JVC QL-A2 Service Manual

7-(2) Platter rotates at high speed
Platter rotates at high speed.
Does rotation stop
when pin 1 of 1C803
is connected to ground?
Does rotation stop
when +22.0 V is applied
to the collector of
transistor X803?
Transistor X804 or X813
is short-circuited between
collector and emitter.
7-(3) Rotation is not locked to the crystal oscillator frequency
Rotation is not locked to the crystal oscillator frequency.
Are the pulse
rectanguler waveforms
of 50 Hz and 67.5 Hz
available at pin 5 of
'C803?
Yes
No
Is the 9.504 MHz
oscillation voltage present
at pin 3 of 1C802?
Yes
No
Check IC802 for defect,
C806 or C807 for discon-
nection or pattern-cut.
OL-A2
No, 2444
Apply +22.0 V to the col-
lector of transistor X803
and stop operation of the
drive circuit.
Transistor X803 is short-
circuited between collector
and emitter.
ls adjustment
with VR801 or VR802
effective?
Yes
Readjust following
justment procedure”.
C814, R820 or C802
defective. Replace.
Is FG output
6 MVp-p present Y
when the platter is rotated =
by hand at about
33-1/3 rpm?
No
Broken connecting wires or
faulty soldering.
Check for broken patterns No
or faulty soldering
Is about normal
rotation obtained with
R818 removed?
No
Yes
C811, D802, C813, R817
or IC802 defective.
1s 5.8 Vp-p
output present
at pin 7 of IC801 when
the platter is rotated
by hand at about
33-1/3 rpm?
No i
eer
8
ts 22.0 V available
at pin 8 of IC801.
Are C809, C810,
VR801 and VR802
correctly employed?
No
Yes
Replace.
ts the
rectangular
waveform of 22 V at
pin 1 of 1C801 available
when the platter is rotated
by hand at about
33-1/3 rpm?
Yes
No
Check for defettive [C801
or incorrect capacitance of
C803.
Defective !C801, incorrect
capacitance of C801 or open
R803 may be the cause.
Is the waveform Yes
present at TP-3 as shown
in wiring diagram 1?
No
ts FG output as
specified? Is 5.8 Vp-p
present at pin 7
of 1C801?
Yes
No
Check motor or replace
1C801.
rectangular waveform
of 4.6 V at TP-3 available
when the platter is rotated
by hand at about
33-1/3 rpm?
Yes
No
Check for broken pattern or
faulty soldering of R808 and
R809.
Check connection or solder-
ing of 1C802.
1C801 defective.
DC2.1 V availabié
available at pin 1 of
at pin 7 of IC802 when Yes 1C803 when the platter Yes
the platter rotated by hand .
at about 33-1/3 rpm? is rotated by hand at
pm about 33-1/3 rpm?
No No
Check for defective !C802, Check for defective 1C803,
short-circuited or open IC short-circuited or open !C
leads. leads.
Normal
Warning !
1. Be careful not to allow metallic dust, etc. to enter
inside the unit, be cause its motor is comprised of
magnetic elements.
2. After replacement of the X813 transistor, apply
KE45RTV (silicone adhesive) or an equivalent
material around the transistor for thermal con-
duction.

JVC QL-A2 Specifications

General

Brand	JVC
Model	QL-A2
Category	Turntable
Language	English