Sony D-E707 Service Manual page 11

Focus/Tracking Gain Adjustment The waveforms are those measured with the oscilloscope set as
A servo analayzer is necessary in order to perform this adjustment shown below.
exactly. • VOLT/DIV: 500 mV
• TIME/DIV: 5 ms
However, this gain has a margin, so even if it is slightly off,
there is no problem. Therefore, do not perform this adjustment.
• Waveform when tracking gain is lowered.
Focus/tracking gain determines the optical pick-up follow-up rela- Fundamental wave appears. (large waves)
tive to mechanical noise and mechanical shock when the 2-axis
device operates. However, as these reciprocate, the adjustment is
at the point where both are satisfied.
• When gain is rased, the noise when 2-axis device operates in-
Fig. 1
crease.
• When gain is lowered, it is more susceptible to mechanical shock
and skipping occurs more easily. • Waveform when fundamental wave disappears. (no large waves)
This adjustment has to be performed upon replacing any of the
following parts.
• Optical pick-up
• RV503 (Focus gain VR)
• RV502 (Tracking gain VR) Fig. 2
Normally, be sure not to move RV503 (focus gain VR) and
• Waveform with no traverse waveform during 100 track jump.
RV502 (tracking gain VR).
(Brake application is smooth because of adjustment)
Adjustment procedure:
– Focus Gain Adjustment –
This adjustment is not performed.
If focus gain VR RV503 is turned, set to mechanical center.
Adjustment Location: MAIN Board (SUFFIX-11: See page12,
SUFFIX-12: See page 13)
– Tracking Gain Adjustment –
100 track jump waveform
(perform at normal operation)
oscilloscope
Fig. 3
(DC range)
• Waveform with traverse waveform during 100 track jump.
MAIN board
10 k Ω
(Brake application is poor because of adjustment)
TP (TE)
+
TP520 (VC) –
SUFFIX-11: See page 12 0.0022 µ F
SUFFIX-12: See page 13
1. Place the optical pick-up level, horizontally. (If the optical
pick-up is not level, the 2-axis device will be weighted and
adjustment cannot be done)
2. Connect the oscilloscope to TP (TE) and TP520 (VC) on the
MAIN board.
3. Set the disc (YEDS-18) and press the ^ key.
4. Turn RV502 slightly clockwise (tracking gain drops) and ob- 100 track jump
waveform traverse waveform
tain a waveform with a fundamental wave (waveform has large
Fig. 4
waves) as in Figure 1.
5. Turn RV502 slowly counterclockwise (tracking gain rises) until
the fundamental wave disappears (no large waves) as in Fig- Adjustment Location: MAIN Board (SUFFIX-11: See page12,
ure 2. SUFFIX-12: See page 13)
6. Set RV502 to the position about 30˚ counterclockwise form
the position obtained in step 5. If RV502 contact point is more
than 90˚ counterclockwise from mechanical center, tracking
gain is too high. In this case, readjust from step 4.
7. Press + or = key and observe the 100 track jump wave-
form. Check that no traverse waveform appears for both +
or = directions. (See Figures 3 and 4)
It is acceptable if the traverse waveform appears only now and
then, but if it appears constantly, raise tracking gain slightly
and check step 7 again.
8. Check that there is not abnormal amount of operation noise
(white noise) from the 2-axis device. If there is, tracking gain
is too high, readjust starting with step 4.
– 11 –
Adjustment and Checking Location:
– MAIN BOARD (Side A) – (SUFFIX-11)
––– 0 V
––– 0 V
––– 0 V
TP522
(RFO)
TP401
(VCC)
––– 0 V
RV503
Focus Gain
Adjustment
TP520
(VC) TP
(TE)
RV502
Tracking Gain
Adjustment
– 12 –
– MAIN BOARD (Side A) – (SUFFIX-12)
TP522
(RFO)
TP401
(VCC)
RV401
(VCC)
RV503
Focus Gain
Adjustment
TP520
TP
(VC)
(TE)
RV502
Tracking Gain
Adjustment
– 13 –
RV401
(VCC)
D-E707/E775