KX-TG8051RUB, KX-TG8051RUW, KX-TG8051RU1, KX-TG8051UAB, KX-TG8051CAB, KX-TG8052RUB, KX-TG8052RUW, KX-TGA806RUB, KX-TGA806RUW, KX-TGA806RU1 - Panasonic Telephone Service Manual Supplement (repair manual). Page 6

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6
3.1.2.2.
Power Supply Circuit
The power is supplied to the DECT BBIC, QSPI FLASH MEMORY, EEPROM and Charge Contact from AC Adaptor (+5.5 V) as
shown in Fig.101. The power supply is as follows;
• DECT BBIC (IC7): 
DC Jack (+5.5 V) 
 IC2  IC7
DC Jack (+5.5 V) 
 IC2  Q8  IC7
• EEPROM (IC401): 
DC Jack (+5.5 V) 
 IC2  IC7 IC401
• Charge Contact (TP16): 
DC Jack (+5.5 V) 
 R56  R55  D22 TP16
• QSPI FLASH MEMORY: 
DC Jack (+5.5 V) 
 IC2  IC7  IC431
<Fig.101>
3.1.2.3.
Telephone Line Interface
<Function>
• Bell signal detection
• Clip signal detection
• ON/OFF hook circuit
Bell & Clip (: Calling Line Identification Presentation: Caller ID) signal detection:
In the standby mode, Q3 is open to cut the DC loop current and decrease the ring load.
When ring voltage appears at the L1T (A) and L1R (B) leads (when the telephone rings), the AC ring voltage is transferred as
follows;
• B 
 P1  C4  R6  R33  IC7 Pin 15 (CID INp) 
• A 
 C3  R4  R35  IC7 Pin 17 (CID INn)
ON/OFF hook circuit:
In the standby mode, Q3 is open, and connected as to cut the DC loop current and to cut the voice signal. The unit is
consequently in an on-hook condition
When IC7 detects a ring signal or press the TALK Key onto the handset, Q4 turns on and then Q3 turns on, thus providing an
off-hook condition (DC current flows through the circuit) and the following signal flow makes the loop current.
• B 
 P1 D3  Q3  Q5  R21  R22  D3  A [OFF HOOK]
AC Adaptor 
DCP
IC2
IC7 
IC401
IC431
5.5 V 
1.8 V 
3.0 V 
3.0 V 
Q8
TP16
D22
R55
R56
DC
Jack
2.85 V 
DCM
1
2
3
On
DC 
S
1.8 V
Reset
(IC7_61pin)
Off
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