Service manual

EPSON Stylus Photo 870/1270 Revision B
OPERATING PRINCIPLES Electrical Circuit Operating Principles 53
2.2.2.5 EEPROM Control Circuit
Since EEPROM is a nonvolatile memory, it keeps information written if
the printer power is turned off. It stores such information as adjustment
values, factory values, and printer status values.
The EEPROM control circuit block diagram is as shown below:
Figure 2-21. EEPROM Circuit Block Diagram
EEPROM is connected to ASIC 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.
2.2.2.6 Sensor Circuit
The Stylus Photo 870/1270 has the following five sensors to detect
printer’s status.
!
PE Sensor
!
ASF Sensor
! BCO (Black head cartridge) sensor
! CCO (Color head cartridge) sensor
! Head Thermistor sensor
!
Liner sensor
The block diagram for the sensor circuit is as shown below:
Figure 2-22. Sensor Circuit Block Diagram
+5V
8
6
5
93C56
(IC7)
Vcc
GND
ORG
E05B70CD
(IC8)
206
205
204
203
1
2
3
4
CS
SK
DI
DO
EECS
EECK
EECO
EECI
op17
DATA Bath
IC20 CPU
C90A11CA
IC8 AISC
E05B70CD
CN5
PE Sensor
+5v
R57
200
C89
SWA1
CN6
ASF Sensor
+5v
R93
200
C93
C90
C94
SWA2
PRV
GND
PE
ASFV
GND
ASF
CN12
PF Motor Encoder Sensor
CRPHAA
CRENBA
CN8
CR Motor Encolder Sensor
CRAI0
CRAI1
ENA
ENB
ENA
ENB
CN9
I/C Detection Sensor & Thermistor
AN0
THM
COB
COC
SWC0
SWC1