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c)rrloNEeR"


ORDERNO.
The photo showsthe model SK-750. HRT- 183- O




soo
PORTABLE
STEREOFM/AM RADIOCASSETTE
RECORDER




KU, KC



sK-75c!
S P ECIFICATIONS
KU. KC


C o n t i n u o u sp o w e r o u t p u t . . . . . . . 3W+3W/FTC sK-750
(3.2O, 80-15,0OOHz 1O% THD.)
(total music power) (Subfunctionsl . Diroct Source Selector {DSS), Dolby NR,
Max. music power.. ...23w
Speakers ...... 16cm 2-way tape selctor {METAL/C.Oz-NORMAL},
Frequency .6sponse .... Normal tape: 30Hz-14kHz auto/manual recoiding, one-touch music
CrO2 tape: 3OHz-1 SkHz search. music repeat, one side rep6at,
Metal tape:30H2-16kHz semi-automatic rcord muting, timer
Frequencyrange... ....FM: 88-108MHz standby mechanism, FM muting,
AM:525^-1.605kH2 microphon6 mixing
(lndicators) . . . . POWER {red LED), Dolby NR (green
Input jacks . . . . MIX MlC, PHONO/AUX, EXT MlC, EXT
FM ANT LED), MIC REC {green LED), PHONO/
Output jacks. .. LINE OUT. EXT SP. PHONES AUX (gieen LED). TAPE PLAY (green
Power source. . 120V AC 60H2. LED), FM (green LED), AM {9re6n LED},
12V DC (6ight 1.5V "D" batteries). EXT REC (rod LED). REC PAUSE (r6d LED),
12V DC ONE SIDE REPEAT (gron LED), MUSIC
REPEAT (green LED), MUSIC SEARCH
Dimensions. ...588(W) x 297(H) x 148(D) mm
1231/aX115/aX57/ainl {green LED x 2}, METAL (green LED},
CrOz (green LED), Level met6r (12
Weight.. ......7.6k9 (16.7 lbs.)without batterios
points redlgreen LED x 2), TUNING
(green LED), STEREO (red LED)

sK-700
(Sublunctions) . Direct Source Selector (DSS), tap6
selector (METAL/CrOz-NORMAL), ons-
touch music search. semi-automatic roc-
ord muting, timer standby mechanism,
FM muting, microphone mixing
(lndicators) . . .. POWER (red LED), MIC REC (green
LED), PHONO/AUX (green LED), TAPE
PLAY (groen LED). FM (greon LED), AM
(green LED), REC (red LED), REC PAUSE
(red LED), MUSIC SEARCH (green LEO
x 2), METAL {green LED}, CrOz (green
LED), lsvel meter (5 point red LED),
TUNING (grean LED), STEREO (red LEDI


Note: Specifications and design are subject to chango without notice'




plctNEEFl ELECTFIC'NIC CC'FIPCIFIATIGIN 4 1, Mesu.o 1-chome, Mesuno_ku. Tokyo 153, Jspan
PICINEEFI ELECTFIONICB CIF AMEFilCA 1925E, Oomrnquez Sc. Long Beach Calif. 9081O
PrcXrlI:F| ELCCTFaC'NIC aEuFlOPEt N.v. Lu,thagen Haven 9. 2O3O Antwe.p, Elelgrum
FlCrNClFl ELECTFIC'NICS AITBTFIALIA PTY. LTO. 1 78 184 Elou.da.v Road, E|.aesrde, V,cco.,a 31 95. Auscnalra

