BASF 6106 - Page 25

2.2.4.
HEAD
LOAD
LOGIC
(Fig..
19
)
The
head
load
mechanism
is
activated
by
the
head
load
solenoid.
This
solenoid is
energized
when
HEAD
LOAD
ENA/ is
active
and the
mini
disk
is
up
to
speed
(SPEED
-»
high)
.SPEED
is
activated by
the
speed
detection
logic.
As
the
head
load
solenoid
is
activated,
Tran-
sistor
Ti
is
closed
for
20 ms
by
the
20
ms
One
Shot,
to
supply
sufficient
starting
cur-
rent
for the
head
load
solenoid
(see
timing
diagram
Fig.
>20
)
If
the
HEAD
LOAD
ENA/-
signal is
deactivated
or the
front
door is
-opened
(SPEED
—
•-
low)
because
mini
disk isn't
turning.)
The
head
load
solenoid
will
drop and
the
head
is
unloaded.
For the
door
lock
solenoid and the
activity
LED two SN
75453
drivers are
used.
The
activit>
Uil)
driver
is
enabled
by SPUED of
the ready
detector circuit
The activity
LED
can
be turned on if
the head
is
loaded
(HEAP
LOAD
ENA active) or
if
the
door
lock
solenoid
is
activated (see
2-20
).
The door
lock
solenoid
is activated
if
HEAD LOAD
ENA or
I/O
ENA or
DOOR
LOCK ENA
is
active (see
2-20
)
.
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SOLENOJI)
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SPEEl^
OLTPl'T
TO THE
INTERFACE
FIGURE
2
-
19
.
HEAD
LOAD
CIRCUIT
DOOR LOCK
SOLENOID
AND ACTIVITY LED
DRIVER
HEAD LOAD LNA/
SPEED
20 msec
OS
HULUSOL/
T
1
FIGURE
2
-
20 .
HEAD
LOAD
-
TIMING
DIAGRAM
2-15