detection:
In the standby mode, Q2 is open to cut the DC loop current and decrease the ring load.
When ring voltage appears at the TP3 (A) and TP40 (B) leads (when the telephone rings), the
signal is transferred as follows;
- A C4 R2 R29 IC2 (DLP) [BELL]
- B C3 R1 R30 IC2 (DLP) [BELL]
ON/OFF hook circuit:
In the standby mode, Q2 is open, and connected as to cut the DC loop current and to cut the
voice signal. The unit is consequently in an off-hook condition.
When IC2 detects a ring signal or press the TALK Key onto the handset, Q3 turns on and then
Q2 turns on, thus providing an off-hook condition (active DC current flow through the circuit)
and the following signal flow is for the loop current.
- A R77 D2 Q2 R8 Q3 D2 B [OFF HOOK]
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Summary of Contents for KX-A143EXB
Page 8: ...5 LOCATION OF CONTROLS 5 1 Base Unit 5 2 Handset 8 ...
Page 18: ...8 OPERATIONS 8 1 Turning the Power On Off 18 ...
Page 22: ...8 6 Selecting a Base Unit 9 DISASSEMBLY INSTRUCTIONS 9 1 Base Unit 22 ...
Page 26: ...11 TROUBLESHOOTING GUIDE Flow Chart 26 ...
Page 49: ...18 FREQUENCY TABLE MHz 49 ...
Page 56: ...25 CPU DATA BASE UNIT 25 1 IC2 BBIC 56 ...
Page 60: ...45 MICP A I 60 ...
Page 73: ...73 ...
Page 75: ...33 ACCESSORIES AND PACKING MATERIALS 75 ...
Page 76: ...33 1 KX TCD430FXB FXC FXW 33 2 KX A143EXB EXC EXW 76 ...
Page 77: ...34 TERMINAL GUIDE OF THE ICs TRANSISTORS AND DIODES 34 1 Base Unit 77 ...
Page 102: ...PbF D1 J1 CIRCUIT BOARD CHARGER UNIT Component View ...
Page 103: ...PbF R1 R2 TP4 TP1 TP2 TP3 CIRCUIT BOARD CHARGER UNIT Flow Solder Side View ...
Page 104: ...Marked PbF IC1 IC3 IC2 1 1 64 49 33 4 5 8 1 11 28 18 ...
Page 106: ...PbF IC1 IC2 100 80 30 50 5 8 4 1 11 18 1 IC3 Marked ...
Page 108: ...PbF D1 J1 Marked PbF R1 R2 TP4 TP1 TP2 TP3 Marked Component View Flow Solder Side View ...
Page 112: ...PbF R1 R2 TP4 TP1 TP2 TP3 Digital Volt Meter 12Ω 2W A ...