F K O J A N . 1 9 8 2 P r i n t e di n J a p a n
CONTENTS
1. P A R T SL O C A T I O N . .2 1 2 . C O N N E C T T OD t A GR A r \ 4 2 )
N {
2. Dl
t \ i l E C H A N t s t vE S C R t p T t O N.. . . .3 (sK.750) . ...46
3. C|RCU|TDESCR|PT|ON....... .7 1 3 . E L E C T R I C AP A R T S I S T . . . . .
L L ...53
4. D ISASSE LY IVIB . tJ 14. CABINET XPLODED IEW,. . .
E V ...59
5. ADJUSTI\4ENT. .17 1 5 . C H A S S I { 1 )E X P L O D E D I E W . .
S V ...62
6, D t A L S T R t N G T N.C. . . . .
, .... .29 1 6 . C H A S S I S2 ) E X P L O D E D I E W
( V
7. S C H I / ] A TC C I R C U I TD I A G R A I V I
E I (sK.7oo) . . . ,65
.
( T U N E RS K . 7 0 0S K . 7 5 0.). . . . .
, .30 1 7 . C H A S S I ( 2 )E X P L O D E D I E W
S V
8 . C O N N E C T T O N A GR A M ( 1 )
D| ( s K -/ 5 0 ) . ...68
{ T U N E RS K . 7 0 0S K . 7 5 0.). . . . .
, , .32 1 8 . C A S S E T T E\ , 1 E C H AS I \ ,E X P L O D E D I E W
I IN 1 V
9 . S C H M A T I C I R C U T D I A G R A I Mtzl
E C I (roP). . . ...71
.
{sK-700} .34 1 9 . C A S S E T T E\ 4 E C H AIN I \ ,E X P L O D E D I E W
I S 1 V
10.coNNECTTON (2)
DtAGRAtul (BOTTOM) . . .74
(sK-700)
. .38 20. PACKING \4 THOD I E . . .11
11 . S C H E I \ i ] A T C IR C U I TD I A G R A I \ i ]
IC e)
{sK-750) . .42




CAUTION
W h e nH a n d l i n gC P D l 0 0 4
l
Please Observe:
l C P D l O 0 4 ( l C i n t h e c o n t r o l u n i t ) i s a C - l V l O SC o f l
e x t r e m e l yl o w p o w e r c o n s u m p t i o n n d v e r y h i g h i n p u t
a
i m p e d a n c e . n l e s s a n d l e d i t h s p e c i ac a r e ,i t c o u l d b e
U h w l
d a m a g e b y s t a t i ce l e c t r i c i t iyn d u c t i o n . h i s l C i s s u p p l i e d
d T
w i t h a s h o r t i n g c a p ( o f a l u m l n i u mf o i l ) a t t a c h e d .W h e n
,
soldering, performingother repair work, alwaysattach
or
this cap as shown below. Removethe cap after the repair
hasbeencompleted,
A l s o ,t h i s t y p e o f l C m u s t n o t b e i n s e r t e dn a p o l y s t y r e n e
i
package storage.
for




'Dolby'
and the double-D symbol are trademarks of
Dolby Laboratories Licensing corporation.
Noise Reduction System manufactured under license
from Dolby Laboratories Licensing Corporation.
1. PARTS LOCATION
NOTE
o For your Parts Stock Control, the fast moving items are indicated with
the marks * * and *.
* * : GENERALLY MOVES FASTER THAN *.
This classification shall be adjusted by each distributor because it de-
pends on model number, temperature, humidity, etc.
. The A mark found on some component parts indicates the importance
of the safety factor of the part. Therefore, when replacing, be sure to
use parS of identical designation.


LEDMeterUnit Volume,20kA(A)(VOLUME)
HWX-386(SK-750) * HCW-101
Tuner Unit
HWE-167




Microphone Microphone Assy
* HPM-1 9
1 * HPM-1 9
1




AF Amp Assy
HWK-215(SK-700) M e c h a n i s mC o n t r o l A s s y
H W K - 2 1( S K - 7 5 0 )
7 H W M - 1 2 7( S K - 7 0 0 1
H W M - 1 2 8( S K - 7 5 0 )
Cassette Mechan ism Assy
HXA-810
I Power Transformer
r HTT-I68


F i s .1

Solenoid Head (REC/PB)
H X P - 1 0 4 * * H p B - 11 6

Button
HNS-522(SK-700)
HN5-556(SK-750)




Fig.2

The photo showsthe Model SK-750.


