Reset Circuits; Figure 2-21. Reset Circuit Block Diagram; Sensor Circuits; Figure 2-22. Sensor Circuit Block Diagram - Epson Stylus 1500 Service Manual

Stylus 1500 Service Manual

2.3.2.1 Reset Circuits

The C172 MAIN Board contains two monitor reset circuits: +5 V and +42 V. The +5 V circuit monitors the
voltage level of the +5 V line (logic line) using a PST592D reset IC (IC9), and outputs a reset signal to the
CPU (IC1) and the E05E16 gate array (IC2) when the voltage level drops below +4.0 V. The +42 V circuit
monitors the voltage level of the +42 V line using an M51955B reset IC (IC8), and outputs a reset signal to
the CPU when the voltage level drops below +33.3 V. This causes a non-maskable interrupt (NMI).

2.3.2.2 Sensor Circuits

The following sensor circuits enable the C172 MAIN Board to monitor printer mechanism status:
Rear PE
P E
Sensor
(CN11)
Front PE
P E
Sensor
(CN10)
HP Sensor H P
(CN9 )
Disengage
Sensor D E
(CN15)

Figure 2-22. Sensor Circuit Block Diagram

Rev. A
+42 V
M51955B
2
6
(IC8)
+5 V
+5 V
PST592D
3
1
(IC9)

Figure 2-21. Reset Circuit Block Diagram

CPU (IC1)
+5 V
4
1
A N 0
P 7 2
2
+5 V
P 7 7
+5 V
3
1
P7 1
2
P7 3 5
+5 V
2
1
P 7 0
2
3
P 7 4
+5 V
1 4
1
P 7 6
P 8 3
2
+5 V
CPU (IC1)
NMI
10
P84
15
RESET
30
E05B16 (IC2)
201
XRESET
+5 V
Thermistor
20 1 3
THS (CN7 )
+5 V
Color Ink Cartridge (Option) Sensor
1 3
9
(CN8 )
C H C O
+5 V
1 0
Black Ink End Sensor
B K E N D
9
(CN12)
5
45
+5 V
1
6
Black Ink Cartridge Sensor
B H C O (CN13)
2
+5 V
1
8
Release Sensor
RE L E A S E
2 (CN14)
Operating Principles
2-17