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applied to the disengage half of the coil. After the pick
pulse drops, the coil continues to move because of the
hold current. When the coil reaches its limit of travel
against a resilient stop, a 0.8 ms pick pulse (pick 2)
is
applied to the coil, and holds the coil against the stop to
suppress bounce.
Pick 2 is derived from the back electromotive force
(emf) generated in the undriven (engage) half of the coil.
The action to engage the pawls is similar but the
functions of the voice coil halves are reversed. The
disengage half of the coil provides a back emf sense
signal for the engage half. The level of hold current for
the engage action is 235 mA and for the disengage action
590 mA.
Upper (Forward) Clutch
Drive Tire
t r - - - - - - -
Drive Disk
(flexible)
Lead screw
~·'"~'"~
Clutch Armature
Lower (Reverse) Clutch
Figure 1-19. Layshaft/Leadscrew Drive
(07479)
5444 (<30100) FETMM
(5/70)
1-11
Screw
Figure 1-20. Detent Mechanism
[07480)
HEAD/ARM ASSEMBLY
• The head/arm assembly consists of a read/write head,
support arm, and connecting cable and plug.
• The four head/arm assemblies are clasped to the
carriage.
• The carriage moves within the actuator frame carrying
the heads over the disks.
Read/Write Head
• The read/write head is mounted on a ceramic slider
and contains a read/write coil, and an erase coil.
Leaf
Pawl
Detent
Wheel
Yoke
Detent
Pawl
Pawl Spring
Leaf Spring
Damping Assembly
Voice Coil Assembly
Note:
Drive tire, drive disk, and clutches omitted for clarity
Figure 1-21. Detail
of
Detent Mechanism
[ 07481]
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