NOTE:
Parts are shipped as an assembly and not as a certain unit within an
assembly. Conseguently, when undertaking repairs on a unit, replace
each part.




e
2. MECHANISM DESCRIPTION
. lnitialization F A SP u t t e y




6
*12
F i g .3



1. The mechanism usessix solenoids performthe opera-
to - StopSotenoid
tions r e q u i r e d n S T O P , F F , R E W , P A U S E .P L A Y a n d
i
R E C m o d e s . F i g u r e4 s h o w st h e p o s i t i o n arle l a t i o n s h i p
between the solenoid and the gears (STOP mode in (
Lever A)
StopLever
t h i sc a s e ) . GeorB)
(
2.When power is switchedON, the motor turns for a pre-
d e t e r m i n e d e n g t h o f t i m e , r o t a t i n g t h e p u l l e y sa n d
l
.-+ d
gear A).(
3. At the same time, the STOP solenoidcomes ON and
p u l l s o n l e v e r( A ) t o u n l o c k g e a r( B ) . A r m ( A ) r o t a t e s
g e a r( B ) a s h o r t d i s t a n c e i n t h e d i r e c t i o n f t h e a r r o w ) ,
whereit engages
t
which in turn presses the STOPlever.
on
(
with gear(A).
4 . W h e ng e a r( B ) s t a r t s u r n i n g , h e c a m p r e s s eo n a r m ( B ) .
t
o

s
v
G e o r( A )
Com
Arm(A)
\
- A r m( B )




Fis.4
5 . T h e S T O Pl e v e rm o v e s h e l o c k p l a t e n t h e d i r e c t i o no f
t i
t h e a r r o w ,r e l e a s i ntg e l e v e rl o c k sf o r P L A Y ,R E C ,F F ,
h
a n dRE W .
6 . W h e r eP A U S Ei s t h e m o d e e n t e r e d r e l e a s i ntg e P L A Y
, h
levercauses pin on the PLAY leverto movethe slider
the
NL
u n d e r n e a t hh e l o c k p l a t e , n d t h i s r e l e a s ets e P A U S E
leverock.l
t a h
r\
Lr--J
7 . A f t e r g e a r ( B ) r o t a t e st h r u o n e f u l l t u r n , s i n c et h e tr
t i--1 1
s o l e n o i ds n o w O F F , i t l o c k s .
i
E
A
Stop
D
r
tl
F i s .5




3
o Auto Stop Mechanism


Geor(C)
Pin(B)
)/ F A SS w i t c h




l.

- Motor

P i n ( A, \
Ar F i g .6 Fig.7

'l
. During PLAY, FF, REW,and REC operations, the rota- drawntoward the centerof gear(C). Thecamalsobrings
tion of the reel unit causes pin (A) to pressagainst arm a r m ( D ) i n w a r d , u r n i n gt h e F A Ss w i t c hO N .
t
( C ) , a n d t h e f o r c e o f t h e s p r i n gp u s h e s r m ( D ) i n t h e
a 3 . After the FAS switch has beenturned on two (or more)
direction f the arrow. Pin (B)on arm(D) moves long
o a t i m e s .t h e S T O Ps o l e n o i d u r n s O N a n d a l l o p e r a t i o n s
t
t h e o u t e rp e r i p h e r y f g e a r( C ) .
o arethus stopped.
2 . W h e nt h e r e e l u n i t s t o p s ,a r m ( D ) i s f r e e da n d p i n ( B ) i s



o PLAY Operation TP UNit
1 . Pressing PLAY button startsthe motor rotating,and
the
a t t h e s a m e t i m e t u r n s t h e P L A Y s o l e n o i dO N . T h e ReeI
PLAY lever is pressed arm (B), and locked by the
by
l o c k p l a t e s e e i g .4 ) .
( F
2. The PLAY lever,via arm (E) moves headmount for- the A r m( G)
w a r d . l t a l s op r e s s ea g a i n sa r m ( F ) , w h i c h c a u s e t h e
s t s Pinch otter
R
pinch-rollerto contact the capstanshaft. Arm (F) is
c o u p l e dt o t h e T P u n i t t h r u a r m ( G ) , a n d t h e a b o v e
action causesthe TP unit to contact the reel unit, Arm(F)
c o m p l e t i n g L A Y m o d ee n t r y .
P


