Technics RS-B765 - Page 25

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Mi TROUBLESHOOTING OF
DIRECT DRIVE MOTOR
¢
OUTLINE
OF
THE
DIRECT
DRIVE
MOTOR
SYSTEM
The
capstan
motor
is
actuated
by
the
DD
motor
digital
servo
system.
The
FG
pulse
is
generated
after
the
detection
of
the
zero
crosspoint,
and
the
reference
signal
generated
from
the
quartz
oscillator
is
compared
with
this
FG
pulse.
From
this
comparison,
the
accelerated
and
reduced
speed
Mi capstan motor(p.p) ciRcuIT
Ic20l
‘
vom]
YY
HAI3440MPEL
coon
|
DUN
130ms.
be
MOTOR
DRIVE
CIRCUIT
(CN201)
HALL
ELEMENTS
HW-IO1A-FT
FL551 ( RSLOO32 -F)
HALL AMP
pc
METER
7
pulses
are
generated,
causing
the
driving
coil
to
function.
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FG SIGNAL
R201 4.7
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2
PS
ag
2
Y
-16.6V
L
PLet
slat
eletgtetalel
ag
s
FG
PULSE
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tin.
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a
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ia
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of © oO
-17.3V
CLOCK PULSE
i 1C551
REGS | -HD404302SA07
MICRO
COMPUTER
Connect
the
IC20I@pin
terminal
51 (FL METER)
to the ground with a lead wire
oev|
AMP ORIVER
av
ov
“Zeus
2ms.|OV/DIV
Q551
2SAI3Z309AQSTA
RESET (DISPLAY MICROCOMPUTER)
SPEED DOWN PULSE
1C202(1/3) 1C202(1/3)
R
1C202(1/3) svP
2SD60IRTW
REGULATOR
1c202
1C203
SN74LSO4MEL SN74LS74AMEL
INVERTER FLIP-FLOP
PERATION SWITCH CIRCUIT
1. The motor does not
rotate.
No power supply (+12V)
2. The Hall element has failed (Current does
not flow).
3. The ceramic (or crystal) does not oscillate.
¢ Check the voltage applied to the
connector.
¢ Check the DC potential on IC pins
@Q~@.
* Check the waveform of IC pin @.
STIO(TIMER )
r 7
R970
ree-=~otf
pla
2.2K i ey
3 R704) R705 R706 R707 R708
47K
70 R709
2K 1.5K 1.8K 2.2K 33K 6.8K
. The motor does not rotate
properly. (When pressed,
it stops at certain
angles. Sometimes it
does not rotate even if
power is ON.)
* Check the conductance of the
coil. If normal, the resistances
between IC pins ©~@, @~@,
(6~48 will reach 20 ohms.
¢ Check the waveform of IC pins
@Q~®@.
. The coil is broken or not properly soldered.
2. Output of the Hall element is not proper.
R716
18
WA
(APRS)
(oe)
—-
s7i
o |
$707
(c)
fo
$708
(B)
px) $709
palin
feo
x ny
R
(DOLBY NR)
on NA ON RY
a
-2
a RB -2
ay
Ra
‘O-—! vt rey ce} 8
Bale
ae
Ayhde
.
The
motor
is
out
of
.
The
FG
coil
is
broken.
¢
Check
the
waveform
of
IC
pin
©.
ge
bee
8
control.
*
Check
if
the
FG
coil
is
broken.
$2
Sa
r
(MEMORY)
[or
4.
Abnormal
wow
1.
Same
as
those
described
for
problem
2.
Note:
Check
the
points
marked
with
an
asterisk
(*)
by
removing
the
DD
motor
control!
P.C.B.
and
then
connecting
IC
pin
@
to
GND
with
a
lead
wire.
(After
the
DD
motor
control
P.C.B.
is
removed,
current
will
start
flowing
through
the
coil,
heating
the
IC.)
0701
3655 EBK RFKFSB6S5EAK
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