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SECTION 5

ELECTRICAL ADJUSTMENTS

Precautions for Adjustment

1. Before beginning adjustment, set the equipment to service

mode.
After the completion of adjustment, be sure to reset the ser-
vice mode.
For more information, see “Service Mode (service program) ”
on page 8.

2. Perform adjustments in the order given.
3. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise

indicated.

4. Power supply voltage requirement: DC2.5 V in battery termi-

nal
VOLUME knob : Minimum
RESUME switch : OFF
ESP switch

: OFF

AVLS switch

: NORMAL

HOLD switch

: OFF

Before Beginning Adjustment

Set the equipment to service mode (See page 8) and check the
following. If there is an error, repair the equipment.

• Checking of the sled motor

1. Open the upper panel.
2. Press the

and

keys and check that the optical pick-

up can move smoothly without sluggishness or abnormal noise
in innermost periphery

outermost periphery

innermost

periphery

: The optical pick-up moves outwardly.

: The optical pick-up moves inwardly.

• Checking of focus searching

1. Open the upper panel.
2. Press the

key. (Focus searching operation is activated

continuously)

3. Check the object lens of the optical pick-up for smooth up/

down motion without sluggishness or abnormal noise.

4. Press the

key.

Check that focus searching operation is deactivated. If not,
again press the

key slightly longer.

VCC Adjustment

Adjustment Procedure:

1. Set the equipment to service mode stop state. (See page 8)
2. Connect the digital voltmeter to TP401 (VCC) on the MAIN

board.

3. Adjust RV401 on the MAIN board so that the reading on digi-

tal voltmeter goes 2.53 V.
Specifications: 2.5 V to 2.55 V

4. After the completion of adjustment, reset service mode. (See

page 8)

Adjustment Location: MAIN Board (See page 11)

Focus bias Check

Condition:
• Hold the set in horizontal state.

Check Procedure:

1. Set the equipment to service mode stop state. (See page 8)
2. Connect the oscilloscope to the test point TP522 (RFO) on the

MAIN board.

3. Move the optical pick-up to the center by pressing the

and

keys.

4. Put the disc. (YEDS-18)
5. Press the

key.

From focus searching, focus is turned ON while entering
CLV drawing-in mode. Tracking and sled are turned OFF.

6. Press the PLAY MODE key. (Both tracking and sled are turned

ON)

7. Check the oscilloscope waveform is as shown below.

A good eye pattern means that the diamond shape (

≈

) in the

center of the waveform can be clearly distinguished.

RF Signal Reference Waveform (Eye Pattern)

VOLT/DIV : 200 mV (With the 10:1 probe in use)
TIME/DIV : 500 ns

To watch the eye pattern, set the oscilloscope to AC range and
increase the vertical sensitivity of the oscilloscope for easy watch-
ing.

8. Stop revolving of the disc motor by pressing the

key.

9. After the completion of adjustment, reset service mode.

(See page 8)

Checking Location: MAIN Board (See page 11)

digital voltmeter

(DC range)

MAIN board

TP401 (VCC)

+
–

(See page 11)

oscilloscope

(AC range)

+
–

MAIN board

TP522 (RFO)
TP520 (VC)

2 k

Ω

(See page 11)

RF level
0.8 to 1.2 Vp-p

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 (See page 11)

– 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.