Panasonic KX-FLC418RU, Service Manual

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KX-FLC418RU
6.5. NCU Section
6.5.1. General
This section is the interface between the telephone line and external telephone. It is composed of an EXT. TEL line relay (RLY200),
bell detection circuit, TAM interface circuit, line amplifier and side tone circuits and a multiplexer.
6.5.2. EXT. TEL. Line Relay (RLY200)
1. Circuit Operation
Normally, this relay switches to the external telephone side (break) and switches to the open side (make) while OFF-HOOK.
{ IC4 (83) High Level
→
CN921 (5) High Level}
→
CN500 (5) High Level
→
Q210 ON
→
RLY200 (ON)
→
(make)
{ IC4 (12) High Level
→
CN921 (10) High Level}
→
CN500 (10) High Level
→
PC203 ON
→
Q206 (ON)
→
(make)
6.5.3. Bell Detection Circuit
1. Circuit Operation
The signal waveform for each point is indicated below. The signal (low level section) input to pin 6 of gate array IC107 on the
digital board is read by ASIC and judged as a bell.
TEL LINE
→
PC205 (1, 2 - 4)
→
IC4 (10)
6.5.4. Calling Line Identification Circuit
1. Function
This unit is compatible with the Caller ID service offered by your local telephone company. To use this feature, you must sub-
scribe to a Caller ID service. The data for the caller ID from the telephone exchange is sent during the interval between the
first and second rings of the bell signal. The data from the telephone exchange is a modem signal which is modulated in an
FSK (Frequency Shift Keying) format. Data “0” is a 1200 Hz sine wave, and data 1 a 2200 Hz sine wave.
There are two type of the message format which can be received: i.e.the single data message format and multiple data mes-
sage format.
The multiple data format allows to transmit the name and data code information in addition to the time and telephone number
data.
When there is multiple data in the unit, the name or telephone number are displayed.
2. Circuit Operation
FSK signal of the caller ID signal input from TEL LINE is processed with BBIC (IC4).
Refer to
Check Sheet (P.123) for the route of caller ID signal.