1
PLAY Lever Fis.
8

r Fast-Forward Operation FRUnitGeor

1. Pressing FF button startsthe motor rotating,and at
the
t h e s a m et i m e t u r n s t h e F F s o l e n o i d N . T h e F F l e v e r
O
Un i t I
is pressed arm (B), and locked by the lockplate(see
by /'-'- Reet Unit
Fig.4).
2. The action of the FF levercauses FF gearto contact the
t h e F R u n i t a n d r e e lu n i t . T h r o u g hc o u p l i n g i t h a r m s
w \ r, G.o,.
( H ) a n d ( l ) , i t a l s o d v a n c e h e h e a dm o u n tt o t h e b l a n k
a ts
1 -Arm (H)
(between selection) detectionposition.
H e o dP t o t eP i n


I
Arm(l ) F i s .9
. REWOperation
FRUnit Geor
1. Pressing REW button startsthe motor rotating,and
the
a t t h e s a m et i m e t u r n s t h e R E W s o l e n o i d N . T h i s
causes the REW leverto be pressed arm (B) and lock-
by
O r
e d b y t h e l o c k p l a t e s e e i g .4 ) .
( F u
R e e rn i t , - g ( o
A --- ReeL nit
U

u\ -
)B
2 . T h e R E W l e v e rm o v e s r m ( J ) c o u p l e dt o t h e F R u n i t .
a .V ./.d

The FR unit thus is forced into contact with the reel
Arm(J)r
u n i t . T h r o u g h o u p l i n g i t h a r m s( H ) a n d ( l ) , t h e R E W
c w Arm(H)
lever also advances head mount to the blank detec-
the R E WL e v e r -
tion position.
+
H e o dP t o t e P i n


Arm(l ) Fis. 0
1


a RECOperation
the REC button startsthe motor rotating,and
1 . Pressing
a t t h e s a m et i m e t u r n s t h e R E Cs o l e n o i d N . T h e R E C
O
l e v e ri s t h e n p r e s s e b y a r m ( B ) ( s e e i g . 4 ) .A t t h e s a m e
d F
time, the REC lever presses the PLAY lever, and both
levers engaged the lockplate.
are by
2 . T h e R E C l e v e r ,v i a t h e R E C a r m p l a c e s h e R E C / P B
t
s w i t c ho n t h e A F a m p u n i t t o t h e R E C s i d e . A l l o t h e r
P L A YL e v e r
operations the sameasthe PLAY mode.
are RECLever F i g .11




o REC PAUSE Operation , T PU n i t
'l Pressing
. the REC PAUSE button in the STOP mode
e n t e r s h e R E C O R D n d P A U S Em o d e . P r e s s i nig f r o m
t a t
a R E Cm o d et u r n st h e P A U S E o l e n o i d N . T h e f o l l o w -
s O
i n g d e s c r i p t i o n i l l a p p l y t o p r e s s i n gt f r o m t h e R E C
w i A r m( G )
mode. + A u t o t o oP i n - - -
S
2. The PAUSEleveris pressed arm (B) and engaged by by
theslider.
3 . T h e a c t i o no f t h e P A U S El e v e r , i a a r m ( G ) r e l e a s e h e
v ts
TP unit from the reel unit, and breaks contact between
t h e p i n c h - r o l l ea n d c a p s t a n h a f t .s t o p p i n g a p et r a v e l .
r s t P A U S EL e v e r
T h e a u t o s t o p p i n ( F i g . 6 ,a r m ( C ) ) i sl o c k e di n a d e p r e s -
P i n c hR o t t e r F i g .1 2
sedposition,preventing Auto Stop from working.

