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D-E808/E885

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Focus/Tracking Gain Adjustment

A servo analayzer 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 optical pick-up follow-up rela-
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-

crease.

• When gain is lowered, it is more susceptible to mechanical shock

and skipping occurs more easily.

This adjustment has to be performed upon replacing any of the
following parts.
• Optical pick-up
• RV503 (Focus gain VR)
• RV502 (Tracking gain VR)

Normally, be sure not to move RV503 (focus gain VR) and
RV502 (tracking gain VR).

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 page 12,

SUFFIX-12: See page 13)

– Tracking Gain Adjustment –

(perform at normal operation)

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-

tain a waveform with a fundamental wave (waveform has large
waves) as in Figure 1.

5. Turn RV502 slowly counterclockwise (tracking gain rises) until

the fundamental wave disappears (no large waves) as in Fig-
ure 2.

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

key and observe the 100 track jump wave-

form. Check that no traverse waveform appears for both

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.

The waveforms are those measured with the oscilloscope set as
shown below.
• VOLT/DIV: 500 mV
• TIME/DIV: 5 ms

• Waveform when tracking gain is lowered.

Fundamental wave appears. (large waves)

Fig. 1

• Waveform when fundamental wave disappears. (no large waves)

Fig. 2

• Waveform with no traverse waveform during 100 track jump.

(Brake application is smooth because of adjustment)

Fig. 3

• Waveform with traverse waveform during 100 track jump.