Aiwa DX-D91 Service Manual page 10

ADJUSTMENT
[AJMAIN C.B
(PATTERN SIDE)
Note: Connect probe(10:1) of frequency counter and
oscilloscope to test point.
(Normal Speed VCO Frequency Adjustment
Open the tray by pressing the OPEN/CLOSE button.
Short between test points TP6 (ASY) and TP4 (GND)
using a short lead wire.
Connect the frequency counter to TP! (VCO) and
TP2 (GND).
Adjust SFR403(VCO) so that the frequency counter
reading is 4.10 + 0.02 MHz.
After this adjustment, remove the short lead wire
from TP6 (ASY) and TP4 (GND).
@ Offset Voltage Adjustment
PS ee is
Connect a voltmeter to TP3 (PLLV) and TP4 (GND).
Turn the power switch on.
Open the tray by pressing the OPEN/CLOSE button.
Short between test points TP6 (ASY) and TP4 (GND)
using a short lead wire. Also, short TP5 (H-SPD)
and TP4 (GND).
13
VIDE-V04661 / Druck 4
OY Oe
TPI3
SFR452 Eb) ©
SFR301
5. Adjust SFR301 so that the voltages at TP3 (PLLV)
and TP4 (GND) are 0 + 0.05 V.
6. After this adjustment, remove the short lead wire
from TP6 (ASY) and TPS (H-SPD).
@ High Speed VCO Frequency Adjustment (Y model only)
1, Put the unit in high speed mode by turning the power
on while pressing the RANDOM and REPEAT/BLANK buttons.
2. Open the tray by pressing the OPEN/CLOSE button.
3. Short between test points TP6 (ASY) and TP4 (GND)
using a short lead wire. Also, short TP5 (H-SPD)
and TP4 (GND).
4. Connect the frequency counter to TP! (VCO) and
TP2 (GND).
5. Adjust TC301 so that the frequency counter reading
is 7.82 + 0,005 MHz. If this specified value is
not met, readjust using L302,
6. Turn the power off,
7. Check that the frequency in the normal speed adjustment
is correct.
8. After this adjustment, remove the short lead wire
from TP6 (ASY) and TPS (H-SPD).
@ Focus Bias Adjustment
Make the focus bias adjustment when replacing and
repairing the optical block.
Oscilloscope
(DC range)
MAIN C.B
——
TP7(RF)o
TP8(GND)o
1. Connect the oscilloscope to TP7(RF), TP8(GND).
2. Turn on the power switch.
3. Insert the disc YEDS-18 (YEDS-1) and play back the
second track.
4, Adjust SFR452(F.B) to make clear and maximize the
waveform, diamond shapes (<>) can be distinguished
in the center of the waveform.
RF signal waveform
\X
RETR
\ KR
CHER
RY
\) \
AY
XXX ,9.9.4,9.0:0
OOXXX)
YX MAX,
VOLT/DIV : 20mV
TIME/DIV : 0.5 usec
® RF Waveform Check
This check should be performed whenever the optical
system block is replaced.
1. Connect the oscilloscope to TP7 (RF) and TP8 (GND).
2. Turn the power switch on.
3. Insert the disc YEDS-18 (YEDS-1) and play back the data
on the second track.
4. Adjust SFR on the pickup board so that a waveform
appears in the oscilloscope as shown in the figure
below.
RF signal waveform
NAY 6.0,0505050.0,0'0°05050.7
OOOO KY
WY OO OOCN a
X 1.4 + 0.3 Vp-p
C KXAN
Ov
VOLT/DIV: 20 mV
TIME/DIV: O.5usec
Note: The current of the laser signal can be checked by
checking the voltage across R458(10Q).
The specified current value is shown on the label
of the pickup. The difference should be + 6.0 mA.
KSS-150A
15Y98 46.4 mA
K464
Voltage across R458
Laser current lop =
: : 102
14
@© Tracking Balance Adjustment
Oscilloscope
(DC range)
MAIN C.B
fs
TPII(T IN)o
TPLO(GND)©O
—_ .
Connect the oscilloscope to TP11(T IN), TP1O(GND).
Connect a center of SFR401(TE) to ground.
. Turn on the power switch.
. Insert disc YEDS-18 (YEDS-1) and press the [>PLAY
but ton.
5. Adjust SFR451(TB) so that the waveform on the
oscilloscope is vertically symmetrical as shown in
the figure below.
i) .
mm oF
A
0 + 20mV, A= 8B
B
VOLT/DIV : 20mV
TIME/DIV : 2msec
6. After adjustment is completed, remove the ground
lead wire.
Focus/Tracking Gain Adjustment
A frequency responese analyzer is necessary ip order
to perform this adjustment exactly.
However, this gain has a margin, so even if it is
Slightly off, there is no problem Therfore, do
not perform this adjustment.
Focus/tracking gain detemines the pick-up follow-up
(vertical and horizontal) relative mechanical
noise and mechanical shock when 2-axis device
operate.
@ When gain is raised, the noise when the 2-axis
device operates increases.
@ When gain is lowered, it is more susceptible to
mechanical shock and skipping occurs more easily.
@ When gain adjustment is off, the symptoms below
appear.