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QL-5
No. 2428
Is23-0.5V
available at TP-5 when the.
Platter does not rotate.
Yes
power switch S3 is
turned on?
1s a voltage present at the
collector of transistor X8172,
1s an AC voltage present
between lapping tabs 7 — 8,
Primary fuse or transformer
disconnected.
AC
cord
soldering defective.
Yes
Transistor X817 — X819 or
diode D811 defective.
Diode 0812 — D815 open or
incorrectly soldered
Hall elements open. Motor
No
disconnected
inside,
dis.
connected resistors,
Yes
Does the platter rotate when
R820 is short-circuited?,
Does platter rotate
when pins
6 and 1 of 1C802
are short-circuited?
Does the platter rotate
'when pins 1 and 8 of IC 803
are short-circuited?
IC8O3 defective
1C802 defective.
Does platter rotate
Yes
transistor X803 are
short-circuited?
Transistor
¥803 is open be-
tween emitter and collector.
Does platter rotate by hand?
1s output available
St voltage terminals of Hall
elements HG-1 and HG-2?,
Transistors X807
— X814
detective. Lead from circuit
board to motor disconnected.
Check
for
loose
socket,
floating
pattern
fective soldering
and
de
Yes
Check
for incorrect
ca
pacitance or defective solder
ing of 1C801.
Is the oscillation waveform
available at TP-3?
Is transistor X815,
capacitor C818, resistor
R847 of R848 not
defective?
Notes for replacement of transistors X811 — X814
There are 4 ranks K1, K2, L1 and L2 for 2 SD571
transistor h FE. Be sure to use those transistors of the same
ranking when replacing.
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