Read Panasonic KX-TCD650RUC / KX-TCD650RUF Service Manual online
77..22.. TTH
HE
E LLIIN
NE
E IIN
NTTE
ER
RFFA
AC
CE
E S
SE
EC
CTTIIO
ON
N ((S
SE
EE
E B
BLLO
OC
CK
K D
DIIA
AG
GR
RA
AM
M FFiigg.. 1177))
77..22..11.. IIN
NTTR
RO
OD
DU
UC
CTTIIO
ON
N
This section consists of the telephone line interface, bell detector, change-pulse detector, hook switch, audio circuits, DC mask
& line impedance circuits, power supplies, and battery charger circuits.
& line impedance circuits, power supplies, and battery charger circuits.
77..22..22.. TTE
ELLE
EP
PH
HO
ON
NE
E LLIIN
NE
E IIN
NTTE
ER
RFFA
AC
CE
E ((S
SE
EE
E FFiigg.. 1199))
The telephone line is connected to a bridge rectifier D8. Surge suppressor SA3 protects against excessive line voltages. Test
points are TP40 (A), TP26 (B). Bridge rectifier D8 provides for lines of either polarity. The output of D8 is Line + (TP39) and
Line - which is ground.
points are TP40 (A), TP26 (B). Bridge rectifier D8 provides for lines of either polarity. The output of D8 is Line + (TP39) and
Line - which is ground.
77..22..33.. B
BE
ELLLL D
DE
ETTE
EC
CTTO
OR
R ((S
SE
EE
E FFiigg.. 1199))
The AC ringing signal is detected by phoptocoupler IC6, using its internal diode in conjunction with D7. DC from the line is
blocked by C2. The other components D2, D5, and R3 reduce current and increase the circuit impedance in line with national
requirements. When ringing is detected IC2 will turn on, and the RING line will be dragged to a low voltage.
blocked by C2. The other components D2, D5, and R3 reduce current and increase the circuit impedance in line with national
requirements. When ringing is detected IC2 will turn on, and the RING line will be dragged to a low voltage.
77..22..44.. C
CLLIIP
P C
CIIR
RC
CU
UIITTS
S ((S
SE
EE
E FFiigg.. 1199))
The CLIP signal is detected by IC3 and sent to the BBIC through the //TTX
XA
AFF.
Fig. 19
15
KX-TCD650RUC / KX-TCD650RUF
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