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Focus Gain Adjustment
A frequency response 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 gain determines the optical pick-up follow-up (vertical and
horizontal) relative to mechanical noise and mechanical shock
when the 2-axis device operate.
However, as these reciprocate, the adjustment is at the point where
both are satisfied.
• When gain is raised, the noise when the 2-axis device operates
increases.
• When gain is lowered, mechanical shock and skipping occurs
more easily.
• When gain adjustment is off, the symptoms below appear.
Symptoms
• 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)
• Sound is interrupted during PLAY.
Or time counter display stops progressing.
• More noise during 2-axis device operation
The following is a simple adjustment method.
– Primary Adjustment –
Note: Since exact adjustment cannot be performed, remember the posi-
tions of the controls before performing the adjustment. If the posi-
tions after the primary adjustment are only a little different, return
the controls to the original position.
Connection:
MAIN board
BP (FEO)
TP504 (VREF)
Gain
Focus
low
–
–
high
oscilloscope
+
–
Procedure:
1. Keep the set horizontal.
(
If the set is not horizontal, this adjustment cannot be per-
formed due to the gravity against the 2-axis device
2. Insert the test disc (YEDS-18) and press the ^ button.
3. Connect the oscilloscope BT (FEO) and TP504 (VREF) on
the MAIN board.
4. Adjustment RV502 on the MAIN board so that the waveform
is as shown in the figure below.
• Incorrect Examples (DC level changes more than on adjusted
waveform)
low focus gain
high focus gain
Adjustment Location: MAIN Board (See page 13)
– 11 –
)
VOLT/DIV: 100 mV
TIME/DIV: 2 mS
100 mV
0 V
VOLT/DIV: 100 mV
TIME/DIV: 2 mS
200 mV
0 V
VOLT/DIV: 100 mV
TIME/DIV: 2 mS
75 mV
0 V
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