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3. BLOCK
DIAGRAM
(IC = PA3006)
+Vcc18V
(to Vec)
i
SWITCHING
CONSTANT
CURRENT
r---
Supply
of current
WT
VT
VTL
TTD
TM
VTE
WT
WT
DD Motor Operation
The control circuit employed
in the
PL-3000
turntable
is an IC version of the control
circuit
in the PXM-030
D.Dmotor
turntable. Opera-
tion is basically
the same,
and has already been
described
in
the
'Additional
Service
Manual"
(ART-292 ) for the PXM-030.
Position Detector Hall Element Output and Coil Current
4.D.D
MOTOR
TROUBLE
SHOOTING
CHART
4.1 MOTOR
FAILS TO ROTATE
Does
18V
register between
Q, emitter
and ground ?
YES
Check
that
external
connections
are
normal
(including pitch VRs and motor
connector plug).
YES
Does 6.3V (to Vcc) register at pin no.7 of
PA3006 ?
YES
Does the voltage across pins 6 and 7 of
PA8006
register 3.4V
for 33 rpm, and
3.6V for 45 rpm ?
NO
YES
Does
the
voltage
across
pins 4 and
7
of PA3006
register 2.9V ? (Connect the
positive probe of the multimeter to pin
no.4
, and
the
negative
probe
to pin
no.7).
YES
Does
the
voltage
across
pins
7 and 9
of
PA38006
register
about
1V
?
(Connect
positive
probe
to
pin no.9,
|NO
and
negative
probe
to pin
no.7).
YES
Defective
Q,,
@Q,,
Ds.
or
other
circuit
components
in the
power
supply stage.
Defective PA3006.
Are
the
same
voltage
readings
obtained when measuring after dis-
connecting
terminal
no.12
of the
printed circuit board ?
Defect in the reference bias circuit
consisting of R,;~R,, VR,,VR2, Di
and
D,.
Defective PA3006.
Defect
in the
speed
detector
circuit
consisting of Ryg~R,,,C,,C3,
and
D3;~D,.
Deffective PA3006.
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