Tandy 1000 SL Technical Reference Manual page 285

e r r o n e o u s step o u t command
is
i n p u t from t h e t r a c k 00 p o s i t i o n , t h e
command w i l l be i g n o r e d by t h e i n t e r n a l c i r c u i t o f t h e FDD.
I f t h e head moves o u t from t h e t r a c k 00 by
some
r e a s o n s u c h
a s
impact d u r i n g t r a n s p o r t a t i o n , t h e head c a r r i a g e s t r i k e s t h e
frame
( f u n c t i o n s l i k e a t r a c k 00 s t o p p e r ) t o p r o t e c t t h e head from moving
o u t o f t h e r e t u r n a b l e r a n g e a t a n e x t power o n .
When s t e p - i n commands
are
i n p u t from t h e i n n e r m o s t t r a c k , t h e head
moves t o w a r d i n w a r d a n d s t o p s w i t h a n a p p r o p r i a t e s p a c e l e f t a g a i n s t
t h e head window e d g e o f t h e d i s k . I n o r d e r t o r e c a l i b r a t e t h e t r a c k
from t h i s p o s i t i o n ( r e t u r n i n g o p e r a t i o n t o t h e t r a c k 001, i t i s
r e q u i r e d t o i n p u t t h e s t e p - o u t command w i t h s e v e r a l a d d i t i o n a l s t e p s
t o t h e maximum t r a c k number.
C a u t i o n : S e n s e t i m i n g of t h e t r a c k 00 p o s i t i o n w i l l change i f you
l o o s e n
a
f i x i n g
screw
o f t h e main PCBA. T h i s
i s
b e c a u s e
t h a t t h e t r a c k 00 p h o t o - i n t e r r u p t e r
i s
mounted o n t h e PCBA.
Be s u r e t o r e a d j u s t t h e t r a c k 00 s e n s o r t i m i n g a c c o r d i n g
t o
i t e m
3-4-13.
( c )
I n d e x d e t e c t i o n mechanism
LED a n d p h o t o - t r a n s i s t o r f o r d e t e c t i n g t h e i n d e x h o l e
a r e
l o c a t e d
a t
t h e i n d e x window
area o f
t h e d i s k j a c k e t .
The LED
i s
mounted o n t h e PCBA DD motor s e r v o ( i n t h e r o t o r o f s p i n d l e
motor) a n d t h e p h o t o - t r a n s i s t o r on t h e PCBA f r o n t OPT. The i n d e x h o l e
w i l l be d e t e c t e d a l o n g t h e r o t a t i o n
of
t h e d i s k .
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206
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