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POWER OFF SEQUENCE
3. With K3 open:
The normal power off sequence beqins when the
controller issues an SSS command, the START
a. The spindle motor is disabled.
b. Power is applied to the hysteresis
brake.
I
swi
tch
is pressed, or in
uni
ts with the power
sequence feature of the Pick and Hold signals
go inactive. Sequencinq is then
as
follows
(see Figures 3-3 and 3-5):
4.
With
IC2
open:
1. The Stop
FP
sets.
This raises
an
Unload
Heads command wi thin the logic.
This
sets the RTZ Latch which,
in
turn, causes
the, carriage
to
retract at 7 ips.
2. When the heads
~load:
a. Relay K3 de-energizes.
b. The speed detection circuit is dis-
abled to de-energize relay Xl.
CONTROL INTERt.OCX
SPINDl.E MOTOR
PO'of£R REl.AY
1(3
REVIRSE POSITIONER
MOTION
FORWARD POSITIONER
MOTION
HYST!RISI$
BRAKE POWER
R/W HEADS
HEADS \.CADED
SW STATE OR ICI
CURRENT OR
-If
IV
FAUl.T ENASl.E
SPUD REl.AY 1(2
+ZOV TO WRITE
ClRCUIT
LOGIC/POSITIONER
DC VOLT AGE.S
RETRACT RELAY 1(5
EMER
RETRA~
PWR (CAP DISCH)
-16 VOI..TS
FIRST SEEK
INT!RLOC< MOTOR
INTERLOCK CYCLE
SiI
NOTES:
NORMAl.
I
--.-r-
I
1..0/),---...... "
!DO
~I-----
~~
1..00
I
I
~
ON
I
OFF~
OFF
. - - -
ON~
<D
RETRACTED STOP ENCCUNTERED.
l.OSS 0' - IIV
RETRACT VOt.TAGE
I
I
:
~~: r<D-~I--
I I
I
"
,
I '
I
" "
"
,
! '
' I
'I
,.
----n'--~----
~
I
~
I
I
LOSS
a. +20v removed from read/write loqic.
b. Relay lCS opens
0
The emergency re-
tract capacitor discharges through
the voice coil to pull it
back
against its retracted stop.
I..OSS (AND ItECOVERf)
orr
INPUT AC Olt 5V
C,ltCUIT SJcEAKER
' , --_....1
•
I
,
' - 1 - -
~
I ,
I
I I
r
~'~':.-------."
I,
,
~
,I
" - - - -
T!I
:r
I I
.... _ _ _ _
~
.
"
,
I I
:r
"
.
I I
I
'1
:r
I'
,
,
' ,
~
\,,;.
----.;._
.....
'
:
' I
I
"
1
~
.
I
:
I I
,:
.
,
I '
,
11~------J~.'
"
,
i.f'...-.
:,
I !
I
v--t---\L
1
,
,
I
I
I
,
,
I
L
I
I
J--1lL
I
I
~OSS
RECOVERyGD
LOSS
(ANO
RECOVERY)
orr
SPIED
,
,
:~
~
.
.
:
I
r
,
,
,
,
I
--:-:-1,-,
_~r
,
!--_ _ _
:."r
, I
,
:r
I
'
"
~
I
I
,
I:
....,
~
!
r--:--
~:
I I
I
I
r
I ,
I
,
, I
I
' I
, .
I
"
~
II
I
I I I
:~I'!
-!..J
!
'-!.!...!..-
I '
I
'"
~
III
I '
I
,
I
I I
I
I
.J,
;
L
"
@
I
I
~
I
I
LOSS
RECOVERY
®
VELOClTY
<3~
IPS.
PERIOD IHOETERM INATE •
®
FAUl.T
DETECTED.I(~
RETRACTS POSITIONER
~
C:YCI..!S WILl.. REPEAT UNTIl. END OF THAT
@
NO BRAKING OCCUltS IF INPUT AC
OR +20Y IS 1.0ST.
3-10
CYCto! DURING WHICH SPEF.D RECOVERS.
SPEED CAN RECOVER
ONl.Y CURING
A
FIRST SEEK CYCt.!.
~ RECOVERY
IS NORMAL
POWER UP,
Figure 3-5.
Power Off Timing
8W 368
83318200
E
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