Teac MT-20D-IO - Page 20

(2) Magnetic head shift mechanism
The main components of the magnetic head shift mechanism are a head
base Ass' y and solenoid Ass' y. A magnetic head is mounted on the
head base of the head base Ass'y.
The head base is shifted up and down (two positions) by the DC
solenoid. The head base Ass'y contains three kinds of adjusting
screws to adjust the appropriate head positions with respect to the
tape winding position (Fig. 305).
(3) Tape drive mechanism
The tape drive mechanism consists of two reel motor assemblies,
encoder and encoder roller.
The tape causes the encoder roller fixed to the shaft of encoder to
be rotated by friction. A feedback signal from the encoder is sent
to the reel motor to apply servo effect to it so that the tape speed
is kept always constant.
(4) Various detection mechanisms
(a) Cassette loading detection mechanism
This mechanism consists of a photo interrupter and a loading arm
(M) to detect the loading condition of the cassette tape. When
the cassette tape is loaded onto the MTU, the optical detection
path of the photo interrupter is interrupted by the tip of the
loading arm (M). In this status,' data can be written or read
(Fig. 306).
(b) Write inhibit hole detection mechanism
This mechanism consists of a photo interrupter and file protector
to detect the wire inhibit hole on the cassette half rear face.
When a cassette tape whose write inhibit hole is open is loaded,
the optical detection path of the photo interrupter is interrupted
by the file protector. In this status, the data write function is
deactivated and new write operation is inhibited, and then the
recorded data is protected (Fig. 307).
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