Citizen CL-S400DT - Sensors; Head up Sensor

Chapter 2 Operating Principles
2-2. Operation of Control Parts
CL-S400DT 2-16
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
2
1
+3.3V
HDUSW
J13
R106
R105
C107
117
PDH3
SWOUT
[SA Main PCB]
Head Up Sensor
Head Up: High
Head Down: Low
(SA Head Up SW]
A
A
A
SA Head Up SW
SA Head Up SW
Head Block
Head block “Up” position
Head block “Down” position