Sony D-E451 Primary Service Manual Download

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– 9 –

1. Place the optical pick-up level, horizontally. (If the optical pick-

up is not level, the 2-axis device will be weighted and adjust-
ment cannot be done.)

2. Connect the oscilloscope between TP514 (TEO) and TP533 (VC)

on the MAIN board.

3. Set the disc (YEDS-18) and Press the

(

) key.

4. Turn RV502 slightly clockwise (tracking gain drops) and obtain

a waveform with a fundamental wave (waveform has large
waves) as in Figure 5-1 .

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

the fundamental wave disappears (no large waves) as in Figure
5-2.

6. Set RV502 to the position about 30 °counterclockwise from 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

keys and observe the 100 track jump

waveform. Check that no traverse waveform appears for both

(

) or

directions. (See Figures 5-3 and 5-4.) 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 no 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 : 50mV
• TIME/DIV : 5mS
• Waveform when tracking gain lowered.

Fundamental wave appears (large waves).

Fig. 5-1

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

Fig. 5-2

• Waveform when no traverse waveform during 100 track jump.

(Brake application is smooth because of adjustment.)

Fig. 5-3

• Waveform when no traverse waveform during 100 track jump.

(Brake application is poor because of adjustment.)

Fig. 5-4

100 track jump waveform

100 track jump
waveform

traverse waveform

Focus/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 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 2-axis device operates in-

creases.

• 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 fol-
lowing parts :
• Optical pick-up
• RV503 (Focus gain)
• RV502 (Tracking gain)

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

– Focus Gain Adjustment –
Procedure :
This adjustment is not performed. If focus gain RV503 is turned,
set to mechanical center.

– Tracking Gain Adjustment –
(perform at normal operation)

[MAIN BOARD] (Side B)

32 30

TP102

TP202

TP302