Head Up And Down Control; Monitor Of Door Sensor; Monitor Of Paper Sensor - Sony UP-895 Service Manual

4-4-4. Head Up and Down Control

A head up/down DC motor is driven by its driving circuit (IC400). The DC motor can rotate in the
forward and reverse directions. It is controlled by a system control (IC304). The head also has three
positions. The head position is detected using optical head position sensors (photo-interrupters PH21 and
PH22) and read by a system control (IC304).
Operation of head up/down motor
Head motor IC304-28pin
UP L
DOWN H
STOP H
Condition of head position sensor
Position IC304-17pin
TOP H
MIDDLE L
BOTTOM H

4-4-5. Monitor of Door Sensor

The door position is detected using an optical door position sensor (photo-interrupter PH32) and read by a
system control (IC304).
Condition of door position sensor
Position IC304-20pin
CLOSE L
OPEN H

4-4-6. Monitor of Paper Sensor

Whether thermosensible paper is properly put in this unit is detected using two pairs of optical paper
sensors (phototransistors PH31 and PH12) and read by a system control (IC304).
Condition of paper sensor
IC304-18pin IC304-19pin
H H
For except "H" For except "H"
4-10
IC304-27pin Operation
H Raises the head.
L Lowers the head.
H Stop
IC304-16pin Condition
H Unlocks the door.
H Wait (Usual)
L Print
Condition
The door is closed.
The door is open.
Condition
Paper exists.
No paper
UP-895/(E)