Ringer Circuit; Power Circuit And Redial Back-Up Circuit; Sending Circuit (Tx); Receiving Circuit (Rx) - Panasonic KX-TS3MXB Service Manual

KX-TS3MXB / KX-TS3MXF / KX-TS3MXP / KX-TS3MXR / KX-TS3MXW

12.3. Ringer Circuit

Circuit Operation:
The bell signal passes through C1 (R1) → supplying power to pin 1 of IC2.
The ring signal is output from Pin 5 of IC2, and its volume is adjusted in 3 steps (H-L-OFF) by SW3 then impressed on the
ceramic sound generator, and so is generated.
Output frequency is controlled by R2 and C3 following below formula.

12.4. Power Circuit and Redial Back-up Circuit

Function:
This set is powered from the line. When it is an OFF-HOOK status, Tel Line → D1 → Q1 → R9 → pin 14 of IC1 (to become
the power supply for IC1 speech network).
The voltage from the line is turned into a constant voltage by D6 and then supplied to the IC1 and sending and receiving circuit
of the set.
At ON-HOOK status the voltage from the line via R40, R5 is turned into a constant voltage by D8, and then become power
supply for IC1 (Pin14), and the redial Back-up will be done.

12.5. Sending Circuit (Tx)

When a person talk through the Handset, the voice analog signal flow from the
mic → C20 → R33 → Q9 → R38 → C23 → Q3 → Q1 → D1 → Tel line.
* Q9 and Q3 is an amplifier for the voice signal.

12.6. Receiving Circuit (Rx)

Receiving signal from the line go through
D1 → Q1 → R15 → Q4 → R19 → C16 → JP8 → C17 → R26 → Q7 → C18 → R29 → Handset speaker.
* Q4 is amplifier for the Receiving signal.
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