12.5. Telephone Line Interface
Function:
- Bell signal detection
- ON/OFF hook and pulse dial circuit
- Side tone circuit
Bell signal detection and OFF HOOK circuit:
In the idle mode, Q3 is open to cut the DC loop current and decrease the ring load. When ring
voltage appears at the Tip (T)
and Ring (R) leads (When the telephone rings), the AC ring voltage is transferred as follows:
T L9 C7 R44 IC2-A, B CPU (Ring DET). [BELL]
When the CPU(IC3) detects a ring signal and press the TALK Key onto the handset. Q3 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.
T L9 R52 T4 RLY1 L10 F1 R [OFF HOOK]
ON HOOK Circuit:
Q3 is open, Q3 connected as to cut the DC loop current via RLY1 and to cut the voice signal.
The unit is consequently in an on-hook
condition.
Pulse Dial Circuit:
DSP (Relay) turns Q3 ON/OFF to make the pulse dialing via RLY1.
Side Tone Circuit:
Basically this circuit prevents the TX signal from feeding back to RX signal.
As for this unit, TX signal feed back from IC2 is canceled by AC3 and so on.
26
Summary of Contents for KX-TC1461LAB
Page 4: ...2 2 Handset 4...
Page 5: ...2 3 Battery Replacement 5...
Page 6: ...3 CONNECTIONS 6...
Page 8: ...4 OPERATIONS 4 1 Making Calls 4 2 Answering Calls 5 DISASSEMBLY INSTRUCUTIONS 8...
Page 15: ...7 4 Check Link Refer to Adjustment Note CPU IC3 RF IC IC1 15...
Page 21: ...Note Refet to CIRCUIT BOARD Handset Signal Route 9 2 Adjustment 21...
Page 36: ...20 CABINET AND ELECTRICAL PARTS LOCATION HANDSET 36...
Page 37: ...21 ACCESSORIES AND PACKING MATERIALS 37...
Page 38: ...22 TERMINAL GUIDE OF THE ICs TRANSISTORS AND DIODES 22 1 Base Unit 22 2 Handset 38...
Page 53: ...R520 ERJ3GEYJ103 10k 53...
Page 58: ...28 3 RF Module M KXTC1461LAB AK KXTC1461LAW AK 58...
Page 59: ...KX TC1461LAB W BASE UNIT Locator Component View...
Page 60: ...KX TC1461LAB W BASE UNIT Locator Flow Solder Side View...
Page 61: ...DC Power Supply Battery...
Page 63: ...U1 X1 KX TC1461LAB W HANDSET Main Flow Solder Side View 1 14 28 15 Rec_O P_B CH_DET U1 25...
Page 65: ...KX TC1461LAB W HANDSET Main Component View SP_OUT...
Page 67: ...IC3 AF OSC LOOP SIMULATOR Audio Analyzer E F Tip Ring...
Page 75: ...IC2 KX TC1461LAB W BASE UNIT Main Component View L seize 1 7 8 14 Power Down Tx Down SIG_OUT...