Service manual

2.3.2.1 Reset Circuits
The C184 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 (IC9), and outputs a reset signal to the CPU (IC1) and the E05E21 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
+5 V
NMI
P62
CPU (IC1)
+5 V
PST592D
(IC X)
E05B21 (IC2)
RES
RESET
80
71
1
672
68
M51955B
(IC8)
TBRST
RST
Type B
55
Figure 2-2. Reset Circuit Block Diagram
Stylus Pro XL+ Service Manual Operating Principles
Rev.A 2-3