Receiving A Telephone Call - Ricoh FAX220 Service Manual

3. Receiving a Telephone Call

LIU Block Diagram
Line
External
Telephone
3-1. Manual Receive Mode
When the user picks up the handset, the Hook Switch goes up to connect the line to the speech circuit for voice
conversation. If the user presses Start to send or receive a fax message, the RY1 relay switches up to connect the
line to the modem, which is on the FCE.
3-2. FAX (Automatic Receive) Mode
When the machine detects a ringing signal, the machine switches up the RY1 relay and starts to send
CED/DIS/NSF for fax reception.
3-3. AUTO (Auto Tel/Fax Switch) Mode
This mode switches the line automatically to the internal telephone unit or to the modem, depending on the type of
remote terminal (phone or fax).
When the machine detects a ringing signal, the machine switches up the RY1 relay (the ringer is disabled by the di-
aler in this mode). Then the machine starts CNG detection, starts to send a voice message (3.5 s after ring detec-
tion), and starts to call the user to the machine (7 s after ring detection). If a CNG is detected during these periods,
the machine starts to send CED/DIS/NSF for fax reception. If the user picks up the handset (the Hook Switch goes
up), the machine switches down the RY1 relay to connect the line to the speech circuit. If CNG is not detected and
the user does not respond to the call within 30 s, the machine sends CED/DIS/NSF before disconnecting the line.
3-4. TAM (Telephone Answering Machine) Mode
This mode is only for use when a telephone answering machine (TAM) is connected to the same line.
When a call is coming in, the external TAM first catches the call; the machine can detect this by checking the
HOOK signal. To let the TAM catch the line first, the number of rings (N) until TAM detects a call has to be pro-
grammed in the machine. The machine automatically waits N+1 rings before it catches the call, in order to let the ex-
ternal TAM catch the call first when the TAM is active.
After catching the call, the TAM sends the pre-recorded message to the other end, and the machine starts to detect
a CNG and a 5 s (variable) silent period. If the machine detects a CNG or a 5 s silent period, the machine regards
the other end as a fax terminal and sends CED/DIS/NSF to receive the fax message.
Refer to section 1-3-1 for more information.
Current
Filter
Sensor
Protection
RY1 Relay
Line Transformer
High Impedance
Transformer
DI Relay
RY2 Relay
Dialer
Hook
Ringing
Switch
Detection
HSB
A-4
Speaker Volume
FCE/
Speech
FDU
Handset
Circuit
DC/DC
Photocouplers
OPU