2.3.2.1 Reset Circuits

The C162 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,
using reset IC PST592D (IC12), and outputs a reset signal to the E05A96 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).

2.3.2.2 Sensor Circuits

Thefollowing sensor circuits enable the C1 62MAIN Boardto monitor printer mechanism status:
HPsensor The photocoupler-type home position (HP) sensor is attached to the surface ofthe
printer mechanism to detect the carriage home position. A LOW level from the
signalindicates that the carriage is in home position.
PEsensor The mechanical switch paper end (PE) sensor is built into the printer me chanism to
determine whether there is paper in the printer or not. A LOW level from the signal
indicatesthat n o paper is loaded.
BCO sensor,
CCO sensor The cartridge out (CO) sensor is micro switch attached to the bottom of each 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 isinstalled into the ink cartridge holder.
Thermistor A thermistor is attached to the color printhead driver board to monitor its
temperature by thermister’s resistance value (at 25°C approx. 10k). The CPU
changes the printhead drive signal’s pulse width (charge pulse width) based on the
temperature level.
+35 V +5 V
NMI
P62
CPU (IC1)
+5 V
PST592D
(IC13)
E05A96 (IC2)
RES
RESET
135
71
1
6
72
68
M51955B
(IC8)
PA8
RST
Type B
55
Figure 2-18. Reset Circuit Block Diagram
1
2
1
2
3
TH
10
9
+5 V
AN3
89
86
(CN12)
CCO
8
AN5 91
CPU (IC1)
AN1
AN0
HP
PE
+5 V
(CN8)
(CN9) AN4
8
90
BCO (CN11)
87
9
Figure 2-19. Sensor Circuit Block Diagram
Operating Principles Stylus Pro XL
2-16 REV.-A