Electrical Adjustments - Sony D-E551 Service Manual

SECTION 5
Q Q

ELECTRICAL ADJUSTMENTS

7
3
Precautions for Adjustment Focus bias Check
1. Before beginning adjustment, set the equipment to service Condition:
mode. • Hold the set in horizontal state.
After the completion of adjustment, be sure to reset the ser-
vice mode. Check Procedure:
For more information, see "Service Mode (service program) " oscilloscope
(AC range)
on page 8.
2. Perform adjustments in the order given.
MAIN board
3. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise 2 k Ω
TP522 (RFO)
indicated.
TP520 (VC)
4. Power supply voltage requirement: DC2.5 V in battery termi-
nal (See page 11)
VOLUME knob : Minimum
RESUME switch : OFF 1. Set the equipment to service mode stop state. (See page 8)
ESP switch : OFF 2. Connect the oscilloscope to the test point TP522 (RFO) on the
AVLS switch : NORMAL MAIN board.
HOLD switch : OFF 3. Move the optical pick-up to the center by pressing the +
and = keys.
Before Beginning Adjustment 4. Put the disc. (YEDS-18)
5. Press the ^ key.
Set the equipment to service mode (See page 8) and check the
following. If there is an error, repair the equipment. From focus searching, focus is turned ON while entering
CLV drawing-in mode. Tracking and sled are turned OFF.
• Checking of the sled motor 6. Press the PLAY MODE key. (Both tracking and sled are turned
1. Open the upper panel. ON)
2. Press the + and = keys and check that the optical pick- 7. Check the oscilloscope waveform is as shown below.
up can move smoothly without sluggishness or abnormal noise A good eye pattern means that the diamond shape (≈) in the
in innermost periphery n outermost periphery n innermost center of the waveform can be clearly distinguished.
periphery
+ : The optical pick-up moves outwardly. RF Signal Reference Waveform (Eye Pattern)
= : The optical pick-up moves inwardly.
VOLT/DIV : 200 mV (With the 10:1 probe in use)
T E
• Checking of focus searching L TIME/DIV : 500 ns 1 3 9
1. Open the upper panel.
2. Press the ^ key. (Focus searching operation is activated con-
tinuously)
3. Check the object lens of the optical pick-up for smooth up/
down motion without sluggishness or abnormal noise.
4. Press the p key.
Check that focus searching operation is deactivated. If not,
again press the p key slightly longer.
To watch the eye pattern, set the oscilloscope to AC range and
VCC Adjustment
increase the vertical sensitivity of the oscilloscope for easy watch-
Adjustment Procedure:
ing.
digital voltmeter
(DC range)
8. Stop revolving of the disc motor by pressing the p key.
MAIN board
9. After the completion of adjustment, reset service mode. (See
page 8)
TP401 (VCC) +
–
(See page 11)
Check Location: MAIN Board (See page 11)
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 2.77 V.
Specifications: 2.75 V to 2.8 V
4. After the completion of adjustment, reset service mode. (See
page 8)
Adjustment Location: MAIN Board (See page 11)
w w w
– 9 –
1 5 1
6 3
Focus/Tracking Gain Adjustment The waveforms are those measured with the oscilloscope set as
A servo analayzer is necessary in order to perform this adjustment shown below.
exactly. • VOLT/DIV: 500 mV
• TIME/DIV: 5 ms
However, this gain has a margin, so even if it is slightly off,
there is no problem. Therefore, do not perform this adjustment.
• Waveform when tracking gain is lowered.
Focus/tracking gain determines the optical pick-up follow-up rela- Fundamental wave appears. (large waves)
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. • Waveform when fundamental wave disappears. (no large waves)
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
• Waveform with no traverse waveform during 100 track jump.
RV502 (tracking gain VR).
(Brake application is smooth because of adjustment)
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)
100 track jump waveform
4 2 2 9 6 5 1 3
oscilloscope
(DC range)
• Waveform with traverse waveform during 100 track jump.
MAIN board
10 k Ω (Brake application is poor because of adjustment)
RF level
TP (TE) +
0.8 to 1.2 Vp-p
TP520 (VC) –
0.0022 µ F
(See page 11)
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 100 track jump
waveform
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. Adjustment Location: MAIN Board (See page 11)
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 + or = key and observe the 100 track jump wave-
form. Check that no traverse waveform appears for both +
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
x a o
and check step 7 again.
y
8. Check that there is not abnormal amount of operation noise
. (white noise) from the 2-axis device. If there is, tracking gain i
is too high, readjust starting with step 4.
– 10 –
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5
0
Adjustment and Checking Location:
– MAIN BOARD (Side A) –
––– 0 V
Fig. 1
––– 0 V
Fig. 2
––– 0 V
Q Q TP522
3 7 6 3
(RFO)
Fig. 3
––– 0 V
traverse waveform
Fig. 4
RV503
Focus Gain
Adjustment
TP520
(VC) TP
(TE)
RV502
Tracking Gain
Adjustment
u 1 6 3
.
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2 4
8 9 9
1 5 1 5 0 8 9 2
TP401
(VCC)
RV401
(VCC)
m
c o
– 11 –
D-E551/E555/E556CK
2
8 9 9
4 9 8 2 9 9