Table of Contents
Advertisement
-
10.9 FOCS ERROR BALANCE
ADJUSTMENT
(VR2)
1. Search frame
#
104.
2. Adjust VR2 so that the crosstalk striped pattern on the left
and right sides of the monitor screen are not visible. (Fig.
10-10)
,r,..,/
-:;:::::::.
-:;:::::::.
~
-:;:::::::.
-:;:::::::.
/',..,,'
~
-:;:::::::.
/',..,,'
~
-:;:::::::.
-:;:::::::.
%
-:;:::::::.
,,.._,_.,
~
-:;:::::::.
~
~
-:;:::::::.
%
~
/"'.;/
~
~
-:;:::::::.
.,,..__,,
-:;:::::::.
~
~
:::::::;
,r,..,/
%
-:;:::::::.
,r,..,/
~
-:;:::::::.
-:;:::::::.
~
/',..,,'
~
# 103
#
104
t
1os
Fig. 10-10 The influence of crosstal
k
10.10 TILT SENSOR
TILT
ADJUSTM
ENT
1. Search frame
#
104.
,,.
2. Turn the tilt sensor tilt adjustment screw until the voltage
at TP7 of the PREB assembly is 0- 50m V. (Use care to
prevent external light reaching the sensor.)
3. Again remove the Mechanical assembly from the chassis and
fully tighten the Pick-up assembly mounting screws
.
4. Mount the
Mechanical
assembly in the chassis and connect
the CN34 connector of the REPB assembly.
5. If there is crosstalk at frames
#
104
and
#
18,914,
readjust
the tilt of the P ick-up assembly from the beginning.
10.11 GRATING FINE ADJUSTM
ENT
• Connecter CN34 of PREB assembly must be connected.
1. Open the TRK G servo.
2. Set the oscilloscope to the X-Y mode, and adjust the X
and
Y zero points. (Set the beam spot of the oscilloscope in the
center of the CRT scale.)
Connect TP4 to the X input and pin (5) (TRKG (A
+
B) o
f
connector CN24 to the Y input.
3. Press the fast forward key of the remote
control
and move
to the area near frame
#
15,000.
• Adjust the grating until the Lissajous figure is
horizontal.
10. 12 TRKG LOOP GAIN ADJUSTMENT (VR5)
G)
Connect the oscilloscope to the oscillator, as shown
in
Fig.
10- ll(a),
and
set t
he oscilloscope to the X-Y mode.
@
Search the area near frame
#
15,000.
@
Set
the oscillator output as shown in Table 10-1.
@
Adjust
VR5 so that the Lissajous figure is horizontal. (Photo
10-4)
Test
Disc
Fl
F2
F3
F4
F5
F requency (kHz)
3.0
3.7
3.3
3.3
3.3
Output (Vp-p)
1.2
1.2
1.2
1.2
1.2
Table 10-1 Oscillator output set values
Photo 10-4 Lissajous figure
X: 100mV /div
Y: 200mV/div
X: oscillator
ou
t put
Y: TR KG
(A-C) signal
(TR KG loop gain adjustment)
y
X
y
X
AF
OSC
AF
O
SC
TP4
IC4
(2/2)
VR 5
(a)
TR KG LOOP
TP2
t
l
OOk
Q
IC 4 ( I
1
2) IC2( I
/
2)
(b) FOCS LOOP
Fig. 10-11 Servo loop gain adjustment
TP3
VR
3
4
9
Advertisement
Table of Contents
