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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.

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)

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)

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.122) for the route of caller ID signal.

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1. Circuit Operation

The reception signal output from the line transformer T201 is input to pin (2) of IC204 via C244, R237 and then the signal is
amplified at pin (1) of IC204 and sent to the reception system.

The transmission signal goes through L225 and enters IC204-pin (6), where the signal is amplified. Then, it is output from pin
(7) of IC204 and transmitted to T201 via C248, R245, R244. Without a side tone circuit, the transmission signal will return to
the reception amplifier via R237, C244. When the side tone circuit is active, the signal output from IC204 pin (7) passes
through R241, R233, C234, R229 and L220 and goes into the amplifier IC204 pin (3). This circuit is used to cancel the trans-
mission return signal.

The TX signal is output to the circuit analog the route from the IC204 7 pin

→C248→R245→R244→T201→TEL LINE.

However, if balance is lost in the bridge, a voltage occurs between the IC209 6 pin and 5 pin and a side tone results, because
the balance cannot be maintained completely at all frequencies in the audio range some side tone always occur.

1. Function

Another telephone connected to same line activates the unit to the FAX mode by using a DTMF signal.

2. Signal Path

Refer to Check Sheet (P.122).

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The general ITS operation is performed by the special IC4 which has a handset circuit. The alarm tone, the key tone, and the
beep are output from the BBIC IC4 (CDL board).

1. Function

This is the function when you are not holding the handset and can hear the caller’s voice from the line.

2. Circuit Operation

(Telephone Monitor Signal Path)
Signals received from the telephone line are output through at the speaker via the following path.

3. Signal Path

Refer to Check Sheet.

1. Function

This circuit controls the conversation over the handset, i.e. the transmitted and received voices to and from the handset.

2. Signal Path (Transmission signal)

Refer to Check Sheet.

3. Signal path (Reception signal)

Refer to Check Sheet.

1. Function

This circuit monitors various tones, such as (1) DTMF tone, (2) Alarm/Beep/Key tone/Bell.

2. Signal Path

a. DTMF MONITOR

(Speaker Operation)
Refer to Check Sheet.
(Handset Operation)
Refer to Check Sheet.

b. ALARM/BEEP/KEY TONE/BELL

Refer to Check Sheet.

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The scanning block of this device consists of a control circuit and a contact image sensor made up of a celfoc lens array, an LED, a
light guide, and photoelectric conversion elements.

When an original document is inserted and the start button pressed, pin 15 of IC107 goes to a high level and the transistor Q106
turns on.This applies voltage to the LED to light it. The contact image sensor is driven by each of the FTG-F1 signals output from
IC106, and the original image illuminated by the LED undergoes photoelectric conversion to output an analog image signal (SIG).
The analog image signal is input to the system ASIC on AIN1 (pin 3 of IC106) and converted into 8-bit data by the A/D converter

inside IC106. Then this signal undergoes digital processing in order to obtain a high-quality image.