a STOP Operation
1 Pressing STOP
the buttonturnsthe STOP
solenoid
ON.
M e c h a n i s mo p e r a t i o n s a r e t h e s a m e a s a t i n i t i a l i z a t i o n .
Switching
FromRECPAUSE REC,FF, or
to , - L o c kP t o t e
REWMode
t . W h e nt h e R E C b u t t o n i s p r e s s e f r o m t h e R E CP A U S E
d
m o d e ,t h e P L A Y s o l e n o i ds t u r n e dO N , a n d t h e P L A Y
i P L A Y r m+
A P LA Y
a r m ( F i g . 4 , a r m ( B ) ) p r e s s ets e s l i d e ra t t h e p o i n t o f
h
the arrow. This causes sliderto moveupward,releas-
the
i n g o n l y t h e P A U S El e v e rl o c k a n d e n t e r i n g h e R E C
t REW A r m{ 1 '
REW
mode. FF nr. --1{ FF
2 . When the FF or REW switch is pressed from the REC
TOP
PAUSE mode, the pauselever lock is released des- as
c r i b e da b o v e . T h i s t i m e h o w e v e rt,h e F F o r R E Wl e v e r 'LOCK
PLATE
movesthe lockplatedownwardto release the REC and
P L A Y l e v e rl o c k s , n t e r i n gh e F F o r R E Wm o d e .
e t F i g .1 3

o EJECT Switch
0N+OFF
Sw i t ch




Arm(M


Arm(K)




R e e tU n i t F i s .1 4

1 . Whenthe cassette loaded,pressure arm (K) causes
is on 2 . When EJECT is pressed removethe cassette, (M)
to arm
a r m ( L ) t o b e u n l o c k e d .A r m ( L ) m o v e sn t h e d i r e c t i o n
i (Via the EJECT Lever) movesaway from the switch,
o f t h e a r r o w ,c a u s i n g r m ( M ) t o a l s om o v ei n t h e d i r e c -
a t u r n i n gt O N .
i
t i o n o f t h e s w i t c ha n d t u r n i t O F F .


o Switch Operations

1 . Switch 51-1 is turned ON/OFF by the STOP lever. S V / I T CU N I T ( B )
H
D u r i n g S T O P o p e r a t i o n st i s O N . a n d g o e sO F F w h e n
i s2
operations completed. S t i d e rS w i t c h
are
2. S w i t c h 5 1 - 2 i s t u r n e d O N / O F F b y t h e P A U S E l e v e r .
sr-2
D u r i n g P A U S Es w i t c h i n g p e r a t i o n st i s O N , a n d g o e s
o i R E C P A U S EL e v e rS w i t c h
O F F w h e ns w i t c h i n g p e r a t i o na r ec o m p l e t e d .
o s
3. S w i t c h 5 2 i s t u r n e d O N / O F F b y t h e s l i d e r . D u r i n g
P L A Y ,F F , R E W ,a n d R E Cs w i t c h i n g p e r a t i o nis i s O N ,
o t
a n d g o e sO F F w h e ns w i t c h i n g p e r a t i o na r ec o m p l e t e d .
o s s r -|
S T 0 P L e v e rS w t t c h F i g .1 5
3. CIRCUIT DESCRIPTION
3 . 1 T U N E RS E C T I O N

Ste reo
C e r o mci C e r o mi c MPX t Ind
BPF FMRFA FMMixer F MI F T F i t t e r F M l F A m p F i l t e r FM Detector 0 ecoder
L Cn

Rch FM out




Auto/ l.4ono
Switch

Locol 0SC


r c a - rL E D D r i v e r




AM FER M E T E RS I G N A L +
Antenno C e r q mi c AM
AM Mixer AM IFT FiLter lF Amp AM IFT AM
Detector




