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6. Troubleshooting
6-(1) Platter does rotate
C Roration is not locked to the crystal oscillator frequency. )
Are the pulse
Fectanguler waveforms
of 50 Hz and 67.5 Hz
available at pin 5 of
1C803?
Is the 9.504 MHz
oscillation voltage present
at pin 3 of 10802?
Yes
Is adjustment
with VR801 or VR802
effective?
Is about normal
rotation obtained with
R818 removed?
Are C805, VR8O1
and VR802 correctly
employed?
Readjust__
following
justment procedure".
C809, D801, C810, R815 or
1C802 detective
Replace.
Check
1C802
for defect,
C812 or C813 for discon
nection or pattern-cut.
816, R845 or 1C802
defective. Replace.
6-(2) Platter rotates at a high speed
C Platter rotates at a
igh speed. D)
Does rotation stop.
when pin 1 of IC803
is connected to ground?
Does rotation stop
when +23.0 V is applied
to the base of transistor
X805 or X806?
Yes
Transistor X804, X805 or
X806 is short-circuited be-
tween collector
and emitter.
Apply +23.0 V to the base
of transistor X805 or X806
and stop operation of the
drive circuit.
Is FG output
4 mVp-p present
when the platter is rotated
by hand at about
3-1/3 rpm?
Trnasistor X803_ is short-
circuited between collector
and emitter.
Broken connecting wires or
faulty soldering.
Check for broken patterns
or faulty soldering
is 2 Vp-p output
present at pin 7 of
1801 when the platter
is rotated by hand at
about 33-1/3 rpm?,
Is the waveform
present at TP-3 as shown
in wiring diagram 1?
Yes
Check connection or solder
ing of 1C802.
Is FG output as
specified? Is 2 Vp-p
output present at
7 of 10801?
Check
motor
or replace
1801
Is the rectangular
waveform of 23 V at
pin 1 of C801 available
when the platter is rotated,
by hand at about
33-1/3 rpm?
1801 defective
Is the rectangular
waveform of 4.5V at
TP-3 available when the
platter is rotated by hand
at about 33-1/3 rmp?
Is about
DC2.7 V available
at pin 7 of 1C802 when
at about 33-1/3 rpm?
the platter rotated by hand,
Is about
0010.9 V
available at pin 1 of
1C803 when the platter
is rotated by hand at
about 33-1/3 rpmz,
Check for defective 1C801 or
incor
capacitance
of
C808.
Check for broken pattern or
faulty soldering of R808 and
R809.
Check for defective 1C802,
1c
short-circuited or open
leads.
IC
Yes
|
Detective |C801, incorrect
capacitance of C801 or open
R803 may be the cause.
Normal
QL-5
No. 2428
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