Aiwa XP-SP90, Руководство по обслуживанию

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15
The bias set value is displayed by hexadecimal notation
in the 64 steps.
Display range of set value 80 to bF
Default value (center value) of setting is displayed as
“9d”. When the value larger than the default value is
displayed, it means that the higher bias value is set to the
machine. When the value smaller than the default value
is displayed, it means that the smaller bias value is set to
the machine.
1 RF level check
• Test point: RF & VC
• Test disc: TCD-782
Confirm that the RF waveform as shown below appears.
RF Signal Waveform
EYE PATTERN
must be CLEAR and MAX
1.0
±
0.2Vp-p
VREF
VOLT/DIV: 200mV
TIME/DIV: 0.5
µ
S
When the mode display appears on the LCD, and when the
PLAY key is pressed in the STOP mode, the LCD shows the
center value at first. Then the display changes to the set value
which is set by the automatic adjustment when the
disc starts rotation.
2 Focus bias control by the manual control
The focus bias value can be set to any desired value by
pressing the F. Skip key or B. Skip key during the focus
bias check mode.
The 64 steps can be set in the range from 80 to bF.
(Center value: 9d)
Make an attempt to change the focus bias using the
F.Skip key or B.Skip key while observing the RF
waveform on an oscilloscope, and confirm that the RF
signal is maximum at the default value (the value before
starting the manual operation).
When the maximum amplitude is confirmed at the default
setting, the automatic adjustment works satisfactorily
2) Tracking Balance
When the machine enters the tracking balance check
mode, the following display appears on LCD.
Tracking balance set value
Tracking
balance
The servo circuit of this model is designed to be adjustment-free
and is automatically adjusted inside IC. However, the adjustment
conditions inside IC of the focus bias, tracking balance and
tracking gain can be monitored using the test mode.
1. How to Start the Test Mode.
1) While the main power is OFF, set the OPEN/CLOSE
switch (S801) to the CLOSE (ON) position.
* Alternately, shorting the short land near S801 puts the
switch (S801) to the CLOSE (ON) position.
2) Insert the AC plug to the power outlet.
3) Press PLAY key , then power on, all LCD light turn on.
4) While all LCD light turn on, keep pressing the PLAY
MODE key and short the TEST LAND (TP1) more than
one second.
5) When all LCD lights turn on in step 4), it indicates test
mode has started up.
Note)
• Once test mode is started, OPEN/CLOSE switch
can not be accepted.
2. Focus Search Mode
The focus search operation can be checked using this mode.
How to start the focus search mode:
Press the STOP button when the machine is stopped (STOP
mode).
If the STOP button is pressed again, the focus search
operation is stopped.
When a disc is inserted while the machine is in the focus
search mode, the disc does not rotate (focus servo is not
locked ON) but the search operation is repeated.
3. Focus Bias, Tracking Balance and Tracking
Gain Check
Selection of either the focus bias check mode, tracking
balance check mode or the tracking gain check mode can be
made by pressing the PLAY MODE key. As the PLAY
MODE key is pressed, the check mode changes in the
following order.
Check mode OFF
™
Focus Bias
™
Tracking Balance
™
Tracking Gain
When the mode display appears on the LCD, and when the
PLAY key is pressed in the STOP mode, the LCD shows the
center value at first. Then the display changes to the set value
which is set by the automatic adjustment when the
disc starts rotation.
1) Focus Bias
When the machine enters the focus bias check mode, the
following display appears on LCD enabling to check the
focus bias setting level inside IC.
Focus bias Bias set value
(
(
(
(