Reset Circuits; Figure 2-18. Reset Circuit Block Diagram; Sensor Circuits; Figure 2-19. Sensor Circuit Block Diagram - Epson Stylus Pro Service Manual

Stylus Pro Service Manual

2.3.2.1 Reset Circuits

The C164 MAIN Board contains 2 reset circuits: the +5 V monitor reset circuit and the +35 V monitor reset
circuit. The +5 V monitor reset circuit monitors the voltage level of the +5 V line (logic line), using reset IC
PST592D (IC13), and outputs a reset signal to the CPU (IC1) and the E05E09 gate array (IC2) when the
voltage level drops below +4.2 V. The +35 V monitor reset circuit monitors the voltage level of the +35 V
line, using reset IC M51955B (IC8), and outputs a reset signal to the CPU. The reset signal is generated when
the voltage level drops below +28 V, and this causes a non-maskable interrupt (NMI).
+35 V
M5 195 5B
(IC8)
+5 V
PST5 92D
(IC13)

2.3.2.2 Sensor Circuits

The following sensor circuits enable the C164 MAIN Board to monitor printer mechanism status:
HP sensor A photocoupler-type HP (home position) sensor is attached to the surface of the printer
mechanism to detect the carriage home position. A HIGH level from the signal indicates
that the carriage is in home position.
PE sensor A mechanical switch PE (paper end) sensor is built into the printer mechanism to determine
whether there is paper in the printer or not. A LOW level from the signal indicates that no
paper is loaded.
BCO sensor, Micro switches (BCO sensor for the monochrome ink cartridge, CCO sensor for the color
CCO sensor ink cartridge) are attached to the bottom of monochrome ink cartridge holder in the carriage
unit. When the ink cartridge is installed, these switches are pressed and a LOW level from
the signal indicates that the ink cartridge is installed into the ink cartridge holder.
Thermistor A thermistor is attached to the color printhead driver board to monitor its temperature by
thermistor's resistance value (at 25 C (77 F) , approximately 10 K
the printhead drive signal's pulse width (charge pulse width) based on the temperature level.
P E
(CN8)
H P
(CN9)

Figure 2-19. Sensor Circuit Block Diagram

Rev.A
6 7 2
6 8
+5 V
7 1
1 1 3 5

Figure 2-18. Reset Circuit Block Diagram

+5 V
CPU (IC1)
8 7
1
A N 1
2
8 6
1
A N0
2
3
CPU (IC1)
NMI
P6 2
RES
E05B09 (IC2)
R E S E T P A 8
5 5
+5 V
89
1 0
A N 3
T H
9
91
7
A N 5
C CO
90
8
A N 4
B CO (CN11)
Operating Principles
RST
Typ e B
). The CPU changes
(CN12)
2-15