Panasonic KX-TS2351UAB / KX-TS2351UAW Service Manual ▷ View online
13 BLOCK DIAGRAM
RINGER IC
Line
ON/OFF
IC502
CPU
Ring_Det
LCD
EEPROM
Transmit
Amp
Tone Detect
Circuit
Handset Amp
Receiving
Handset Amp
Sending
ToneIn
Batt. Low
VDD
STOP
C-ID
Reset
Keyboard
Switch
IC302
IC803
UART
(T XtoPC)
Self Ringing
Circuit
Ringer
Handset
Q401, Q403, Q404
Q108
Q102, Q104
D101
LINE
T
R
T1
IC1
PC1
C1
R1
Q422
Speaker
Mic
IC802
Q2, Q5, Q6
Q801
Reset IC
Regulator
D302
IC201
D303
IC301
KX-TS2351: BLOCK DIAGRAM
Battery 4.5
KX
-T
S
235
1UAB
/
K
X
-T
S
235
1UAW
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14 CIRCUIT OPERATION
14.1. Bell Detector Circuit
When the bell signal is input between T/R, the signal are outputted at the speaker via the following path:
TEL line
→ R1/C1 → IC1 (pin 8) → IC1 (pin 5) → PC1 → T1 → C5 → SW1 → Ringer
14.1.1. Self Ringing Circuit
When [ABH] button is pressed during bell rings, selfringing circuit will be activated.
IC502 (pin 70) is changed from low to high logic, causing Q104, Q102, Q6 and Q5 to turn on, and resulting the set is in off-hook
status.
status.
The bell signal from T/R stops and starts generating from IC502 via the following path:
IC502 (pin 57)
→ Q2 → SW1 → Ringer
14.2. Line Interface
In talk status, SW101 become ON and Q104 base changes to high level, causing Q104, Q102 to turn on and resulting in a line
loop. The loop current flows from D101(+)
loop. The loop current flows from D101(+)
→ Q102 → Q108 → R114 → D103 in that order, A pulse signal that repeated
switches between high and low logic is output from pin 39 of the CPU. This switches the line loop on and off, generating the
dial pulse signal.
dial pulse signal.
14.3. MODULE BLOCK DIAGRAM
14.3.1. Telephone Line Interface
14.3.1.1. Circuit operation
•
•
•
• On hook
Q102 is open, Q102 is connected as to cut DC loop current and cut the voice signal.
•
•
•
• Off hook
Q102 turns on thus providing an off-hook condition (active DC current flow through the circuit) and the following signal flow is
for the DC loop current.
for the DC loop current.
T
→ D101 → Q102 → Q108 → R114 → D103 → D101 → R
•
•
•
• The receiving signal flows:
TEL line
→ Q102 → C401 → R401 → Q401 → Q403 → Q404 → H/S SP
•
•
•
• The transmission signal flows
MIC
→ Q422 → R428 → C427 → Q108 → TEL Line
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KX-TS2351UAB / KX-TS2351UAW
14.3.2. Initializing Circuit
14.3.2.1. Function
This circuit is used to initialize the CPU when the batteries are installed.
14.3.2.2. Circuit operation
When the batteries are inserted into the unit, then the voltage is regulated by IC302 and power is supplied to the CPU. The unit
starts operating soon after the voltage goes beyond point A in the voltage diagram.
starts operating soon after the voltage goes beyond point A in the voltage diagram.
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KX-TS2351UAB / KX-TS2351UAW
14.4. Caller ID Detect Circuit
14.4.1. Function (FSK signal)
The caller ID is a chargeable ID which the user ofa telephone circuit obtains by entering a contract with the telephone company
to utilize a caller ID service. For this reason, the operation ofthis circuit assumes that a caller ID service contract has been
entered for the circuit being used.
to utilize a caller ID service. For this reason, the operation ofthis circuit assumes that a caller ID service contract has been
entered for the circuit being used.
The Caller-ID data from exchange is supplied to the telephone using the method ofFSK and displayed on LCD ofthe unit.
•
•
•
• FSK (Frequency Shift Keying) format
14.4.2. Circuit operation
Caller ID
Caller ID signal is sent through the circuit via the following path:
TEL Line
→ C501, C502 → R551, R552 → Pin92,93 ofIC502
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KX-TS2351UAB / KX-TS2351UAW
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