Epson 900N, Service Manual

Page: 52 / 201

EPSON Stylus COLOR 900/900N Chapter 2 Operating Principles
47
The following tables list the major components of the C265 main board
and their functions.
Table 2-10. Major Components on the C265 Main Board (1/2)
Table 2-11. Major Components on the C265 Main Board (2/2)
Component Functions
CPU:
• A Hitachi H8-series CPU.
• Performs high-speed data processing running at 24.0
MHz.
• Bus width is 16-bit.
ASIC 1:
(E05B60: IC3)
• Controls all interfaces but USB.
• Monitors the signal from each sensor.
ASIC 2:
(E05B59: IC2)
• Controls printheads, motors, ASF solenoid, cooling fan,
USB I/F, and EEPROM.
PROM/MROM:
• For PROM, either one-time PROM or Mask ROM is
used. Specifications vary depending on the
destinations, as shown below:
Standard version:
• PROM size: 16 M bit
• Contents: Unattached
• Bus width: 16 bit
NLSP version:
• PROM size: 16 M bit
• Contents: 16 M bit
• Bus width: 16 bit
D-RAM:
• Manages the various buffers and work area.
• Bus width is 16 M bit.
Timer IC:
(RTC9810: IC8)
• Keeps track of the total power off time of the printer, to
determine the cleaning type to be performed at the next
power on. Power is supplied by an external button-cell
battery (a lithium battery). This IC also produces the
reset signals for all the major ICs, such as the CPU,
ASIC1, ASIC 2, and motor drive ICs. The head driver
ICs (CXA2128 x 2: IC15 and IC16) produce their own
reset signals when detecting abnormal voltage so the
printhead can stop in the proper sequence.
Component Functions
Motor driver IC
(LB1847: IC11, 12)
(A3957: IC13, 14)
• The LB1847 (IC11 and IC12) drives the PF motor and
CR motor using 4W1-2 phase excitation. This control
system, called micro stepping, minimizes carriage
vibration during printing and improves accuracy in paper
feeding.
• The A3957 (IC13 and IC14) drives the Pump/ASF motor
and also supports 4W1-2 phase excitation. It differs from
LB1847 in that each IC can generate only one phase
(either A or B).
Head driver IC
(CXA2128 x 2: IC15,
16)
• The head driver ICs, directly attached to the main board,
consist of two separate circuits, for charging and
discharging, to produce the trapezoidal waveform. These
ICs create the trapezoidal waveform by combining the
signals received from E05B59 (IC2). These signals
change the characteristics and voltage levels of the
trapezoidal waveforms to produce consistent normal dot
and micro dot print output.