Read Panasonic KX-TS2365CAB / KX-TS2365CAW Service Manual online
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KX-TS2365CAB/KX-TS2365CAW
4.2.
Circuit Operation
4.2.1.
Bell Detection Circuit
When the bell signal is input between T/R, the signal are outputted at the speaker via the following path:
Tel line
Tel line
→ R1/C1 → D3/D4 → Pin 1 of IC1 → Pin 8 of IC1 → C6 → T1 → C625 → Speaker
4.2.2.
Line Interface
In talk status, SW101 become ON and Q103 base changes to high level, causing Q103, Q101 to turn on and resulting in a line
loop.The loop current flows from D7
loop.The loop current flows from D7
→ Q101 → Q108 → R124 → D106 in that order. A pulse signal that repeated
switches between high and low logic is output from pin 22 of the CPU.This switches the line loop on and off, generating the dial
pulse signal.
pulse signal.
4.3.
Module Block Diagram
4.3.1.
Telephone Line Interface
4.3.1.1.
Circuit operation
• On hook
Q101 is open, Q101 is connected as to cut DC loop current and cut the voice signal.
• Off hook
Q101 turns on thus providing an off-hook condition (active DC current flow through the circuit) and the following signal flow id for
the DC loop current
T
the DC loop current
T
→ PO101 → L1→ D7 → Q101 → Q108 → R124 → D106 → D10 → L2→ R
• Receiving signal flow :
Tel line
→ PO101 → Q101 → R115 → R120 → R121→ Q108 → R123 → R125 → C108 → Q109 → C112→ R401→ C405 →
R405
→ Q405 → R409 → C408 →Q406 → C414 → VR402 → Headset Jack → Handset (SP)
• Transmission signal flow :
MIC
→ C422 → L3 → VR401 → R432 → C426 → Q424 → C435 → R437 → Q108 → Q101→ D7 → L1 → PO101 → Tel Line
4.3.2.
Tone Detect
This circuit is used to sense the status of the line (busy tone or dial tone) during Auto Redial.
4.3.2.1.
Circuit operation
D7
→ Q101 → C201 → R201 → R205 → Pin 5 of IC201 → Pin 1 of IC201 → D202 → R208 → Q201
When the subscriber hangs-up, check the intermittent tone. If cycle tone is detected, the collector of Q201 goes to a low logic.
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