Kenwood DP-1100 B Service Manual page 48

1 - 5 - 1 3 . C O N T R O L S I G N A L O P E R A T I O N
1 . A " H " level is o u t p u t at pin 1 4 (FOKG) of IC15 by the
m i c r o p r o c e s s o r , w h e n t h e f o c u s servo is a c t i v e . It is i n p u t
t o pin 5 of I C 1 6 . After level-shifted t o a c t u a t e the FET
( " L " level is — 1 2 V a n d " H " is + 5 V ) , an inverted o u t ­
p u t is available at pin 1 1 . T h e signal is applied to the gate
of Q 1 2 t h r o u g h R 5 6 . W h e n the f o c u s servo is not w o r k ­
i n g , Q 1 2 is p l a c e d u n d e r ON state. It w o r k s to disable the
t r a c k i n g o p e r a t i o n by s h o r t i n g a part of the f e e d b a c k loop
f o r t h e t r a c k i n g a m p l i f i e r .
2 . A " H " level o u t p u t is p r o v i d e d at pin 13 (PLAY) of IC15
by the m i c r o p r o c e s s o r d u r i n g n o r m a l PLAY m o d e . T h e
signal is f e d t o pin 6 of I C 1 6 . It is level-shifted to activate
the FET, a n d t h e inverted o u t p u t is available at pin 1 0 . T h e
signal is a p p l i e d t o the gate of Q 1 4 t o m a k e it t u r n ON dur­
ing t h e m o d e s o t h e r t h a n PLAY. This bypasses the p i c k u p
c a r r y m o t o r a m p a n d p r e v e n t s the t r a c k i n g error signal
f r o m d r i v i n g the p i c k u p f e e d m o t o r .
3 . W h e n an RF signal d r o p s o u t f o r a certain period of t i m e
b e c a u s e of s c r a t c h e s or dusts o n a disc, a d r o p o u t d e t e c ­
t i o n signal of " L " level is p r o v i d e d at pin 12 (DCON) of
IC15 at the s a m e s p o t per every r e v o l u t i o n of the disc. T h e
signal is a p p l i e d t o pin 2 of I C 1 6 . It is level-shifted, a n d
D P - 1 1 0 G B II D P - 1 1 0 0 B II
1 . CIRCUIT DESCRIPTION
its inverted o u t p u t is available at pin 1 4 . T h e signal is f e d
to the base of Q 8 a n d t o the g a t e of Q 9 in o r d e r t o r e d u c e
the gain of Q 8 a n d also t o v a r y t h e phase c o m p e n s a t i o n of
Q 9 , so t h a t t h e p i c k u p d o e s n o t j u m p f r o m a t r a c k b e c a u s e
of an excessive a m p l i t u d e of the TE s i g n a l .
4 . W h e n the laser d i o d e e m i t s laser, a " H " level is o u t p u t t o
pin 11 (LDC) of I C 1 5 . T h e signal is f e d t o pin 3 or I C 1 6 . It
is level-shifted a n d the inverted o u t p u t is available at pin
1 3 . T h e signal m a k e s t h e laser d i o d e activate by c o n t r o l l ­
ing the APC c i r c u i t d e s c r i b e d in a n o t h e r s e c t i o n a n d is a p ­
plied t o the gate of Q 4 at t h e s a m e t i m e . Q 4 t u r n s ON t o
bypass f o c u s servo a m p l i f i e r , so t h a t t h e f o c u s i n g o p e r a ­
t i o n is d i s c o n t i n u e d w h e n t h e laser d i o d e is n o t b e i n g ac­
t i v a t e d .
5. A " H " level o u t p u t is a p p l i e d t o pin 1 (TEP) of IC15 only
d u r i n g n o r m a l PLAY m o d e . It, h o w e v e r , b e c o m e s " L "
level, w h e n a kick signal is g i v e n d u r i n g the n o r m a l PLAY
m o d e . T h e signal is i n t e g r a t e d by R 2 1 0 , R 2 0 9 , D 3 6 a n d
C 7 4 t o t u r n o n Q 2 9 a n d Q 3 0 . In this i n s t a n c e , Q 2 7 a n d
Q 2 8 are p l a c e d u n d e r OFF c o n d i t i o n by m a k i n g Q 3 0 t u r n
O N d u r i n g the kick m o d e . T h e noise limiter c i r c u i t is t h u s
disabled d u r i n g s e a r c h m o d e .
t
Fig. 1 - 5 - 1 3
5 1