Sensors; Head Up Sensor - Citizen CL-S400DT Technical Manual

Chapter 2 Operating Principles
2-2. Operation of Control Parts

2-2-3. Sensors

(1) Head up sensor

The head up sensor (SA2 Head Up SW) is used to detect the head position (up or down). This
sensor is a mechanical micro switch.
When the head block is closed (in the down position), the protrusion "A" of the head block
pushes the "SA2 Head Up SW" and the switch turns ON. In this state, pin 117 (HDUSW) of
CPU (U1A) goes "Low".
When the head block is opened (in the up position), the protrusion "A" of the head block comes
off the "SA2 Head Up SW" and the switch turns OFF. In this state, pin 117 (HDUSW) of CPU
(U1A) goes "High".
When the head block is opened, the POWER LED blinks in red and the LCD displays "Error
Cover Open".
U1A
CPU
117
PDH3
Head Up: High
Head Down: Low
Head Block
SA Head Up SW
CL-S400DT
R106
HDUSW
C107
A
+3.3V
R105
1
SWOUT
2
[SA Main PCB]
Head block "Up" position
Head block "Down" position
SA Head Up SW
2-16
Head Up Sensor
J13
(SA Head Up SW]
A
A