Epson Stylus pro 7700m, Service Manual

Page: 44 / 139

2.3.2 Operating Principles of the Main Control Circuit
The main control circuit for this printer is the C164 MAIN Board. This circuit is controlled by a 16-bit
H8/3003 CPU (IC1), running at 14.7456 MHz. The CPU has a unique architecture, capable of handling data
on the data bus at either an 8-bit or 16-bit bus width. Because of this, a 16-bit or 8-bit data bus width-type
ROM is used on this board, increasing the internal processing speed. Also, the CPU’s unique architecture is
capable of the refresh control function. A 4M DRAM (2 CAS method) on the main board is controlled by the
CPU itself. In addition, the CPU controls the serial interface control (RS-422 for Mac).
Gate array E05B06 (IC2) manages printhead drive control, the external Centronics
®
parallel I/F, extension
CG board and the control panel, and the controls that create the 4-bit signal for the carriage or the paper feed
motor. (The carriage and paper feed motor are controlled by the current duty data.)
This board also is equipped with EEPROM 93C46 (IC12) to store certain parameters, such as the printer
mechanism control parameter, default setting parameters, as well as a special counter value used for printhead
(ink management) protection.
The timer IC NJU6355E (IC7) counts each time the printer is cleaned and keeps track of how long the printer
is not used, thereby allowing the printer to be cleared only when necessary.
CL
K
S
D
I/O
DMAREQ
Data Bus
Battery
Note:2
D R A M
(IC5)
Refresh
Address Bus
EEPROM
(IC12)
93C46
Reset
(Power)
(IC8)
M51955B
Vx
NJU6355E
(Timer
Counter)
(IC7)
Reset
(Logic)
(IC13)
P S T5 92D
RS-422 Serial I/F
Type B I/F
P
a
ra
ll
e
l I/F
(C
ent
roni
c
s
)
Panel
Bl
a
c
k
/Co
lo
r H
e
a
d
C
o
m
m
on an
d
N
o
zz
le
S
e
le
ct
or
D
ri
v
e
S
ig
nal
C
a
rr
ia
ge/
P
a
p
e
r Fe
ed
D
ri
v
e S
igna
l
To
A
To
B
From A
From B
C164 MAIN Board
SED5620
(U1,U2)
Bla ck 6 4 No zzles
Color 48 Nozzles
Carriage
Carriage/Paper Feed
Motor Driver
SLA7041MS (IC14,15)
H8/3003
(IC1)
C P U
E05B09
(IC2)
Notes 1: 32-pin IC socket only
2: IC 17 is socket only.
16M (IC16), IC17 are only installed in JAPAN version.
CG-ROM (IC17)
(8M)
PROM (4M)
(IC3) CG-ROM
(IC4)
Note:1
CG-ROM (IC16)
(8M or16M)
Black/Colo r Head
Commo n Driver Circ uit
Figure 2-17. Main Control Circuit Block Diagram
Operating Principles Stylus Pro Service Manual
2-14 Rev.A