Signal Flow - Sanyo SFX-32 Service Manual

9-2. Signal flow
(a) Transmission
@The image data of the original conveyed through
the reading mechanism is read by the Contact
Image Sensor (CIS) and this data is transfered to
Ml PCB.
@In the Ml PCB, the data is amplified, rectified and
turned into two values (black and white) or halftone
signal through the image processing, then this data
is written into one line memory (SRAM).
@The CPU reads out and encodes the data written in
line memory, then stores the data into the FIFO
(SRAM). At the same time, the CPU transfers one
byte data in the FIFO to the MODEM with an
interruption signal requested by the MODEM.
@Through repetition of above operations, the image
data for each line is encoded, modulated through
the MODEM, and transmitted over the line through
the NCU.
(b) Reception
.
@The signals received from the line enter the
MODEM through the NCU.
@In the same manner as in transmission, the coded
data which is demodulated by the MODEM is
stored into the FIFO as one byte data with an
interruption signal requested by the MODEM.
@The CPU reads out and decodes each one bit of the
data from the FIFO, and outputs to the thermal head
when each one bit portion of decoded data is
aligned as one line data.
@Through repetition of above operation, the received
data is printed to the recording paper.
(c) COPY
@In the same manner as image reading in transmis-
sion, the image data read by the CIS is turned into
two values (black and white) or halftone signal, then
it is stored into one line memory (SRAM).
@The CPU reads out the data of one line memory,
d
and outputs the data of each line to the thermal
head.
(d) TAS (Voice Recording and playing)
@A voice that comes from microphone or the tele-
phone line is digitized and compressed by DSP
(TC88451 F-02) and stored into memory (A-
RAM)
@Digitized and compressed signal is converted to
the Voice by DSP and it is output to the SPEAK-
ER or the telephone line
Circuil Description
Power Supply Circuil
(M7)
. Foward type switching regulator.
output
+24V . . . . . . . . . . . . . . NCU (Network control unit).
. . . . . . . . . . . . . . Pulse motor (Transmit & Receive)
. . . . . . . . . . . . .. LED Array.
+12V . . . . . . . . . . . . . . Main Board (CPU).
-1 2V . . . . . . . . . . . . .. Main Board (CPU).
+5V . . . . . . . . . . . . .. Main Board (CPU).
HV (+24V) . . . . . . . . .. Thermal head.
1. Noise Filter Block
L701 , L702 . . . . . . . . . .. Line Filter.
C702, C707 . . . . . . . . . . . Across the line capacitor.
C703, C705, C706,
C708, C709 . . . . . . . . . . Line-by-path capacitor.
2. AC+DC convetier Block (Primary)
D701
(Bridge Rectifier) . . . . . Full wave rectificating diode.
C701 . . . . . . . . . . . . . . . .Smoothing capacitor.
3. Switching circuit Block
Q701
(Power MOS FET) . . . . Main power transistor.
T701 . . . . . . . . . . . . . . . . . Switching power transformer.
4. Switching control Block
IC701 . . . . . . . . . . . . . . . .
pulse wide
modulation (PWM).
Over current limitation (OCP).
. Stabilize the output (+24V) and
protect against electric hazards.
5. AC+DC Converter Block (Secondary)
6.
7.
8.
43—
D704 . . . . . . . . . . . . . . . . Rectificating diode (3 pin type).
L703 . . . . . . . . . . . . . . . .. Smoothing choke coil.
C720 . . . . . . . . . . . . . . .. Smoothing capacitor.
Comparator Block
Q704 . . . . . . . . . . . . . . . . Comparative transistor.
ZD704 . . . . . . . . . . . . . .. Reference Voltage 506V
VR701 . . . . . . . . . . . . . . . Variable resistor (adjust the +24V)
DC-DC Converter Block
VIN
(+24V) —
VOUT(+5V,*12V)
IC702 . . . . . . . . . . . . . . . . Step-down chopper control IC.
IC703 . . . . ..o . . . . . . . ..3pintype voltage regulator (+12V).
IC704 . . . . . . . . . . . . . . ..3pin type voltage regulator (-12V).
D705 . . . . . . . . . . . . . . . . Fly-wheel diode.
D706, D707 . . . . . . . . . . . Rectificating diode.
L704 . . . . . . . . . . . . . . . .. Smoothing choke coil
(Triple output inductor).
C724, 725,726,729 . . . Smoothing capacitor.
Semiconductor Switch Block
Q702
(Power MOS FET) . . . . Supply +24V for thermal head.
Q703 . . . . . . . . . . . . . . .. ON/OFF controlled the sianal
(HVON) from CPU.