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EPSON Stylus PHOTO 810/820/830 Revision B
Operating Principles Electrical Circuit Operating Principles 51
2.2.2.5 Reset Circuit
Reset IC (IC2) on the MAIN board monitors the two voltage: +5V for the logic line
and +42V for the drive line. Reset IC outputs the reset signal to CPU (IC1) in the
following case.
1. When the printer power is turned on and reset IC detects 4.2V on +5V line/36.3V
on +42V line, reset signal is output to perform the initialize operation correctly.
2. When the printer power is turned off and reset IC detects 4.2V on +5V line/36.3V
on +42V line, reset signal is output to stop the printer operation safely.
3. When reset IC detects 4.2V on +5V line/36.3V on +42V line with fail during the
printer operation, reset signal is output to stop the printer operation safely.
Unlike the previous products, the timer IC is not built in the reset IC and the Lithium
battery is not mounted on this Main board either.
.
Figure 2-22. Reset circuit block diagram
Main line for reset IC has the following function.
OUT1: Interrupt signal
OUT2: Reset line
IN: +42V line monitoring line
VCC: +5V line monitoring line
2.2.2.6 EEPROM Control Circuit
When the printer power is turned off, the following information is stored in EEPROM
(IC3) which is nonvolatile memory. And, when the printer power is on, CPU (IC1)
reads the information from EEPROM.
Information stored in EEPROM is listed below.
Various ink counter (I/C consumption counter, waste pad counter, etc.)
Mechanical setting value (Head ID, Bi-D adjustment, USB ID, etc.)
Refer to 7.1.2 that provides the detailed information stored in EEPROM.
Figure 2-23. EEPROM circuit diagram
EEPROM is connected to CPU with 4 lines and each line has the following function.
CS: Chip selection signal
CK: Data synchronism clock pulse
DI: Data writing line (serial data) at power off.
DO: Data reading line (serial data) at power on.
IC2
BH6150F-E2
IC1
E01A24CA
+5V
+42V
8
7
6
5
MEWS
VCC
OUT1
OUT2
NC1
IN
NC2
GND
1
2
3
4
38
37
36
MRES
NMI
RESET
EEPROM-93C
(IC3)
E01A24CA
(IC1)
+5V
VCC
NC
ORG
GND
CS
SK
DI
DO
C-P20
C-P21
C-P22
C-P23
42
41
40
39
1
2
3
4
8
7
6
5