SECTION 5
ELECTRICAL ADJUSTMENTS
Precautions for AdjustmentFocus bias CheckFocus/Tracking Gain AdjustmentThe waveforms are those measured with the oscilloscope set asAdjustment and Checking Location:
1. Before beginning adjustment, set the equipment to serCondition: viceA servo analayzer is necessary in order to perforshom this adjustmentwn below.
mode.Y Hold the set in horizontal state.exactly.Y VOLT/DIV: 500 mV� MAIN BOARD (Side A) �
After the completion of adjustment, be sure to reset the ser-Y TIME/DIV: 5 ms
However, this gain has a margin, so even if it is slightly off,
vice mode.Check Procedure:
there is no problem. Therefore, do not perform this adjustment.
For more information, see OService Mode (service program) �Y Waveform when tracking gain is lowered.
oscilloscope
on page 8.(AC range)Focus/tracking gain determines the optical pick-up folloFundamental ww-up rela-ave appears. (large waves)
2. Perform adjustments in the order given.tive to mechanical noise and mechanical shock when the 2-axis
MAIN board
3. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwisedevice operates. However, as these reciprocate, the adjustment is
2 k W
��� 0 V
indicated.TP522 (RFO)+at the point where both are satisfied.
4. Power supply voltage requirement: DC2.5 V in battery terTP520 (VC)mi-�Y When gain is rased, the noise when 2-axis device operates in-
nalcrease.Fig. 1
(See page 11)
VOLUME knob : MinimumY When gain is lowered, it is more susceptible to mechanical shock
RESUME switch : OFFand skipping occurs more easily.Y Waveform when fundamental wave disappears. (no large waves)
ESP switch: OFF1. Set the equipment to service mode stop state. (See page 8)This adjustment has to be performed upon replacing any of the
AVLS switch: NORMAL2. Connect the oscilloscope to the test point TP522 (RFO) on thefollowing parts.
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HOLD switch: OFFMAIN board.Y Optical pick-up
3. Move the optical pick-up to the center by pressing the +Y RV503 (Focus gain VR)
Before Beginning Adjustmentand = keys.Y RV502 (Tracking gain VR)Fig. 2
Set the equipment to service mode (See page 8) and check the4. Put the disc. (YEDS-18)
Normally, be sure not to move RV503 (focus gain VR) and
following. If there is an error, repair the equipment.5. Press the ^ key.Y Waveform with no traverse waveform during 100 track jump.
RV502 (tracking gain VR).
From focus searching, focus is turned ON while entering(Brake application is smooth because of adjustment)
Y Checking of the sled motorCLV drawing-in mode. Tracking and sled are turned OFF.
1. Open the upper panel.6. Press the PLAY MODE key. (Both tracking and sled are turnedAdjustment procedure:
2. Press the + and = keys and check that the optical pick-ON)� Focus Gain Adjustment �
up can move smoothly without sluggishness or abnor7. Checmal noisek the oscilloscope waveform is as shown beloThis adjustment is not performed.w.��� 0 V
in innermost periphery n outermost periphery n innermostA good eye pattern means that the diamond shape (A) in theIf focus gain VR RV503 is turned, set to mechanical center.
peripherycenter of the waveform can be clearly distinguished.
+ : The optical pick-up moves outwardly.Adjustment Location:MAIN Board (See page 11)
= : The optical pick-up moves inwardly.RF Signal Reference Waveform (Eye Pattern)
TP522
� Tracking Gain Adjustment �(RFO)
100 track jump waveformTP401
Y Checking of focus searching VOLT/DIV : 200 mV (With the 10:1 probe in use) (perform at normal operation)
(VCC)
1. Open the upper panel. TIME/DIV : 500 nsFig. 3
2. Press the ^ key. (Focus searching operation is activated con-oscilloscope
tinuously)(DC range)Y Waveform with traverse waveform during 100 track jump.
3. Check the object lens of the optical pick-up for smooth up/(Brake application is poor because of adjustment)
RV401
MAIN board
down motion without sluggishness or abnormal noise.VCC
10 k W
4. Press the p key.RF levelTP (TE)+Adjustment
Check that focus searching operation is deactivated. If not,0.8 to 1.2 Vp-pTP520 (VC)�
again press the p key slightly longer.0.0022 ?F
(See page 11)��� 0 V
VCC Adjustment
Adjustment Procedure:1. Place the optical pick-up level, horizontally. (If the optical
To watch the eye pattern, set the oscilloscope to AC range and
digital voltmeterpick-up is not level, the 2-axis device will be weighted and
increase the vertical sensitivity of the oscilloscope for easy watch-
(DC range)adjustment cannot be done)
ing.
MAIN board2. Connect the oscilloscope to TP (TE) and TP520 (VC) on the
MAIN board.
8. Stop revolving of the disc motor by pressing the p key.
TP401 (VCC)+3. Set the disc (YEDS-18) and press the ^ key.100 track jump
9. After the completion of adjustment, reset service mode. (See
�waveformtraverse waveform
4. Turn RV502 slightly clockwise (tracking gain drops) and ob-
(See page 11)page 8)
RV503
tain a waveform with a fundamental wave (waveform has largeFig. 4
Focus Gain
waves) as in Figure 1.
Checking Location:MAIN Board (See page 11)Adjustment
1. Set the equipment to service mode stop state. (See page 8)5. Turn RV502 slowly counterclockwise (tracking gain rises) untilAdjustment Location:MAIN Board (See page 11)
2. Connect the digital voltmeter to TP401 (VCC) on the MAINthe fundamental wave disappears (no large waves) as in Fig-TP520
board.ure 2.(VC)RV502
TP
3. Adjust RV401 on the MAIN board so that the reading on digi-6. Set RV502 to the position about 30u counterclockwise formTracking Gain
(TE)
tal voltmeter goes 2.77 V.the position obtained in step 5. If RV502 contact point is moreAdjustment
Specifications: 2.75 V to 2.8 Vthan 90u counterclockwise from mechanical center, tracking
4. After the completion of adjustment, reset service mode. (Seegain is too high. In this case, readjust from step 4.
page 8)7. Press + or = key and observe the 100 track jump wave-
form. Check that no traverse waveform a+ppears for both
Adjustment Location:MAIN Board (See page 11)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.
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ACEC
