Kenwood DP-1100 B Service Manual page 47

1 - 5 - 1 2 . F O C U S S E R V O C O N T R O L S I G N A L O P E R A I T O N
1. W H E N N O D I S C I S L O A D E D :
1. W h e n no disc is l o a d e d , Q 6 2 S K 3 0 A a n d Q 2 2 S C 2 8 7 8
are t u r n e d O N n o t t o w o r k the f o c u s coil drive c i r c u i t , so
that the f o c u s coil c a n n o t be a c t i v a t e d .
2 . Since no signal is increased across the 4-division
p h o t o d e t e c t o r , n o RF is available a n d pin 2 of IC10 ( 1 / 2 )
T A 7 5 3 9 3 S b e c o m e s " H " level. T h e c o l l e c t o r of Q 3 1
2 S A 1 0 1 5 is in t u r n held at a " L " level. It is fed t o pin 4 of
Inverter IC16 a n d pin 12 b e c o m e s " H " level.
3 . T h e " H " level signal is applied t o the gate of Q6 2 S K 3 0 A
t h r o u g h R 2 9 1 0 0 kO. It t u r n s ON t o c u t the signal t o pin 2
of IC1 ( 1 / 2 )
4 . On the o t h e r h a n d , the " H " level signal is applied t o the
base of Q 2 2 S C 2 8 7 8 t h r o u g h R3 2 2 kO. Q 2 is t u r n e d on
t o g r o u n d t h e FE s i g n a l . T h u s , no signals are into IC1 (112)
A N 6 5 5 5 .
5. T h e s w i t c h i n g f u n c t i o n of Q6 a n d Q 2 c o n t r o l s the o p e r a ­
t i o n of f o c u s c o i l . It is disabled by this c i r c u i t , w h e n no
f o c u s i n g is r e q u i r e d .
D P - 1 1 0 0 B II D P - 1 1 0 0 B II
1. CIRCUIT DESCRIPTION
2 . W H E N A D I S C IS L O A D E D A N D IN P L A Y M O D E :
1 . W h e n a disc is l o a d e d , a signal p i c k e d up by the 4-division
p h o t o d e t e c t o r is divided into t w o signals, S i a n d S by
2
Q 1 0 3 ( T A 7 3 3 1 P ) . T h e y are a m p l i f i e d by Q 2 1 a n d fed to
pin 3 of IC10 ( 1 / 2 ) .
2 . W h e n the RF signal is present at pin 3 of IC10 ( 1 / 2 ) , pin 2
b e c o m e s " L " level. It is a p p l i e d t o the base of Q31
( 2 S A 1 0 1 5 ) t h r o u g h R 1 4 0 a n d R 2 2 0 , p l a c i n g the collec­
tor of Q 3 1 at a " H " level.
3 . The " H " level signal is fed t o pin 4 of IC16 t h r o u g h D 3 8
a n d R 2 1 3 . Its inverted signal is available at pin 12 as an
" L " level signal. T h e " L " level signal is t h e n a p p l i e d t o the
gate of Q6 ( 2 S K 3 0 A ) t h r o u g h R 2 9 , a n d Q 6 is t u r n e d OFF.
4 . A n o t h e r signal g o i n g t h r o u g h R3 is a p p l i e d t o the base of
Q 2 2 S C 2 8 7 8 t u r n i n g it OFF.
Both of Q6 a n d Q 2 are u n d e r OFF state, t h e f o c u s servo
c i r c u i t w o r k s .
FCO-