Sony TC-766-2 Service Manual page 56

TC-766-2
12. STOP Circuit (Refer to Fig. 14) S605 S606
- i
i
shut off Aut off
(Shut-Off Circuit)
Tea el ies an
1, When
the tape has finished winding,
or when
we \ | = nd ep sae
slack, tension arm micro-switch (S605, 606) is \ ape {
closed adding 24V to Q723 through R756.
(Path 4) )
2. Because of this, Q723 is turned ON activating
the IC701 input.
3. When AC is ON, Q722 slowly goes to the ON
state as determined by time constant of R751
and C717. (Refer to TIMER-activated opera-
tion)
To supplement this, while Q722 is OFF, Q723
is ON and the STOP input of IC701 is activated. C7I7
(Path (2) )
R75I> .5., | Lauro n-- B+
7~—1C input
STOP
|
|
i
Fig. 14
13. TIMER-Activated Operation (Refer to Fig. 15)
1. With TIMER switch (S603) ON, when the
POWER switch (S604) is turned on, the voltage
at point @ supplied through D726 and Bt
voltage (+24 V) rise after 0.2 to 0.5 seconds.
2. At this time, C717 is charged through R751
and the charged voltage turns on zener diode
D768 after 5 seconds determined by a time
constant of R751 and C717, and then turns on
Q722.
3. As aresult of 2., the (+) side of C719 becomes
-5 to -6V and passing through $603, D766 and
767 are turned ON to produce the record and
forward signals for the Record or Playback
modes.
(The circuit containing D726, 727, C716 and R750
makes C717 quickly discharged, when the power
supply is turned off.)
$603
TIMER
OFF > ON
0767 ;
to input of
a function button »p (Forward)
D766
3
$604
POWER
to input of
oN function button @ (Record)
Keays supply for ley.
solenoid hold etc.
Fig. 15