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 serviceCondition:A servo analayzer is necessary in order to perform this adjustmentshown below.� MAIN Board (Side A) �
mode.Y Hold the set in horizontal state.exactly.Y VOLT/DIV: 500 mV
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 follow-up rela-Fundamental wave 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
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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-
nal(See page 11)crease.Fig. 1
VOLUME knob : MinimumY When gain is lowered, it is more susceptible to mechanical shock
RESUME switch : OFF1. Set the equipment to service mode stop state. (See page 8)and skipping occurs more easily.Y Waveform when fundamental wave disappears. (no large waves)
ESP switch: OFF2. Connect the oscilloscope to the test point TP522 (RFO) on theThis adjustment has to be performed upon replacing any of the
AVLS switch: NORMALMAIN board.following parts.
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HOLD switch: OFF3. Move the optical pick-up to the center by pressing the +Y Optical pick-up
and = keys.Y RV503 (Focus gain VR)
Before Beginning Adjustment4. Put the disc. (YEDS-18)Y RV502 (Tracking gain VR)Fig. 2
Set the equipment to service mode (See page 8) and check the5. Press the ^ key.
Normally, be sure not to move RV503 (focus gain VR) and
following. If there is an error, repair the equipment.From focus searching, focus is turned ON while enteringY Waveform with no traverse waveform during 100 track jump.
RV502 (tracking gain VR).
CLV drawing-in mode. Tracking and sled are turned OFF.(Brake application is smooth because of adjustment)
Y Checking of the sled motor6. Press the PLAY MODE key. (Both tracking and sled are turned
1. Open the upper panel.ON)Adjustment procedure:
2. Press the + and = keys and check that the optical pick-7. Check the oscilloscope waveform is as shown belo� Focus Gain Adjustment �w.
up can move smoothly without sluggishness or abnormal noiseA good eye pattern means that the diamond shape (A) in theThis adjustment is not performed.��� 0 V
in innermost periphery n outermost periphery n innermostcenter of the waveform can be clearly distinguished.If focus gain VR RV503 is turned, set to mechanical center.
peripheryAdjustment Location:MAIN Board (See page 11)
+: The optical pick-up moves outwardly.RF Signal Reference Waveform (Eye Pattern)TP522
(RFO)
=: The optical pick-up moves inwardly.� Tracking Gain Adjustment �
TP401
VOLT/DIV : 200 mV (With the 10:1 probe in use) (perform at normal operation)
100 track jump waveform(VCC)
Y Checking of focus searching TIME/DIV : 500 ns
oscilloscope
1. Open the upper panel.Fig. 3
(DC range)
2. Press the ^ key. (Focus searching operation is activated
continuously)Y Waveform with traverse waveform during 100 track jump.RV401
MAIN board
3. Check the object lens of the optical pick-up for smooth up/10 k W(Brake application is poor because of adjustment)VCC
TP (TE)+
down motion without sluggishness or abnormal noise.RF levelAdjustment
0.8 to 1.2 Vp-pTP520 (VC)�
4. Press the p key.
(See page 11)
0.0022 ?F
Check that focus searching operation is deactivated. If not,
again press the p key slightly longer.
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1. Place the optical pick-up level, horizontally. (If the optical
To watch the eye pattern, set the oscilloscope to AC range and
VCC Adjustmentpick-up is not level, the 2-axis device will be weighted and
increase the vertical sensitivity of the oscilloscope for easy watch-
Adjustment Procedure:adjustment cannot be done)
ing.
digital voltmeter2. Connect the oscilloscope to TP (TE) and TP520 (VC) on the
(DC range)MAIN board.
8. Stop revolving of the disc motor bp keyy pressing the .
MAIN board9. After the completion of adjustment, reset service mode.3. Set the disc (YEDS-18) and pr^ keess the y.
4. Turn RV502 slightly clockwise (tracking gain drops) and ob-
(See page 8)
TP401 (VCC)+tain a waveform with a fundamental wave (wavefor100 track jumpm has largeRV503
(See page 11)�waveformtraverse waveformFocus Gain
waves) as in Figure 1.
Checking Location:MAIN Board (See page 11)
Adjustment
5. Turn RV502 slowly counterclockwise (tracking gain rises) untilFig. 4
TP520
1. Set the equipment to service mode stop state. (See page 8)the fundamental wave disappears (no large waves) as in Fig-TP
(VC)
2. Connect the digital voltmeter to TP401 (VCC) on the MAINure 2.Adjustment Location:MAIN Board (See page 11)(TE)
RV502
board.6. Set RV502 to the position about 30u counterclockwise form
Tracking Gain
3. Adjust RV401 on the MAIN board so that the reading on digi-the position obtained in step 5. If RV502 contact point is more
Adjustment
tal voltmeter goes 2.53 V.than 90u counterclockwise from mechanical center, tracking
Specifications: 2.5 V to 2.55 Vgain is too high. In this case, readjust from step 4.
4. After the completion of adjustment, reset service mode. (See7. Press + or = key and observe the 100 track jump wave-
page 8)form. Check that no traverse waveform appears for both +
or = directions. (See Figures 3 and 4)
Adjustment Location:MAIN Board (See page 11)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.
� 9 �� 10 �� 11 � |
ACEC
SONY
