V.
CAM
MOTOR
DRIVE
CIRCUIT
R59
IK
+7,5V
"'
"'
..-x
.,x
"'"'
,._x
co"'
NO,
"'"'
NN
.,.
....
"'"'
_..,
-"l
er-=
a:..:
irN
0::N
iii:.,
TRIO
TRII
TRl2
TRl3
TRl4
EJECT FF/REW
CUE
STOP PLAY
+ 7,5 V
VRI
The cam motor
is
used for the operation
of
mechanism.
It
determines the position
of
the head base
in
each
mode; power eject mode and auto loading mode.
(Plunger used to
be
employed for this operation.)
Circuit functions (Symbol numbers
of
GX-F71 are used
for the explanation, but the functions are same as those
of
GX-F31/F51 ).
TRIO~
TR14 are turned on by the signal from IC8
(MICOM)
in each mode.
By the difference
in
the value
of
resistances
of
RI 24 ~
Rl28,
the voltage at point ® is determined in each
mode and this voltage
is
used
as
the standard voltage
of
OP Amp (IC9).
At IC9, the voltage at point
® is compared with
that
at
point ® and when ® >
@,
point © becomes
"L"
(-7V)
and when ® < , point © becomes
"H"
(+7V) and when ® , point © becomes
"0"
(Approx.
-3V
~ +3V).
Supposing that point
is
"H"
( +7V).
TR23
"ON"
➔ TR24
"OFF"
➔
TR30
"OFF"
➔
TRI
9
"OFF"
and the collector
of
TRl
9 becomes
"H''
/
V
VR901
/
/
/
+7,5V
',
2'l------<.----'ll
...
TO
TR23,25
♦
!MOTOR
DRIVE
CIRCUIT)
©
4+
r,,,.
,,,.,
-7,5V
CAM
MOTOR
/,,--
-
--®
________
__J
VR2
Fig. 8 Motor Revolution Indication Circuit
while at the same time, TR25
"ON"
➔ TR29
"OFF"
➔
TR20 "ON" and the collector
of
TR20 becomes
"L".
Therefore, the motor turns.
Since the cam motor and VR901 are interlock each
other, the voltage at point
is
changed
as
the motor
turns. The motor stops when the voltage at point
®
becomes equal to the voltage at point
@,
that
is,
when
the voltage at point
(G)
becomes
"0".
While
point ©
is
"L"
(-7V), the
on/off
of
TR
is
reverse direction.
TR3 l and 32 are provided for shorting
both
ends
of
motor and applying brakes when the voltage at point
©
is
"0".
When point ©
is
"H"
or
"L",
"H"
is applied
to
IC7
®
and
IC7
becomes
"L"
and then TR33
"OFF"
➔
TR31 and 32
"OFF"
and, therefore, both ends
of
motor
are not shorted.
When
point
is
"0",
IC7 ®
is
"L"
and
IC7
"H"
➔ TR33
"ON"
➔
TR3 l and 32 "ON"
and, consequently, both ends
of
motor are shorted and
brake
is
applied.
1-13
To Next Page
Loading...
