Read Sony ICF-CD873L Service Manual online
– 10 –
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
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.
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.
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:
• The time until music starts becomes longer for
STOP
→
PLAY or automatic selection.
(=, + buttons pressed)
(Normally takes about 2 seconds)
(Normally takes about 2 seconds)
• Music does not start and disc continues to
rotate for STOP
→
PLAY or automatic
selection.
(=, + buttons pressed)
(=, + buttons pressed)
• Sound is interrupted during PLAY.
Or time counter display stops progressing.
• More noise during 2-axis device operation
Gain
Focus
Symptoms
low
–
–
high
Procedure:
1. Keep the set horizontal.
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
formed due to the gravity against the 2-axis device
2. Insert the test disc (YEDS-18) and press the fl button.
3. Connect the oscilloscope BT (FEO) and TP504 (VREF) on
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)
)
(
VOLT/DIV: 100 mV
TIME/DIV: 2 mS
TIME/DIV: 2 mS
100 mV
0 V
VOLT/DIV: 100 mV
TIME/DIV: 2 mS
TIME/DIV: 2 mS
200 mV
0 V
VOLT/DIV: 100 mV
TIME/DIV: 2 mS
TIME/DIV: 2 mS
75 mV
0 V
low focus gain
high focus gain
MAIN board
BP (FEO)
TP504 (VREF)
+
–
–
oscilloscope
Adjustment Location: MAIN Board (See page 12)
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