Read Panasonic KX-TG2560B / KX-TG2560S Service Manual online
46
KX-TG2560B/KX-TG2560S
17. Telephone Line Interface
Circuit Operation:
• ANSWER
In the idle mode, Q101 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
→
PO101
→
L101
→
R121
→
C116
→
Q106
→
IC701 pin 64.
When the CPU (DSP) detects a ring signal, Q101 turns on, thus providing an off-hook condition (active DC current flow through
the circuit) and the following signal flow is for the voice signal.
T
→
PO101
→
D101
→
Q101
→
Q105
→
R115
→
D106
→
D101
→
R
• ON HOOK
Q101 is open, Q101 is connected as to cut the DC loop current and to cut the voice signal. The unit is consequently in an
on-hook condition.
• SPECIFICATIONS
In the on-hook state (idle), the current flows between the telephone line and the unit is as follows:
T
→
PO101
→
L101
→
R121
→
C116
→
R122
→
C115
→
R120
→
L102
→
R.
The DC component is blocked by C115, C116: thereby providing an on-hook condition.
The AC interface impedance is over 47 K
Ω
thus, satisfying the telephone company requirements.
18. Intercom Mode
1. When LOCATOR/INTERCOM button of the base unit is pressed, a call monitor signal (intercom sound) is output from pins
32 and33 of C701. Thus a monitor tone is heard from the speaker.
2. At the same time, pin 25 of IC701 goes “Low”, and the transmission state is reached. Then the modulated data signal is
outputfrom pin 97 of IC701. Flashing of the IN USE/CHARGE (LED701) is obtained from pin 65 of IC701. This status is called
“Intercom stand-by”.
3. The receiving signal flows:
RF
→
pin 13 of CN102
→
C423
→
R424
→
VR402
→
C419
→
R418
→
R417
→
pin 9 of IC401
→
pin 12 of IC401
→
C409
→
R414
→
pin 13 of IC401
→
pin 14 of IC401
→
C407
→
R412
→
C718
→
R711
→
pin 45 of IC701
→
pins 32 and 33 of IC701
→
SP
4. The transmission signal flows:
MIC
→
C715
→
C714
→
C733
→
R755
→
pin 47 of IC701
→
pin 35 of IC701
→
C410
→
R415
→
C411
→
pin 3 of IC401
→
pin 6 of IC401
→
C425
→
R408
→
R421
→
VR401
→
pin 2 of IC801
→
RF
Circuit Diagram
D105
D102
C108
R116
R118
R115
R113
C111
Q105
C113
R117
R114
C107
C106
R112
C110
C709
R103
C105
L101
PO101
SA101
1
2
2
T
R
L102
R122
R123
Vcc
To IC701 64
(Bell)
(Bell)
Q106
R120
D101
3
4
2
1
R121
R101
Q101
Q102
R104
R105
R102
C117
C115
C116
C103
C104
C118
To IC701 99pin
(RLY)
(RLY)
To IC701 40pin
(EX-Hook)
(EX-Hook)
~ +
~ -
D106
R124
Click on the first or last page to see other KX-TG2560B / KX-TG2560S service manuals if exist.