Operating Principles Of The Main Control Circuit; Figure 2-21. Main Control Circuit Block Diagram - Epson Stylus 820 Service Manual

Operating Principles

2.3.2 Operating Principles of the Main Control Circuit

The main control circuit for this printer is the C160 MAIN Board, which is controlled by the 16-bit CPU
M3772 (IC2), running at 16 MHz. This 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. Additionally, auto refresh for the 1M PS-RAM is
controlled by custom gate array E05B08 ( IC1).
Gate array E05B08 (IC1) manages printhead drive control, the parallel I/F, extension CG board, and the
control panel. The gate array also manages the controls that create the 2-bit signal for the carriage or the paper
feed motor. (The carriage and paper feed motors are controlled by current duty data with micro step control.)
This board also is equipped with EEPROM 93C46 (IC10) to store certain parameters, such as the printer
mechanism control parameters, default setting parameters, as well as the the value in the special counter used
for printhead (ink management) protection.
Because this control board has no lithium battery that allows the printer to keep track of the amount of time
that has elapsed since it was last used, there is no power on cleaning operation for this printer.
PROM (4M)
(IC3)
OE
(IC10)
EEPROM
93C46
(IC9)
Reset IC for
M51955B
Power System
MACH Serial
(Only JAPAN ver. )
C160 MAIN Control Board
Head Common Driver
From A and Nozzle Selector
Circuit
A2919 (IC12, 16)
From B
CR/PF Drive Circuit

Figure 2-21. Main Control Circuit Block Diagram

2-20
PS-RAM (1M) CG-RAM (16M)
(IC4)
OE CE RFRSH OE
CPU
M3772
(IC2)
Panel
Stylus Color IIs / Stylus 820
CG-ROM (8M)
(IC6)
(IC5)
E05B08
(IC1)
Printhead Unit
SED5629
(U1, U2)
CG-ROM (16M)
(IC7)
(IC13)
PST592D
Reset IC for
Logic System
Mono 64 Nozzles
CMY 60 Nozzles
Rev. A