C393Main Board Circuit Operation Principles - Epson Stylus PHOTO 890 Service Manual

EPSON Stylus Photo 890/1280/1290

2.2.2 C393MAIN Board Circuit Operation Principles

The C393MAIN board includes the following:
n
Logic circuit (CPU, ASIC, DRAM, EEPROM, and so on)
n
Various motor control/driver circuits (CR motor, PF motor, and ASF/Pump
motor)
n
Head control/driver circuits
n
Interface circuit (parallel I/F, USB I/F)
n
Sensor circuit
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Timer circuit
n
Reset circuit
The C393MAIN/C393MAIN-B/C393MAIN-C board is mainly different from other
main boards in the following points.
o
Use of 3.3V drive logic chips
IC21, the 3.3 V regulator IC on the C393MAIN, produces 3.3 V by pressuring
down the 5.5 VDC generated on the C378PSB/PSE board to drive several chips.
These chips are used to reduce power used to drive the logic circuit. See the table
below that separately shows the chips driven by the +5V and +3V.
Table 2-14. 3.3V Drive Chips & 5.5V Drive Chips
Table 2-15.
+5V
Sensors
USB I/F Circuit
(Except high speed)
PNL Board
OPERATING PRINCIPLES
3.3V
CPU
ASIC
P-ROM
D-RAM
RTC/Reset/EEPROM
USB I/F Circuit
(During high speed)
Electrical Circuit Operating Principles
There are three kinds of main board installed on EPSON Stylus Photo 890/1280/1290.
Stylus Photo 890 is equipped with either C393MAIN-B or C393MAIN-C while Stylus
Photo 1290 is equipped with either C393MAIN or C393MAIN-B. Block diagram of
each main board are shown in the following figures below.
CR Encoder senser
Head
IC7
E0BA13KA
Figure 2-13. Block Diagram for the C393MAIN Board
(For Stylus Photo 1290 only)
Revision C
CR1
Timer &
Reset IC
(IC4)
IC4
47