Switchinq
L o c a L0 S C




Function
Switch
F i g .1 6



o Front End o Tuning Indicator Circuit
T h e a n t e n n ai n p u t s e c t i o nc o n s i s t so f a b a n d - p a s f i l t e r e d
s D u r i n g F M o p e r a t i o n st,u n i n g a s t a t i o nc a u s e a r i s ei n
s
s i n g l es t a g e R F a m p l i f i e r ( O l ) , a b a s ei n j e c t i o n m i x e r ( 0 2 ) , t h e v o l t a g e r e s e n a t t h e p i n 1 0 o f l C 1 ( K 8 4 4 1 9 C ) .S i n c e
p t
a n d a m o d i f i e d C o l p i t t s l o c a l o s c i l l a t o rc i r c u i t . t h i s t u r n s 0 8 O N a n d 0 1 1 O F F , c u r r e n tb e g i n s o f l o w t
f r o m R 6 5 t o D 8 , l i g h t i n g h e t u n i n gi n d i c a t o r .
t
o lF Amp, DetectorCircuit N e x t , m o v i n gt h e t u n i n gd i a l p o i n t e rt o a p o i n t n e a rt h e
T h i s s e c t i o n s c o n t a i n e dn t h e F M ( A t t l t ) F S y s t e m C
i i t l s t a t i o n ,b u t l o w e r o n t h e f r e q u e n c y c a l e i l l c a u s e n e o f
s w o
(LAl 140) and consists f the FM lF amp, two double-
o the comparators lC3 to gate,droppingthe potentialat
of
e l e m e n t e r a m i c i l t e r s ,t h e p r e a m p o n s i s t i n g f t r a n s i s t o r
c f c o o
t h e b a s e f Q 8 a n d t u r n i n gi t O F F . T h i sc a u s e Q 11 t o t u r n
s
03. Togetherthey form a four-stage differentialamplifier. O n a n d t h e t u n i n g i n d i c a t o r i l l n o t l i g h t . l f t h e p o i n t e ri s
w
K B 4 4 1 9 Cf u n c t i o n sa s a n l F a m p l i f i e r ,l i m i t e r , a n d a s a m o v e d n e a r t h e t u n e d p o i n t , b u t h i g h e ro n t h e f r e q u e n c y
quandrature detector. scale,the oppositecomparator(lC3) will gate,preventing
t h e t u n i n gi n d i c a t o r o r m l i g h t i n g se x p l a i n e d b o v e .
f a a
o FM Muting Circuit A d d i t i o n a l l yi,n a f r e q u e n c y r e a h e r en o s t a t i o n s x i s t ,
a w e
o r w h e r et h e i n c o m i n g i g n a l s s o w e a k t h a t t h e S / N r a t i o
s i
O u t p u t l e v e li s d e t e c t e d t t h e m e t e ro u t p u t p i n ( p i n 1 0 )
a
is unacceptabl08 will be OFF and 01 l will be ON. and
e,
o f K B 4 4 ' l 9 Cb y A N 6 9 1 3 ( l C 3 ) . W h e na d e t u n e d t a t u si s
s
t h e t u n i n gi n d i c a t o w i l l r e m a i n x t i n g u i s h e d .
r e
detected,the signalis passed through AND gatesand used
T h e a b o v eo p e r a t i o n s p p l y w h e n F M m u t i n g i s a c t i -
a
t o a c t i v a t eh e m u t i n gt r a n s i s t o( O 1 0 ) .
t r
v a t e d ,a n d t h e y a r e s y n c h r o n i z ew i t h m u t i n go p e r a t i o n s .
d
D u r i n gA M o p e r a t i o n s .B i s a p p l i e d o l C 3a n di n d i c a t o r
+ t
o FM Multiplex Circuit o p e r a t i o n s r e i n a c c o r d a n cw i t h t h e v o l t a g e t p i n 1 0 o f
a e a
T h e F M m u l t i p l e x c i r c u i t u s e sa P L L m u l t i p l e x l C K 8 4 4 19 C .
(KP'44248\.
3 . 2 D E C KC O N T R O L I G N A LS E C T I O N
S
o Basic Operations
T h e c a s s e t t e e c k m e c h a n i s mu s e ss w i t c h e s ( S 1 - 1 , S 1 - 2 ,
d PLAY KEY INPUT

52) to detect mode switching operations. Pressing the keys
t o s w i t c h m o d e s t u r n t h e s w i t c h e sO N / O F F . T h e l i s t b e l o w
shows the switch-mode status.
PLAY SOLENOID
ON


3)ru
OFF
li
s 2 (s L rD E R w r t c r . io F F
s t
5 1 - 1 ( S T O P l e v e r s w i t c h. ). . . . STOP ON

