Table of Contents
Advertisement
light source and a phototransistor, posi-
tioned to generate a signal when an
index hole on the diskette is detected.
The drive can determine if a single-
sided or double-sided diskette is
installed. This output signal is present
at the interface.
3. A Write Protect sensor disables the
write electronics when a write-enable
tab is removed from the diskette.
POWER ONSELF- TESTS
The drive conducts a power on self-test as part
of the normal power on sequence. Two of the
tests do not require a diskette to be inserted.
These tests are: the head carriage stepping in,
away from, Track 0, and the head carriage
stepping out toward Track O. Failure of either
of these tests is indicated on the front panel
L.E.D. by the following flashing sequence:
3 flashes, then 2:
Fails to step in from
Track 0 or Track 0
sensor is always equal
to zero.
3 flashes, then 3:
Fails to step out to
Track 0 or Track 0
sensor is always equal
to one.
A third test monitors the index sensors when-
ever the diskette lever is closed, and must
have a diskette inserted into the drive. If the
diskette lever is closed without a diskette in
place, or the spindle motor fails to operate, an
error message flashes on the front panel
L.E.D. in the following sequence:
3 flashes, then 4 : No index pulse with
lever closed.
1-3
Opening and closing the diskette lever is
required to repeat a test that has failed. The
diskette lever must be left open to complete
an error cycle.
1.5 PHYSICAL DESCRIPTION
A representative drive is shown in Figure 1-1.
The drive can be mounted in a vertical or hori-
zontal plane. However, the logic circuit board
must be on the uppermost side when the drive
is mounted horizontally.
The spindle is rotated by a direct drive, brush-
less D. C. motor with an integral tachometer.
The crystal-controlled servo circuit and
tachometer control the speed of the spindle.
Operator access for diskette loading is pro-
vided via a horizontal slot located at the front
of the drive.
The read/write double-head assembly is posi-
tioned by a split band positioner mounted to a
microprocessor-controlled stepper motor. The
read/write heads are glass-bonded, ferrite/
ceramic structures with a life expectancy of
15,000 operating hours.
The control electronics of the drive are
mounted on a printed circuit board located
above the chassis. Power and interface signals
are routed through connectors plugging
directly into the logic circuit board. A second
circuit board, mounted under the drive, oper-
ates the brushless D. C. spindle motor.
Advertisement
Table of Contents
