57
58
The following is a simple adjustment method.
– Simple adjustment –
Note : Since exact adjustment cannot be performed,
remember the position of the control before
performing the adjustment.
If the position after the simple adjustment is only
a little different, return the control to the original
position.
Procedure :
1) Keep the set horizontal. (If the set is not kept
horizontally, this adjustment cannot be performed
due to the gravity against the 2–axis device.)
2) Insert test disc TCD–782 and play back the second
composition.
3) Connect an oscilloscope to TP3 (TB) and TP2 (VC).
2. Tracking Balance Adjustment
1) Connect an oscilloscope to the test points TP3 (TB )
and TP2 (VC).
2) Turn on the power switch.
3) Insert test disc TCD–782 and press the PLAY
button.
4) Connect the center point of SFR703 to TP2 (VC).
5) Adjust SFR702 so that the waveform on the
oscilloscope is vertically symmetrical as shown in
the figure below.
6) After the adjustment is completed, remove the
connected lead wires from the terminals.
3. Tracking Gain Adjustment
A servo analyzer is necessary in order to perform this
adjustment exactly. However, this gain has a margin, so
even if it is slightly off, there is no problem. Therefore,
do not perform this adjustment.
Focus/tracking gain determines the pick-up follow-up
(vertical and horizontal) relative to mechanical noise
and mechanical shock when 2-axis device operates.
However, as these reciprocate, the adjustment is at the
point where both are satisfied.
•
When gain is raised, the noise increases when the
2–axis device operates increases.
•
When gain is lowered, it is more susceptible to
mechanical shock and skipping occurs more easily.
When the gain adjustment is off, the symptoms
below appear.
Oscilloscope
(DC range)
TP3 (TB)
TP2 (VC)
+
-
A
VOLT / DIV: 0.2V
TIME / DIV: 1mS
B
A=B
0V
VC(VREF)
Oscilloscope
(DC range)
TP3 (TB)
TP2 (VC)
+
-
Symptoms
Gain
• The time until music starts
becomes longer for STOP
PLAY or automatic
selection ( , buttons
pressed.) (Normally takes
about 2 seconds.)
• Music does not start and disc
continues to rotate for
STOP PLAY or
automatic selection
( , buttons pressed.)
• Disc stops to rotate shortly
after STOP PLAY.
• Sound is interrupted during
PLAY, or time counter
display stops.
• More noises during the 2-axis
device operation.
(
Focus)
low
–
low or high
–
high
Tracking
low or high
low
–
low
high
4) Adjust SFR703 so that the waveform appears as
shown in the figure below. (tracking gain
adjustment)
VC(VREF)
0V
VOLT/DIV: 0.1 V
TIME/DIV: 1 mS
•
Incorrect example
Low tracking gain
(The fundamental wave appears as compared with
the waveform adjusted)
VC(VREF)
0V
VOLT/DIV: 0.1 V
TIME/DIV: 1 mS
High tracking gain
(The frequency of the fundamental wave is higher
than in low gain.)
VC(VREF)
0V
VOLT/DIV: 0.1 V
TIME/DIV: 1 mS
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