5 1 - 2( R E C P A U S E s w i t c h ) . . . P A U S E
.
5 2 ( S L I D E RS W I T C H ) .. . . . . P L A Y , R E C , F F , R E W
PLAY mode operations will be used as an example to Fig.17
describe the role the switches play. The relationship bet-
ween the solenoid and switches at PLAY key entry is shown
i s F i g .1 7 . C . . . . A f t e r m o d e s w i t c h i n go p e r a t i o n sa r e c o m p l e t e d ,
A . . . . PLAY key entry turns the solenoid ON, and switch 52 turns OFF.
s t a r t st h e m e c h a n i s mm o d e s w i t c h i n go p e r a t i o n . D u r i n g t h e A - C i n t e r v a l ,o t h e r k e y e n t r i e sa r e i n h i b i t e d .
B . . . . Next. 52 is turned ON, and it functions to ( H o w e v e r , S T O P i s e f f e c t i v ea n y t i m e , a n d s w i t c h i n gf r o m
detect the proper switching operation (PLAY R E C t o R E C P A U S E i s o n l y i n h i b i t e d b e t w e e nA a n d B . )
m o d e i n t h i s c a s e ) .a n d t h i s t u r n s t h e s o l e n o i d From a STOP status, a key entry turns the motor on at
OFF. A, and pressing TOPwill turn the motor off at C.
S

. Tape End Detector Circuit
The cassettemechanism'stape end detector switch (FAS
swtich) alsocomes ON at times other that at the end of the
DECK MODE
tape, so PD1004 is designed to recognize the end of the
tape as the second time this switch is turned ON. The
s e c o n dt i m e m e a n s t h e s e c o n d t i m e w i t h i n t h e s a m e o p e r a - OFF
FAS SWITCH
oN
tional mode; if the mode is changed somewhere before the
end of the tape, the switch will have to come ON twice in
+
END

that mode before the end of the tape is recognized. lf the
F i s .1 8
switch is turned ON during a mode switching operation,
it will be ignored.

o Muting Output

D E C KM O O E PLAYMODE


P L A YS O E N O I D
L

T3
(PDtOO4 rN 24)
P

M U T EO U T P U T
( P D l O 0 4 P r N2 0 )
OPEN N
OPE F i s .l 9

M u t i n gi s o u t p u t f r o m p i n 2 Oo f l C P D 1 0 0 4 a n d d u r i n g
, p o i n t s h o w ni n F i g . i 9 A l l o t h e rc i r c u m s t a n c e s l d t h e
ho
t h e t a p e P L A Y m o d e , i s o n l y l i f t e d ( d r o p p i n go w ) a t t h e
l o u t p u tc i r c u i to p e n .

