Teac FD-55 Series, Maintenance Manual

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The disk rotation mechanism comprises DD motor Ass'y which includes
spindle.
The DD motor is an outor-rotor type DC brushless motor which has the
long life of 30,000 hours or more in continuous rotation.
The rotational speed is 300rpm (or 360rpm) and maintains stable rotat­
ional speed against load variations and environmental changes. This is
achieved by a feedback signal from the internal AC tachometer.
The precisely combined collet and spindle are attached at the correct
angle to maintain the center position correctly without damaging the
center hole of the disk and so as to make the head be in contact with
disk at the correct angle.-
(4) Magnetic head and carriage
(Fig.302) External view of magnetic head core
For single sided FDDs, the external view of the magnetic head is button
shaped and it is mounted on the carriage so that it is in contact
with the SIDE 0 (the buttom side when the FDD is placed horizontally)
head window area of the disk.
For double sided FDDs, both the SIDE 1 head and the SIDE 0 head are
special flat type supported with the gimballed mechanisms. The two
magnetic heads are mounted accross the disk on one carriage.
In both types of head, the surface is designed for minimum disk wear
and maximum read output. The head itself is a long life type for
improved head wear. Each head,is constructed with a read/write gap
used for data reading and data writing and two erase gaps to erase the
recorded track edge immediately after the recording (tunnel erase).
The magnetic head and the carriage on which the head is mounted form the
303