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light source and a phototransistor, posi-
t ioned to g en erate a
index hole on the diskette is detected.
T he driv e ca n d e t er m in e i f a s i n g l e -
sided
o r dou b l e - s i de d d i s k e t t e i s
installed. This output signal is present
at the interface.
3 . A
W r i t e P r o t ec t s e nsor d i s ables t h e
write electronics when a w r i t e -enable
tab is removed from the diskette.
POWER ON SELF- TESTS
The drive conducts a power on self-test as part
o f the normal power on sequence. Two of th e
tests do not require a di skette to be inserted.
These tests are: the head carriage stepping in,
away from, Track 0, and the head carriage
stepping out toward Tr ack 0. Failure of either
of these tests is in dicated on th e f r on t p a n el
L.E.D. by the following flashing sequence:
3 flashes, then 2:
F a i l s t o s t e p i n f r o m
Track
sensor is a l w ay s equal
to zero.
3 flashes, then 3:
F a i l s t o st e p o ut
Track
sensor is a l w ay s equal
to one.
A third t est monitors the index sensors when-
e ver th e d i s k ett e l e ve r i s c l o sed, and m u s t
have a diskette inserted into the drive. If the
d iskette lever i s closed wi t h out a d i s k ette i n
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:
N o in d e x pu l s e wi t h
lever closed.
s i g na l w h e n a n
0 or
Tr a c k 0
t o
0 or
Tr ac k 0
1-3
O pening an d
c l o s in g t h e d i s k e tt e l e v e r i s
required to repeat a t est t ha t ha s f a i l ed. The
diskette lever must be left open to complete
an error cycle.
1.5 P H YSICAL DESCRIPTION
A representative drive is shown in Fi gure 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 w it h a n i n t e gral t a chometer.
T he c r y s t a l - con t r o l l e d s e r v o c i r c u i t an d
tachometer control the speed of the spindle.
O perator access for d i s k e tt e l o a ding i s p r o -
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
r ead/writ e h e ad s a r e g l a s s-bonded, f e r r i t e /
ceramic stru ctures w it h a
15,000 operating hours.
The c o n t ro l
e l e c t r onics o f t h e dri v e ar e
mounted on a printed circuit board located
above the chassis. Power and interface signals
a re
r o u t e d t hr o u g h co n n e c t or s p l u g g i n g
directly i nt o th e l ogic circuit board. A second
circuit board, mounted under the drive, oper-
ates the brushless D. C. spindle motor.
l i f e e x p ectancy of
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