. POWER STOP
ON
W h e nt h e p o w e ri s t u r n e dO N , t h e d e c km e c h a n i s m i l l w s e t t i n g a s . T h e s i g n a l f o r t h i s o p e r a t i o n r ep r o c e s s e d
w s a by
g o t h r o u g ho n e S T O Po p e r a t i o n a f t e ri n i t i a l r e s e t ) n d b e
( a l C P D 1 0 0 4 , w i t h o u t p u t b e i n g t h e s a m ea s f o r n o r m a l
p l a c e d n a S T O Ps t a t u sn o m a t t e rw h a t t h e p r e v i o u s o d e
i m STOPkey entry.
o Timer Standby Circuit
T h e t i m e rs t a n d b y i r c u i ti sc o n f i g u r e w i t h i n l C P D1 0 0 4 .
c d m o d e ,a n d t h i s c u t s o f f t h e n - c h a n n eT R ( T M o u t p u t
l
The TM signal is transmitted from pin 33 and is passed p i n ) w i t h t h e r e s u l t i n g p e n s t a t u sa l l o w i n gt h e R E C
o
through the timer standby switch and connectedto the (PLAY) input to go from low to high. This opera-
P L A Y / R E Ce n t r y i n p u t o f P D 1 0 0 4 . T h e c o n v e n t i o n a l tion occursonceat powerON.
d i f f e r e n t i a l u l s e ( C R ) r e q u i r e m e n t s e l i m i n a t e ds o t h e
p i , 2 . W h e nt h e t i m e r s t a n d ys w i t c hi s O F F a t t h e t i m e p o w e r
c u r c u i tc o n s i s t o f o n l y w i r i n ga n d t h e s w i t c h .
s i s t u r n e d O N , n e i t h e rR E C o r P L A Y i n p u t sa r e p r e s e n t
1. Whenthe timer standbyswitch is set for REC or PLAY, a t t h e p o i n t i n i t i a l r e s e ti s c o m p l e t e ds o t h e T M o u t p u t
,
the TM output is pulled low duringthe initial reset p i n i m m e d i a t e l y o e sf r o m l o w t o o p e n a n d w i l l n o t g o
g
o c c u r r i n gi m m e d i a t e l y f t e r p o w e r i s t u r n e d O N . a n d
a l o w a g a i n . I n t h i s c a s e ,o n l y t h e P O W E RO N S T O P
t h i s c a u s e t h e k e y i n p u t f r o m R E C o r P L A Y t o a l s ob e
s operationwill be performed.
l o w . ( T M o u t p u t i s n - c h a n n eo p e n d r a i n . ) W h e n t h e
l 3 . T i m e r s t a n d b ya t E J E C T. . . . . W h e nt h e t i m e r s t a n d b y
resetstatus is released, PD1004goesthrough a POWER switch is set to REC or PLAY and the cassette ejected, is
O N S T O P o p e r a t i o n , n d a f t e r t h a t o p e r a t i o ni s c o m -
a t h e E J E C Ts w i t c hc u t s 0 2 ( c o n t r o lu n i t ) O F F a n d t h i s
pleted, the REC or PLAY entry is acceptedand the breaksthe path betweenthe timer standbyswitch and
respective mode set. Switch 52 (slider switch)comeson TM output. Thus,timer operationis stoppedas described
t o d e t e c t h e s w i t c h i n g p e r a t i o nis t ot h e RE Co r P L A Y
o n in 2. above.



. SOL (Solenoid)
Output Circuit
The cassette mechanism mode switching operations are +B+
accomplished singthe motor as a drive source. This sub-
u t2v
jects the motor to quite a heavy load during these opera-
t i o n s . C o n s e q u e n t l y ,i f b a t t e r y c o n d i t i o n s h a v e d r o p p e d
t h e s o u r c e v o l t a g et o a l e v e l t h a t w i l l b a r e l y s u s t a i n m o t o r
operations and solenoid operation were simultaneously SOLENOID
added to that load, the motor would likely stop during
mode switchingoperations. To preventthis from happen-
GNO
ing, voltage limitations are placed on solenoidoperations.
T h e S O L o u t p u t c i r c u i t p r e v e n t st h e s o l e n o i d s r o m o p e r a -
f Fis.2O
ting when the power source voltage has dropped below the
value required for motor operation. A basic description of f o r m o t o r o p e r a t i o n s , e v o l t a g e u p p l i e do t h e s o l e n o i d
th s t
the circuit is presented ere. (Referto Fig.20)
h i s i n s u f f i c i e n tf o r o p e r a t i o n ,a n d b y u s i n g t h e p r o p e r
Normally the capacitor C is charged through R to the resistance valuefor R, can be stoppedthere without inter-
same potential that exists at point A. When the solenoid feringwith motor operation.
driver comes ON, current flows through R to the solenoid. I n t h e a c t u a lc i r c u i t , t h e S T O Ps o l e n o i d s d e s i g n e do
i t
but since the resistance restricts the flow of current to a operateat a lower voltage,so it is not connectedto this
levelinsufficientfor solenoid operation, it must be supple- c i r c u i t . A l s o ,s i n c et h e R E C s o l e n o i d n d P A U S E o l e n o i d
a s
mentedby discharge urrent from C. c c a n c o m e O N a t t h e s a m e i m e ( R E CP A U S E ) t h e v t o o u s e
t ,
When the potential at point A drops to the lower limit a seoarate circuit.
o F a i l - S a f eC i r c u i t
When low sourcevoltageor some other problem with Consequently, pin voltageriseswith the time constant
TC
the deck mecha