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e Servo gain adjuster and its connection
Bein, a
Low frequency
' oscillator
{-15V)
Blue
Chassis 4
Green
Oscilloscope
Caution:
(1) Do not look into the lens when power is applied to
the unit, since there is laser radiation (H.H.S./D.H.W./
etc., regulation).
(2) These steps must be followed in order.
. Connect the gain adjusting jig with conversion
connector to
the set.
Red
........ Jumper
beside
1C301
pin 13 on 01 P.C.B.
Blue........ Jumper
beside
1C301
pin 12 on 01 P.C.B.
Green....... Chassis
Connector... . Pull out the shorting pins of CN103 on 03
P.C.B. and connect the conversion connector
to the jig and then connect then connector
(SP) from conversion
connector to CN103.
2. Adjust the low frequency oscillator to 750 Hz frequency and
150mVp-p
output voltage, and connect
it to TEST pin OSC
IN and GND of the servo gain adjuster.
3. Connect CH1 and CH2 of oscilloscope to TP1 and TP2 of the
servo gain adjuster.
(TP3 is GND).
Oscilloscope setting:
VOLT 100mV (both channels), SWEEP 2ms, Input AC, Mode CHOP
4. Set the servo gain adjuster power SW "'on" and the rotary selector switch to ''1"' and place the disc on turntable.
5. Turn power switch ON.
When turntable beings to rotate, 750 Hz signal appears on the oscilloscope.
Then adjust VR101 so that the waveforms of both channels are equal to each other.
. Focus balance adjustment
. Set the servo gain adjuster power SW "on" and the
rotary
selector
switch
to
'2'
and disconnect
the
input from the oscillator.
2. Connect TJ102 on O03 P.C.B. to ground by use of
clip lead.
-
TJ101
3. Pull out connector CN501 on 01 P.C.B.
4, Connect
the oscilloscope
to TJ101
on
O3
P.C.B.
and place the disc on turntable.
Oscilloscope setting:
VOLT 500mV, SWEEP 5ms, Input AC
5. Turn
power
switch
ON.
When
the laser
lights up,
S-shaped
waveform
appears
on
the
oscilloscope.
Then
adjust
VR102
so that
the
top and
bottom
peak values are equal to each other.
Note:
The
above-mentioned
S-shaped
waveform
will
continue
for about
2 minutes
if CN412
pin 4
(01 P.C.B) is connected to ground while LD is
lighted as LD stops in 5 ~6 sec.
6. After the adjustment, shift the clip lead and CN501
back as they were.
3. Focus offset adjustment
1. Set the servo gain adjuster power SW ''on" and the rotary selector switch at 2".
2. Place the unit in the Eject mode. (tray open).
3. Connect a voltmeter to TJ101 on 03 P.C.B. (Optical servo).
4. Turn power switch ON, and adjust VR103 so that DC voltage is O + 10 mV.
4. Tracking gain adjustment
1. Set
the
servo
gain adjuster
power
SW
"on"
and the
rotary selector switch to "3",
2. Adjust
the
low
frequency
oscillator
to
1.5 kHz
and
150mVp-p
output.
And connect
it to TEST
pin OSC
IN and GND of servo gain adjuster.
3. Connect
CH1
and
CH2
of oscilloscope
to TEST
pin
TP1
and TP2 of the servo gain adjuster. (TP3 is GND),
and place the disc on turntable.
Oscilloscope setting:
VOLT
100mV
(both channels),
SWEEP
2ms,
Input
AC,
Mode
CHOP
4. Turn power switch ON.
When turntabie beings to rotate,
1.5 kHz signal appears on the oscilloscope.
Then adjust
VR104 so that the waveform amplitudes of both channels,
are equal to each other.
5. Tracking offset temporary adjustment
1. Set the servo gain adjuster power SW "'on" and the rotary selector switch to ''2'', and disconnect the input from
oscillator.
2. Place the unit in the Eject mode (tray open).
3. Connect a voltmeter to TJ103 on 03 P.C.B. (Optical servo).
4. Turn power switch ON, and adjust VR106 so that DC voltage is
0+ 3 mV.
6. Tracking balance adjustment
1. Set the
servo
gain adjuster
power
SW
"on"
and the
rotary selector switch at "2".
2. Connect
the oscilloscope to TJ103
on
03 P.C.B. and
then place the disc on turntable.
a,b
VOLT 200mV, SWEEP 5ms, Input DC
3. Turn power switch ON.
When turntable begins to rotate
and the tracking servo switch of servo gain adjuster is
turned OFF, TE
(tracking error) signal appears, on the
oscilloscope.
Then
adjust VR105
so that the top and bottom
peak
values are equal to each other.
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1. Set the servo gain adjuster power SW "on" and the rotary selector switch at "2".
2. Place the unit in the Eject mode (tray open).
3. Connect a voltmeter to TJ103 on 03 P.C.B (Optical servo).
4. Turn power switch ON, and adjust VR106 so that the DC voitage is 0 + 3mV.
Note:
After completing the above-mentioned adjustment, remove the servo gain adjuster and insert the shorting pin
into CN103 as it was.
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